Habitual Functional Electrical Stimulation Therapy Improves Gait Kinematics and Walking Performance, but Not Patient-Reported Functional Outcomes, of People with Multiple Sclerosis who Present with Foot-Drop

Abstract

BackgroundPeople with Multiple Sclerosis (pwMS) often experience a disturbed gait function such as foot-drop. The objective of this pilot study was to investigate the medium term effects of using Functional Electrical Stimulation (FES) to treat foot-drop over a period 12 weeks on gait and patient reported outcomes of pwMS.Methods and FindingsNine pwMS aged 35 to 64 (2 males, 7 females) were assessed on four occasions; four weeks before baseline, at baseline and after six weeks and twelve weeks of FES use. Joint kinematics and performance on the 10 meter and 2 minute walk tests (10WT, 2 minWT) were assessed with and without FES. Participants also completed the MS walking Scale (MSWS), MS impact scale (MSIS29), Fatigue Severity Score (FSS) and wore an activity monitor for seven days after each assessment. Compared to unassisted walking, FES resulted in statistically significant improvements in peak dorsiflexion in swing (p = 0.006), 10MWT (p = 0.006) and 2 minWT (p = 0.002). Effect sizes for the training effect, defined as the change from unassisted walking at baseline to that at 12 weeks, indicated improved ankle angle at initial contact (2.6°, 95% CI −1° to 4°, d = 0.78), and a decrease in perceived exertion over the 2 min walking tests (−1.2 points, 95% CI −5.7 to 3.4, d = −0.86). Five participants exceeded the Minimally Detectable Change (MDC) for a training effect on the 10mWT, but only two did so for the 2 minWT. No effects of the use of FES for 12 weeks were found for MSWS, MSIS29, FSS or step count.ConclusionAlthough FES to treat foot-drop appears to offer the potential for a medium term training effect on ankle kinematics and walking speed, this was not reflected in the patient reported outcomes. This observed lack of relationship between objective walking performance and patient reported outcomes warrants further investigation.Trial RegistrationClinicalTrials.gov NCT01977287

Orthotic and therapeutic effect of functional electrical stimulation on fatigue induced gait patterns in people with multiple sclerosis

“…The present data suggests that for people with MS who walk faster than 0.8m/s the benefits of FES on walking speed and gait mechanics may require more time before changes occur due to the need to become conditioned to the stimulation and adapt their gait pattern to its action. The findings of van der Linden et al [29,32] lend support to this suggestion since their work showed positive orthotic effects of FES on walking speed, spatiotemporal parameters and kinematics of the hip, knee and ankle in groups of people with MS with mean walking speeds around 0.8 m/s but still less than that of the participants in the current study. Additionally, our own findings indicating that clinically meaningful increases in walking speed (i.e.…”

“…It is interesting to note that in some instances the values return to non-fatigued levels. The fact that at both the baseline and week 8 assessments there was no change in ankle angles at initial contact or during swing, as has been reported previously [29,32], may be due to our inclusion criteria whereby our participants had an EDSS score range of 3-4 and could reach at least a neutral ankle angle. While the stimulation did not significantly change the angle of the ankle during gait it is evident it had other beneficial effects on mechanics of the lower limb, including at the ankle.…”

“…This reflects the combined effect of the orthotic effect superimposed on the training effect over time. Positive training effects and total orthotic effects of FES on walking speed and ankle kinematics have been reported in people with MS [32].…”

“…When FES is used for the first time these effects have been termed an 'initial orthotic effect" of the stimulation [28]. Recent evidence shows the initial orthotic effects of FES on the gait of people with MS extend to improvements in the overall kinematic pattern of lower limbs during gait [27,29], including increased ankle dorsiflexion during swing [29,30], and at initial foot contact [29][30][31] leading to increases in stride length [29,32]. The maintenance of an orthotic effect with prolonged use of FES has been referred to as a 'continuing orthotic effect' [28].…”

“…Despite the increased interest in the effects of FES on gait in MS [29,30,32], no studies to date have investigated the initial orthotic effect of FES on fatigue induced changes in gait that occur in people with MS [18]. Additionally it remains unclear whether prolonged use of FES delivers continuing orthotic effects and therapeutic effects (i.e.…”