LIPOMAS OF THE INTERNAL AUDITORY-CANAL AND CEREBELLOPONTINE ANGLE

Objective: To evaluate lipomas of the internal auditory canal (IAC) an d cerebellopontine angle (CPA). Study Design: Retrospective review. Me thods: Review of a multi-institutional series of 17 lipomas of the IAC /CPA, combined with a Medline review of the 67 cases reported in the w orld literature. Results: This series of 17 IAC/CPA lipomas is the lar gest reported series to date, bringing the total number of documented cases to 84. There appears to be a nearly 2:1 male to female predomina nce. Sixty percent were left-sided lesions, and three were bilateral. Rearing loss, dizziness, and tinnitus were the most common presenting symptoms. Surgical resection was performed in 52 (62%) of these lesion s; however, total tumor removal was accomplished in only 17 (33%), whi ch is most likely because of the fact that these tumors tend to have a poorly defined matrix and a dense adherence to neurovascular structur es. Sixty eight percent of patients experienced a new deficit postoper atively, 11% were unchanged, and only 19% improved with no new deficit . Only one documented case of tumor growth was identified; however, th e reported follow-up was short (average, less than 3 years). Conclusio n: With the magnetic resonance imaging techniques now available, lipom as can be reliably differentiated from other masses within the CPA and IAC, so histopathologic diagnosis is rarely necessary. Because of the potential for significant morbidity with resection of these lesions, we believe that conservative follow-up is the best treatment option fo r patients with these rare lesions. Surgery is indicated only when sig nificant progressive or disabling symptoms are present.