Imaging findings in schwannomas of the jugular foramen

BACKGROUND AND PURPOSE: Tumors of the cranial nerve sheath constitute 5% to 10% of all intracranial neoplasms, yet few articles have described their C T and MR characteristics. We report the imaging findings in a relatively la rge series of schwannomas of the jugular foramen, contrasting them with oth er disease entities, especially vestibular schwannomas and tumors of the gl omus jugulare, METHODS: CT and/or MR studies of eight patients who underwent surgery for h istologically proved schwannomas were reviewed retrospectively, One additio nal patient with an assumed schwannoma of the jugular foramen, who did not have surgery, was also included. RESULTS: Surgical findings showed schwannomas of the glossopharyngeal nerve in seven patients and tumor involvement of both the glossopharyngeal and v agal nerves in one patient. All tumors were partially located within the ju gular foramen, Growth extending within the temporal bone was typical. Tumor extended into the posterior cranial fossa in all nine patients and produce d mass effect on the brain stem and/or cerebellum in seven patients; in fiv e patients, tumor extended below the skull base, On unenhanced CT scans, tu mors were isodense with brain in six patients and hypodense in two. In seve n patients, CT scans with bone algorithm showed an enlarged jugular foramen with sharply rounded bone borders and a sclerotic rim. On MR images, T1 si gnal from tumor was low and T2 signal was high relative to white matter in all patients, Contrast enhancement on CT and/or MR studies was strong in ei ght patients and moderate in one, CONCLUSION: Schwannoma of the jugular foramen is characteristically a sharp ly demarcated, contrast-enhancing tumor, typically centered on or based in an enlarged jugular foramen with sharply rounded bone borders and a sclerot ic rim. Intraosseous extension may be marked.