- Type I – Small tumor involving the jugular bulb, middle ear and mastoid
- Type II – Tumor extending under the internal auditory canal. There may be intracranial extension
- Type III – Tumor extending into the petrous apex. There may be intracranial extension
- Type IV – Tumor extending beyond the petrous apex into the clivus and infratemporal fossa. There may be intracranial extension
Reference:
Jackson CG, Glasscock ME, Harris PF. Glomus Tumors. Diagnosis, classification, and management of large lesions. Arch Otolaryngol. 1982;108(7):401-10.