Stimulator for Treating Post-stroke Shoulder Subluxation

A miniature stimulator was developed to drive a set of percutaneous wire electrodes implanted into the shoulder muscles for treating shoulder subluxation and pain in stroke survivors. The 8-channel stimulator was built around a low-power microcontroller and packaged into a pager-sized box. A single AA-size battery can power the device for about 50 hours of operation. Stimulation pulse trains with duty cycle of 10-sec on and 8-sec off were applied 6 hours per day for 6 weeks. Among the 7 chronic subjects enrolled in the study, shoulder subluxation was reduced from a median of 7mm to 3mm (p=0.05) as evidenced by radiograph; pain intensity decreased from 5 to 0 (p=0.03) as reported on the Brief Pain Inventory. The preliminary clinical tests showed that the device was well accepted by the users and the intervention may be effective for the indicated use.