Fundal Fluid as a Predictor of Hearing Preservation in the Middle Cranial Fossa Approach for Vestibular Schwannoma

Objectives: Determine if the presence of cerebrospinal fluid in the fundal region of the internal auditory canal on preoperative magnetic resonance imaging (MRI) scans is predictive of improved hearing preservation after removal of vestibular schwannoma through the middle cranial fossa approach. Relationships between fundal fluid, tumor nerve of origin, tumor size, and hearing preservation also are examined. Study Design: Retrospective review. Setting: Private practice tertiary neurotology referral center. Patients: One hundred one patients with preoperative MRI, complete preoperative and postoperative audiologic data, and histopathologically confirmed vestibular schwannoma treated with a middle cranial fossa approach between January 1, 2006, and June 30, 2009. Interventions: Primary middle cranial fossa approach for removal of vestibular schwannoma. Main Outcome Measures: Fundal fluid status (presence or absence), preoperative and postoperative pure-tone average, and speech discrimination scores and tumor nerve of origin. Results: Fundal fluid was present in 75% of cases. Those with fluid had a higher rate of postoperative measurable hearing (77.6%) compared with those without fundal fluid (52%) (p <= 0.014). Tumors arising from the superior vestibular nerve also were associated with a higher rate of preserved, serviceable, and measurable hearing, whereas the combination of the presence of fundal fluid and superior nerve tumor had a significantly better chance of hearing preservation than either factor alone. Conclusion: The presence of fundal fluid on preoperative MRI is predictive of hearing outcomes and should be used in counseling patients who are considering hearing preservation surgery via a middle cranial fossa approach for the treatment of isolated vestibular schwannoma.