Quantification and Clinical Correlation of Posterior Cranial Fossa Cerebrospinal Fluid Volume in Primary Hemifacial Spasm Using Magnetic Resonance Imaging.

Background and objective: Primary hemifacial spasm (HFS) is caused by neurovascular conflict (NVC) at the root entry zone of the facial nerve. Whether reduction of posterior cranial fossa (PCF) cerebrospinal fluid (CSF) volume is a risk factor for HFS is not clear. The study aims at the radiologic assessment of PCF CSF volume and its clinical correlation.

Methods: A cross-sectional, hospital-based, case-control study was conducted, in which 50 cases of primary HFS and 50 age- and sex-matched controls were recruited. PCF CSF volume was quantified in 3-T brain magnetic resonance imaging.

Results: The mean age at presentation of cases was 50.7 ± 10.7 years (42-69 years) and controls was 52.4 ± 8.7 years (45-68 years). The mean duration of symptoms was 3.5 ± 1.3 years (1.5-8 years). About 52% of patients had grade 2 (mild) severity of HFS. The mean PCF CSF volume of patients was 13,725.1 ± 909.5 mm 3 and controls was 14,458.5 ± 973.5 mm 3 ( P < 0.001). The mean PCF CSF volume of females with HFS was 13,714.8 ± 852.5 mm 3 and female controls was 14,521.8 ± 973.5 mm 3 ( P = 0.006). PCF CSF volume was significantly associated with the presence of HFS ( P = 0.007), the severity of HFS ( P < 0.001), and the presence of NVC ( P = 0.02).

Conclusion: PCF CSF volume was lesser in HFS patients and was associated with the presence of HFS, the severity of HFS, and the presence of NVC. Females with HFS had smaller PCF CSF volume. Small PCF CSF volume is a risk factor for HFS, particularly in females with HFS.