Impulse (Improved Mobility through Implantable Stimulation of Nerves)
The effect of an implantable peroneal nerve stimulator as treatment option for a drop foot in chronic stroke patients in comparison with the conventional treatment

Dropped foot is a condition found in several patient groups, including Multiple Sclerosis, incomplete spinal cord injury and most notably, stroke. Stroke is one of the most common disorders affecting the neuromuscular system. The conventional management of dropped foot has been to use a rigid orthosis to maintain the ankle in a neutral position. This has major limitations as a treatment, being both uncomfortable and awkward to use and hence is often rejected by patients.

Currently, functional electrical stimulation ( FES) systems for the treatment of dropped foot are in clinical use in significant numbers. FES is the artificial stimulation of muscles with the purpose of evoking a motor response. Compared with the use of orthosis electrical stimulation has a number of advantages: it prevents muscle atrophy, the blood flow remains normal or even improves and it is cosmetically better accepted.

The aim of these studies was to evaluate the benefits of the implantable device on impairment, disability and quality of life in comparison with the conventional treatment in stroke patients with a drop foot. Twenty-nine stroke patients with a drop foot participated in a RCT, of which 15 patients received the implantable stimulator, determined by randomization. Different parameters were measured during the six months follow-up period, i.e. walking speed, 6-minute walk test, maximal voluntary contraction, muscle activity, activity level and some questionnaires. The implantable two-channel peroneal nerve stimulator used in the present study was fabricated by Finetech Medical Limited and consists of an external transmitter with a built in antenna, a foot switch, and an implantable part consisting of the stimulator, the two leads and the bipolar intra-neural electrodes. The transmitter weighs approximately 0.1 kg and is attached with a strap on the lateral side of the lower leg, over the site of the implant, just below the knee. One electrode of the implant is placed under the epineurium of the superficial peroneal nerve (eversion) and one under the epineurium of the deep peroneal nerve (dorsiflexion). A footswitch placed under the heel of the patient’s foot inside the shoe determines the on-and-off switching of the stimulation.

This project has been sponsored by:

Eureka program of the Dutch Ministry of Economical Affairs (Senter)

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