Differentials
Meningioma
SIGNS / SYMPTOMS
Highly dependent on the location and size of the tumour.
Hearing loss is a less prominent symptom.
INVESTIGATIONS
Meningiomas of the cerebellopontine angle classically present eccentric to the porus acusticus, often have limited or tapering extension into the meatus, exhibit dural tails along the posterior petrous dura, typically exhibit more homogeneous enhancement, and may acquire intratumoral bone formation or hyperostosis at the base.
CT and MRI findings show a large angle between the tumour and dura not centred over the internal acoustic meatus. Also, imaging displays bone hyperostosis, no internal acoustic meatus enlargement, and no or less extension into the internal acoustic meatus.
Epidermoid cyst
SIGNS / SYMPTOMS
Epidermoid cysts are congenital, non-cancerous lesions that contain an outer cyst wall of keratinising squamous epithelium and a core of keratin debris. Hearing loss is often a less prominent symptom.
INVESTIGATIONS
Epidermoids have similar signal characteristics to arachnoid cysts on non-contrast T1- and T2-weighted MRI; however, they characteristically exhibit restricted diffusion on non-echo planar diffusion-weighted imaging sequences.
Facial nerve schwannoma
SIGNS / SYMPTOMS
Facial nerve paresis or facial spasm is a prominent symptom, occurring in at least half of people; hearing loss also commonly occurs.
INVESTIGATIONS
CT and MRI results are similar to those of vestibular schwannoma; however, nodular enhancement often extends into the labyrinthine segment of the facial nerve and geniculate ganglion on MRI; CT may show widening of the fallopian canal.
Trigeminal schwannoma
SIGNS / SYMPTOMS
Clinically associated with more prominent facial numbness and less severe hearing loss.
INVESTIGATIONS
CT and MRI display a dumbbell-shaped mass spanning the posterior and middle fossae and involving Meckel's cave. The tumour enhancement does not extend into the internal auditory canal.
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