Electrical Stimulation for Recovery of Ankle Dorsiflexion in Chronic Stroke Survivors

Ankle dorsiflexor weakness results in inefficient and unstable gait. While routine physical therapy is beneficial, for many individuals it remains limited in its effectiveness, and consequently many stroke survivors have difficulty walking safely or remain non-ambulatory. Ankle-foot-orthoses (AFOs) are often prescribed to provide ankle stability, but because they limit ankle mobility they may actually inhibit recovery of dorsiflexion. Advanced rehabilitation techniques that emphasize active, repetitive, goal-oriented movement of the impaired limb have produced measurable functional improvements, yet a significant degree of lower extremity disability often remains. In addition, some of these emerging therapies are difficult to administer and are applicable only to patients who retain at least some degree of ambulation. Thus, there is a need for alternative treatments. This is an exploratory study of an innovative neuromuscular electrical stimulation (NMES) treatment for restoring lower extremity motor control following stroke. We will investigate whether stroke survivors with chronic footdrop recover voluntary ankle dorsiflexion after a novel treatment of NMES. Surface electrodes will deliver stimulation to dorsiflex the ankle with an intensity that is proportional to the amount of dorsiflexion of the other unimpaired ankle. Thus, voluntary dorsiflexion of the unaffected ankle produces stimulated dorsiflexion of the affected ankle. We refer to this stimulation paradigm as Contralaterally Controlled Neuromuscular Electrical Stimulation (CCNMES). In contrast to existing peroneal nerve stimulators, CCNMES is not intended to be used to assist ambulation; rather it is intended as solely a motor retraining paradigm that may reduce lower extremity impairment and improve ambulation. The primary objective of the proposed study is to obtain pilot data so that an estimate can be made of the efficacy of CCNMES in reducing lower extremity impairment and improving ambulation. Twenty-six chronic stroke survivors (\>6 months post-stroke) will be randomized to either CCNMES or cyclic NMES, an intervention that provides electrical stimulation of the ankle dorsiflexors, but with preprogrammed timing and intensity. For both groups, the treatment will last 6 weeks. Assessments of ankle impairment and ambulation will be made at baseline and at end of treatment. This study is the first randomized controlled trial of CCNMES for restoring ankle dorsiflexion in patients with chronic hemiplegia.