Methods and apparatus for adjusting neurostimulation intensity using evoked responses

A system for delivering neurostimulation to a body having a vagus nerve and a laryngeal muscle, the system comprising:

• a stimulation output circuit configured to deliver neurostimulation pulses to the vagus nerve;
• an evoked neural response detection circuit configured to receive a neural signal representative of neural activities in the vagus nerve including evoked neural responses evoked by the neurostimulation pulses and detect one of the evoked neural responses using the neural signal for each pulse of the neurostimulation pulses delivered, the evoked neural response detection circuit including:
• a detection timer configured to time a delay interval, a first detection window, and a second detection window in response to delivery of the one of the neurostimulation pulses, the delay interval starting upon the delivery of the one of the neurostimulation pulses, the first detection window starting upon expiration of the delay interval, the second detection window starting upon expiration of the first detection interval;
• and
• a comparator configured to detect an evoked A-fiber response of the evoked neural responses by comparing the sensed neural signal to a first detection threshold during the first detection window and detect an evoked B-fiber response of the evoked neural responses by comparing the sensed neural signal to a second detection threshold during the second detection window;
• and
• a control circuit configured to control the delivery of the neurostimulation pulses using a stimulation intensity, the control circuit including a stimulation parameter adjustor configured to adjust the stimulation intensity in response to a specified number of the evoked responses not detected for a specified number of the neurostimulation pulses delivered.

A non-transitory computer-readable storage medium including instructions, which when executed by a system, cause the system to perform a method for delivering neurostimulation to a body having a vagus nerve and a laryngeal muscle, the method comprising:

• delivering neurostimulation pulses to the vagus nerve;
• controlling the delivery of the neurostimulation using a stimulation intensity;
• sensing a physiological signal indicative of evoked responses each being a physiologic event evoked by one of the neurostimulation pulses;
• control ling timing of one or more detection windows based on a type of a response of the evoked responses anticipated to be detected within each window of the one or more detection windows;
• detecting one of the evoked responses during a detection window of the one or more detections windows for each pulse of the neurostimulation pulses delivered;
• and
• adjusting the stimulation intensity in response to a specified first number of the evoked responses not detected for a specified second number of the neurostimulation pulses delivered.