Association study of the pneumatization degree of mastoid air cells and postoperative complications after microvascular decompression in hemifacial spasm

This study aimed to analyse the association between the degree of pneumatization of mastoid air cells (MACs) and postoperative complications after microvascular decompression in hemifacial spasm. We retrospectively reviewed 308 patients with hemifacial spasm who underwent surgery at our institute between January 2017 and March 2021. The degree of pneumatization of MACs was classified into four grades (grades 1, 2, 3, and 4) according to method of Han et al. The clinical data of the four grades were analysed and statistically examined. There were no statistically significant differences between the four grades in terms of the operative time, intraoperative blood loss, and postoperative hospital stay (all, P > 0.05). The incidence of hearing loss was higher in grade 4 MACs (26.56%) than in grades 1 and 2 MACs (5.41% and 2.89%, respectively; P < 0.05). The incidence of facial paralysis was higher in grade 4 MACs (28.13%) than in grades 1 and 2 MACs (5.41% and 9.18%, respectively; P < 0.001). The incidence of intracranial infection was higher in grade 3 MACs (17.65%) than in grade 2 MACs (3.89%) (P < 0.05). All four patients with cerebrospinal fluid leakage belonged to grade 4 MACs. The incidence of cerebrospinal fluid leakage was higher in grade 4 MACs (5.13%) than in grade 2 MACs (P < 0.05). This study found that the degree of pneumatization of MACs was closely related to the postoperative complications after MVD surgeries. Well-pneumatized MACs increase the risk of cerebrospinal fluid leakage and intracranial infection. However, insufficient exposure increases the risk of facial paralysis and hearing loss. For patients with well-pneumatized MACs, sufficient surgical exposure is the top priority when locating the bone hole. For those who may have a latent MAC opening, preventive occlusion should be considered.