Evaluating magnetic resonance imaging characteristics and risk factors for hemifacial spasm.

PURPOSE: The specific neurovascular compression (NVC) event responsible for the symptomatic manifestation of hemifacial spasm (HFS) remains difficult to assess accurately using magnetic resonance imaging (MRI). We aim to evaluate the MRI characteristics of HFS. METHOD: We retrospectively included patients with HFS and divided them into a test group (n = 186) and a validation group (n = 28). The presence, severity, and offending vessel type of NVC in each portion, and the orientation of the offending vessel around the facial nerve, were recorded. Conditional logistic regression analyses were performed to evaluate correlations using test group. The validation group was used to verify whether our findings improved diagnostic performance. RESULTS: Deformity in the proximal cisternal segment was significantly correlated with HFS occurrence (odds ratio [OR]: 256.58, p = .002), whereas contact was not (p = .233). Both contact and deformity in the root detachment point (OR: 19.98 and 37.22, p < .001 and p = .013, respectively) or attached segment (OR: 4.99 and 252.52, p = .001 and p < .001, respectively) were significantly correlated with HFS occurrence. Our findings improved specificity, positive predictive value, and accuracy of diagnosis than conventional diagnostic methods. The vertebral artery predominantly compress the facial nerve in the inferior-anterior position, the anterior inferior cerebellar artery predominantly in the inferior position, the posterior inferior cerebellar artery predominantly in the inferior position, vein predominantly in the posterior-superior position. CONCLUSIONS: This study further demonstrates that within the susceptible portion of facial nerve, different portions of the nerve respond differently to NVC. Each offending vessel has its own preferred conflict orientation. Our study offers reference for neurosurgeons in diagnosis and treatment.

Radiological characteristics predicting early poor drug response in patients with hemifacial spasm.

OBJECTIVES: Patients with hemifacial spasm (HFS) often resort to botulinum toxin injections or microvascular decompression surgery when medication exhibits limited effectiveness. This study aimed to identify MRI and demographic factors associated with poor drug response at an early stage in patients with HFS. METHODS: We retrospectively included patients with HFS who underwent pre-therapeutic MRI examination. The presence, location, severity, and the offending vessels of neurovascular compression were blindly evaluated using MRI. Drug responses and clinical data were obtained from the medical notes or phone follow-ups. Logistic regression analysis was performed to identify potential factors. RESULTS: A total of 116 patients were included, with an average age at the time of first examination of 50.4 years and a median duration of onset of 18 months. Forty-nine (42.2%) patients reported no symptom relief. Thirty-seven (31.9%) patients reported poor symptom relief. Twenty-two (19.0%) patients reported partial symptom relief. Eight (6.9%) patients achieved complete symptom relief. The factors that were statistically significant associated with poor drug responses were contact in the attach segment of the facial nerve and aged 70 and above, with an odds ratio of 7.772 (p = 0.002) and 0.160 (p = 0.028), respectively. CONCLUSIONS: This study revealed that mild compression in the attach segment of the facial nerve in pre-therapeutic MRI increases the risk of poor drug responses in patients with HFS, while patients aged 70 and above showed a decreased risk. These findings may assist clinician to choose optimal treatment at an early stage.