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.

Inclusion Criteria:

- Age 21 to 80 years

- >6 months from a first clinical non-hemorrhagic or hemorrhagic stroke

- Medically stable

- Unilateral lower extremity hemiparesis

- Ankle dorsiflexor strength of ≤4/5 on the Medical Research Council (MRC) scale, while
seated

- Able to ambulate 16 feet (5 meters) continuously with minimal assistance or less,
without the use of an ankle-foot orthosis (AFO).

- AFO is clinically indicated (footdrop during ambulation or inefficient gait patterns)

- Neuromuscular electrical stimulation (NMES) of the paretic ankle dorsiflexors produces
ankle dorsiflexion to neutral without pain.

- Full voluntary dorsiflexion of the contralateral ankle

- Skin intact on hemiparetic lower extremity

- Able to don the NMES system or caregiver available to assist with device if needed.

- Able to hear and respond to stimulator auditory cues

- Able to follow 3-stage commands

- Able to recall 2 of 3 items after 30 minutes

Exclusion Criteria:

- Brainstem stroke

- Severely impaired cognition and communication

- History of peroneal nerve injury

- History of Parkinson's, spinal cord injury, traumatic brain injury, or multiple
sclerosis

- Uncontrolled seizure disorder

- Uncompensated hemi-neglect (extinguishing to double simultaneous stimulation)

- Edema of the affected lower extremity

- Absent sensation of lower leg and foot

- Evidence of deep venous thrombosis or thromboembolism

- History of cardiac arrhythmias with hemodynamic instability

- Cardiac pacemaker or other implanted electronic system

- Botulinum toxin injections to any lower extremity muscle in the last 3 months

- Pregnancy

- Currently receiving Physical Therapy for the lower extremity