Objective: To report 4 patients who have developed a conductive and/or mixed hearing loss due to dehiscence of the inner ear after retrosigmoid approach for removal of acoustic neuroma.

Patients: Four patients who presented with conductive and/or mixed hearing loss after retrosigmoid approach for removal of acoustic neuroma.

Main Outcome Measure: Evidence of inner ear dehiscence on postoperative computed tomographic scan of the temporal bones.

Conclusion: The occurrence of conductive hearing loss after the surgical removal of an acoustic neuroma has not previously been documented. Computed tomographic scan of the temporal bones showing inner ear dehiscence may explain this finding. Formal documentation of such cases may allow techniques to be developed to reduce its occurrence or reconstruction of the defect at the time of primary surgery.