Jugular Schwannoma Classification

Type

Description

A Primarily limited to cerebellopontine angle, with minimal jugular foramen enlargement

B Primarily in the jugular foramen, with minimal intracranial extension

C Primarily extracranial with extension into the jugular foramen

D Dumbbell-shaped with intra- and extracranial components

From Samii et al.51

Meningiomas

Meningiomas of the jugular foramen are relatively rare, yet they are the second or third most common tumor of this region.14 Most meningiomas of the jugular foramen invade from adjacent regions: medially, from the lower clivus; laterally, from the sigmoid sinus; superiorly, from the petrous bone or cerebellopontine angle; and inferiorly, from the foramen magnum.58 Rarely, a meningioma may arise from cells of the arachnoid villi of the jugular bulb.58 The anatomic relationship of the tumor to the cranial nerves depends on its site of origin. In general, menin-giomas of the jugular foramen are thought to be more invasive into surrounding bone and cranial nerves than are glomus tumors; they tend to recur more frequently after surgery as well.58

CN IX laterally toward the surgeon's view (an unfavorable position); conversely, schwannomas originating from CN IX displace CN X and XI medially away from the surgeon's view (a favorable position).14 In actuality, it is quite difficult to determine intraop-eratively the nerve of origin of jugular schwannomas.54'55

Samii et al.51 proposed a four-tiered anatomically based classification system (Table 82-3) of jugular foramen schwannomas similar to classifications systems of other schwannomas such as trigeminal neuromas.56 Fisch and colleagues57 proposed a four-tiered anatomically based classification system similar to the one he developed for glomus tumors (Table 82-4).

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