Introduction to Automatic Adaption
Effective SCS therapy requires that stimulation-induced paresthesia be comfortable and provide coverage of the patient’s painful areas. During posture changes the distance between the spinal cord and stimulating electrodes change as the spinal cord moves in the subarachnoid space changing the perception of stimulation. To maintain optimal paresthesia during posture changes, the stimulation intensity must vary as the distance between the cord and electrodes varies. Currently, SCS patients must adjust their stimulation intensity manually to maintain consistent paresthesia, which can be burdensome for some SCS patients. In this study we examine the feasibility of automatic adjustment of the stimulation amplitude of an implantable neurostimulator as a patient changes body position.
Methods of Automatic Adaption
Twenty patients (ages 43-66 years; 6 men and 14 women) previously implanted with a Restore® or RestoreAdvanced® implantable neurostimulation system (Medtronic, Inc., Minneapolis, MN) for ≥ 3 months for chronic low back and/or leg pain enrolled in the study. Sixteen patients completed an in-clinic analysis during which study instrumentation externally fitted on patients was used to telemeter accelerometer signals to a specially designed programmer that adjusted the stimulation output of the patients’ neurostimulators in response to positional changes. Patient satisfaction ratings were recorded during various physical tasks under automatic stimulation adjustment and manual adjustment. Patients’ preferred therapy amplitudes and therapy impedances were recorded for eight different postures.
Results of Automatic Adaption
Patients were more satisfied with automatic than manual adjustments. Significant differences in preferred stimulation amplitudes from the standing to supine positions were identified. Therapy impedance did not vary with posture changes.
Conclusions from Automatic Adaption
This study demonstrated the feasibility of a neurostimulation system with an accelerometer sensor that automatically adjusts stimulation amplitude based on sensed patient position.
This work was supported through funding by Medtronic, Inc.