Residual and recurrent acoustic neuroma in hearing preservation procedures: Neuroradiologic and surgical findings

Magnetic resonance imaging with gadolinium-DTPA is currently the most accurate method for detecting small intracanalicular vestibular schwannomas. This imaging modality is not nearly as clear in diagnosis of a small residual or recurrent neuroma after a hearing preservation procedure. This study looked for gadolinium-enhanced MRI images mimicking recurrent lesions in 104 consecutive cases of unilateral acoustic neuroma removed with a hearing preservation technique by the retrosigmoid transmeatal approach. A number of cases with enhancing MRI images in the internal auditory canal were reoperated, permitting the histologic examination of the enhancing tissue. Criteria for the MRI diagnosis of residual-recurrent acoustic neuroma are presented, along with the short-to mid-term rate of ''residual-recurrent'' tumor.