Update management of intralabyrinthine schwannomas including subtotal cochleoectomy and hearing rehabilitation with cochlear implants
23 April 2019 (online)
Intralabyrinthine schwannomas (ILS) are a rare differential diagnosis of sudden hearing loss and vertigo. The common management of these tumors is often a "wait-and-test-and-scan (W&T&S)" strategy. We here describe the audiological outcome of cochlear implantation (CI) after surgical removal of these tumors through subtotal or partial cochleoectomy and/or labyrinthectomy.
In an own case series of 35 patients, 21 tumors showed an intracochlear, 3 an intravestibular, 3 an intravestibulocochlear, 4 a transmodiolar (including 1 with cerebello-pontine angle (CPA) extension, 1 a transmacular, 1 a transotic with CPA and 2 a multilocular location. Twenty-six patients received surgery for tumor removal, with 22 patients receiving a cochlear implant in the same session.
In all but one case, hearing rehabilitation with CI was successful, with a good word recognition for monosyllables in quiet already at first fitting and 70% on average at 65 dB SPL at 12 months follow up. For total removal of transmodiolar tumors reaching the CPA (x2), the cochlear could not be preserved.
It those patients, where semicircular canal function was normal before surgery, this function could be mostly preserved despite partial or subtotal cochleoectomy.
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. If done early enough, cochlear implantation after surgical removal of ILS appears as an interesting option for auditory rehabilitation and an alternative to a "W&T&S" strategy.