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Differential Diagnosis

5th or 8th nerve schwannoma

Arachnoid cyst

Epidermoid cyst

Meningioma

Cholesterol granuloma

Mets

Skull base tumor – chordoma, chondrosarcoma

5th Nerve Schwannoma

Rare (0.4% brain tumors), second most common CN schwannoma

No sex predilection, peak incidence in 4th decade

Symptoms of trigeminal dysfunction = pain, numbness, paresthesias

Can be predominately within the posterior fossa, within Meckel’s cave (most common), in the middle cranial fossa, or a combination (“saddle tumor”)

Imaging

MR

Smooth masses – isointense on T1, hyperintense on T2, avid enhancement

Can have prominent areas of cystic change

CT

As above, good for identifying associated bony erosions (petrous apex, neural foramina)