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3 Cards in this Set

  • Front
  • Back
What is ddx of a CPA mass?
Most common:
- Vestibular schwannoma (AKA acoustic neuroma)
- Meningioma

Less Common:
- Giant aneurysm: may arise from the PICA. Look for a lamellated appearance and phase artifact.
- Epidermoid cyst : similar to CSF on all sequences except FLAIR and DWI; ENCASES neurovascular structures traversing the CPA rather than displacing them.
- Arachnoid cyst:
- Glioma: exophtic mass arising from the brainstem extending into the IAC; look for a irregular interface between the mass and adjacent brain.

Fat containing:
- Dermoid: displaces neurovascular structures; contains fat.
- Lipoma: neurovascular structures traverse the lesion. Resection of the lipoma may injure these structures.
1. What is the most common CPA mass?
2. What are the imaging features of vestibular schwannoma?
3. What appears similar to a heterogeneously enhancing vestibular schwannoma?
4. What is a common complication of a vestibular schwannoma?
1. Vestibular schwannoma (accounts for 75-80% of CPA mass).
- Enhancing extraaxial mass positioned in the CPA and/or IAC.
- Widening of IAC.
- Small lesions enhance homogeneously
- Larger lesions enhance heterogeneous 2/2 cysts, hemorrhage, and fatty degeneration.
3. Large hemorrhagic vestibular schwannoma may mimic a giant aneurysm. NOTE: aneurysm will not enhance if thrombosed.
4. Acute 7th nerve palsy 2/2 the vestibular schwannoma.
What are the features of CPA meningioma?
- Flatter than round
- Wide dural base with dural tails
- Hyperostosis
- RARELY widens or extends into IAC.