Intralabyrinthine Schwannomas in 52 Cases: Radiological and Therapeutic Aspects

Objective: To determine radiological and therapeutic properties of our intralabyrinthine schwannoma population in the period between 1991 and 2007. Study Design: Retrospective study. ILS with an extralabyrinthine component on initial MRI was excluded. Material and Methods: The population consisted of 27 male and 25 female patients (mean age: 53 years; range, 24-78 years). The radiological characteristics were: Unenhanced T1 images, hyperintense IL lesion; Gd-enhanced T1 images, strongly enhancing sharp edges; heavy T2-weighted images, tumor replaces high signal intensity fluid. Results: The most common location was within the cochlea (80%), followed by the vestibule and semicircular canals (14%), cochlea, vestibule, and SCC in 6% of the cases. ILS grew in 56% of the cases, but few intrameatally (11%). If an intracochlear schwannoma started to grow, it was always first seen in the scala tympani and later evolved toward the scala vestibuli. Cochlear ILS usually grows in the anterior vestibule when the cochlea is completely obliterated. For the same reason, vestibular ILS will grow selectively into the SV of the basal turn when they grow toward the cochlea. Most cases (77%) were managed conservatively. Surgery was performed due to growth or symptoms in 23% of the cases. None of the cases in this study had radiotherapy. Conclusions: Anew classification of surgical approaches to these rare tumors is proposed based on the approach and target organ.