Efficacy of the Disappearance of Lateral Spread Response before and after Microvascular Decompression for Predicting the Long-Term Results of Hemifacial Spasm Over Two Years

Abstract

ObjectiveThe purpose of this large prospective study is to assess the association between the disappearance of the lateral spread response (LSR) before and after microvascular decompression (MVD) and clinical long term results over two years following hemifacial spasm (HFS) treatment.MethodsContinuous intra-operative monitoring during MVD was performed in 244 consecutive patients with HFS. Patients with persistent LSR after decompression (n=22, 9.0%), without LSR from the start of the surgery (n=4, 1.7%), and with re-operation (n=15, 6.1%) and follow-up loss (n=4, 1.7%) were excluded. For the statistical analysis, patients were categorized into two groups according to the disappearance of their LSR before or after MVD.ResultsIntra-operatively, the LSR was checked during facial electromyogram monitoring in 199 (81.5%) of the 244 patients. The mean follow-up duration was 40.9±6.9 months (range 25-51 months) in all the patients. Among them, the LSR disappeared after the decompression (Group A) in 128 (64.3%) patients; but in the remaining 71 (35.6%) patients, the LSR disappeared before the decompression (Group B). In the post-operative follow-up visits over more than one year, there were significant differences between the clinical outcomes of the two groups (p<0.05).ConclusionIt was observed that the long-term clinical outcomes of the intra-operative LSR disappearance before and after MVD were correlated. Thus, this factor may be considered a prognostic factor of HFS after MVD.

Fully endoscopic microvascular decompression for hemifacial spasm

“…6,24,38 Other studies have reported that intraoperative LSR accurately predicts clinical outcome. 19 A meta-analysis showed that if the LSR is abolished intraoperatively, the success rate of achieving symptom relief will be 90.5% but will drop to 61% when the LSR cannot be abolished intraoperatively. 34 A study of 322 HFS patients showed a significant predictive value of LSR and a success rate of 94.7% when the LSR was abolished and only 67.3% when it is not.…”

Microvascular decompression for atypical hemifacial spasm: lessons learned from a retrospective study of 12 cases

“…If the LSR remained unstimulated even when increasing the stimulation intensity to the maximal value, we considered the facial nerve to be completely decompressed. 8 …”

“…The stimulating needle electrodes were inserted intradermally over the zygomatic branches of the facial nerve, and a 0.3-msec pulse wave with an intensity of 5-30 mA was used. 8 When the nerve in charge of the frontalis muscle was stimulated, a lateral spread response (LSR) appeared in other facial muscles, including the orbicularis oculi, the orbicularis oris, and the mentalis muscles. During decompression of the offending vessels, the LSR may decrease in amplitude or frequency.…”

Advances in microvascular decompression for hemifacial spasm

“…(2009) studied 32 cases of HFS and concluded that use of intraoperative LRS monitoring could not only predict short term outcomes but also impact long term treatment results. Reports from Kang et al. (2012) and Kim et al.…”