Investigation

As in paraganglioma' high-resolution computed tomography (HRCT) is superior in defining skull base bony erosion. Imaging should include the posterior cranial fossa' skull base' and the upper cervical region. On CT, schwannomas display ovoid enlargement of the jugular foramen, involving predominantly the pars nervosa, with smooth indistinct sclerotic margins.1'4 In contrast, temporal bone paragangliomas causes irregular enlargement of the jugular foramen, with indistinct margins (Table 83-4). Lesions in the pars nervosa of the jugular foramen, may often be distinguished from hypoglossal schwannomas, which often present as dumbbell-shaped with intra- and extracranial extension.54

On MRI, their appearance is similar to that of a vestibular schwannoma. Carotid and vertebral angiography may help differentiate neural sheath tumors from a temporal bone paraganglioma, since the paraganglioma is highly vascular, while schwannoma has only slight, but variable, vascularity.4,54

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