Cervical vestibular evoked myogenic potentials are not disturbed in hemifacial spasm and blepharospasm.

Introduction: Hemifacial spasm (HFS) and blepharospasm (BS) are movement disorders involving the facial muscles. HFS is linked to facial nerve, nucleus irritation and BS to basal ganglia dysfunction causing hyperexcitability of brainstem interneurons. Cervical vestibular-evoked myogenic potential (cVEMP) responses demonstrate the saccullocollic reflex. This study aimed to evaluate saccullocollic pathways using the cVEMP test in HFS and BS patients with abnormal brainstem activity.

Methods: Our study was conducted between July 2022 and December 2023 at Movement Disorders Outpatient Clinic of Neurology Department, including 54 HFS and 32 BS patients and 50 healthy volunteers. Peak p13 and n23 latencies, peak-to-peak p13-n23 amplitudes, and amplitude asymmetry ratios (AAR) of the responses recorded from the sternocleidomastoid muscle ipsilateral to the stimulated ear was recorded and the results gathered from the patients were compared with the results of the healthy controls. Results of the affected and unaffected sides of the HFS patients were also compared.

Results: There was no significant difference regarding age between patient and control groups. The female gender was higher in the BS group. No statistically significant differences were observed in terms of right and left p13 and n23 latencies and p13-n23 amplitude parameters in comparison of the patient groups and healthy controls. Comparison of the affected and unaffected sides of the HFS patients did not reveal a significant difference.

Conclusions: This study found no evidence of saccullocollic involvement in HFS and BS patients using the cVEMP test. It is important as a guiding study for future research.