"Fully Endoscopic Microvascular Decompression with Combined Lateral Spread Response and Zhong-Lee Response Monitoring for Hemifacial Spasm: A Consecutive Case Series".

OBJECTIVE

To evaluate the feasibility and clinical value of combined lateral spread response (LSR) and Zhong-Lee response (ZLR) monitoring during fully endoscopic microvascular decompression (E-MVD) for hemifacial spasm.

METHODS

This case series included 18 consecutive patients with hemifacial spasm who underwent E-MVD with multimodal intraoperative neurophysiological monitoring from September 2024 to March 2026. Monitoring included LSR, ZLR, and brainstem auditory evoked potentials. LSR was recorded from four facial muscles at six predefined stages. ZLR was elicited by direct stimulation of the neurovascular conflict. Outcomes were assessed using the validated hemifacial spasm grading questionnaire.

RESULTS

LSR was detected in 83% of patients and disappeared intraoperatively in 93% of those in whom it was detected, with early disappearance in 13%. ZLR was present in all patients before decompression and disappeared in all cases after decompression. ZLR was particularly useful when LSR was absent or disappeared early, and in identifying the true offending vessel in complex neurovascular conflicts. Immediate symptomatic resolution occurred in 78% of patients, and delayed resolution in 22%. The median clinical score improved from 13 (IQR 13-14) preoperatively to 0 (IQR 0-2) at discharge. Mean quality-of-life impairment decreased from 82% to less than 0.2% at 6 months (p < 0.001).

CONCLUSIONS

E-MVD combined with LSR and ZLR monitoring was feasible and demonstrated favorable short-term clinical outcomes in this consecutive case series. The two monitoring modalities provided complementary intraoperative electrophysiological information, particularly in patients with absent or inconclusive LSR.