Diagnosis and Management of Intralabyrinthine Schwannomas

Abstract

Objectives/Hypothesis: Describe the symptoms, signs, radiographic findings, and treatment results for four patients with intralabyrinthine schwannoma beginning either primarily within the labyrinth or extending secondarily into the labyrinth from the internal auditory canal. Study Design: Retrospective review. Methods: Review of clinic records, operative records, imaging studies with follow-up telephone interview, and when possible, repeat examination. Results: Four patients with intralabyrinthine schwannoma treated by the first author were identified. Episodic vertigo, indistinguishable from Meniere's disease, was present in all but one of the patients in this study. A progressive unilateral hearing loss was also found in all of the patients. Magnetic resonance imaging revealed tumor isolated to the vestibule in two patients with the cochlea primarily involved in the other two patients. Intracochlear tumor extending into the internal auditory canal had been missed on preoperative imaging in one patient and was found during a translabyrinthine vestibular nerve section. In another patient with an intracanalicular schwannoma, tumor extending into the basal turn of the cochlea was not removed during a translabyrinthine approach to the internal auditory canal. The tumor subsequently recurred, necessitating a transotic approach for removal. A transmastoid/translabyrinthine approach was used to successfully remove tumor in one patient. Another patient with good hearing and no vestibular symptoms at time of this writing is being followed with serial imaging studies. As expected, the three patients who underwent surgery have anacusis in the operated ear and are free of vertigo at follow-up intervals of 12, 26, and 65 months. Conclusions: Intralabyrinthine schwannomas are rare tumors with optimal treatment being determined by the symptoms, tumor location, and hearing. Findings of an intralabyrinthine schwannoma on magnetic resonance imaging may be easily over-looked and attributed to inflammatory changes.