Right Acoustic nerve schwannoma
Benign tumor arising from Schwann cell that warps around vestibulocochlear nerve in CPA-IAC.
Benign tumor arising from Schwann cell that warps around vestibulocochlear nerve in CPA-IAC.
General features –
1) Avidly enhancing cylindrical (IAC), ice cream on cone mass.
2) Location – small lesion – intracanalicular, large lesion – intracanalicular with CPA cistern extension.
3) Size- small lesion - 2-10mm
Larger lesion up to 5cm in diameter.
CT finding-
CECT-
1) Well delineated, enhancing mass of CPA –IAC cistern.
2) Calcification not present.
3) May flare IAC when larger,
4) Smaller intracanalicular lesion < 6 mm may miss on CECT.
MR finding-
1) T1W1-
Intermediate signal is most common .High signal foci if rare hemorrhagic lesion is present.
2) T2W1-
High resolution T2 MR- Filling defect high signal CSF, of CPA IAC cisterns.
3) T1C+-
Focal enhancing mass of CPA IAC cisterns center on porus acusticus, 100% enhance strongly.
Clinical features –
1) Presented adults with sensory neural hearing loss.
2) BERA-most sensitive pre imaging test for AS.
3) Small AS – tinnitus , disequilibrium
4) Large AS – trigeminal, or facial neuropathy.
5) Age - 30 – 70 years.
Differential diagnosis-
1) Epidermoid cyst.
2) Arachnoids cyst.
3) Meningioma.
4) Facial nerve schwannomas.
5) Metastasis.
6) Lymphoma.