Vestibular Schwannoma (VS)
Last Updated: March 27, 2020
- Benign peripheral nerve sheath tumor arising from Schwann cells of CN 8 (vestibular portion) within the CPA-IAC
- WHO grade 1
- Originates from Schwann cells surrounding CN 8 vestibular segment
- CN 8 inferior vestibular branch > superior branch
- CN 5 and CN 7 schwannomas not uncommon
- Origin in CN 8 cochlear portion is rare
- Bilateral VS hallmark of Neurofibromatosis type 2 (NF-2)
- Mutations in NF2 tumor suppressor gene in majority of sporadic and familial cases
- Associated abnormality: arachnoid cyst or “CSF cap” (7-10% of cases)
- Variable hypercellular (Antoni A) and more hypocellular (Antoni B) areas are characteristic microscopic features
- ± Intratumoral cysts, microhemorrhage
- Most common during adulthood (ages 40-60)
- Uncommon in children unless associated with NF-2
- Majority of cases exhibit slow growth over time
- Common presenting signs/symptoms: unilateral sensorineural hearing loss
- Treatment: surgical resection
- Prognosis: size >2 cm and involvement of IAC fundus and/or cochlear aperture are negative prognosticators for hearing preservation
- Well-marginated, enhancing mass within the CPA or CPA-IAC with “ice cream on cone” morphology
- Expansion of the IAC (in contrast to meningiomas)
- Small lesions may be entirely intracanalicular
- Calcification, cystic degeneration may be seen; hemorrhage rare
- Small lesions may be entirely intracanalicular and nonvisible on CT
- Enhancement on contrast-enhanced CT
- T1WI: usually hypo- to isointense
- T2WI: high resolution sequences (SPACE, CISS, or FIESTA) optimize visualization; appears as a hypo- to isointense CPA-IAC filling defect (ovoid if small, “ice cream on cone” if larger); ± hyperintense tumoral cysts
- T2*GRE: ± signal blooming from foci of microhemorrhage
- T1WI+C: avid enhancement
- MRI without and with IV contrast including high-resolution T2-weighted sequences through the CPA-IAC (SPACE, CISS, or FIESTA); serial MR imaging for small lesions to ensure stability
For more information, please see the corresponding chapter in Radiopaedia.
Contributor: Rachel Seltman, MD; Jacob A. Eitel, MD
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Osborn AG, Salzman KL, Jhaveri MD. Diagnostic Imaging (3rd ed). Philadelphia, PA: Elsevier, 2016.
Thamburaj K, et al. Intratumoral microhemorrhages on T2*-weighted gradient-echo imaging helps differentiate vestibular schwannoma from meningioma. AJNR Am J Neuroradiol. 2008;29:552-557.
Woodruff JM, et al. Schwannoma, in Kleihues P et al (eds): Tumours of the Nervous System. Lyon: IARC Press, 2000; 164-166.
Zealley IA, et al. MRI screening for acoustic neuroma: a comparison of fast spin echo and contrast enhanced imaging in 1233 patients. Br J Radiol. 2000;73:242-247.
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