- 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
Jackson CG, Glasscock ME, Harris PF. Glomus Tumors. Diagnosis, classification, and management of large lesions. Arch Otolaryngol. 1982;108(7):401-10.