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Vestibular Schwannoma

Summary

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  • Benign tumour arising from Schwann cells of the vestibular nerve
  • Typically presents with unilateral hearing loss, tinnitus, and balance disturbances
  • Characteristic imaging finding: enhancing mass in the cerebellopontine angle cistern1

Pathophysiology

  • Originates from Schwann cells of the vestibular portion of CN VIII
  • Slow-growing, encapsulated tumour
  • May compress adjacent structures, including:
    • Cochlear nerve
    • Facial nerve
    • Brainstem
    • Cerebellum
  • Associated with NF2 gene mutations in some cases

Demographics

  • Incidence: 1-2 per 100,000 person-years
  • Peak age: 40-60 years
  • Slight female predominance
  • Bilateral tumours associated with Neurofibromatosis Type 2 (NF2)

Diagnosis

  • Clinical presentation:
    • Gradual, unilateral sensorineural hearing loss (95%)
    • Tinnitus (63%)
    • Balance disturbances (61%)
    • Facial numbness or weakness (17%)
  • Audiometry:
    • Asymmetric sensorineural hearing loss
    • Poor speech discrimination
  • Vestibular function tests:
    • Caloric testing may show reduced vestibular function

Imaging

  • MRI (gold standard):
    • T1-weighted: isointense to hypointense
    • T2-weighted: heterogeneous signal intensity
    • Contrast-enhanced T1: intense, homogeneous enhancement
    • Characteristic "ice cream cone" appearance in internal auditory canal
  • CT:
    • Widening of internal auditory canal
    • Erosion of petrous bone in larger tumours
  • Cystic changes and heterogeneous enhancement more common in larger tumours

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  • 40-year-old presenting with right sided sensorineural hearing loss.
  • MRI showed an avidly enhancing lesion filling the right internal auditory canal and cerebellopontine angle cistern.

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  • 50-year-old patient presented with total right-sided sensorineural hearing loss.
  • MRI showed an enhancing lesion in the internal auditory canal.
  • Enhancement and loss of fluid signal within the cochlea and vestibule indicated labyrinthine extension of the schwannoma.

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  • 30-year-old patient with left sided facial weakness and sensorineural hearing loss.
  • CT showed a widened internal auditory canal due to a large solid-cystic lesion centred on the left cerebellopontine angle cistern.

Treatment

  • Small tumours are observed; growth or symptoms prompt radiosurgery or microsurgical resection. The enhancing IAC/CPA "ice-cream cone" mass is characteristic; bilateral tumours indicate NF2

Differential diagnosis

Differential Diagnosis Differentiating Feature
Meningioma Typically has a dural tail on MRI; often enhances more homogeneously
Facial nerve schwannoma Involves the facial nerve canal; may cause facial weakness
Cholesteatoma Appears hypointense on T1-weighted MRI; does not enhance with contrast
Arachnoid cyst Non-enhancing, CSF-like signal on all MRI sequences
Metastasis Often multiple CPA lesions; irregular margins; may show adjacent bone destruction
Glomus jugulare tumour "Salt and pepper" appearance on T2-weighted MRI; extends into jugular foramen
Epidermoid cyst Restricted diffusion on DWI; irregular margins
Aneurysm Flow voids on MRI; enhances on CTA or MRA
Multiple sclerosis plaque Ovoid lesions; often multiple; may enhance with contrast in active phase
Lipoma Hyperintense on T1-weighted images; suppresses on fat-saturated sequences

  1. Gupta et al. Vestibular Schwannoma: What We Know and Where We are Heading. 2020. Head and neck pathology - Open in new tab. ↩