Labyrinthine schwannoma

Case contributed by Dr Chris O'Donnell

Presentation

Sudden right-sided hearing loss 7 years ago. Initial MRI 6 years ago. Thought to be labyrinthitis. No improvement and now vertigo for follow-up.

Patient Data

Age: 70 years
Gender: Male
MRI

Original MRI 6 years ago

Subtle but definite assymetrical enhancement of the right basal turn of the cochlea and modiolus.

MRI

Follow-up MRI 6 years later

Mass lesion with abnormal enhancement involving the cochlea, vestibule and components of the VIIIth nerve at the apex of the internal auditory canal.

Case Discussion

Most "acoustic' schwannomas arise in the vestibular nerve at the vestibular ganglion that is at the junction of the central and peripheral myelin (in the fundus of the IAC). Schwannomas can actually occur anywhere along the canal where there are Schwann cells supporting peripheral myelin but can involve the membranous labyrinth i.e. cochlea, vestibule, or semicircular canals where there are also peripheral nerves.  These are known as labyrinthine schwannomas and are quite rare.

In this case, the very early finding of enhancement without mass effect in the modiolus and basal turn of the cochlea has been interpreted as an inflammatory process but over time the true tumourfactive nature of a schwannoma has been revealed.

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Case information

rID: 50336
Case created: 30th Dec 2016
Last edited: 8th Jan 2017
System: Head & Neck
Inclusion in quiz mode: Included

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