Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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October 12, 2015
Jugular Schwannoma
- Backgounds:
- Jugular schwannomas are very rare tumors, accounting for about 2–4% of intracranial schwannomas
- Relevant Clinical Information:
- They occur commonly between the 3rd and 6th decades, with female predilection.
- Hearing loss, tinnitus, ataxia, and vertigo are the most common initial symptoms.
- A constellation of symptoms localizing to the jugular foramen (9th, 10th, and 11th cranial nerve palsy) can sometimes be seen — called Vernet syndrome or jugular foramen syndrome — comprised of hoarseness; nasal regurgitation; uvula deviation to the contralateral side and dysphagia with loss of gag reflex; sternomastoid and trapezius palsy; and loss of sensation of the posterior third of tongue.
- Key Imaging Features:
- Well defined lesion arising from jugular foramen, expanding it and further extending intracranially into the posterior fossa, below the skull base, or both (dumbbell shaped if both)
- Hypointense on T1WI, hyperintense on T2WI, and moderate-to-marked contrast enhancement
- Larger lesions may be heterogeneous due to necrosis or cystic formation. Intratumoral microhemorrhages can be appreciated in T2*-weighted gradient echo sequences.
- 3D CISS and 3D postcontrast sequences might help in further localizing the lesion within the jugular foramen, whether it arises from pars nervosa (indicating IX nerve origin) or pars vascularis (indicating X or XI nerve origin).
- On CT the lesion appears well defined and iso-to-hypodense compared to brain parenchyma, and the affected jugular foramen will show expansion and remodeling.
- DDx:
- Meningioma: Dural tail, hyperostosis, calcification, homogeneous isointense T1 and T2 signal, and intense homogeneous enhancement favor diagnosis of meningioma over schwannoma
- Schwannoma from other cranial nerves (vestibular, hypoglossal): The diagnosis will depend on which cranial foramen or canal is widened
- Glomus jugulare or jugulotympanicum: Bone destruction instead of bone remodeling, intratumoral flow voids, and dilated feeding arteries and draining veins, due to the hypervascular nature of the lesion
- Metastatic skull base lesions: Bone destruction and symptoms appear with smaller-sized lesions. Clinical history is fundamental for the DDx.
- Treatment: Excision. Small tumors can be followed up with imaging or treated with stereotactic radiosurgery.
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