====== Petrous bone meningioma classification ======

Bricolo et al.
((Bricolo AP, , Turazzi S, , Talacchi A, & Cristofori L: Microsurgical removal of petroclival meningiomas: a report of 33 patients. Neurosurgery 31:813–828, 1992)) divided posterior [[petrous bone meningioma]]s into tumors anterior to the IAC and tumors posterior to the IAC. D

Desgeorges et al. refined this description when they introduced the A-M-P classification:


[[Petrous bone meningioma]]s were classified into 3 types following the Desgeorges classification,
((Desgeorges M, Sterkers O, Poncet JL, Rey A, Sterkers JM. [Surgery for
meningioma of the posterior skull base. 135 cases. Choice of approach and
results]. Neurochirurgie. 1995;41(4):265-90; discussion 290-4. French. PubMed
PMID: 8524441.
))
which is based on the tumor's dural attachment to the posterior [[petrous bone]] surface: 

Type A (anterior) meningiomas originate from the [[petrous apex]]. see [[petrous apex meningioma]].

Type M (middle) meningiomas originate at the level of the [[internal auditory canal]] (IAC)

Type P (posterior) meningiomas develop from the posterior part of the [[petrous bone]], between the posterior wall of the IAC and the groove of the [[sigmoid sinus]].

see [[Posterior petrous bone meningioma]].