Histopathologic Evaluation of Intralabyrinthine Schwannoma

Abstract

<b><i>Objectives:</i></b> The aim of this study is to perform a histopathologic analysis of temporal bones with an intralabyrinthine schwannoma (ILS) in order to characterize its extension. <b><i>Methods:</i></b> Archival temporal bones with a diagnosis of sporadic schwannoma were identified. Both symptomatic and occult nonoperated ILS were included for further analysis. <b><i>Results:</i></b> A total of 6 ILS were identified, with 4 intracochlear and 2 intravestibular schwannomas. All intracochlear schwannomas involved the osseous spiral lamina, with 2 extending into the modiolus. The intravestibular schwannomas were limited to the vestibule, but growth into the bone next to the crista of the lateral semicircular canal was observed in 1 patient. <b><i>Conclusions:</i></b> Complete removal of an ILS may require partial removal of the modiolus or bone surrounding the crista ampullaris as an ILS may extend into these structures, risking damage of the neuronal structures. Due to the slow growth of the ILS, it remains unclear if a complete resection is required with the risk of destroying neural structures hindering hearing rehabilitation with a cochlear implant.

Challenges of Cochlear Implantation in Intralabyrinthine Schwannoma Patients: Surgical Procedures and Auditory Outcome

“…Bagattini, Quesnel, and Röösli demonstrated the degree of neurodegeneration caused by untreated ILS [37]. The authors performed histopathological analyses of temporal bones obtained from deceased patients with known medical history.…”

Quality Control after Intracochlear Intralabyrinthine Schwannoma Resection and Cochlear Implantation

“…The fact that a visual tumor was not observed intraoperatively led us to assume that a partial, very small ingrowth under the radiological visual resolution of 2 mm was persistent preoperatively. Very small areas of ingrowth into the modiolus and the IAC have been described histologically [ 28 ]. The additional small signal in the basal turn can be interpreted as a residual tumor.…”

Seltene Erkrankungen des vestibulären Labyrinths: von Zebras, Chamäleons und Wölfen im Schafspelz

“…This peculiar schwannoma of the eighth cranial nerve – also called primary inner ear schwannoma 248 – originates from Schwann cells of the vestibular or cochlear nerve within the labyrinth 249 250 . Although first described back in 1917 251 , these benign inner ear tumors were considered a rarity for many years.…”

“…Diese Sonderform der Schwannome des achten Hirnnerven – auch primäres Innenohrschwannom genannt 248 – geht von Schwann-Zellen des N. vestibularis bzw. cochlearis innerhalb des Labyrinths aus 249 250 . Wenngleich erstmals 1917 beschrieben 251 , galten diese gutartigen Innenohrtumore lange als Rarität.…”

“…Hinter dem «Hufgeklapper» eines BPLS können sich aber auch einige «Zebras» mit ähnlicher klinischer Präsentation verbergen. Generell sollte die Diagnose eines BPLS in folgenden Fällen kritisch hinterfragt werden [50,247] [249,250]. Wenngleich erstmals 1917 beschrieben [251], galten diese gutartigen Innenohrtumore lange als Rarität.…”