Intralabyrinthine Schwannomas in 52 Cases

This study is the largest series of intralabyrinthine schwannomas (ILS) so far (52 cases). It was performed to evaluate prevalence, clinical signs, MR characteristics (including location, growth potential, and growth patterns), and therapeutic management. The patients most often presented with progressive hearing loss (84%) and non-pulsatile tinnitus (43%). ILSs most frequently occurred in the cochlea (81%) and were most frequently situated in the basal and second turn of the cochlea. ILSs initially situated in the vestibular labyrinth (13%) or in both the cochlea and vestibular labyrinth (6%) were rare. The scala tympani was more frequently and more extensively involved than the scala vestibuli in most patients. Follow-up MR was available in 27 patients, and growth occurred in 16 (59%) of them. Growth was seen from the scala tympani into the scala vestibuli and from the perilymph space in the scala vestibuli to the perilymphatic space around the saccule and vice versa. The ILS was surgically removed and confirmed in 12 patients. The most frequent indication for surgery was tumor growth (four patients) or fear for tumor growth (six patients). Today the authors would recommend tumor removal only in cases of MRI-proven growth and extension into the IAC/CPA.