Efficacy of the WalkAide and AFOs for CVA

To assess the effectiveness of a new stimulator (WalkAide) for the treatment of foot drop. The comparison will involve physical measurements (e.g. walking speed, physiological cost index, Modified Rivermead Mobility Index, etc.) and questionnaires on the quality of life and acceptance of the technology by stroke survivors.

Stroke is the third leading cause of death in the United States and other developed countries and a major source of disability, often leading to hospitalization. Prognosis for regaining the ability to walk is good, with 64% of those initially dependent in walking regaining independence by three months. However, many gait abnormalities persist.

Reduced hip, knee and ankle excursions during swing are among the persistent gait abnormalities contributing to poor or inefficient limb clearance. This is generally referred to as "foot drop", since the foot drops or drags along the ground during the swing phase. Swing phase abnormalities can result in decreased velocity, limited endurance and an increased risk for falls. These factors can limit mobility and independence in the community. Therefore, intervention is warranted.

The conventional approach to address the poor swing limb function, specifically, insufficient ankle dorsiflexion, is the prescription of an ankle-foot orthosis (AFO). An AFO commonly limits ankle plantarflexion to enhance limb clearance during swing. An alternative approach is to stimulate the ankle dorsiflexors electrically during swing phase to reproduce motion, which can no longer be performed volitionally.

The WalkAide is a new foot drop stimulator. This small, self-contained device attaches to the leg below the knee. The WalkAide contains a number of patented features, including a tilt sensor that measures the orientation of the leg with respect to the vertical. When the leg is tilted back at the end of stance, stimulation of the common peroneal nerve is initiated. This produces flexion of the ankle and other joints (if a flexion reflex is elicited) so that the leg can clear the ground during swing. When the leg is tilted forward at the end of swing phase, the stimulus is terminated. The electrodes attach to the inside of a cuff that is molded to the leg for reproducible positioning from day to day. The device is also designed so that all operations can be done with a single hand, since hemiparesis may prevent the subject from using the other hand. Because of its enhanced features, the WalkAide is anticipated to increase walking speed and improve the quality of life.

Eligibility Criteria:
Inclusion Criteria:

1. Adults aged 18 years or older
2. Diagnosed with cerebrovascular accident (CVA) within the last 365 days
3. Inadequate dorsiflexion during the swing phase of gait, resulting in inadequate limb clearance
4. Medically stable for six months prior to the most recent episode of stroke resulting in hemiplegia or hemiparesis with foot drop
5. Medical clearance by the attending physician to participate in the study
6. Expectation that current medication can be maintained without drastic change for at least six months
7. Adequate stability at the ankle during stance (with stimulation)
8. Adequate cognitive and communication function to give informed consent, understand the training instructions, use the device and give adequate feedback
9. Ability to ambulate with or without an assistive device (or assistance) at least 10 meters

Exclusion Criteria:

1. Lower motor neuron injury with inadequate response to stimulation
2. History of falls greater than once a week prior to the CVA
3. Severe cardiac disease such as myocardial infarction, congestive heart failure or a demand pacemaker (or other electrical stimulator)
4. Fixed ankle contractures of five degrees of plantarflexion with knee extended
5. Moderate to normal ambulation velocity (greater than 1.2 m/s)
6. Unable to operate the device safely by self and caregiver assistance not available
7. Need for an AFO for stance control of the foot, ankle and/or knee
8. Comorbid conditions unlikely to survive one year
9. Pre-existing history of seizure disorder prior to most recent episode of CVA
10. Pre-existing pathology resulting in a significant disruption in alignment or function of the lower extremity
11. Morbid obesity that limits the subject's response to stimulation due to adipose tissue \[BMI \> 40\]
12. Excessive dysesthetic pain secondary to neurological involvement
13. Severe hypertonicity resulting in the need for more involved orthotic strategies or pharmacological interventions (e.g. Botox)