TECHNICAL FIELD

The disclosure relates to medical devices and, more particularly, to medical devices that may be configured to deliver electrical stimulation therapy.

BACKGROUND

Various pathological neuromuscular conditions, including some that are resistant to first-line forms of treatment such as pharmaceuticals or lifestyle modifications, may be successfully treated by implantable medical devices (e.g., neurostimulation devices) that apply electrical stimulation in part to motor or sensory neurons. Some illustrative areas for which neurostimulation devices may provide successful therapy are pain, urinary and fecal incontinence (e.g., an inability to control bladder and bowel function, respectively). Those problems affect people of all ages, genders, and races. Various muscles, nerves, organs, and conduits within the pelvic floor cooperate to collect, store and release bladder and bowel contents. A variety of disorders may compromise urinary tract and bowel performance, and contribute to incontinence. Many of the disorders may be associated with aging, injury, or illness.

Urinary incontinence, or degree of urgency associated with incontinence, may originate from disorders of portions of the peripheral or central nervous system which control the bladder micturition reflex. Nerve disorders may also lead to overactive bladder activities and/or may prevent proper triggering and operation of the bladder. Furthermore, urinary incontinence may also result from improper communication between the nervous system and the urethra.

Sacral neuromodulation (SNM) at the third sacral foramen (S3) is an FDA-approved therapy for urinary urge incontinence, urgency-frequency and fecal incontinence. The generally recommended pulse width value for SNM is 210 microseconds (μs).

SUMMARY

This disclosure describes devices, systems, and techniques for identifying stimulation vectors that are able to evoke therapeutic responses in sensory or motor neurons by neurostimulation with efficient pulse widths and/or enhanced therapeutic windows in terms of available amplitude range without inducing non-therapeutic side effects. Some examples may be directed to neurostimulation for managing incontinence (bladder incontinence and/or fecal incontinence) of a patient and/or other patient conditions. In some examples, processing circuitry of a medical device system is configured to acquire strength-duration curve data for each of a plurality of stimulation vectors, and select one or more of the stimulation vectors as preferred based on a comparison of vector-specific values for one or more metrics derived from the strength-duration curve data for the vectors.

Metrics derived from the strength-duration curve data for a stimulation vector may include area under the curve (AUC) (e.g., determined using an integral of the curve), slope (e.g., determined using a derivative of the curve at a particular point or as a slope relative to two points on the curve), or any other metric that characterizes the magnitude, curvature, and/or shape of the strength-duration curve. In general, stimulation vectors better targeted to the neuron target will be flatter, with lower amplitudes necessary for capture, including at shorter pulse-widths. Use of such a stimulation vector to deliver electrical stimulation therapy to a patient may facilitate efficacious stimulation with electrical pulses having more efficient, i.e., shorter, pulse widths and/or enhanced therapeutic windows.

For example, a medical device may be configured to deliver electrical stimulation therapy via a stimulation vector selected according to the techniques of this disclosure with pulse widths below the 210 μs pulse width generally used and recommended, such as in a range of 20 to 180 μs. Stimulation with pulse widths in or proximate to this range may evoke a similar therapeutic response as the conventionally used 210 μs, but using substantially less energy per pulse (e.g., approximately 20% to 90% less energy per pulse). Using the shorter pulse width may thereby substantially extend (e.g., approximately tripling) the life or the time between charges of a power source (e.g., a lithium ion battery) for an implanted medical device (e.g., an implanted neurostimulation device). Using the shorter pulse width may also increase the therapy window or operating range in terms of amplitude of neurostimulation that may be applied without evoking an undesirable or non-therapeutic response, such as stimulation of additional proximate tissues in a non-therapeutic manner (e.g., in an incontinence therapy application, evoking contraction of the semitendinosus muscle).

Various examples of the present disclosure relate to a method of programming an implantable medical device configured to provide electrical stimulation using a plurality of stimulation vectors addressable by the stimulator device during delivery of electrical stimulation of different pulse widths to a neural target. The method comprises comparing, by the medical device system, strength-duration curve data for the plurality of stimulation vectors, the strength-duration curve data representing, for respective pulse widths, a stimulation strength that evokes a physiological response associated with the neural target. At least one stimulation vector of the plurality of stimulation vectors is selected based on the comparison of the strength-duration curve data for the set of stimulation vectors. The stimulator device is programmed to deliver electrical stimulation to the neural target via the selected stimulation vector.

Certain examples are directed toward a medical device system that includes a stimulator device coupled to at least one multi-electrode lead and configured to address a plurality of stimulation vectors. Processing circuitry is configured to, for each stimulation vector of at least a subset of the plurality of stimulation vectors: determine, for each of a plurality of pulse width values, a respective threshold pulse amplitude value that evokes a physiological response indicative of target nerve modulation; generate, from the threshold pulse amplitude values, a strength-duration curve for the respective stimulation vector, determine a value for a metric from the strength-duration curve; compare the values of the metric for respective stimulation vector of the at least a subset; and select a stimulation vector from the plurality of stimulation vectors based on the comparison.

Various aspects of the present disclosure are directed towards a medical device or system that is used to create a strength-duration curve for each of the plurality of stimulation vectors. The strength-duration curve can be created by delivering, using the implantable stimulator device, electrical stimulation at different threshold pulse amplitudes, and by determining a threshold pulse amplitude value that evokes the physiological response for each one of a plurality of pulse width values. The medical device or system can then determine, for the strength-duration curves of the plurality of stimulation vectors, respective values for at least one metric, and then select at least one stimulation vector is based on a comparison between the values of the at least one metric.

Consistent with some examples, a method of programming a stimulator device of a medical device system comprises collecting, by the medical device system, strength-duration curve data for each stimulation vector of a plurality of stimulation vectors addressable by the stimulator device during delivery of electrical stimulation to a neural target via the stimulation vector, selecting at least one stimulation vector of the plurality of stimulation vectors based on a comparison of the strength-duration curve data for the set of stimulation vectors, and controlling the stimulator device to deliver electrical stimulation to the neural target via the selected stimulation vector.

In various examples, a method of operation of a stimulator device comprises delivering electrical stimulation to a neural target using a stimulation vector that is selected from a plurality of stimulation vectors addressable by the stimulator device based on a comparison of strength-duration curve data captured for each one of the plurality of stimulation vectors during delivery of stimulation to the neural target via the stimulation vector.

In some examples, a method comprises, for each stimulation vector of a plurality of stimulation vectors addressable by a stimulator device, obtaining a set of strength-duration curve data by controlling delivery of electrical stimulation by the stimulator device to determine a threshold pulse amplitude value that evokes a physiological response indicative of target nerve modulation for each one of a plurality of pulse width values, and determining at least one metric from the set of strength-duration curve data. The method further comprises selecting a stimulation vector from the plurality of stimulation vectors for target nerve modulation by the stimulator device based on a comparison between the at least one metric calculated from the set of strength-duration curve data for each stimulation vector of the set of stimulation vectors.

In various examples, a medical device system comprises a stimulator device, and processing circuitry configured to perform any method described herein.

In certain examples, a medical device system comprises a stimulator device coupled to at least one multi-electrode lead and configured to address a plurality of stimulation vectors, wherein at least some of the stimulation vectors include at least one electrode of the at least one multi-electrode lead, and processing circuitry configured to, for each stimulation vector of a plurality of stimulation vectors addressable by a stimulator device, obtain a set of strength-duration curve data by controlling delivery of electrical stimulation by the stimulator device to determine a threshold pulse amplitude value that evokes a physiological response indicative of target nerve modulation for each one of a plurality of pulse width values, and determine at least one metric from the set of strength-duration curve data. The processing circuitry is further configured to select a stimulation vector from the plurality of stimulation vectors for target nerve modulation by the stimulator device based on a comparison between the at least one metric calculated from the set of strength-duration curve data for each stimulation vector of the set of stimulation vectors.

Various examples include at least one of a medical device, system, method and non-transitory computer-readable storage medium comprising executable instructions, for utilizing strength-duration data for electrode targeting and selection as described in the specification and/or shown in any of the drawings.

Some examples include at least one of a medical device, system, method and non-transitory computer-readable storage medium comprising executable instructions, for targeted stimulation or targeted stimulation programming as described in the specification and/or shown in any of the drawings.

In various examples, a medical device or system comprises means for performing any method described herein.

Consistent with certain examples, a non-transitory computer-readable storage medium comprises instructions, that when executed by processing circuitry of a medical device or system, cause the medical device or system to perform any method described herein.

