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Diagnostics and Therapy for intralabyrinthine Schwannomas
18 April 2018 (online)
Intralabyrinthine schwannomas (ILS) are a rare differential diagnosis of sudden hearing loss and vertigo.
In an own case series of 23 patients, 11 tumors showed an intracochlear, 3 an intravestibular, 3 an intravestibulocochlear, 2 a transmodiolar, 1 a transmodiolar with CPA, 1 a transotic with CPA and 2 a multilocular location. 15 patients received surgery for tumor removal via labyrinthectomy (x3), an extended cochleostomy (x1), partial or subtotal cochleoectomy (x9) or via a transotic-translabyrinthine approach to the internal auditory canal and the cerebellopontine angle.
For the intracochlear tumors, vestibular function could partially be preserved after surgery. In all but one case with subtotal cochleoectomy, hearing rehabilitation was successful.
Radiological work up of ILS should be based on thin slice, contrast enhance temporal bone MRI, which is the gold standard. Surgical removal of ILS is recommended before tumor growth leads to a complete filling of the cochlea or before a transmodiolar or transmacular growth complicates surgical removal and prevents cochlear implantation. Radiotherapy of ILS may lead to destruction of the spiral ganglion cells hindering hearing rehabilitation with CI. Sufficient data, however, are not yet available. If done early enough, cochlear implantation after surgical removal of ILS is an option for auditory rehabilitation and an alternative to a „wait-and-test-and-scan“ strategy.