A method and device for performing electrical current therapy on biological tissue. The device can operate continuously as a bio-energetic thermostat to continuously provide electrical current therapy, or based on sensing parameters and providing electrical current therapy only when the parameters indicate that the electrical current therapy is to be applied.

Methods and systems for testing and treating spinal cord stimulation (SCS) patients are disclosed. Patients are eventually treated with sub-perception (paresthesia free) therapy. However, supra-perception stimulation is used during sweet spot searching during which active electrodes are selected for the patient. This allows sweet spot searching to occur much more quickly and without the need to wash in the various electrode combinations that are tried. After selecting electrodes using supra-perception therapy, therapy is titrated to sub-perception levels using the selected electrodes. Such sub-perception therapy has been investigated using pulses at or below 10 kHz, and it has been determined that a statistically significant correlation exists between pulse width (PW) and frequency (F) in this frequency range at which SCS patients experience significant reduction in symptoms such as back pain. Beneficially, sub-perception stimulation at such low frequencies significantly lowers power consumption in the patient's neurostimulator.

A DC nerve conduction block can be maintained by delivering a subthreshold direct current (DC) after priming a neural structure with a suprathreshold DC. A waveform generator can provide a DC waveform including a first phase with a first amplitude capable of providing a nerve conduction block of a neural structure within 1 second and a second phase with a second amplitude less than the first amplitude. One or more electrodes can deliver the first phase for to the neural structure for a first time to provide the nerve conduction block of the neural structure within 1 second and deliver the second phase to the neural structure for a second time to maintain the block of the neural structure. By maintaining the DC nerve conduction block with the subthreshold DC, significant power can be saved, resulting in an extended battery life of the waveform generator.

A device for neurostimulation has a number N of electrodes. N is equal to or larger than 3. The device is configured to deliver via each electrode therapeutic electric phases of amplitudes I.sub.1, I.sub.2, . . . I.sub.N, with a frequency f and after each therapeutic electric phase a number of N-1 charge balancing electric phases. The charge balancing electric phases of the respective electrode each have a polarity that is opposite the polarity of the preceding therapeutic electric phase of the respective electrode. The device is configured to return for each electrode the current of each therapeutic electric phase in the other N-1 electrodes.

An example of a system to program a neuromodulator to deliver neuromodulation to a neural target using a plurality of electrodes may comprise a programming control circuit configured to determine target energy allocations for the plurality of electrodes based on at least one target pole to provide a target sub-perception modulation field, and normalize the target sub-perception modulation field, including determine a time domain scaling factor to account for at least one property of a neural target or of a neuromodulation waveform, and apply the time domain scaling factor to the target energy allocations.

Techniques for therapy delivery are described. A processing circuit may adjust a first therapy parameter from a first level to a second level, and responsive to the adjustment of the first therapy parameter, compare a level of an evoked compound action potential (ECAP) generated from therapy delivery based on the adjusted first therapy parameter to an ECAP threshold. The processing circuit may adjust a second therapy parameter from a third level to a fourth level based on the comparison. The second therapy parameter is different than the first therapy parameter. The processing circuit may cause therapy delivery with the first therapy parameter at the second level and the second therapy parameter at the fourth level.

Medical device systems and methods for providing spinal cord stimulation (SCS) are disclosed. The SCS systems and methods provide therapy below the perception threshold of the patient. The methods and systems are configured to measure neurological responses to stimulation and use the neurological responses as biomarkers to maintain and adjust therapy. An example of neurological responses includes an evoked compound action potential (ECAP).

Medical device systems and methods for providing spinal cord stimulation (SCS) are disclosed. The SCS systems and methods provide therapy below the perception threshold of the patient. The methods and systems are configured to measure neurological responses to stimulation and use the neurological responses as biomarkers to maintain and adjust therapy. An example of neurological responses includes an evoked compound action potential (ECAP).

In some examples, a medical device is configured to deliver sub-threshold electrical stimulation therapy to a patient at a stimulation intensity that is significantly less than a perception or paresthesia threshold intensity level for the patient. The medical device may deliver the sub-threshold electrical stimulation therapy to a first anatomical location near a spine of a patient. The first anatomical location may be below a T9-10 spinal disc space in a lateral view of the patient or within 2 millimeters of a midline of the spine of the patient or both.

In some examples, a medical device is configured to deliver sub-threshold electrical stimulation therapy to a patient at a stimulation intensity that is significantly less than a perception or paresthesia threshold intensity level for the patient. The medical device may determine the particular intensity level for the patient through a titration process. The medical device may titrate automatically or based upon the input of the patient, a clinician or a physician.