Effects of biofeedback versus switch-triggered functional electrical stimulation on sciatica-related foot drop.

BACKGROUND

Sciatica-related Foot Drop is a peripheral nervous condition that produces a loss of power in the ankle dorsiflexion muscles. Functional electrical stimulation is a modality of electrical stimulation that produces muscle contraction in a functional movement of the limb. This technique was utilized with positive effects in central nervous afflictions but it is not known whether or not it has any influence in motor recovery following peripheral nervous system problems. This study aims to clarify the effects of functional electrical stimulation on foot drop caused by peripheral nerve compression resulting from lumbar disc herniation.

METHODS

Fifty patients were enrolled in our study; of whom 25 were treated with EMG triggered electrical stimulation (EMG-FES) and 25 with heel-floor sensor triggered electrical stimulation (SWITCH-FES) during normal gait cycle. Patients received functional electrical stimulation (with a pulse of 60 Hz and phase duration of 200 ms) once a day, for 30 minutes during 5 consecutive days, over a period of 4 weeks. Electrical diagnostic tests (nerve conduction velocity/NCV and the amplitude of compound muscle action potential/CMAP), dynamometry and Osvestry Disability Index scores were measured at baseline and after treatment.

RESULTS

We found that axonal loss was lower in the EMG-FES group than in the SWITCH-FES group (p< 0.004). The motor functional recovery was higher in terms of muscle force and overall functional status for the EMG-FES group compared to the SWITCH-FES group. This was underlined by Dynamometry test with a p value of < 0.0001 and ODI score with a statistical significant p value of < 0.0001.

CONCLUSIONS

The overall results showed that there was a significant increase in all the parameters studied for both types of FES applications. However we found that the EMG triggered electrical stimulation technique had a higher influence on the quality of the muscle action control. For patients who cannot yet produce minimal muscle active contraction we recommend switch triggered stimulation first and then, immediately after the recovery of the motor control, to change to EMG triggered functional electrical stimulation.