Long-term outcomes of semi-implantable functional electrical stimulation for central drop foot.

BACKGROUND: Central drop foot is a common problem in patients with stroke or multiple sclerosis (MS). For decades, it has been treated with orthotic devices, keeping the ankle in a fixed position. It has been shown recently that semi-implantable functional electrical stimulation (siFES) of the peroneal nerve can lead to a greater gait velocity increase than orthotic devices immediately after being switched on. Little is known, however, about long-term outcomes over 12 months, and the relationship between quality of life (QoL) and gait speed using siFES has never been reported applying a validated tool. We provide here a report of short (3 months) and long-term (12 months) outcomes for gait speed and QoL. METHODS: Forty-five consecutive patients (91% chronic stroke, 9% MS) with central drop foot received siFES (Actigait®). A 10 m walking test was carried out on day 1 of stimulation (T1), in stimulation ON and OFF conditions, and repeated after 3 (T2) and 12 (T3) months. A 36-item Short Form questionnaire was applied at all three time points. RESULTS: We found a main effect of stimulation on both maximum (p < 0.001) and comfortable gait velocity (p < 0.001) and a main effect of time (p = 0.015) only on maximum gait velocity. There were no significant interactions. Mean maximum gait velocity across the three assessment time points was 0.13 m/s greater with stimulation ON than OFF, and mean comfortable gait velocity was 0.083 m/s faster with stimulation ON than OFF. The increase in maximum gait velocity over time was 0.096 m/s, with post hoc testing revealing a significant increase from T1 to T2 (p = 0.012), which was maintained but not significantly further increased at T3. QoL scores showed a main effect of time (p < 0.001), with post hoc testing revealing an increase from T1 to T2 (p < 0.001), which was maintained at T3 (p < 0.001). Finally, overall absolute QoL scores correlated with the absolute maximum and comfortable gait speeds at T2 and T3, and the increase in overall QoL scores correlated with the increase in comfortable gait velocity from T1 to T3. Pain was reduced at T2 (p < 0.001) and was independent of gait speed but correlated with overall QoL (p < 0.001). CONCLUSIONS: Peroneal siFES increased maximal and comfortable gait velocity and QoL, with the greatest increase in both over the first three months, which was maintained at one year, suggesting that 3 months is an adequate follow-up time. Pain after 3 months correlated with QoL and was independent of gait velocity, suggesting pain as an independent outcome measure in siFES for drop foot.

Electric stimulation of the medial forebrain bundle influences sensorimotor gaiting in humans.

BACKGROUND: Prepulse inhibition (PPI) of the acoustic startle response, a measurement of sensorimotor gaiting, is modulated by monoaminergic, presumably dopaminergic neurotransmission. Disturbances of the dopaminergic system can cause deficient PPI as found in neuropsychiatric diseases. A target specific influence of deep brain stimulation (DBS) on PPI has been shown in animal models of neuropsychiatric disorders. In the present study, three patients with early dementia of Alzheimer type underwent DBS of the median forebrain bundle (MFB) in a compassionate use program to maintain cognitive abilities. This provided us the unique possibility to investigate the effects of different stimulation conditions of DBS of the MFB on PPI in humans. RESULTS: Separate analysis of each patient consistently showed a frequency dependent pattern with a DBS-induced increase of PPI at 60 Hz and unchanged PPI at 20 or 130 Hz, as compared to sham stimulation. CONCLUSIONS: Our data demonstrate that electrical stimulation of the MFB modulates PPI in a frequency-dependent manner. PPI measurement could serve as a potential marker for optimization of DBS settings independent of the patient or the examiner.

Active prosthesis dependent functional cortical reorganization following stroke.

The present study investigated the neural correlates associated with gait improvements triggered by an active prosthesis in patients with drop-foot following stroke during the chronic stage. Eleven patients took part in the study. MEG recordings in conjunction with somatosensory stimulation of the left and right hand as well as gait analyses were performed shortly before or after prosthesis implantation surgery and 3-4 months later. Plastic changes of the sensorimotor cortex of the ipsi- and contralesional hemisphere were revealed. Gait analysis indicated that all patients improved their gait with the active prosthesis. Patients with larger plastic changes within the lesioned hemisphere maintained their improved gait performance even when the prosthesis was turned off. Patients with larger contralesional changes also improved their gait with the active prosthesis. However, their gait measures decreased when the prosthesis was turned off. The current data provide the neural basis of gait improvement triggered by an active prosthesis and has important implications with respect to the choice of the type of active prosthesis (implantable vs removable) and to the selection procedure of the patients (length of testing period).

Functional electrical stimulation through direct 4-channel nerve stimulation to improve gait in multiple sclerosis: a feasibility study.

BACKGROUND: Gait dysfunction due to lower limb central paralysis, frequently involving drop foot, is a common cause of disability in multiple sclerosis and has been treated with transcutaneous functional electrical stimulation (FES). We provide here the first report of 4-channel semi-implantable FES of the peroneal nerve which has been successfully used for rehabilitation in patients following stroke. METHODS: FES was implemented via a 4-channel semi-implantable closed-loop system (ActiGait(®), ©Ottobock), generating dorsiflexion in drop foot. Walking distance, gait symmetry (temporospatial gait analyses, Vicon Motion Systems(®)), gait velocity (10 m walking test) and quality of life (SF-36 questionnaire) were measured to evaluate the therapeutic benefit of this system in two patients with progressive MS. RESULTS: Walking distance increased from 517 to 1884 m in Patient 1 and from 52 to 506 m in Patient 2. Gait velocity did not change significantly in Patient 1 and increased from 0.6 to 0.8 m/s in Patient 2. Maximum deviations of center of mass from the midline to each side changed significantly after 3 months of stimulation compared to baseline, decreasing from 15 to 12 mm in Patient 1 and from 47 to 37 mm in Patient 2. Both patients experienced reduced pain and fatigue and benefits to quality of life. Adverse events did not occur during the observation period. CONCLUSION: We conclude that implantable 4-channel FES systems are not only feasible but present a promising new alternative for treating central drop foot in MS patients.