Surface electrical stimulation for facial paralysis is not harmful

Abstract

Introduction Does electrical stimulation (ES) of denervated muscles delay or prevent reinnervation, or increase synkinesis? In this retrospective study we evaluate the outcome, with and without ES, of patients with acutely denervated facial muscles. Methods The effect of ES was analyzed in two experiments. In the first experiment, 39 patients (6 with home‐based ES, median 17.5 months) underwent facial nerve reconstruction surgery. Time to recovery of volitional movements was analyzed. The second experiment involved 13 patients (7 with ES, median 19 months) during spontaneous reinnervation. Sunnybrook and eFACE scores provided functional outcome measures. Results No difference in time of reinnervation after facial nerve reconstruction surgery was seen between the patients with and without ES (median [interquartile range]: 4.5 [3.0‐5.25] vs 5.7 [3.5‐9.5] months; P = .2). After spontaneous reinnervation, less synkinesis was noted (Sunnybrook synkinesis score: 3.0 [2.0–3.0] vs 5.5 [4.75‐7.0]; P = .02) with ES. Discussion We find no evidence that ES prevents or delays reinnervation or increases synkinesis in facial paralysis.

Selective Electrical Surface Stimulation to Support Functional Recovery in the Early Phase After Unilateral Acute Facial Nerve or Vocal Fold Paralysis

“…The mean motor nerve latencies and compound muscle action potential amplitudes of both facial muscles were statistically shorter after electrical stimulation. Puls et al compared patients with spontaneous regeneration without and with biphasic triangular electrical stimulation after typical etiologies (for instance, postsurgical, idiopathic, infectious) for severe degenerative facial nerve lesion ( 52 ). On average, an amplitude of 14 mA (range 6–20) and a pulse duration of 110 ms (range 100–280) was used.…”

“…Outcomes were quantified using standardized grading systems. According to this grading, synkinesis was significantly lower with than without electrical stimulation ( 52 ). In a recent small but long prospective observational study, Arnold et al also included three patients with early onset (15 days to 3.5 months) of electrical stimulation of the zygomatic muscle as home training after facial nerve lesion during schwannoma surgery with spontaneous regeneration or after facial nerve repair ( 22 ).…”

“…Both blink studies can be interpreted in such a way that very short pulse durations (<1 ms) are able to stimulate intact muscle fibers but not denervated muscles fibers. The studies from Puls et al or Arnold et al clearly show that short-term denervated facial muscles fibers need pulse duration of about 50–200 ms to be effective and tolerable ( 22 , 52 ).…”

“…In the early phase of facial palsy, electrical stimulation of the denervated facial muscles seems to be optimal with pulse lengths of 50–200 ms. Most of the published reports focus on the zygomatic muscle ( 22 , 52 ). Some data have been published for frontalis, corrugator supercilii, palpebral part of orbicularis oculi, levator labii superioris alaeque nasi, levator labii superioris, levator anguli oris, risorius, orbicularis oris, depressor anguli oris, depressor, labii inferioris, and levator menti muscles ( 56 ).…”

Can MRI quantify the volume changes of denervated facial muscles?

“…Recently, we conducted a research that proves that FES for facial musculature is tolerable and does not delay or in any way interrupt the reinnervation process and does not contribute to the synkinesis. 13,14 What we are interested in, is the use of FES training therapy in cases of complete peripheral facial paralysis and the use of MRI as a method to quantify the changes.…”