Modified Jackson

Glomus tumors classification

Type I

Small; involves jugular bulb, middle ear and mastoid. No intracranial extension.

Type II

Extends under internal auditory meatus. Intracranial extension possible.

Type III

Extends into petrous apex. Intracranial extension possible.

Type IV

Extends beyond petrous apex into clivus or infratemporal fossa. Intracranial extension possible.

Reference

Greenberg's Handbook of Neurosurgery, 7th edition