gms | German Medical Science

Objective: Stroke pts present often with drop foot due to 1^st motoneuron damage. This may prevail despite rehabilitation and use of walking aids. It can alter gait symmetry, stability and walking distance. Unphysiologic gait patterns can lead to pain under prolonged walking. FES of the peroneal nerve using a 4channel cuff electrode is a relatively new method to treat central drop foot. Aim of this study is to evaluate safety of the operational procedure and monitoring of gait parameters. In addition the influence on quality of life (QoL) is examined.

Method: 15 pts received a 4channel cuff electrode with subcutaneous antenna for FES of the peroneal nerve via a programmable external pulse generator (Actigait^®, ottobock). We examined operative and postoperative complications, gait velocity, shift of center of mass (CoM) during walking using temporospatial gait analysis (Vicon Motion Systems). QoL parameters were assessed by SF36 questionnaire before, 3 and 12 months after system activation.

Results: During the observation period there were no procedural complications. We observed one hematoma of the subcutaneous antenna pocket which was evacuated for patient comfort and in one case an atypical course of the antenna wiring without functional consequences. Infection rate was 0%. Technical defects or nerve damage were not observed. Gait analysis: Increase in gait velocity after system activation with further increase after 3 and 12 months (aov tp: F=6,2; p=0,02) with higher velocity in on- than in off-mode at every time point (aov mode: F=8,5; p<0,01). There was a lower shift of CoM towards the unaffected body side after 3 months and the difference between on and off diminished with therapy duration (aov tpxmode: F=14, p=0,03). QoL measures showed an improvement of physical health (t=2,3; df=7; p=0,05), general health (t=3,3; df=7; p=0,01) and in overall score (t=2,4; df=7; p=0,04) after 3 months. There was a marked reduction of pain after 3 and still after 12 months (F=4,2; df=2; p=0,03).

Conclusions: FES using a semi-implantable closed loop system in pts suffering from central drop foot seems to be a safe functional neurosurgical procedure. In this case series an improvement towards physiological gait patterns was observed. Along with reduction of physical pain and improvement of physical health an increase of QoL was noted. Improvements gained after prolonged stimulation seem to persist during the off-mode. These observations need confirmation by a higher number of cases and long-term observations.