Relationship between posterior fossa space and hemifacial spasm

Abstract

Objective To quantitatively study the posterior fossa effective space and its relationship with hemifacial spasm(HFS). Methods We conducted a case-control study of patients diagnosed with HFS and sex- and age-matched healthy controls. All subjects underwent high-resolution three-dimensional MRI. The software of 3D-Slicer was used to measure the posterior fossa space and hindbrain tissue volume between the two groups. Results Sixty patients and 60 controls were enrolled in this study. Compared to controls, patients with HFS had a higher posterior fossa crowdedness index (PFCI; 83.7%±0.6% vs 79.2%±0.4%; t=2.58, P=0.01). The multivariate linear regression analysis revealed that a higher PFCI was associated with younger age (r=-0.61, P=0.02), female gender (r=0.76, P=0.003) and HFS (r=-0.43, P=0.01). Conclusions Patients with HFS have a more crowded posterior fossa space than healthy controls, potentially leading to cranial nerve and vascular structure crowding, thus increasing HFS risk. Women have a higher PFCI, which may explain the strong female preponderance in epidemiologic studies. Key words: Cranial fossa, posterior; Hemifacial spasm; Nerve compression syndromes