Prediction of Intraoperative CSF Gusher and Postoperative Facial Nerve Stimulation in Patients With Cochleovestibular Malformations Undergoing Cochlear Implantation Surgery

Objective: To determine parameters in computed tomography (CT) of the temporal bone that would be useful for prediction of cerebrospinal fluid (CSF)gusher during cochlear implantation (CI) surgery and postoperative facial nerve stimulation (FNS) in patients with inner ear malformations. Study Design: Retrospective study. Setting: Tertiary referral center. Patients: Three hundred seventy-five cases who had undergone CI surgery including 54 inner ear malformation cases were analyzed. Main Outcome Measures: The diameters of the cochlea modiolar base and porus of the internal auditory canal (IAC), length of IAC, diameter of the vestibular aqueduct (VA) at the operculum, and presence or absence of the modiolus of the cochlea were evaluated by using CT. Results: CSF gusher occurred in 12 (22%) cases, in whom the diameters of the cochlea modiolar base (2.7 +/- 0.6 mm, p < 0.01) and widths of VA (1.5 +/- 1.0 mm, p < 0.05) were significantly greater compared with those without gusher. The modiolus was significantly less formed (8%) in cases with gusher compared with those without gusher (p < 0.01). FNS occurred in 10 (19%) cases, and the widths of VA and lengths of IAC were significantly shorter in these cases compared with those without FNS (p < 0.05). Conclusion: The absence of the modiolus, larger cochlea modiolar base, and wider VA in CT images were important predictors of CSF gusher during CI surgery. The width of VA was also an important factor in predicting FNS.