Treatment of Shoulder Subluxation in Chronic Stroke Patients

Overview

The study looks at treatments for reversing chronic shoulder subluxation after a stroke. It compares electrical stimulation with surface electrodes (stimulation through the skin) with intra-muscular stimulation (from inside the muscle)using an implanted micro-stimulator (BION). Subjects are put either in a surface stimulation or a BION® group. In the BION® group, two BION®s are implanted in the shoulder, the medial deltoid and supraspinatus muscles. Treatment consists of a baseline of 6 weeks, and 6 weeks of therapy, consisting of 2 sessions per day for 10 to 30 minutes each time. This is followed by 6 weeks without therapy. If testing shows that after 6 weeks of therapy there is no reversal of subluxation, more intense therapy is carried out for another 6 weeks. Treatment is similar in the surface electrode group, but surface electrodes deliver the stimulation instead of BION®s. A total of 30 subjects is expected to complete the study.

The BION™ is a novel implantable neuromuscular stimulator whose intended use in this study is to reanimate the shoulder muscles of stroke survivors with shoulder subluxation. Strokes are considered to be the most important cause of adult disability in North America, with 500,000 new cases per year in the U.S. (National Stroke Association) and 45,000 in Canada (Langton-Hewer, 1990; Shuaib \& Hachinski, 1991). Three-quarters of these patients survive and half of the survivors have substantial muscle weakness after 6 months (Gresham et al., 1979) with little chance of spontaneous recovery (Anderson, 1990; Bonita \& Beaglehole, 1988). The most commonly affected region in the early phases of recovery is the shoulder; 80% of hemiplegic stroke patients suffer from shoulder subluxation and associated chronic pain (Smith et al., 1980). The shoulder muscles that are normally active tonically are flaccidly paralyzed; the weight of the pendant arm gradually stretches and damages the atrophic muscles and ligaments, allowing the head of the humerus to descend out of the glenoid fossa. This results in chronic shoulder pain that is difficult to treat and tends to obstruct physical therapy directed toward regaining some use of the paretic arm. Our hypothesis is that electrical stimulation delivered by the BIONs should be fundamentally equivalent to muscle activation achieved voluntarily or by transcutaneous electrical nerve stimulation (TENS), but that the BIONs will prove to be a more clinically acceptable and effective approach. The BION system consists of the BION implants themselves, a controller that is operated by the study participant, and fitting hardware and software used by the clinician to implant, test, and program BION function. In this study, the BION will be used to reanimate the shoulder muscles of stroke survivors experiencing shoulder subluxation. The objective of this study is to evaluate the safety and efficacy of intramuscular stimulation of BIONs to correct established, symptomatic shoulder subluxation in chronic stroke survivors. The results of intramuscular stimulation by BIONs will be compared with the results of treatment with conventional therapy: surface stimulation. Degree of shoulder subluxation will be the primary outcome measure for the study. We have included other (secondary) outcome measures (i.e., muscle strength, range of motion, functional activity, spasticity/tone, subject satisfaction and pain) which may reveal secondary benefits of treatment with BIONs. The investigation is expected to last up to 21 weeks for each study participant. The study will be completed over a 5-year period.