TECHNICAL FIELD

This disclosure generally relates to electrical stimulation therapy.

BACKGROUND

Medical devices may be external or implanted, and may be used to deliver electrical stimulation therapy to patients via various tissue sites to treat a variety of symptoms or conditions such as chronic pain, tremor, Parkinson's disease, epilepsy, urinary or fecal incontinence, sexual dysfunction, obesity, or gastroparesis. A medical device may deliver electrical stimulation therapy via one or more leads that include electrodes located proximate to target locations associated with the brain, the spinal cord, pelvic nerves, peripheral nerves, or the gastrointestinal tract of a patient. Hence, electrical stimulation may be used in different therapeutic applications, such as deep brain stimulation (DBS), spinal cord stimulation (SCS), pelvic stimulation, gastric stimulation, or peripheral nerve field stimulation (PNFS).

A clinician may select values for a number of programmable parameters in order to define the electrical stimulation therapy to be delivered by the implantable stimulator to a patient. For example, the clinician may select one or more electrodes, a polarity of each selected electrode, a voltage or current amplitude, a pulse width, and a pulse frequency as stimulation parameters. A set of parameters, such as a set including electrode combination, electrode polarity, amplitude, pulse width and pulse rate, may be referred to as a program in the sense that they define the electrical stimulation therapy to be delivered to the patient.

SUMMARY

In some examples, the disclosure describes example medical devices, systems, and techniques for adjusting therapy parameters based on whether adjustment to different therapy parameters causes an evoked compound action potential (ECAP) to be greater than or less than an ECAP threshold. Over time, a patient may become accommodated to the therapy, impacting its effectiveness. To avoid accommodation, in the example techniques, a medical device may adjust the therapy parameters of the therapy that is delivered. However, adjustment of therapy parameters may also result in discomfort to the patient if the patient perceives changes in the intensity the therapy.

One way to determine intensity of the therapy is the level of the ECAP that is evoked in response to the delivery of therapy. For example, if the level of the ECAP is greater than an ECAP threshold, then the intensity may be too high, and if the level of the ECAP is less than the ECAP threshold, then the intensity may not be high enough. In the example techniques described in this disclosure, the medical device may adjust a first therapy parameter and, during or after adjustment, compare the level of the ECAP to the ECAP threshold. Based on the comparison, the medical device may adjust another therapy parameter to increase or decrease the level of the ECAP as appropriate. In this manner, by periodically or randomly adjusting a first therapy parameter, the patient may not experience accommodation, and by adjusting a second, different therapy parameter, the medical device may reduce the likelihood that the intensity of the therapy will cause discomfort.

In one example, this disclosure describes a method of therapy delivery, the method comprising adjusting a first therapy parameter from a first level to a second level different than the first level, responsive to the adjustment of the first therapy parameter, comparing a level of an evoked compound action potential (ECAP) generated in response to therapy delivered with the adjusted first therapy parameter to an ECAP threshold, adjusting a second therapy parameter from a third level to a fourth level different than the third level based on the comparison, wherein the second therapy parameter is different than the first therapy parameter, and causing delivery of the therapy with the first therapy parameter at the second level and the second therapy parameter at the fourth level.

In one example, this disclosure describes a device for therapy delivery, the device comprising a stimulation circuit and a processing circuit. The processing circuit is configured to adjust a first therapy parameter from a first level to a second level different than the first level, responsive to the adjustment of the first therapy parameter, compare a level of an evoked compound action potential (ECAP) generated in response to therapy delivered with the adjusted first therapy parameter to an ECAP threshold, adjust a second therapy parameter from a third level to a fourth level different than the third level based on the comparison, wherein the second therapy parameter is different than the first therapy parameter, and cause the stimulation circuit to deliver therapy with the first therapy parameter at the second level and the second therapy parameter at the fourth level.

In one example, the disclosure describes a computer-readable storage medium storing instructions thereon that when executed cause one or more processors of a device for therapy delivery to adjust a first therapy parameter from a first level to a second level different than the first level, responsive to the adjustment of the first therapy parameter, compare a level of an evoked compound action potential (ECAP) generated in response to therapy delivered with the adjusted first therapy parameter to an ECAP threshold, adjust a second therapy parameter from a third level to a fourth level different than the third level based on the comparison, wherein the second therapy parameter is different than the first therapy parameter, and cause delivery of the therapy with the first therapy parameter at the second level and the second therapy parameter at the fourth level.

In one example, the disclosure describes a device for therapy delivery, the device comprising means for adjusting a first therapy parameter from a first level to a second level different than the first level, responsive to the adjustment of the first therapy parameter, means for comparing a level of an evoked compound action potential (ECAP) generated in response to therapy delivered with the adjusted first therapy parameter to an ECAP threshold, means for adjusting a second therapy parameter from a third level to a fourth level different than the third level based on the comparison, wherein the second therapy parameter is different than the first therapy parameter, and means for causing delivery of the therapy with the first therapy parameter at the second level and the second therapy parameter at the fourth level.

In one example, the disclosure describes a system for therapy delivery, the system comprising an implantable medical device (IMD) comprising a stimulation circuit, one or more leads coupled to the IMD, and a processing circuit. The processing circuit is configured to adjust a first therapy parameter from a first level to a second level different than the first level, responsive to the adjustment of the first therapy parameter, compare a level of an evoked compound action potential (ECAP), sensed via at least one of the one or more leads, generated in response to therapy delivered with the adjusted first therapy parameter to an ECAP threshold, adjust a second therapy parameter from a third level to a fourth level different than the third level based on the comparison, wherein the second therapy parameter is different than the first therapy parameter, and cause the stimulation circuit to deliver therapy with the first therapy parameter at the second level and the second therapy parameter at the fourth level via at least one of the one or more leads.

The details of one or more examples of the techniques of this disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the techniques will be apparent from the description and drawings, and from the claims.

