A New Score to Predict the Risk of Hearing Impairment After Microvascular Decompression for Hemifacial Spasm

Abstract

Background: Intraoperative monitoring of brainstem auditory evoked potentials (BAEPs) has been implemented to reduce the risk of hearing impairment during microvascular decompression for hemifacial spasm.

Objective: To evaluate intraoperative monitoring of BAEPs during microvascular decompression in patients with hemifacial spasm for predicting the risk of hearing impairment after surgery.

Methods: This prospective study included 100 patients. BAEPs were recorded for all patients. We established a scoring system for the changes in wave I amplitude, I-III interpeak latency, and wave V amplitude and latency. For each change, total points were calculated, and a score out of 6 was assigned to every patient. We classified the patients based on the points scored into 3 risk groups: low-risk (0-3), medium-risk (4-5), and high-risk (6). Further, the correlation between the score and the hearing outcome was evaluated to detect the incidence and degree of hearing impairment.

Results: Eighty-seven patients scored 0 to 3, 10 scored 4 to 5, and 3 scored 6. The degree of hearing impairment was proportionate to the score recorded at the end of surgery, and patients in the low-risk group showed no impairment; medium-risk group, deterioration of maximum 2 grades according to World Health Organization classification of hearing impairment; and high-risk group, deterioration of 3 to 4 grades.

Conclusion: Intraoperative monitoring of BAEPs evaluated through our scoring system was valuable in predicting hearing impairment after surgery.

Keywords: BAEPs; Endoscope assisted; Hemifacial spasm; Intraoperative monitoring; Microvascular decompression.