Intralabyrinthine schwannomas

Abstract

Intralabyrinthine schwannomas (ILS) are a rare differential diagnosis of sudden hearing loss and vertigo. In an own case series of 12 patients, 6 tumors showed an intracochlear, 3 an intravestibular, 1 a transmodiolar including the cerebellopontine angle (CPA), 1a transotic including the CPA, and 1 a multilocular location. The tumors were removed surgically in 9 patients, whereas 3 patients decided for a “wait-and-test-and-scan” strategy. Of the surgical patients, 3 underwent labyrinthectomy and cochlear implant (CI) surgery in a single-stage procedure; 1 patient had extended cochleostomy with CI surgery; 3 underwent partial or subtotal cochleoectomy, with partial cochlear reconstruction and CI surgery (n = 1) or implantation of electrode dummies for possible later CI after repeated MRI follow-up (n = 2); and in 2 patients, the tumors of the internal auditory canal and cerebellopontine angle exhibiting transmodiolar or transmacular growth were removed by combined translabyrinthine–transotic resection. For the intracochlear tumors, vestibular function could mostly be preserved after surgery. In all cases with CI surgery, hearing rehabilitation was successful, although speech discrimination was limited for the case with subtotal cochleoectomy. Surgical removal of intracochlear schwannomas via partial or subtotal cochleoectomy is, in principle, possible with preservation of vestibular function. In the authors’ opinion, radiotherapy of ILS is only indicated in isolated cases. Cochlear implantation during or after tumor resection (i. e., as synchronous or staged surgeries) is an option for hearing rehabilitation in cartain cases and represents a therapeutic approach in contrast to a “wait-and-test-and-scan” strategy.

Cochlear Implantation After Partial or Subtotal Cochleoectomy for Intracochlear Schwannoma Removal—A Technical Report

“…The disadvantage of a “wait-and-test-and-scan” strategy includes transmodiolar tumor progress into the internal auditory canal (IAC). A transotic-translabyrinthine tumor removal in these cases would not allow rehabilitation with a CI ( 13 , 14 , 16 ).…”

“…4PTA indicates average air conducted pure tone threshold of four frequencies (0.5, 1, 2, 4 kHz); CI, cochlear implant (CI512, Cochlear, Sydney, Australia); CPA, cerebellopontine angle; IAC, internal auditory canal; m/f, male/female; R/L, right/left; WRS max , maximum number of monosyllabic words understood (in %); WRS 65 , percentage of words understood (numbers and monosyllables separately tested). Patients 1 to 4 have been reported in a previous case series ( 16 ) and case report ( 19 ), as referenced in the “Procedure” column of this table.…”

Long-Term in vivo Release Profile of Dexamethasone-Loaded Silicone Rods Implanted Into the Cochlea of Guinea Pigs

“…A perimodiolar CI electrode is then placed around the remaining modiolus for hearing rehabilitation afterwards. The preservation of the residual spiral ganglia in these patients is of particular importance for rehabilitative success (19).…”

The role of subtotal petrosectomy in cochlear implant recipients: Our preliminary results

“…Intralabyrinthine schwannomas are a rare subgroup of benign tumors of the 8th cranial nerve [15]. Several strategies have been proposed to perform CI in those patients, including insertion of the electrode through the tumor without its removal [16].…”