Head and Neck Imaging

internal auditory canal, pathology

Abnormal size
A unilateral wide IAC may be caused by an acoustic schwannoma . Bilateral wide IACs may be due to dural ectasia, as seen in neurofibromatosis . A wide canal may be associated with an abnormal bony partition between the canal and the inner ear; such an ear may show a gusher during surgery (see also X-linked hearing loss ). A very narrow canal may imply absence of the vestibulocochlear nerve, or part of it.
Other congenital lesions
- a vascular malformation, head and neck may be present in the IAC; this may mimic radiologically an intracanalicular tumour.
- vestibulocochlear nerve, congenital anomalies .
Inflammation
- meningeal inflammation in the IAC may originate from the middle ear, spreading through the inner ear, or may represent intracanalicular extension from meningitis in the cerebellopontine angle.
Tumours
- acoustic schwannoma is the most common tumour of the IAC (see also acoustic schwannoma , hook shape sign, in acoustic schwannoma ).
- meningioma , arising from the posteromedial side of the petrous bone, may extend in the IAC.
- rare tumours include lipoma, hamartoma, haemangioma and meningeal carcinomatosis. Facial nerve schwannoma may extend in the IAC; squamous cell carcinoma, head and neck may reach the IAC via perineural tumour spread, head and neck .

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