A reappraisal of the value of lateral spread response monitoring in the treatment of hemifacial spasm by microvascular decompression

Abstract

Background: Primary hemifacial spasm (HFS) has specific electrophysiological features, like the existence of lateral spread responses (LSRs) to the stimulation of facial nerve branches. The curative treatment of HFS is based on surgical microvascular decompression (MVD), although the outcome of this procedure is not always satisfactory.

Objective: To evaluate the correlation between intraoperative LSR changes after MVD and the short- and long-term postoperative clinical outcomes.

Methods: Thirty-two consecutive patients with primary HFS treated by MVD performed with intraoperative LSR monitoring were retrospectively included. The patients were assessed for the presence of HFS and surgical complications at one day, one month, and six months after surgery. Long-term clinical result was assessed between one and 10 years (mean 5.4 years) using a self-report questionnaire.

Results: Patients were divided into three groups based on intraoperative LSR changes: (i) in 15 patients, LSRs were present before incision and disappeared after MVD (47%); (ii) in nine patients, LSRs were present before incision but persisted despite MVD (28%); (iii) in eight patients, LSRs were absent before surgery and remained so after the procedure (25%). Intraoperative LSR abolition during the MVD procedure correlated with HFS relief in the long term (p< 0.0001, Fisher’s exact test), but not on the first day after surgery (p= 0.3564).

Conclusions: Monitoring MVD by intraoperative LSR recording could be of value not only to indicate the resolution of the vasculo-nervous conflict at the end of surgery, but also to indicate a positive clinical outcome in the long term after the surgical intervention.