Clinical History
53-year-old female patient who presented with a traumatic brain injury after being in a car accident. A head CT and a cervical spine CT were performed.
Imaging Findings
Head CT demonstrated a focal subarachnoid hemorrhage (not shown).
Cervical spine CT showed no fractures but revealed a smooth left jugular foramen enlargement, right hypoglossal canal expansion and bone remodeling without destruction. Sagittal soft tissue algorithm image at the level of the jugular foramen showed a hypodense mass extending to the carotid space.
MRI revealed a homogeneous and well defined mass in the left jugular foramen. The lesion was hyperintense on T2-weighted sequence. Following administration of contrast, the T1-weighted images demonstrated a peripheral enhancement.
Discussion
Schwannomas are benign nerve sheath tumors arising from Schwann cells. They may develop along the course of any nerve sheath of the peripheral or cranial nerves. Jugular foramen schwannomas arise around the IXth to XIth, Jacobsen and Arnold nerves. [1] They are rare and constitute only 3% of all intracranial schwannomas. [1] Histologically they show regions of compactly arranged cells (Antoni type A) mixed with regions of loosely arranged cells (Antoni type B). [2]
Schwannomas are often asymptomatic and discovered incidentally at imaging. The clinical manifestations of CN schwannomas may vary according to the nerve of origin, therefore cranial nerve deficits should guide a targeted search of the lesion. Some of these patients present with unilateral dysphagia, dysphonia or dysarthria and other symptoms due to the proximity of the lower cranial nerves. [2] Because of their slow growth and asymptomatic condition, they can cause sensorineural hearing loss owing to the mass effect on VIII cranial nerve [2].
These lesions remodel and expand the jugular foramen. Bone algorithm CT shows smooth jugular foramen enlargement with sharp margins. Findings differ from paragangliomas, which show a destructive pattern, or meningiomas, which are frequently associated with sclerosis. [3] Owing to their mixoid content or cystic changes they may be hypodense on soft tissue algorithm CT.
On MRI they are seen as well-circumscribed masses with high signal intensity on T2-weighted MR images. On T1-weighted images, they have low or intermediate signal intensity. They may demonstrate avid enhancement after contrast material administration, and can show nonenhancing cystic spaces. These lesions also displace adjacent structures without invasion [2].
Surgical resection or stereotactic radiosurgery are the treatments of choice.
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Differential Diagnosis List
Jugular foramen schwannoma
Jugular foramen schwannoma
Paraganglioma
Meningioma
Metastases
Final Diagnosis
Jugular foramen schwannoma
