J Korean Neurosurg Soc.  2012 Oct;52(4):372-376. 10.3340/jkns.2012.52.4.372.

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

  • 1Department of Neurosurgery, Cerebro-Vascular Center, Bongseng Memorial Hospital, Busan, Korea.
  • 2Department of Neurosurgery, Cerebro-Vascular Center, Dong-Rae Bongseng Hospital, Busan, Korea.
  • 3Department of Neurosurgery, Cerebro-Vascular Center, Dong-San Medical Center, Keimyung University School of Medicine, Daegu, Korea. ppori2k@naver.com


The 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.
Continuous 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.
Intra-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).
It 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.


Clinical outcome; Hemifacial spasm; Lateral spread response; Microvascular decompression

MeSH Terms

Follow-Up Studies
Hemifacial Spasm
Microvascular Decompression Surgery
Prospective Studies


  • Fig. 1 Mean value of the improved percentage of the spasm compared to the initial symptom according to the follow-up duration. This graph shows remarkable differences in these values between Groups A and B, since the post-operative one-year follow-up.


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