阅读说明：本技术 用于进行神经刺激以减轻膀胱功能障碍和其他适应症的可植入引线附着结构 (Implantable lead attachment structures for neurostimulation to alleviate bladder dysfunction and other indications ) 是由 H·李 A·胡 于 2015-08-14 设计创作，主要内容包括：本文中提供了用于将神经刺激系统的植入式引线附着在患者体内的目标位置处的锚定设备和方法。这种锚定设备包括螺旋主体,所述螺旋主体具有当被展开时从所述引线横向地向外延伸的多个尖齿,所述多个尖齿与组织接合以便抑制所述植入式引线的轴向运动。所述多个尖齿被偏置朝向所述横向延伸的展开构型并且朝向所述引线向内折叠成递送构型以便促进通过护套来递送所述引线。所述尖齿可以在近端方向上或者在近端方向和远端方向两者上成一定角度并且可以包括用于辅助对所述引线的可视化和递送的各种特征。所述锚定件可以根据各种方法形成,包括对管状区段的激光切割连同用于将材料与所述锚定件一起定形为所述展开构型的加热和回流、以及注塑成型。(Anchoring devices and methods for attaching an implantable lead of a neurostimulation system at a target location within a patient's body are provided herein. Such an anchoring device includes a helical body having a plurality of tines that extend laterally outward from the lead when deployed, the plurality of tines engaging tissue to inhibit axial movement of the implantable lead. The plurality of tines are biased toward the laterally extending deployed configuration and fold inward toward the lead into a delivery configuration to facilitate delivery of the lead through a sheath. The tines may be angled in the proximal direction or in both the proximal and distal directions and may include various features to aid in visualization and delivery of the lead. The anchor may be formed according to various methods, including laser cutting of the tubular section along with heating and reflow to shape the material with the anchor into the deployed configuration, and injection molding.)

1. A neurostimulation lead, comprising:

an implantable lead having a plurality of conductors disposed within a lead body, the plurality of conductors extending from a proximal end of the lead to a plurality of neurostimulation electrodes disposed at or near a distal end of the lead, each conductor of the plurality corresponding to a respective neurostimulation electrode of the plurality; and

a single anchor coupled with the lead body and configured to anchor the implantable lead within a body of a patient, wherein the lead includes only the single anchor, the anchor comprising:

a helical body extending helically along a longitudinal axis outside the lead body and arranged along a recessed portion of the lead body, an

A plurality of tines extending from the helical body, wherein each tine of the plurality of tines is biased toward an expanded configuration, wherein in the expanded configuration the plurality of tines extend laterally away from the longitudinal axis and the plurality of tines are resiliently deflectable toward a delivery configuration in which the plurality of tines are folded inward toward the longitudinal axis to facilitate delivery of the neurostimulation lead during implantation,

wherein the recessed portion, the helical body, and the plurality of tines are sized to facilitate fine-tune placement of the lead during delivery and deployment.

2. The neurostimulation lead of claim 1, wherein the anchor is configured such that: in the delivery configuration, each tine of the plurality of tines folds against the lead body.

3. The neurostimulation lead of claim 1, wherein the anchor is sized such that: in the delivery configuration, the anchor has a cross-sectional profile compatible with a sheath having a diameter of 5Fr or greater.

4. The neurostimulation lead of claim 1, wherein the helical body and the plurality of tines are integrally formed.

5. A neurostimulation lead as in claim 1, wherein the anchor is formed of a material having sufficient rigidity such that, when the anchor is implanted at the target location within the tissue of the patient, engagement of the tissue with the plurality of tines inhibits axial movement of the lead.

6. The neurostimulation lead of claim 5, wherein the anchor is molded from a polyurethane-based material having a Shore hardness ranging from 50A to 80D.

7. The neurostimulation lead of claim 1, wherein the anchor is sized such that: the helical body extends along a distal portion of the lead body for a length ranging from 10mm to 30mm when the helical body is coupled to the lead body.

8. The neurostimulation lead of claim 1, wherein the anchor is disposed entirely proximal of the plurality of neurostimulation electrodes.

9. A neurostimulation lead, comprising:

an implantable lead having a lead body and one or more neurostimulation electrodes disposed at or near a distal end of the lead; and

a single anchor coupled to the lead body, wherein the anchor is formed as a single unitary component and is configured to anchor the implantable lead within a body of a patient, the anchor comprising:

a helical body wound around a portion of the lead body along a longitudinal axis of the lead body and disposed entirely within a recessed portion of the lead body, an

A plurality of tines extending from the helical body, wherein each tine of the plurality of tines extends laterally outward and is resiliently deflectable to allow a reduced profile delivery configuration when constrained by a sheath to facilitate delivery of the neurostimulation lead during implantation,

wherein the recessed portion, the helical body, and the plurality of tines are sized to facilitate fine-tune placement of the lead during delivery and deployment.

10. A neurostimulation lead, comprising:

an implantable lead having a lead body and at least four neurostimulation electrodes disposed at or near a distal end of the lead; and

an anchor coupled with the lead body and configured to anchor the lead within a body of a patient so as to maintain the at least four neurostimulation electrodes at or near a target tissue location, the anchor comprising:

a helical body attached to the lead body along a recessed portion of the lead body and extending helically along a longitudinal axis thereof, an

A plurality of tines extending from the helical body, wherein, when in a deployed configuration, each tine of the plurality of tines extends laterally away from a longitudinal axis of the helical body to facilitate anchoring of the lead, and wherein each tine of the plurality of tines is deflectable inward toward the lead body in a constrained configuration to allow for a reduced delivery profile to facilitate implantation of the lead

Wherein the anchor is sized such that an outer surface of the helical body is substantially flush with an outer surface of the lead body outside of the recessed portion to improve ease and accuracy of delivery and positioning during deployment to facilitate fine-tuning lead placement.

Technical Field

The present invention relates to neurostimulation therapy systems and associated devices; and methods of treatment, implantation and deployment of such treatment systems.

Background

In recent years, the use of implantable neurostimulation systems for treatment has become increasingly popular. While such systems have shown promise in treating many conditions, the effectiveness of the treatment can vary significantly from patient to patient. Many factors may cause patients to experience very different therapeutic effects and it may be difficult to determine the feasibility of the treatment prior to implantation. For example, stimulation systems typically utilize an electrode array to treat one or more target neural structures. The electrodes are typically mounted together on a multi-electrode lead, and the lead is implanted in the patient's tissue at a location intended to cause electrical coupling of the electrode with the target neural structure, at least a portion of the coupling typically being provided via intervening tissue. Other means may also be employed, such as one or more electrodes attached to the skin overlying the target neural structure, implanted in a cuff surrounding the target nerve, and so forth. In any event, the physician will typically attempt to establish an appropriate treatment regime by varying the electrical stimulation applied to the electrodes.

Current stimulation electrode placement/implantation techniques and well-known therapy placement techniques have significant drawbacks. The neural tissue structures of different patients can vary widely, and accurately predicting or identifying the location and branches of nerves that perform particular functions and/or weaken particular organs is a challenge. The electrical characteristics of the tissue structures surrounding the target neural structure may also vary widely among patients, and the neural response to stimulation may differ significantly with the electrical stimulation pulse pattern, pulse width, frequency, and/or amplitude effectively affecting one patient's bodily functions and potentially applying significant discomfort or pain to another patient or having limited effect on the other patient. Even in patients who provide effective treatment for implantation of a neurostimulation system, frequent adjustments and changes to the stimulation protocol are often required before an appropriate treatment procedure can be determined, often involving repeated visits and significant discomfort to the patient before an effect is achieved. While many complex and sophisticated lead structures and stimulation setup schemes have been implemented in an attempt to overcome these challenges, the variability of lead placement results, clinician time to establish an appropriate stimulation signal, and discomfort (and in some cases, significant pain) applied to the patient remain less than ideal. Moreover, the lifetime and battery life of such devices are relatively short, allowing for routine replacement of implanted systems every few years, which requires additional surgery, patient discomfort, and significant expense of medical systems.

Furthermore, because the morphology of neural structures varies significantly between patients, it can be difficult to control the placement and alignment of the neurostimulation leads relative to the target neural structure, which can lead to inconsistent placement, unpredictable results, and very different patient outcomes. For these reasons, neurostimulation leads typically include a plurality of electrodes, such that at least one electrode or a pair of electrodes will be disposed in a location suitable for delivering neurostimulation. One drawback of this approach is that repeated visits may be required to determine the appropriate electrodes to use and/or the neural stimulation procedure to achieve delivery of an effective therapy. In general, the number of available neurostimulation procedures may be limited by imprecise lead placement.

The great benefits of these neurostimulation treatments have not yet been fully realized. Accordingly, it is desirable to provide improved neurostimulation methods, systems, and devices, as well as methods for implanting such neurostimulation systems for the particular patient or condition being treated. It would be particularly helpful to provide such systems and methods in order to improve the ease of use of physicians in positioning and attaching such leads in order to ensure that proper lead placement is maintained after implantation, thereby providing consistent and predictable results after delivery of neurostimulation therapy. Accordingly, it is desirable to provide methods and devices for implanting neurostimulation leads that improve anchoring of the lead during implantation and allow for a reduced lead delivery profile.

Disclosure of Invention

The present application relates to implantable neurostimulation systems, and in particular to devices and methods for anchoring implanted neurostimulation leads. In one aspect, the invention includes an anchoring body extending helically around a lead and a plurality of tines arranged along the anchoring body. The plurality of tines are biased toward a deployed position in which the tines extend laterally outward from the helical body to sufficiently engage tissue to inhibit axial displacement of the implantable lead. The tines are configured to be resiliently deflectable toward the helical body during implantation to fold inwardly toward the helical anchoring body when constrained by the delivery sheath to facilitate delivery to a target location during implantation.

In one aspect, a neurostimulation system according to aspects of the invention includes an implantable lead having one or more conductors disposed within a lead body, the one or more conductors extending from a proximal end of the lead to one or more neurostimulation electrodes disposed at or near a distal end of the lead; a pulse generator coupleable to the proximal end of the implantable lead, the pulse generator being electrically coupled with the one or more neural stimulation electrodes when the pulse generator is coupled to the implantable lead, the pulse generator configured to generate a plurality of electrical pulses when implanted at a target location for delivering neural stimulation therapy to a patient through the one or more neural stimulation electrodes; and an anchor coupled to the lead body just proximal to the electrode.

In one aspect, the anchor includes a helical body extending helically along its longitudinal axis outside the lead body and a plurality of tines extending transversely away from the helical body. Each tine of the plurality of tines is biased toward a deployed configuration and a delivery configuration. In the deployed configuration, the plurality of tines extend laterally away from the longitudinal axis (when the helical body is disposed thereon), and in the delivery configuration, the plurality of tines are folded inwardly toward the longitudinal axis of the lead body to facilitate delivery of the neurostimulation lead during implantation. In certain embodiments, the anchor is configured such that in a delivery configuration, in which the anchor has a cross-sectional profile compatible with a sheath having a diameter of 5fr (french) or greater, each of the plurality of tines is folded against the lead body to further reduce the delivery profile. In some embodiments, the helical body and the plurality of tines are integrally formed of the same material, while in other embodiments, the tines may be separate elements attached to the helical body. The tines are formed of a material having sufficient rigidity such that when the tines are implanted at the target location within the tissue of the patient, the engagement of the tissue with the plurality of tines inhibits axial movement of the lead. In some embodiments, the anchor may be molded from a polyurethane-based material having a shore hardness in a range between 50A and 80D. In other embodiments, the anchor may be formed from a metal such as a shape memory alloy. In still other embodiments, the anchor may be formed from a combination of materials such as polymer-based materials and metals (e.g., shape memory alloy wires).

In certain embodiments, the anchor is sized such that the helical body extends a length of between 10mm and 30mm, preferably about 20mm, along the lead body when the helical body is coupled to the lead body. Each tine of the plurality of tines may extend laterally outward from the longitudinal axis a distance of between 1mm and 4 mm. Each tine of the plurality of tines may have a length between 1.5mm and 3mm and a width between 0.5mm and 2.0 mm. In some embodiments, the plurality of tines includes tines having varying lengths, widths, and angles in the proximal direction, while in other embodiments, the plurality of tines may have different lengths or may be angled in both the proximal and distal directions. The plurality of tines may have a substantially rectangular tag shape and may include rounded or chamfered corners and/or edges to inhibit tissue damage at the corners and/or edges. In some embodiments, the tines are biased toward an angle of between 30 and 80 degrees from the longitudinal axis in the deployed configuration.

In one aspect, the helical body is attached to an anchor portion of the lead body having a recessed portion with a reduced profile to further reduce the cross-section, e.g., to 2mm or less to accommodate a 5Fr sheath for implanting the lead. In some embodiments, the anchor includes a plurality of anchor segments that can be attached to and deployed adjacent to one another. This feature may allow a user to customize the anchor portion with respect to the length of the anchor and tine orientation, by reversing the anchor or combining different types of anchors within the anchor portion. The anchor may further include one or more additional features, including any of the following: extending a substantial length of the radiopaque element of the helical body to facilitate positioning using visualization techniques; an embedded shielding material adapted to shield heating caused by magnetic resonance; and biodegradable or drug eluting tines.

In certain embodiments, the helical body is a continuous helical flap, and the plurality of tines comprises a plurality of sections of the continuous helical flap defined by a plurality of cuts along a length of the continuous helical flap so as to allow the plurality of sections to fold inward without overlapping one another.

In other embodiments, the anchor is formed by: laser cutting a tubular section of material (e.g., a polymer or metal, such as nitinol), and setting the material by heat setting or reflow while the anchor is in the deployed configuration. In still other embodiments, the anchor may be formed by injection molding the polymeric material in a multi-piece mold assembly, which allows for further variability in the anchoring structure, such as varying thicknesses of different portions of the anchor.

Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating various embodiments, are intended for purposes of illustration only and are not intended to necessarily limit the scope of the disclosure.

Drawings

Fig. 1 schematically illustrates a neurostimulation system including a clinician programmer and patient remote for positioning and/or programming both a trial neurostimulation system and a permanently implanted neurostimulation system, in accordance with aspects of the present invention.

Fig. 2A-2C show illustrations of neural structures along the spinal column, lower back, and sacral regions that may be stimulated in accordance with aspects of the present invention.

Fig. 3A illustrates an example of a fully implantable neurostimulation system according to aspects of the present invention.

Fig. 3B shows an example of a neurostimulation system having a partially implanted stimulation lead for trial stimulation and an external pulse generator adhered to the patient's skin, in accordance with aspects of the invention.

Fig. 4 shows an example of a neurostimulation system having an implantable stimulation lead, an implantable pulse generator, and an external charging device, in accordance with aspects of the present invention.

Fig. 5A-5C show detailed views of an implantable pulse generator and associated components for a neurostimulation system, according to aspects of the present invention.

Fig. 6A-6C illustrate strain relief structures for use with a neurostimulation lead and an implantable pulse generator, according to aspects of the present invention.

Fig. 7 illustrates a neurostimulation lead having an anchor structure thereon, in accordance with aspects of the present invention.

Fig. 8 illustrates an example anchor structure, in accordance with aspects of the present invention.

Fig. 9A and 9B illustrate a neurostimulation lead having an anchor structure thereon before and after deployment, in accordance with aspects of the present invention.

Fig. 10A and 10B illustrate example anchor structures, according to aspects of the invention.

Fig. 11A and 11B illustrate example anchor structures, according to aspects of the invention.

Fig. 12A and 12B illustrate example anchor structures, according to aspects of the invention.

Fig. 13A and 13B illustrate example anchor structures, according to aspects of the invention.

Fig. 14A and 14B illustrate example anchor structures, according to aspects of the invention.

Fig. 15A-15C illustrate example anchor structures before and after deployment, and fig. 15C illustrates an end view of the deployed anchor structure, in accordance with aspects of the present invention.

Fig. 16A and 16B illustrate example anchor structures (structures shown before and after deployment) formed by laser cutting, according to aspects of the present invention.

Fig. 17A and 17B illustrate an alternative example anchor structure formed by an injection molding process, according to aspects of the present invention.

Figures 18-20 illustrate a method of forming an anchor and a method of anchoring a neurostimulation lead, according to aspects of the present invention.

Detailed Description

The present invention relates to neurostimulation therapy systems and associated devices; and methods of treatment, implantation/placement and deployment of such treatment systems. In particular embodiments, the present invention relates to sacral nerve stimulation treatment systems configured to treat Bladder dysfunction, including Overactive Bladder ("OAB"), as well as stool dysfunction and relieve symptoms associated therewith. However, it will be appreciated that the invention may also be used to treat pain or other indications, such as dyskinesias or affective disorders, as will be appreciated by those skilled in the art.

I. Neurostimulation indications

Neurostimulation therapy systems (e.g., any of the neurostimulation therapy systems described herein) can be used to treat a wide variety of diseases and associated symptoms (e.g., acute pain disorders, movement disorders, affective disorders, and bladder-related and bowel and stool disorders). Examples of pain disorders that can be treated by neural stimulation include failed lumbar surgery syndrome, reflex sympathetic dystrophy or complex regional pain syndrome, causalgia, arachnoiditis, and peripheral neuropathy. The motor sequences include muscle paralysis, tremor, dystonia, and parkinson's disease. Affective disorders include depression, obsessive compulsive disorder, cluster headache, Tourette's syndrome, and certain types of chronic pain. Bladder-related dysfunction includes, but is not limited to, OAB, urge incontinence, urgency-frequency, and urinary retention. OABs may include urge incontinence and urgency-frequency, either alone or in combination. Urge incontinence is the involuntary loss or urine (urgency) associated with a sudden, intense desire to discharge. Urgency-frequency is the frequent, often uncontrollable desire to urinate (urgency) which usually results in a very small amount of voiding (frequency). Urinary retention is the inability to empty the bladder. The neural stimulation therapy may be configured to treat a particular condition by administering neural stimulation related to sensory and/or motor control associated with the condition or associated symptoms to the target neural tissue.

In one aspect, the methods and systems described herein are particularly suitable for treating urinary and fecal dysfunction. The medical community has historically not realized these conditions and is significantly deficient in medical and drug. OAB is one of the most common urinary dysfunctions. It is a complex condition characterized by the presence of troublesome urinary symptoms, including urgency, frequency, nocturia, and urge incontinence. It is estimated that about 4 million americans have OABs. In the adult population, approximately 16% of all men and women suffer from OAB symptoms.

OAB symptoms can have a significant negative impact on the psychosocial functioning and quality of life of a patient. Persons with OAB often limit activities and/or develop coping strategies. Furthermore, OABs place a significant financial burden on individuals, their families, and medical institutions. The prevalence of comorbid disease is significantly higher in patients with OAB than in the general population. Complications may include fall fractures, urinary tract infections, skin infections, vulvovaginitis, cardiovascular disease, and central nervous system pathologies. Chronic constipation, fecal incontinence, and overlapping chronic constipation occur more frequently in patients with OAB.

Conventional treatment of OAB typically involves lifestyle changes as a first ambulatory step. Lifestyle changes include elimination of bladder irritants (e.g., caffeine) from food, management of fluid intake, weight loss, cessation of smoking, and management of bowel regularity. Behavioral modification includes altering voiding habits (e.g., bladder training and delayed voiding), training pelvic floor muscles to improve strength and control of the urethral sphincter, biofeedback, and techniques for desire suppression. The drug is considered a second line treatment for OAB. These include anticholinergic drugs (oral, transdermal patches, and gels) and oral beta 3 adrenergic agonists. However, anticholinergic drugs are often associated with troublesome systemic side effects (e.g., dry mouth, constipation, urinary retention, blurred vision, lethargy, and confusion). Studies have found that over 50% of patients discontinue the use of anticholinergic drugs within 90 days due to lack of efficacy, adverse events or cost reasons.

When these modalities are successful, the american urinary association proposed three-line treatment options include the detrusor (bladder smooth muscle) injection of Botulinum Toxin (BTX), Percutaneous Tibial Nerve Stimulation (PTNS), and sacral nerve Stimulation (SNM). BTX is provided via an intradetrusor injection under cystoscopic guidance, but repeated BTX injections are typically required every 4 to 12 months to maintain efficacy, and BTX can undesirably cause urinary retention. Many randomized controlled studies have shown some effect of BTX injection on OAB patients, but the long-term safety and efficacy of BTX on OAB is largely unknown.

PTNS therapy consists of 30 minute sessions per week (over a 12 week period), each using electrical stimulation delivered from a handheld stimulator to the sacral plexus via the tibial nerve. For patients who respond well and continue treatment, a continuous course of therapy (usually every 3 to 4 weeks) is required to maintain remission. If the patient fails to adhere to the treatment schedule, the effect may be reduced. The effects of PTNS have been demonstrated in few randomized controlled studies, however, data on PTNS effectiveness over 3 years is limited and PTNS is not recommended for patients seeking to cure Urge Urinary Incontinence (UUI) (e.g., 100% reduced incontinence events) (EAU guidelines).

Sacral nerve modulation

SNM is an established treatment that provides a safe, effective, reversible, and durable treatment option for urge incontinence, urgency-frequency, and non-obstructive urinary retention. SNM treatment involves the use of mild electrical pulses to stimulate the sacral nerve located in the lower back. Electrodes are placed beside the sacral nerve (usually at level S3) by inserting electrode leads into respective foramina of the sacrum. The electrodes are inserted subcutaneously and then attached to an Implantable Pulse Generator (IPG). The safety and efficacy of SNM on OAB treatment (including the durability of patients with urge incontinence and urgency-frequency within five years) is supported by and well documented by multiple studies. SNM is also approved for the treatment of chronic fecal incontinence in human patients who have failed or are not more conservative treatments.

A. Implantation of the sacral nerve modulation System

Currently, SNM qualification is in the experimental phase and, if successful, is followed by permanent implantation. The experimental phase is a test stimulation period during which the patient is allowed to assess whether the treatment is effective. Generally, there are two techniques for performing test stimuli. The first technique is a consulting room-based procedure known as transcutaneous nerve evaluation (PNE), and the other technique is a staging test.

In PNE, a foramen needle is typically first used to identify the optimal stimulation location (typically at level S3) and to assess the integrity of the sacral nerve. As described in table 1 below, motor responses and sensory responses were used to verify proper needle placement. A temporary stimulation lead (monopolar electrode) is then placed near the locally anesthetized sacral nerve. This process can be performed in a consulting room setting without the need for fluoroscopy. The temporary lead is then connected to an External Pulse Generator (EPG) that is taped to the patient's skin during the testing phase. The stimulation level may be adjusted to provide an optimal level of comfort to a particular patient. The patient will monitor his or her voiding for 3 to 7 days in order to see if there is any improvement in symptoms. The advantages of PNE are: it is an incisionless procedure that can be performed in a physician's office using local anesthesia. The disadvantages are that: temporary leads are not firmly anchored in place and have a tendency to migrate away from the nerve through physical activity and thereby cause treatment failure. If the patient fails this trial test, the physician may still recommend a staging trial as described below. If the PNE test is positive, the temporary test lead is removed and a permanent quadripolar tine lead is implanted under general anesthesia along with the IPG.

The staging trial involves initially implanting a permanent quadripolar, spiked stimulation lead into the patient. It also requires the use of a bore needle to identify the nerve and optimal stimulation location. A lead is implanted near the sacral nerve of S3 and connected to the EPG via a lead extension. This procedure is performed in the operating room, under fluoroscopic guidance, and under local and general anesthesia. The EPG is adjusted to provide the patient with the optimal comfort level and the patient monitors his or her voiding for up to two weeks. If the patient achieves meaningful symptom improvement, he or she is considered an appropriate choice for permanent implantation of an IPG under general anesthesia (typically in the upper hip region as shown in fig. 1 and 3A).

Table 1: motor and sensory responses of SNM at different sacral nerve roots

Clamping: contraction of the anal sphincter; and in males, the root of the penis retracts. The buttocks were moved aside and the anterior/posterior shortening of the perineal structure was sought.

Tube: lifting and lowering of the pelvic floor. Looking for deepening and flattening of the gluteal fold.

With respect to measuring the efficacy of SNM treatment for voiding dysfunction, voiding dysfunction indications (e.g., urge incontinence, urgency-frequency, and non-obstructive urinary retention) are evaluated by a single primary voiding diary variable. These same variables were used to measure treatment efficacy. SNM treatment was considered successful if a minimum of 50% improvement occurred in any of the primary voiding diary variables compared to baseline. For urge incontinence patients, these voiding diary variables may include: number of leakage events per day, number of severe leakage events per day, and number of pads used per day. For patients with urgency-frequency, the primary voiding diary variables may include: the number of excretions per day, the amount of excretion per excretion, and the degree of urgency experienced prior to each excretion. For patients with retention, the primary voiding diary variables may include: the amount of catheterization per catheterization and the number of times of catheterization per day. For patients with fecal incontinence, the efficacy measurements captured by the voiding diary included: the number of weekly leak events, the number of weekly leak days, and the degree of urgency experienced before each leak.

The motor mechanism of SNM is multifactorial and affects the neural axis at several different levels. For patients with OAB, it is believed that the pudendal afferents may activate inhibitory reflexes that promote bladder storage by inhibiting the afferent limbs of abnormal voiding reflexes. This blocks input to the pons micturition center, thereby limiting involuntary detrusor contraction without interfering with the normal voiding pattern. For patients with urinary retention, SNM is thought to activate pudendal afferents that originate from pelvic organs into the spinal cord. At the spinal level, pudendal afferents may initiate the voiding reflex by inhibiting the overprotection reflex, thereby alleviating symptoms in patients with urinary retention, which may promote normal voiding. For patients with fecal incontinence, it is hypothesized that SNM stimulates pudendal afferent body fibers that inhibit colonic propulsive activity and activates the internal anal sphincter, which in turn improves the symptoms of patients with fecal incontinence.

The present invention relates to systems adapted to deliver neural stimulation to target neural tissue in a manner that results in partial or complete activation of target neural fibers, resulting in enhancement or inhibition of neural activity in nerves (possibly the same or different from the stimulation target) that control organs and structures associated with bladder and bowel function.

EMG assisted neurostimulation lead placement and programming

While conventional sacral nerve stimulation modalities have shown efficacy in treating bladder and bowel related dysfunction, there is a need for improved positioning of the nerve stimulation leads and consistency between trial and permanent implant locations of the leads, and improved programming methods. Neural stimulation relies on consistent delivery of therapeutic stimulation from a pulse generator to a particular nerve or target area via one or more neural stimulation electrodes. A nerve stimulation electrode is provided on a distal end of an implantable lead that can be advanced through a tunnel formed in patient tissue. Implantable neurostimulation systems provide great freedom and mobility to the patient, but may be more easily adjusted before the neurostimulation electrodes of such systems are surgically implanted. It is desirable that prior to implantation of the IPG, the physician confirm that the patient has the desired motor and/or sensory response. For at least some treatments, including treatments for at least some forms of urinary and/or fecal dysfunction, it may be very beneficial to accurate and objective lead placement to demonstrate an appropriate motor response, which may not require or be available for a sensory response (e.g., the patient is under general anesthesia).

It may be beneficial to place and calibrate the nerve stimulation electrodes and implantable leads close enough to a particular nerve for the effect of the treatment. Accordingly, aspects and embodiments of the present disclosure relate to aiding and improving the accuracy and precision of neurostimulation electrode placement. Further, aspects and embodiments of the present disclosure are directed to facilitating and improving the scheme for setting therapy treatment signal parameters for a stimulation procedure implemented by an implantable neurostimulation electrode.

Prior to implantation of the permanent device, the patient may undergo an initial testing phase in order to assess the potential response to treatment. As described above, PNE can be done under local anesthesia, using a test needle to identify the appropriate sacral nerve(s) based on the patient's subjective sensory response. Other testing procedures may involve a two-stage surgical procedure in which a quadripolar, cuspated lead is implanted for a testing stage (first stage) to determine whether the patient exhibits sufficient frequency of symptom relief, and, where appropriate, to continue permanent surgical implantation of the neuromodulation device. For both the testing phase and permanent implantation, determining the location of lead placement may depend on subjective qualitative analysis of either or both the patient or the physician.

In an exemplary embodiment, determining whether the implantable lead and the nerve stimulation electrode are in the desired or correct position may be accomplished using electromyography ("EMG"), also known as surface EMG. EMG is a technique that uses an EMG system or module to evaluate and record the electrical activity produced by muscles, producing a record called an electromyogram. EMG detects the electrical potentials generated by muscle cells when those cells are electrically or neuronally activated. The signal may be analyzed to detect the level of activation or recruitment phase. EMG may be performed through the surface of the patient's skin, intramuscularly, or through electrodes placed within the patient's body near the target muscle, or using a combination of external or internal structures. When a muscle or nerve is stimulated by an electrode, EMG may be used to determine whether the relevant muscle is activated (i.e., whether the muscle is fully contracted, partially contracted, or not contracted) in response to the stimulation. Accordingly, the degree of activation of the muscle may indicate whether the implantable lead or neurostimulation electrode is located in a desired or correct position on the patient's body. Further, the degree of activation of the muscle may indicate whether the neurostimulation electrodes are providing stimulation of sufficient intensity, amplitude, frequency, or duration to implement a treatment regimen on the patient's body. Thus, the use of EMG provides an objective and quantitative way by which to standardize the placement of implantable leads and neurostimulation electrodes, reducing subjective assessment of the patient's sensory response.

In some approaches, the location titration process may optionally be based in part on paresthesia from the patient or on subjective responses to pain. In contrast, EMG triggers a measurable and discrete muscle response. Since the therapeutic effect generally depends on the precise placement of the neurostimulation electrodes at the target tissue location and constant repeated delivery of the neurostimulation therapy, the use of objective EMG measurements can greatly improve the utility and success of SNM therapy. Depending on the stimulation of the target muscle, the measurable muscle response may be partial or complete muscle contraction, including responses below the trigger for an observable motor response as shown in table 1. Furthermore, by utilizing a trial system that allows the neurostimulation leads to remain implanted for use with a permanently implanted system, the effectiveness and efficacy of the permanently implanted system is more consistent with the results of the trial period, which in turn results in improved patient efficacy.

C. Example System embodiments

Fig. 1 schematically illustrates example neurostimulation system settings including settings for a trial neurostimulation system 200 and settings for a permanently implanted neurostimulation system 100, in accordance with aspects of the present invention. Each of the EPG 80 and the IPG 50 is compatible and wirelessly communicates with a Clinician Programmer (CP)60 and a patient remote control 70 for locating and/or programming the trial neurostimulation system 200 and/or (after a successful trial) the permanent implantable system 100. As discussed above, the system utilizes a set of cables and EMG sensor patches in the test system setup 100 to facilitate lead placement and neural stimulation programming. The CP may include specialized software, specialized hardware, and/or both for assisting in lead placement, programming, reprogramming, stimulation control, and/or parameter setting. Further, each of the IPG and EPG allow the patient to have at least some control over the stimulation (e.g., initiate a preset program, increase or decrease the stimulation) and/or monitor battery status using the patient's remote control. This approach also allows for a nearly seamless transition between the trial system and the permanent system.

In one aspect, the CP 60 is used by a physician to adjust settings of the EPG and/or IPG while the lead is implanted in the patient. The CP may be a tablet computer used by the clinician to program the IPG or to control the EPG over the trial period. The CP may also include the ability to record stimulus induced electromyography to facilitate lead placement and programming. The patient remote control 70 may allow the patient to turn stimulation on or off, or to change stimulation from the IPG when implanted or from the EPG during the trial phase.

In another aspect, the CP 60 has a control unit that may include a microprocessor and special purpose computer code instructions for implementing a method and system for a clinician to deploy a treatment system and set treatment parameters. The CP generally includes a graphical user interface, an EMG module, an EMG input that may be coupled to an EMG output stimulation cable, an EMG stimulation signal generator, and a stimulation power source. The stimulation cable may be further configured to couple to any or all of an access device (e.g., a bore needle), a therapy lead of the system, and the like. The EMG input may be configured to couple with one or more sensory patch electrodes for attachment to the patient's skin adjacent to muscles (e.g., muscles weakened by the target nerve). Other connectors of the CP may be configured to couple with an electrical ground or ground patch, an electrical pulse generator (e.g., EPG or IPG), or the like. As indicated above, the CP may comprise a module with hardware or computer code for performing EMG analysis, wherein the module may be a component of a control unit microprocessor, a pre-processing unit coupled to or connected with stimulation and/or sensation cables, etc.

In other aspects, the CP 60 allows the clinician to read the impedance of each electrode contact whenever the lead is connected to the EPG, IPG, or CP in order to ensure that a reliable connection is made and the lead is intact. This can be used as an initial step both to position and program the lead to ensure that the electrodes are functioning properly. The CP 60 is also able to save and display previous (e.g., up to the last four) procedures that the patient used to help facilitate the programming. In some embodiments, CP 60 further includes a USB port and a charging port for saving the report to a USB drive. The CP is configured to operate in conjunction with the EPG when the lead is placed within the patient's body and with the IPG during programming. The CP may be electronically coupled to the EPG through a dedicated cable set or through wireless communication during test simulation, allowing the CP to configure, modify, or otherwise program electrodes on leads connected to the EPG. The CP may also include physical on/off buttons for turning the CP on and off and/or for turning the stimulus on and off.

The electrical pulses generated by the EPG and IPG are delivered to the one or more target nerves via one or more nerve stimulation electrodes at or near a distal end of each of the one or more electrodes. The leads can have a variety of shapes, can be a variety of sizes, and can be made from a variety of materials that can be customized for a particular therapeutic application. While in this embodiment, the lead has a size and length suitable for extending from the IPG and through one of the foramina of the sacrum to reach the target sacral nerve, in various other applications, the lead may be implanted, for example, in a peripheral portion of the patient's body (e.g., in an arm or leg), and may be configured for delivering electrical impulses to the peripheral nerve as may be used to alleviate chronic pain. It should be understood that the lead and/or stimulation program may vary depending on the nerve being oriented.

Fig. 2A-2C show diagrams of various neural structures of a patient that may be used for neurostimulation therapy, in accordance with aspects of the present invention. Fig. 2A shows different sections of the spinal cord and the corresponding nerves within each section. The spinal cord is an elongated bundle of nerves and supporting cells that extends from the brainstem along the cervical medulla, through the thoracic medulla, and to the space between the first and second lumbar vertebrae in the lumbar medulla. After leaving the spinal cord, the nerve fibers divide into branches that innervate various muscles and organs that transmit sensory and control impulses between the brain and the organs and muscles. Because certain nerves may include branches that innervate certain organs such as the bladder and branches that innervate certain muscles of the legs and feet, stimulation of nerves at or near nerve roots near the spinal cord may stimulate nerve branches that innervate target organs, which may also result in a muscle response associated with stimulation of another nerve branch. Thus, by monitoring certain muscle responses (e.g., responses in table 1) visually, by using EMG as described herein, or both, a physician can determine whether a target nerve is stimulated. While a certain level of stimulation may elicit a macroscopically robust muscle response, a lower level (e.g., sub-threshold) of stimulation may still provide activation of an organ associated with the target organ while not eliciting any corresponding muscle response or a response that is only visible using EMG. In some embodiments, such low level stimulation may also not cause any paresthesia. This is advantageous because it allows the condition to be treated by nerve stimulation without otherwise causing discomfort, pain, or undesirable muscle reactions in the patient.

Fig. 2B shows nerves associated with the lower back segment in the lower lumbar medullary region where nerve bundles exit the spinal cord and travel through the sacral foramina of the sacrum. In some embodiments, a nerve stimulating lead is advanced through the aperture until the nerve stimulating electrode is positioned at the anterior sacral nerve root, while an anchoring portion of the lead proximal to the stimulating electrode is disposed generally dorsal to the sacral aperture through which the lead passes in order to anchor the lead in place. Fig. 2C shows a detailed view of the nerves of the lumbosacral trunk and sacral plexus (specifically, the S1 to S5 nerves of the lower sacrum). The S3 sacral nerve is of particular interest for the treatment of bladder-related dysfunction (and OAB in particular).

Fig. 3A schematically illustrates an example of a fully implantable neurostimulation system 100 adapted for sacral nerve stimulation. The neurostimulation system 100 includes an IPG implanted in the lower dorsal region and connected to a neurostimulation lead that extends through the S3 aperture for stimulating the S3 sacral nerve. The lead is anchored by a spiked anchor 30 (which maintains the position of a set of nerve stimulation electrodes 40 along the target nerve, in this example, the anterior sacral nerve root S3 innervating the bladder), in order to provide treatment for various bladder-related dysfunctions. While this embodiment is adapted for sacral nerve stimulation, it will be appreciated that a similar system may be used to treat patients suffering from chronic, severe, refractory neuropathic pain, e.g., from peripheral nerves or various urinary dysfunctions or still further other indications. An implantable neurostimulation system may be used to stimulate a target peripheral nerve or the posterior epidural space of the spine.

The characteristics of the electrical pulses may be controlled via a controller of the implanted pulse generator. In some embodiments, these characteristics may include, for example, the frequency, amplitude, pattern, duration, or other aspects of the electrical pulses. These characteristics may include, for example, voltage, current, etc. Such control of the electrical pulses may include creating one or more electrical pulse programs, plans, or patterns, and in some embodiments, this may include selecting one or more existing electrical pulse programs, plans, or patterns. In the embodiment depicted in fig. 3A, the implantable neurostimulation system 100 includes a controller in the IPG having one or more pulse programs, plans or patterns that may be reprogrammed or created in the manner discussed above. In some embodiments, these same characteristics associated with an IPG may be used in the EPG of the partially implanted trial system used prior to implantation of the permanent neurostimulation system 100.

Fig. 3B shows a schematic of a trial neurostimulation system 200 using an EPG patch 81 adhered to the skin of a patient (specifically, attached to the abdomen of the patient), the EPG 80 being encased within the patch. The leads are, on the one hand, hardwired to the EPG, and, on the other hand, are movably coupled to the EPG through a port or aperture in the top surface of the flexible patch 81. The excess leads may be secured by an additional adhesive patch. In an aspect, the EPG patch may be arranged such that the lead connection may be disconnected and used in a permanently implanted system without moving the distal end of the lead away from the target location. Alternatively, the entire system is disposable and may be replaced with permanent leads and an IPG. As previously discussed, when a lead of an experimental system is implanted, EMG obtained via CP using one or more sensor patches may be used to ensure that the lead is placed at a location proximate to a target nerve or muscle.

In some embodiments, the experimental neurostimulation system utilizes an EPG 80 within an EPG patch 81 that is adhered to the skin of the patient and coupled to the implantable neurostimulation lead 20 by a lead extension 22, which is coupled to the lead 20 by a connector 21. This extension and connector structure allows for extension of the lead so that the EPG patch can be placed on the abdomen and, if trials prove successful, allows for the use of a lead having a length suitable for permanent implantation. This approach may utilize two percutaneous incisions, with the connector provided in the first incision and the lead extension extending through the second percutaneous incision, with a short tunneling distance (e.g., about 10cm) between them. This technique may also minimize movement of the implanted lead during conversion of the experimental system to a permanently implanted system.

In one aspect, the EPG unit is wirelessly controlled by the patient remote and/or CP in a manner similar or identical to the IPG of a permanently implanted system. A physician or patient can change the therapy provided by the EPG by using such a portable remote control or programmer, and the delivered therapy is recorded on the memory of the programmer for use in determining the appropriate therapy for use in the permanently implanted system. In each of the trial and permanent neurostimulation systems, the CP may be used for lead placement, programming, and/or stimulation control. In addition, each neurostimulation system allows the patient to control stimulation or monitor battery status using the patient remote control. This configuration is advantageous because it allows for an almost seamless transition between the trial system and the permanent system. From the patient's perspective, the system will operate in the same manner and will control the system in the same manner, so that the patient's subjective experience with the trial system more closely matches what would be experienced when using a permanently implanted system. Thus, this configuration reduces any uncertainty that the patient may have about how the system will operate and control it, making it more likely that the patient will accept an experimental system or a permanent system.

As shown in the detailed view of fig. 3B, the EPG 80 is encased within a flexible layered patch 81 that includes an aperture or port through which the EPG 80 is connected to the lead extension 22. The patch may further include an "on/off" button 83 having molded tactile features for allowing the patient to turn the EPG on and/or off by adhering to the outer surface of the patch 81. The underside of the patch 81 is covered with a skin compatible adhesive 82 for continuous attachment to the patient for the duration of the trial period. For example, a breathable strip with a skin compatible adhesive 82 will allow the EPG 80 to remain continuously attached to the patient during the trial, which may last for more than one week (typically two to four weeks) or even longer.

While the system described above provides considerable improvement in locating the optimal position of the lead and fine-tuning the lead placement and determining the optimal neurostimulation procedure, it is imperative that after the lead is placed in power, the lead position is ensured to be maintained throughout the treatment. If the neurostimulation lead migrates, even a small axial distance, the electrode may move from the target nerve, such that the neurostimulation therapy may not deliver a consistent result or provide a therapeutic effect without reprogramming or repositioning the lead.

In a fully implantable system, the pulse generator is implanted in a region of the patient's body that is large enough to comfortably contain the pulse generator, typically in the lower dorsal or lower abdominal region. Because the electrodes may need to be positioned a considerable distance from the implantable pulse generator, but depending on the therapy or therapy being delivered, neurostimulation leads are used to deliver electrical pulses from the implanted pulse generator to the electrodes. While many such systems have proven effective, studies have shown that neurostimulation leads may move over time, particularly when the lead extends through an area subject to movement. Such movement may misalign the electrodes from the target location, thereby rendering the neural stimulation therapy ineffective, requiring adjustment or replacement of the lead. It is therefore desirable to provide an anchoring device on the stimulation lead in such systems in order to inhibit movement of the lead and electrode dislocation. While conventional neurostimulation has developed various anchoring mechanisms, such mechanisms often complicate the implantation procedure, undesirably increase the delivery profile of the lead, are difficult to replace or remove, or prove ineffective.

Fig. 4 illustrates an example neurostimulation system 100 that is fully implantable and adapted for use in a sacral nerve stimulation therapy. The implantable system 100 includes an IPG 90 coupled to a neurostimulation lead 20 that includes a set of neurostimulation electrodes 40 at a distal end of the lead. The lead includes a lead anchoring portion 30 having a series of tines that extend radially outward to anchor the lead and maintain the position of the neurostimulation lead 20 after implantation. Lead 20 may further include one or more opaque line markers (e.g., silicon markers) 25 for aiding in the placement and positioning of the lead using visualization techniques such as fluoroscopy. In some embodiments, the IPG provides monopolar or bipolar electrical pulses delivered to the target nerve through one or more nerve stimulation electrodes. Upon sacral nerve stimulation, a lead is typically implanted through the S3 aperture as described herein.

As can be seen in fig. 4, the neurostimulation lead 20 comprises a plurality of neurostimulation electrodes 30 at the distal end of the lead, and the anchor 10 is arranged at the proximal end of the electrodes 30. Typically, anchors are disposed adjacent and proximal to the plurality of electrodes so as to provide anchoring of the lead in relatively close proximity to the electrodes. This configuration is also advantageous because it allows testing of the neurostimulation electrodes during implantation, prior to deployment of the anchors (as described below), which allows the optimal position of the neurostimulation electrodes to be determined before the lead is anchored in place. As shown, the anchor 10 includes an anchor body 12 that sweeps helically around the lead body and a plurality of tines 14 extending laterally outward from the helical body 12. This configuration is advantageous because it provides a plurality of tines that are distributed both circumferentially and axially around the lead while extending from the common anchor body (thereby simplifying attachment and replacement of anchoring tines). Furthermore, because the anchor body extends helically around the lead body, this allows the flexibility of the lead body to be preserved in the region of the cusp form. In one aspect, the anchor is constructed of a suitable material that is biocompatible and compatible with the material forming the lead body and flexible enough to provide an anchoring force against tissue without damaging the tissue.

In one aspect, the IPG may be wirelessly recharged by conductive coupling using a charging device 50(CD), which is a portable device powered by a rechargeable battery to allow patient mobility while charging. The CD is used to transcutaneously charge the IPG via RF induction. The CD may be applied to the patient's skin using an adhesive or may be held in place using a tape 53 or adhesive patch 52 as shown in the schematic of fig. 1. The CD may be charged by plugging it directly into a socket or by placing it in a charging or charging station 51 connected to an AC wall socket or other power source

Fig. 5A-5C show detailed views of the IPG and its internal components. In some embodiments, the pulse generator may generate one or more non-ablative electrical pulses that are delivered to the nerve in order to control pain or cause some other desired effect (e.g., in order to inhibit, block, or interrupt nerve activity) in order to treat OAB or bladder related workIt can be abnormal. In some applications, pulses having pulse amplitudes ranging between 0mA and 1,000mA, 0mA and 100mA, 0mA and 50mA, 0mA and 25mA, and/or any other or intermediate amplitude range may be used. One or more of the pulse generators may include a processor and/or memory adapted to provide instructions to and receive information from other components of the implantable neurostimulation system. The processor may comprise, for example, from OrAnd the like, commercially available microprocessors and the like. The IPG may include energy storage features such as one or more capacitors or batteries, one or more batteries, and typically includes a wireless charging unit.

One or more characteristics of the electrical pulses may be controlled via a controller of the IPG or EPG. In some embodiments, these characteristics may include, for example, the frequency, amplitude, pattern, duration, or other timing and amplitude aspects of the electrical pulses. These characteristics may further include, for example, voltage, current, and the like. Such control of the electrical pulses may include creating one or more electrical pulse programs, plans, or patterns, and in some embodiments, this may include selecting one or more existing electrical pulse programs, plans, or patterns. In one aspect, the IPG 90 includes a controller having one or more pulse programs, schedules, or modes that can be created and/or reprogrammed. In some embodiments, the IPG may be programmed to vary stimulation parameters, including pulse amplitude in the range from 0mA to 10mA, pulse width in the range from 50 μ s to 500 μ s, pulse frequency in the range from 5Hz to 250Hz, stimulation mode (e.g., continuous or cyclic), and electrode configuration (e.g., anodal, cathodal, or off) in order to achieve optimal patient-specific therapeutic efficacy. In particular, this allows the optimal settings to be determined for each patient (even though each parameter may vary from person to person).

As shown in fig. 5A and 5B, the IPG may include a head portion 11 at one end and a ceramic portion 14 at an opposite end. Head portion 11 houses feedthrough assembly 12 and connector stack 13, while ceramic housing portion 14 houses antenna assembly 16 for facilitating wireless communication with a clinician program, a patient remote control, and/or a charging coil for facilitating wireless charging using a CD. The remainder of the IPG is covered by a titanium shell portion 17 that encases the printed circuit board, memory and controller components that facilitate the electrical pulse sequencing described above. In the example shown in fig. 5C, the header portion of the IPG includes a four-pin feedthrough assembly 12 coupled with a connector stack 13 in which the proximal end of the lead is coupled. The four pins correspond to the four electrodes of the neurostimulation lead. In some embodiments, the balmThe connection block was electrically connected to four platinum/iridium alloy feedthrough pins that were brazed to the alumina ceramic insulator plate along with the titanium alloy flange. The feedthrough assembly is laser seam welded to a titanium-ceramic brazed housing to form a complete hermetic enclosure for the electronic device.

In the IPG shown in fig. 5A, a ceramic and titanium brazed shell is utilized on one end of the IPG, where the ferrite coil and PCB antenna assembly are positioned. Reliable hermetic sealing is provided via Ceramic-to-Metal (Ceramic-to-Metal) brazing techniques. Zirconia ceramics may include 3Y-TZP (3 mol% yttria stabilized tetragonal zirconia polycrystalline) ceramics, which have high flexural strength and impact resistance and have been commercially used in many implantable medical technologies. However, it will be understood that other ceramics or other suitable materials may be used to construct the IPG.

Since the communication antenna is housed within the hermetically sealed ceramic housing, the utilization of the ceramic material provides an effective radio frequency transparent window for wireless communication with external patient remote controls and clinician's programmer. This ceramic window has further facilitated the miniaturization of implants while maintaining an effective radio frequency transparent window for long term and reliable wireless communication between the IPG and external controls (e.g., patient remote control and CP). Unlike prior art products in which the communication antenna is placed in the head outside the airtight enclosure, the wireless communication of the IPG is generally stable over the lifetime of the device. The communication reliability of such prior art devices tends to degrade due to the change in the dielectric constant of the head material in the human body over time. The ferrite core is part of a charging coil assembly 95 shown in fig. 5B positioned within a ceramic housing 94. The ferrite core concentrates the magnetic field flux through the ceramic shell opposite the metal shell portion 97. This configuration maximizes coupling efficiency, which reduces the required magnetic field and thus reduces device heating during charging. In particular, since the magnetic field flux is oriented in a direction perpendicular to the smallest metal cross-sectional area, heating during charging is minimized. It should be understood that these IPG structures and neurostimulation leads are described for illustrative purposes only, and that the anchoring structures described herein may be used with various other neurostimulation leads and IPGs in accordance with the principles of the present invention.

The proximal end of the lead includes a plurality of conductors corresponding to a plurality of electrodes that are electrically coupled at the distal end with corresponding contacts within a connector stack 93 within the head portion 91 (thereby connecting the IPG contacts with the neurostimulation electrodes 40 of the lead 20 for delivering the neurostimulation therapy). Although limiting movement in the area of the back where the IPG is located, the lead may still experience forces and slight movement for various reasons, for example, due to changes in tissue volume, trauma to the tissue area where the system is implanted, or regular muscle movements. As these forces and motions repeat over time, the connection between the proximal portion of the lead and the IPG may become compromised due to fatigue caused by repeated stress and strain at the point of stiffness mismatch existing at the junction of the flexible lead and the IPG head portion 91. In some embodiments, a strain relief element is included that extends along the proximal portion of the lead away from head portion 91 to provide strain relief at the junction of the proximal portion of the lead and the IPG, thereby maintaining the integrity of the electrical connection and extending the useful life of the lead.

In some embodiments, the system includes a strain relief element extending along a proximal portion of the lead adjacent the head portion of the IPG. The strain relief element may be disposed about the proximal portion of the lead or may be integrated into the lead itself. The strain relief element may include a proximal base attached or interfacing with the head portion of the IPG. In some embodiments, the strain relief element is a helical element extending around the proximal portion of the lead. The strain relief element may be formed from a metal (e.g., stainless steel), a polymer, or any other suitable material. The proximal portion of the lead may include a recessed portion where the strain relief element resides such that the outer surface of the strain relief element is substantially flush or about flush with the outer surface of the lead. Alternatively, the strain relief element may be applied to the non-recessed portion or the standard sized portion at any location along the lead as desired. Typically, the strain relief element length is in the range of about 1 inch to about 6 inches in order to reduce bending or bowing of the proximal portion of the lead near the IPG, which can compromise the electrical connection over time. In one aspect, the strain relief element is formed so as to have increased stiffness along the longitudinal axis to inhibit lateral bending of the proximal portion of the lead. Any of the aspects described herein with respect to the structure and design of the helical anchor body may be applicable to the strain relief element.

In some embodiments, as shown in fig. 6C, the strain relief element 27 comprises a helical structure that extends along a proximal portion of the lead 20 adjacent to where the lead 20 is inserted into the head portion 91 of the IPG 90. The strain relief element 27 may include a proximal base 28 configured for secure attachment to the head portion 91 and a helical portion 29 surrounding the proximal portion of the lead. Generally, the coiled portion 29 inhibits increased stiffness as compared to the lead, such that the coiled portion 29 experiences any stress or force applied to the lead in the proximal region. Furthermore, the helical structure limits the minimum bend radius in the region, which prevents abrupt bends that could damage the lead at the strain relief location. The strain relief element may be formed of any suitable biocompatible material, including polymers or various metals (e.g., stainless steel, nitinol).

In one aspect, the strain relief element is sufficiently thin such that its low profile does not substantially increase the maximum cross-sectional profile or transverse profile of the lead passing through the sheath. In some embodiments, the proximal portion of the lead may have a reduced diameter and size to fittingly receive the strain relief member such that the strain relief member is substantially flush with the lead outer surface distal of the strain relief member.

Fig. 6A and 6B illustrate detailed views of example strain relief members 27 and 27', respectively, each including a proximal base 28 for securing to an IPG head portion and a helical strain relief portion 29 for winding on a proximal portion of the lead 20. Proximal base portion 28 may be sized and dimensioned according to the particular IPG head portion. In one aspect, the helical portion 29 can be configured to provide variable stiffness along the length of the proximal portion of the lead. For example, the helical portion 29 may have a variable thickness along the length of the strain relief to provide a gradual stiffness transition in the region and/or the pitch and/or width of the helical portion may vary along the length of the strain relief to provide gradual stiffness and limit the bend radius in the region. In another aspect, the strain relief element 27 can include one or more tines (not shown) similar to the anchors described herein to provide tissue fixation to the strain relief portion and further inhibit movement or migration of the proximal portion of the lead.

Wire attachment by screw anchor

Fig. 7 illustrates a detailed view of a neurostimulation lead 20, similar to that of fig. 4, having an anchor body 10 mounted on an anchor portion 22 of the lead, shown in a deployed configuration. As can be seen, the helical body 12 sweeps helically about a central longitudinal axis for placement over the lead body, and the plurality of tines 14 are distributed along the helical body 12, extending laterally outward from the central axis and angled in a proximal direction. As shown in the detailed views of fig. 8-10, the plurality of tines 14 of the anchoring body are distributed so as to be radially offset from one another at regular intervals (e.g., 30 °, 45 °, 90 °) within a range of intervals (e.g., between 10 ° and 90 °), such that the plurality of tines extend circumferentially outward in different directions about the central axis. This distributes any anchoring force around the lead body so as to improve the anchoring of the lead.

In one aspect, the anchor 10 includes a radiopaque band 16 embedded within the helical body 12 to allow positioning of the anchor 10 by visualization techniques. The radiopaque band may be made of any radiopaque material, such as platinum alloy (e.g., Pt/lr) so as to be visible using standard visualization techniques. Such a strip is advantageous because it facilitates positioning of the lead at the target location. In other embodiments, the helical body may be formed of a radiopaque material, for example, the radiopaque material may be mixed into the polymeric material forming the anchor.

Fig. 9A and 9B illustrate a neurostimulation lead with attached anchors in a delivery configuration and a deployed configuration, respectively. In fig. 9A, the plurality of tines 14 are folded against adjacent sections of the lead 20 body (without overlapping each other) or the helical body. Typically, the tines are constrained in a delivery configuration by an outer sheath (not shown) as the lead is advanced through the tunnel in the tissue to the target location. The helical body is swept at a pitch to allow sufficient space between adjacent turns of the helical body for the label to fold inward against the lead body, which allows for a reduced delivery profile. In one aspect, the cross-section of the anchor is less than 2.0mm, small enough to be delivered through a 5Fr sheath. In one aspect, the lead body includes a recessed portion 22 having a reduced outer diameter in which the helical body 12 is attached. This feature facilitates coupling between the anchor 10 and the lead body 20 because the proximal and distal ends of the anchor abut the proximal and distal ends of the recessed portion and allow for a reduced cross-sectional profile or transverse profile of the anchor portion of the lead. Once delivery of the electrode to the target location is confirmed, the sheath can be withdrawn proximally, thereby allowing the plurality of tines to resiliently return to the deployed configuration as shown in fig. 9B (the tines are biased toward the deployed configuration).

Fig. 10A and 10B illustrate a detailed view of the anchor 10 shown in fig. 9B in a deployed configuration. In this embodiment, the tines 14 are all angled proximally. However, it should be understood that in other embodiments, the anchor body 10 may be configured such that the tines extend distally or proximally, perpendicular to the longitudinal axis of the helical body, or in a number of different directions as desired for a particular application.

In one aspect, the anchor is stiff enough to apply sufficient anchoring force to maintain the lead in place and flexible enough to fold inward against the lead and avoid damaging the tissue (if the lead is removed from the tissue). In some embodiments, the anchor is made of molded polyurethane having a shore hardness in a range between 50A and 80D (preferably, about 70D). The width of the helical body may be between 1.0mm and 3.0mm (preferably, about 2.0mm) and the overall length may be between 10mm and 30mm (preferably, about 20 mm). The anchor is configured such that the transverse profile is less than 2.0mm (preferably 1.7mm or less) so that the lead wire with the anchor attached thereto can be delivered through a standard sheath (e.g., a 5Fr sheath). In certain embodiments, the length of the tines is between 1mm and 3mm (preferably, about 1.8 mm); a width of between 0.5mm and 2.0mm (preferably, about 0.8 mm); the thickness is between about 0.2mm and 0.5mm (preferably, about 0.3 mm). In certain embodiments, the anchor comprises 10 to 20 tines (preferably 12 to 16 tines) spaced along the length of the helical body so as to extend circumferentially in different directions around the lead. In some embodiments, all tines have the same length and are angled in the same direction, while in other embodiments, the tines may have varying lengths and widths and may be angled in both the distal and proximal directions. While it is advantageous to size any of the anchors described herein according to the configurations described above to facilitate delivery of the anchor through a 5Fr sheath, it should be understood that the anchors may be configured according to various other sizes (length, number of tines, etc.) as desired for a particular application or neurostimulation lead.

Fig. 10A and 10B and fig. 11A and 11B illustrate an example anchor similar to the anchor shown in fig. 8, except that the tines 14 are formed in a different shape. For example, in one aspect, as shown in fig. 8, the tines can be formed such that the end faces are angled or pointed. In another aspect, as shown in fig. 10A and 10B, the tines can be formed in a substantially rectangular shape. In another aspect, as shown in fig. 11A and 11B, the tines may be formed such that the corners and/or edges are curved, rounded, or chamfered. This feature can help reduce the likelihood of trauma to adjacent tissue by the corners or edges of the tines when the tines are engaged with tissue during anchoring of the lead.

Fig. 12A and 12B illustrate an example anchor similar to the anchor in fig. 8, except that the plurality of tines are angled in a proximal direction and a distal direction. As can be seen, the most proximal tines are angled in the distal direction, while the remaining tines are angled in the proximal direction. This aspect may be useful in applications where the lead tends to experience forces in both the proximal and distal directions. For example, while studies have shown that neurostimulation leads implanted through the sacral foramina experience primarily forces directed in the proximal direction, various other applications, such as peripherally implanted leads in the arm or leg, may experience significant forces in the proximal and distal directions.

Fig. 13A and 13B illustrate an anchor 10 comprising a plurality of anchor segments 10'. As shown, the anchor is comprised of two sections connected together. The anchor segment 10' may be modular, allowing for the use of one or more anchor segments on the lead as required by a particular lead or application. The anchor segments may include means for attaching or coupling the segments to one another, or may be joined together by various methods known to those skilled in the art (e.g., by using adhesives, mechanical or chemical coupling, or oxidative joining methods). Such a feature may allow a user to customize the anchoring portion as desired, according to different lengths of different tines, and different sizes and/or orientations.

Fig. 14A and 14B illustrate an anchor 10 having a cork-screw type shape. The anchor includes a continuous helical flap having a plurality of segments defined by cutting the helical flap into a plurality of segments that can be folded toward the lead body without overlapping each other. In one aspect, the anchor 10 is monolithically formed from a single unitary component. For example, the anchor 10 may be formed from a cork-screw type structure in which the spiral petals are pointed by wedge-shaped notches 15 cut in the spiral petals to define a plurality of pointed teeth 14 that can be folded down against the lead (to deliver the anchor by constraining insertion into the sheath).

In another aspect, any of the anchors described herein can include one or more of a variety of other features, including: biodegradable tines, drug eluting tines, and flexible disk-like tines that open or fold after reaching a certain angle of bending to allow easy insertion or retraction. In another aspect, the anchor may include a strip or embedded material that shields or interrupts the heating caused by the MRI.

In one aspect, the anchor 10 includes one or more drug eluting components that release one or more therapeutic compounds for a period of time after implantation. Such a drug eluting component may include a portion of the anchor, a strip wrapped along the length of the anchor, the material forming the anchor, or a coating deposited on the anchor or a portion thereof. For example, the drug or therapeutic mixture may be sprayed onto the anchor, the anchor may be soaked in the drug or mixture, or the drug or mixture may be mixed into the polymer forming the anchor. In some embodiments, the anchor may be formed from a combination of bioabsorbable or non-absorbable polymer material or a non-absorbable base coated with a layer of drug eluting polymer. In an aspect, the drug or therapeutic mixture can be applied to facilitate release of the drug in a particular direction, e.g., the drug or mixture can be applied to facilitate release of the drug isotropically or anisotropically along the axis of the tines. The eluting drug may be selected to promote and shorten healing time to minimize the risk of lead migration. Alternatively or additionally, the anchor may be configured to elute various other drugs, providing various other therapeutic benefits. For example, the anchor 10 may be formed to elute a mixture for promoting fixation within tissue, such as a bioadhesive or mixture for promoting tissue formation after implantation to further minimize the risk of lead migration.

While in many of the illustrated embodiments the tines are configured to protrude and fold along an axis parallel to the longitudinal axis along which the helical portion extends, in some embodiments the anchor can be designed such that the tines fold inwardly along a helical or inclined axis. Such a configuration may allow retraction of the tines by twisting the lead in one direction to facilitate removal of the lead, and/or allow further deployment of the tines by twisting the lead in the opposite direction. In other embodiments (e.g., embodiments in which the tines are folded along an axis parallel to the longitudinal axis), the tines may be flexible and/or frangible enough to allow removal of the lead by retracting the lead with only sufficient force.

In one aspect, the anchors can be formed by cutting a pattern in a monolithic piece of material (e.g., a shape memory metal such as nitinol). For example, the anchors may be formed by laser cutting a helical pattern in a tube or a piece of cylindrical material, the pattern corresponding to the anchors in the constrained configuration as shown in the example of fig. 15B. The tines can then be supported on the mold or held in place by various other means so that the material can be heat set while the anchor is in the deployed configuration as shown in fig. 15A. Generally, as shown in fig. 15C, the pattern is defined such that the tines are evenly distributed along the length of the helical body, the tines extending outwardly along the extent of the helix in multiple radial directions so as to provide evenly distributed tissue fixation in all directions.

In one aspect, the helical base may be heat-set to have a smaller inner diameter than the lead body to provide an interference fit, after which the helical base may be twisted to open and then loaded onto the lead body. After release, the helical base automatically tightens on the lead body, providing a secure attachment to the lead. The helical design is configured such that when the tines are folded down, the tines do not overlap each other or the helical body of the anchor.

In another aspect, as shown in fig. 15A, the anchor design may include one or more retention features 11, 13 at the proximal and distal ends, respectively, that enable precise anchoring of the anchor to the device. In this embodiment, the proximal and distal retention features 11, 13 are designed to abut against the respective proximal and distal ends of the reduced diameter anchor portion 22 of the lead in which the anchor 10 is received to attach the anchor 10 to the body of the lead 20 and prevent axial movement of the anchor 10 before, during, and/or after delivery of the lead and deployment of the anchor 10. In another aspect, the proximal and distal retention features 11, 13 may be designed in various shapes (e.g., serrated, curved, angled) along the proximal and distal facing edges to interlock with corresponding shapes along the lead at the proximal and distal ends of the anchor portion 22. Such a configuration can be used to prevent free rotational movement of the anchor 10 relative to the lead body 20 or to assist in translating rotational movement to the anchor after rotation of the lead.

In one aspect, the anchor 10 may be formed of any type of implantable biocompatible polymer. Radiopaque fillers such as barium sulfate, bismuth, and tungsten may be added to the polymer to make the tines radiopaque under x-ray. Alternatively or additionally, a band made of a radiopaque metal, such as gold or platinum, may be embedded into the helical body to add radiopacity to the tines. In another approach, the anchor may include one or more discrete radiopaque markers that may be used with visualization techniques to locate the anchor or to determine when the tines are deployed. For example, by placing one marker of a pair of markers on the end of the tines and the other marker on the helical body directly adjacent to the end of the tines, separation of the pair of markers when the anchor is in the constrained configuration can indicate when the tines are deployed and the extent to which they are deployed within the tissue.

Fig. 16A illustrates another method by which the anchor 10 may be formed. As shown in fig. 16A, the anchor may be cut from a length of extruded polymer tubing, for example, by laser cutting. The tines may then be shaped to have an outwardly protruding bias by a heat setting or reflow process. For example, the anchor 10 may be mounted on an internal mold (not shown) that supports the tines in an outwardly projecting configuration corresponding to the deployed anchor configuration and heats or allows the polymer to set. After setting, the tines 14 of the anchor 10 are biased toward the deployed configuration as illustrated in fig. 16B. In one aspect, this heating and reflow process can also be used to incorporate one or more radiopaque markers, such as Pt/Ir wire or ribbon wound at the same pitch as the helix. In another aspect, polymer tube extrusion can incorporate a band or coil (e.g., nitinol or gold) band to provide self-expanding or self-closing shape memory elements to the anchor tines. The laser cutting may be programmed to cut around the embedded ribbon wire to include the wire in the helical body.

Fig. 17A and 17B illustrate yet another method by which the anchor 10 may be formed. The helical anchor, such as any of the helical anchors described herein, can be formed by injection molding using a multi-piece mold design. For example, a two-piece mold design, a three-piece mold design, or a four-piece mold design may be used to mold the anchor as a single integral part. In one aspect, the mold can be configured to release the anchor at an angle specific to the anchor's design. As shown in fig. 17A, a three-piece mold 17 is used to form the anchor 10 by an injection molding process. The core pin 18 together with the mold is used to form the open cavity of the anchor. Fig. 17B illustrates a four-piece mold design 17' also configured to be used with the core pin 18 to allow the anchor 10 to be formed by an injection molding process. One advantage of using an injection molding process to form the anchor is that the molded anchor can have varying thicknesses along the length of the component. For example, such anchors may be formed such that the base is thinner to improve the transverse profile and the protruding tines are thicker to provide retention strength after implantation. In another aspect, a metal element can be incorporated along the entire length at the location of the tines or at the distal and proximal ends for radiopacity.

A method of forming an anchor according to the above described aspect of the invention is shown in the example of fig. 18 and 19. The example method of fig. 18 includes the following method steps: laser cutting a helical pattern into a tubular section of material, the pattern corresponding to a neurostimulation lead anchor having a plurality of tines in a constrained configuration 180; supporting the tines of the tubular section in an outwardly protruding position corresponding to the deployed configuration of the anchor 182; and heat setting the tubular section while the tines are supported, thereby setting 184 the material when the anchor is in the deployed configuration. In one aspect, the material is nitinol (preferably in a superelastic phase and having an austenite finish temperature from about 15 ℃ to about 35 ℃), such that upon heating within the body, the anchor will return to the deployed configuration. In another aspect, the material may be formed of a polymeric material that may be shaped by heating and reflowing in the deployed configuration. The method may be provided to the user for application to the lead or may be attached to the lead by wrapping the anchor over the anchor portion 186 prior to transport to the user. The example method of fig. 19 includes the steps of: assembling a multi-piece mold defining an outer surface of a helical anchor having a plurality of outwardly extending tines, the multi-piece mold having a central core pin 190 defining a central lumen of the anchor; injecting flowable material into the assembled mold and allowing the material to at least partially set 194; and removing the mold to release the anchor 196. In some embodiments, the mold is configured such that the outer piece of the mold is removed along the direction in which the tines extend, which reduces the stress and force applied to the tines during removal. In some embodiments, a radiopaque band is added to the mold during assembly and/or a radiopaque material is added to the flowable material used to form the anchor 192. Again, the anchor may be provided to the user for assembly with the lead, or the anchor may be applied to the lead 198 and the anchor may be provided to the user for assembly with the lead. In another aspect, the anchor may be provided with a lead within a constraining sheath ready for insertion into a patient according to the implantation methods described herein.

A method of attaching an implanted neurostimulation lead using an anchor according to aspects of the present invention is shown in the example of fig. 20. The example method of fig. 20 includes the steps of: providing a neurostimulation lead having one or more neurostimulation electrodes and an anchor proximal to the one or more electrodes, the anchor comprising a helical body coiled along the length of the lead and one or more tines attached to the helical body that fold inwardly against the lead body, the helical body being constrained 210 by a sheath; advancing the lead through tissue of the patient to a target location 212 as the one or more tines fold inward against the lead body constrained by the sheath; resiliently deploying the one or more tines into a deployed configuration extending laterally outward from the helical body by withdrawing the sheath 214; and anchoring the neurostimulation lead at the target location by engaging the one or more tines in the deployed configuration with adjacent tissue thereby inhibiting axial movement of the lead 216. Wire removal may be achieved by: the lead is withdrawn proximally until the anchoring force provided by the flexible tines is overcome. Thus, the tines are made of a material that is rigid enough to provide the desired anchoring force but flexible enough to avoid tissue damage when withdrawn.

In the foregoing specification, the invention has been described with reference to specific embodiments thereof, but those skilled in the art will recognize that the invention is not limited thereto. The various features and aspects of the above-described invention may be used separately or together. Moreover, the present invention may be utilized in any number of environments and applications beyond those described herein without departing from the broader spirit and scope of the specification. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. It will be appreciated that the terms "comprising", "including" and "having", as used herein, are specifically intended to be understood as open-ended terms of art.