[Intracochlear schwannoma : Tumor removal via subtotal cochleoectomy and partial cochlear reconstruction with preservation of semicircular canal function. German version]

[Does sealing the oval window in addition to the round window bring an advantage in reserve therapy of acute idiopathic deafness?]

BACKGROUND

Following sudden unilateral deafness or severe sensorineural hearing loss, patients with unsuccessful intravenous steroid therapy can be treated with explorative tympanotomy with sealing of the round (RW) and/or oval window (OW), due to suspected rupture of the RW with perilymph fistula (PLF) or a fissula ante fenestram (FAF). This study investigated whether additional sealing of the oval window (RW+OW) achieved an improved hearing benefit as compared to sealing of the round window only (RW) .

METHODS

This retrospective study investigated 54 patients with acute profound hearing loss who underwent tympanoscopy. Audiometric examinations were performed preoperatively and at two postoperative intervals (1 month and 3-6 months after surgery). In 28 patients, the OW was sealed in addition to the RW.

RESULTS

No intraoperatively visible PLF or FAF were reported. Hearing thresholds were significantly reduced in the early postoperative follow-up period and further improvement was observed 3-6 months later. No significant differences between the RW and RW+OW subgroups were seen at either follow-up timepoint. In 65% (Kanzaki criteria) and 74% (Siegel criteria) of patients, partial or complete postoperative hearing improvement was observed. Upon comparing the groups of patients with and without hearing improvement, no statistical significance was found in terms of gender, age, secondary diagnoses, or latency period between symptom onset and surgery.

CONCLUSION

Additional sealing of the OW did not lead to significantly better postoperative hearing thresholds. In general, postoperative hearing improvement corresponds to published spontaneous remission rates.

Intralabyrinthine schwannomas : Surgical management and hearing rehabilitation with cochlear implants

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.