Objective:To investigate the role of lateral spread response (LSR) of the facial nerves in distinguishing primary hemifacial spasm (HFS), HFS caused by facial palsy and Meige syndrome, and explore the relationship between LSR presence or absence before microvascular decompression (MVD) and MVD efficacy in patients with primary HFS.Methods:A retrospective analysis was performed; 127 patients with HFS, including primary HFS ( n=86), HFS caused by facial palsy ( n=27) and Meige syndrome ( n=14), were enrolled in Department of Neurology, Zhongshan Hospital, Fudan University from November 2021 to July 2023. All patients underwent needle electrode electromyography in the lateral facial muscles, and tests of motor branch conduction of facial nerves, blinking reflex and LSR; the general data, myokymia incidence, latency of facial nerves, abnormal rate and R1 amplitude of blinking reflex, and LSR detection rate and latency were compared among the 3 groups. Spearman correlation was used to analyze the correlation between course of primary HFS and LSR presence or absence. For patients with primary HFS accepted MVD, MVD efficacy was evaluated according to Shorr efficacy evaluation criteria 1 month after procedure, and efficacy differences between patients with LSR presence and LSR absence were compared. Results:(1) Compared with the Meige syndrome group, the group of HFS caused by facial palsy had significantly younger age, and the group of HFS caused by facial palsy and primary HFS group had statistically higher incidence of left side lesions ( P<0.05). The latency of facial nerves in group of HFS caused by facial palsy ([2.97±0.63] ms) was significantly longer than that in the primary HFS group ([2.46±0.59] ms) and Meige syndrome group ([2.53±0.62] ms, P<0.05). The abnormal rate of blinking reflex in group of HFS caused by facial palsy (59.26%) was significantly higher than that in primary HFS group (23.26%) and Meige syndrome group (21.43%, P<0.05). The LSR detection rate in primary HSF group (48.84%) was statistically higher than that in group of HFS caused by facial palsy (37.04%) and Meige syndrome group (7.14%, P<0.05). The LSR latency in group of HFS caused by facial palsy (12.30[12.30, 13.80] ms) was significantly longer than that in the primary HFS group (11.20[9.73, 11.20] ms, P<0.05). (2) No significant correlation was noted between course of primary HFS and LSR presence or absence ( rs=0.051, P=0.640). (3) In 33 patients with primary HFS accepted MVD, no significant difference in MVD efficacy was noted between patients with LSR presence ( n=22) and those with LSR absence ( n=11, P>0.05). Conclusion:In patients with LSR presence and long latency of facial nerves and LSR, HFS caused by facial palsy should be considered; preoperative LSR can not predict the MVD efficacy in patients with primary HFS.

Objective:To investigate the role of lateral spread response (LSR) of the facial nerves in distinguishing primary hemifacial spasm (HFS), HFS caused by facial palsy and Meige syndrome, and explore the relationship between LSR presence or absence before microvascular decompression (MVD) and MVD efficacy in patients with primary HFS.Methods:A retrospective analysis was performed; 127 patients with HFS, including primary HFS ( n=86), HFS caused by facial palsy ( n=27) and Meige syndrome ( n=14), were enrolled in Department of Neurology, Zhongshan Hospital, Fudan University from November 2021 to July 2023. All patients underwent needle electrode electromyography in the lateral facial muscles, and tests of motor branch conduction of facial nerves, blinking reflex and LSR; the general data, myokymia incidence, latency of facial nerves, abnormal rate and R1 amplitude of blinking reflex, and LSR detection rate and latency were compared among the 3 groups. Spearman correlation was used to analyze the correlation between course of primary HFS and LSR presence or absence. For patients with primary HFS accepted MVD, MVD efficacy was evaluated according to Shorr efficacy evaluation criteria 1 month after procedure, and efficacy differences between patients with LSR presence and LSR absence were compared. Results:(1) Compared with the Meige syndrome group, the group of HFS caused by facial palsy had significantly younger age, and the group of HFS caused by facial palsy and primary HFS group had statistically higher incidence of left side lesions ( P<0.05). The latency of facial nerves in group of HFS caused by facial palsy ([2.97±0.63] ms) was significantly longer than that in the primary HFS group ([2.46±0.59] ms) and Meige syndrome group ([2.53±0.62] ms, P<0.05). The abnormal rate of blinking reflex in group of HFS caused by facial palsy (59.26%) was significantly higher than that in primary HFS group (23.26%) and Meige syndrome group (21.43%, P<0.05). The LSR detection rate in primary HSF group (48.84%) was statistically higher than that in group of HFS caused by facial palsy (37.04%) and Meige syndrome group (7.14%, P<0.05). The LSR latency in group of HFS caused by facial palsy (12.30[12.30, 13.80] ms) was significantly longer than that in the primary HFS group (11.20[9.73, 11.20] ms, P<0.05). (2) No significant correlation was noted between course of primary HFS and LSR presence or absence ( rs=0.051, P=0.640). (3) In 33 patients with primary HFS accepted MVD, no significant difference in MVD efficacy was noted between patients with LSR presence ( n=22) and those with LSR absence ( n=11, P>0.05). Conclusion:In patients with LSR presence and long latency of facial nerves and LSR, HFS caused by facial palsy should be considered; preoperative LSR can not predict the MVD efficacy in patients with primary HFS.