Prognostic value of the lateral spread response for intraoperative electromyography monitoring of the facial musculature during microvascular decompression for hemifacial spasm.

Object: The authors conducted a large retrospective study in which they evaluated the efficacy of intraoperative electromyography (EMG) monitoring of facial musculature during microvascular decompression (MVD) and assessed the predictive value of the lateral spread response (LSR) as a prognostic indicator for the treatment outcome of hemifacial spasm (HFS).

Methods: The authors undertook intraoperative monitoring during MVD in 300 consecutive patients with HFS. The patients were divided into two groups based on whether the LSR disappeared or persisted following decompression.