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Trigeminal Schwannoma

Summary

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  • Rare benign tumour arising from Schwann cells of the trigeminal nerve
  • Presents with facial pain, numbness, or weakness in trigeminal nerve distribution
  • Imaging shows a dumbbell-shaped mass in the middle cranial fossa and/or posterior fossa1

Pathophysiology

  • Originates from Schwann cells of the trigeminal nerve sheath
  • Most commonly arises from the gasserian ganglion in the middle cranial fossa
  • Can extend into the posterior fossa through Meckel's cave
  • May involve one or more divisions of the trigeminal nerve

Demographics

  • Accounts for 0.07-0.36% of all intracranial tumours
  • Peak incidence in 4th to 5th decades of life
  • No significant gender predilection
  • Rare association with neurofibromatosis type 2 (NF2)

Diagnosis

  • Clinical presentation:
    • Facial pain or numbness in trigeminal nerve distribution
    • Facial weakness or paralysis
    • Headache
    • Hearing loss or tinnitus (if involving the cerebellopontine angle)
  • Physical examination:
    • Decreased sensation in trigeminal nerve distribution
    • Weakness of masticatory muscles
    • Corneal reflex abnormalities

Imaging

  • MRI:
    • T1-weighted: iso- to hypointense
    • T2-weighted: hyperintense
    • Contrast-enhanced T1: heterogeneous enhancement
    • Characteristic dumbbell shape extending through Meckel's cave
  • CT:
    • Isodense to brain parenchyma
    • Bone window: widening of foramen ovale or rotundum
  • Angiography:
    • May show tumour blush or displacement of adjacent vessels

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  • An incidental heterogeneously enhancing lesion was traversing an expanded left foramen ovale.
  • As the lesion was incidental and there was no growth over 3 years, no treatment was planned.
  • The putative diagnosis was a V3 trigeminal schwannoma.

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  • An incidental lesion was found expanding the foramen ovale on the left.
  • The lesion was avidly enhancing with small cystic components.

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  • A 25-year-old patient presented with right sided facial numbness and diplopia.
  • MRI showed a solid-cystic partially enhancing lesion that involved the cavernous sinus.
  • A schwannoma was confirmed following resection.

Treatment

  • Resection or radiosurgery for symptomatic/growing tumours; small lesions are observed. A dumbbell mass along the nerve through Meckel's cave, widening the foramen ovale/rotundum, is characteristic

Differential diagnosis

Differential Diagnosis Differentiating Feature
Meningioma Typically has a dural tail on MRI; schwannomas do not
Acoustic neuroma Primarily affects the vestibulocochlear nerve; trigeminal schwannomas affect the trigeminal nerve
Epidermoid cyst Demonstrates restricted diffusion on DWI; schwannomas do not
Metastasis Often multiple lesions; schwannomas are typically solitary
Chordoma Occurs in the clivus; trigeminal schwannomas are along the course of the trigeminal nerve
Pituitary adenoma Centered in the sella turcica; trigeminal schwannomas are not
Aneurysm Demonstrates flow voids on MRI; solid enhancement in schwannomas
Glioma Infiltrative appearance; schwannomas are well-circumscribed
Hemangiopericytoma Typically has a multilobulated appearance; schwannomas are more uniform
Chondrosarcoma Often has calcifications; not typical in schwannomas

  1. Li et al. Trigeminal schwannoma: a single-center experience with 43 cases and review of literature. 2021. British journal of neurosurgery - Open in new tab. ↩