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. 2023 Dec;71(12):802-808.
doi: 10.1007/s00106-023-01379-7. Epub 2023 Oct 30.

Bilateral intracochlear schwannomas: histopathological confirmation and outcomes following tumour removal and cochlear implantation with lateral wall electrodes

Mark E Quick  1   2 , Shannon Withers  3 , Stefan K Plontke  4 , Ronel Chester-Browne  5 , Jafri Kuthubutheen  3   6
Affiliations

Bilateral intracochlear schwannomas: histopathological confirmation and outcomes following tumour removal and cochlear implantation with lateral wall electrodes

Mark E Quick et al. HNO. 2023 Dec.

Abstract
in English, German

Intracochlear schwannomas (ICS) are very rare benign tumours of the inner ear. We present histopathological proof of the extremely rare bilateral occurrence of intracochlear schwannomas with negative blood genetic testing for neurofibromatosis type 2 (NF2). Bilateral schwannomas are typically associated with the condition NF2 and this case is presumed to have either mosaicism for NF2 or sporadic development of bilateral tumours. For progressive bilateral tumour growth and associated profound hearing loss, surgical intervention via partial cochleoectomy, tumour removal, preservation of the modiolus, and simultaneous cochlear implantation with lateral wall electrode carrier with basal double electrode contacts was performed. The right side was operated on first with a 14-month gap between each side. The hearing in aided speech recognition for consonant-nucleus-consonant (CNC) phonemes in quiet improved from 57% to 83% 12 months after bilateral cochlear implantation (CI). Bilateral intracochlear schwannomas in non-NF2 patients are extremely rare but should be considered in cases of progressive bilateral hearing loss. Successful tumour removal and cochlear implantation utilizing a lateral wall electrode is possible and can achieve good hearing outcomes.

Intracochleäre Schwannome (ICS) sind sehr seltene benigne Tumoren des Innenohrs. In der vorliegenden Arbeit wird die histopathologische Bestätigung des extrem seltenen bilateralen Vorkommens von intracochleären Schwannomen mit negativem genetischem Bluttest auf Neurofibromatose 2 (NF2) vorgestellt. Bilaterale Schwannome sind typischerweise mit NF2 assoziiert, und bei dem vorliegenden Fall wird vermutet, dass entweder ein Mosaik für NF2 oder die sporadische Entwicklung von bilateralen Tumoren besteht. Bei progressivem bilateralem Tumorwachstum und damit einhergehender hochgradiger Schwerhörigkeit wurde eine chirurgische Intervention mit partieller Cochleoektomie, Tumorentfernung, Erhalt des Modiolus und gleichzeitiger Cochleaimplantation unter Einsatz eines „lateral wall“-Elektrodenträgers mit basal doppelten Elektrodenkontakten durchgeführt. Zuerst wurde die rechte Seite operiert und mit einem Abstand von 14 Monaten die zweite Seite. Das Sprachverstehen für Konsonant-Nucleus-Konsonant(CNC)-Phoneme in Ruhe verbesserte sich 12 Monate nach bilateraler Cochleaimplantation von 57 auf 83%. Bilaterale intracochleäre Schwannome bei Nicht-NF2-Patienten sind extrem selten, aber sollten in Fällen mit progressiver bilateraler Schwerhörigkeit in Erwägung gezogen werden. Die erfolgreiche Tumorentfernung und Cochleaimplantation unter Verwendung von „lateral wall“-Elektrodenträgern ist möglich und kann zu guten Hörergebnissen führen.

Keywords: Acoustic neuroma; Cochlea; Cochlear implant; Inner ear; Intralabyrinthine.

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Conflict of interest statement

M.E. Quick, S. Withers, S.K. Plontke, R. Chester-Browne and J. Kuthubutheen declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
Intracochlear schwannomas (ICS) identified on axial and coronal gadolinium (Gd)-enhanced T1-weighted magnetic resonance imaging (MRI; Philips DRIVE T3 MRI scanner). Enhancing right ICS (solid arrows) on axial (a) and coronal (b) and early small left ICS (dashed arrows) prior to right-sided surgical intervention. Progressive growth of left-sided ICS (dashed arrows) on axial (c) and coronal (d) repeat MRI after right-sided surgery with artifact (star) from cochlear implant
Fig. 2
Fig. 2
Time course of pure tone audiogram thresholds (only air conduction shown) for the right (a) and left ear (b) prior to the respective surgical interventions
Fig. 3
Fig. 3
Intra-operative image after subtotal petrosectomy. Initially an opening along the basal turn is drilled with identification of the intracochlear schwannoma (solid arrow). S stapes, P promontory, RW round window. Dark lines: suction tip (left) and Shambaugh Ear Hook (right)
Fig. 4
Fig. 4
a Complete tumour resection after subtotal cochleoectomy (dashed arrow) preserving the modiolus and lateral round window arch (solid arrow). b Standard cochlear insertion technique through the round window and confirmation of insertion along the basal turn. S stapes, RW round window
Fig. 5
Fig. 5
Right-sided intracochlear schwannoma confirmed on histology and immunohistochemistry. a Compact spindle shaped cells with Antoni A and Antoni B pattern palisading around a nuclear free area; H&E. b Strong positive tumour cells; S‑100. c EMA and d CK-AE1/AE3 both of tumour cells. H&E haematoxylin and eosin stain. EMA epithelial membrane antigen
Fig. 6
Fig. 6
Left-sided intracochlear schwannoma confirmed on histology and immunohistochemistry. a Compact spindle-shaped cells with Antoni A and Antoni B pattern palisading around a nuclear-free area; H&E. b Strong positive tumour cells; S‑100. c EMA and d CK-AE1/AE3 both of tumour cells. H&E, haematoxylin and eosin stain. EMA epithelial membrane antigen
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