The effects of an implantable FES device (Actigait) on walking skills in stroke patients with a drop foot

In the Netherlands, every year 30.000 people sustain a cerebrovasular accident
(CVA or stroke). Although a large proportion of these people (approximately
60%) experience partly recovery, irreversible physical impairments remain. An
estimated 20% of strokes result in a drop foot, which is caused by the
inability to (efficiently) activate the muscles that dorsiflex the ankle joint.
While walking, patients with a drop foot tend to drag the foot during the swing
phase (lack of toe clearance), which places them at risk for tripping.
Furthermore, a drop foot usually is part of a general stereotyped walking
pattern of the affected leg, characterized by insufficient knee and hip flexion
during swing. This lack of flexion predominantly causes stroke patients to
experience difficulties when stepping over obstacles, due to insufficient foot
clearance.
Recently, a new (implanted) FES system has been developed for stroke patients
with a drop foot. This system is expected to improve walking ability, not only
on regular, but even more on irregular terrain. On irregular terrain, the
locomotor pattern has to be continuously adjusted in order not to stumble or
fall. These complex gait skills are essential for independent and safe mobility
in daily life and highly associated with fall incidence. Especially in this
domain of complex gait skills, Actigait® is expected to be superior to a
conventional AFO or orthopedic shoes. Also walking efficiency, in terms of
energy cost, is expected to benefit from the Actigait® system.

The main goal of this study is to evaluate the effectiveness of Actigait on
walking skills in stroke patients with a drop foot.

Step 1: Patients will be informed about this study by their physiatrists and
eligible patients will be invited to participate. A 90-minute intake visit will
be planned with the physiatrists of the department of rehabilitation in
Nijmegen or Amsterdam. One week after the intake visit, an external FES system
will be provided and adjusted to the patient. In addition, a baseline gait
assessment will be scheduled at the mobility labs in Nijmegen and Amsterdam.
During this visit, the quality of gait will be assessed when walking (if
applicable, with AFO). After 4 weeks, the functional response to the external
stimulation will be evaluated. When a good response to the external FES device
is present, the patient will be admitted to step 2 of the study.
Step 2: The Actigait system will be implanted in a 45-minutes neurosurgical
procedure. Ten days after surgery, the system will be set up and the patient
can start its use. Repeated gait assessments will be conducted at 3 (Nijmegen
only), 9, and 26 weeks, both with and without stimulation. In week 2, 3, 4, 6,
9 en 26 of step 2, a telephone interview will be held to evaluate the extent of
usage and the activities performed with Actigait. Activity level will be
monitored in week 1 of step 1 and in week 8 en 25 of step 2 by means of a
pedometer.

Implantation and usage of an FES system to correct drop foot

The common risks associated to (minor) surgical procedures to the extremities,
like wound infections, apply to this study. The use of a cuff-electrode around
the n. peroneus communis could theoretically lead to nerve damage when the
electrode used is too small. In a prior study on the safety of the Actigait
system by Burridge et al. (2007) no such events occurred. Furthermore, no
additional device-related adverse events occurred during a 15-months follow-up
period.