SURGERY OF POSTERIOR SKULL BASE MENINGIOM AS - 135 CASES - CHOICE OF SURGICAL APPROACH AND RESULTS

One hundred and thirty-five patients with posterior skull base meningi omas were seen and treated by a neurosurgical - neurotological team ov er the last 12 years. Ten tumors were ''true'' clival meningiomas and 125 were posterior petrous meningiomas: 25 were located anterior to th e internal auditory meatus (IAM) (zone A); 29 were located around the IAM (zone M) and 18 were posterior to the IAM (zone P). 53 tumors had a larger zone of implantation and are accordingly called AM (31 cases) , MP (15 cases), AMP (7 cases). The choice of routes was guided by a r adiological anatomy classification system (17). Transpetrous approache s, alone or in combination with subtemporal transtentorial or retrosig moid approaches were the surgical routes of choice for posterior petro us meningiomas, making it possible to reach the tumoral osteodural imp lantation, reduce the tumoral mass and perform a subarachnoidal dissec tion of the tumor poles. A retrolabyrinthine (RL) approach allows acce ss to zone P and a translabyrinthine approach to zone MP. Zones A, M a nd P can be reached via the anterior extended translabyrinthine (AETL) approach. Anterolateral transclival approaches with apex petrectomy w ere used to reach the clival meningiomas with a wide implantation zone . Standard microsurgical techniques were used in 32 cases and 103 proc edures included the use of a microscope-guided laser. Complete tumor r emoval was accomplished in 88 % of cases (120/135), Overall mortality was 3,7 % (2 cases at 30 days and 3 cases between 31 days and 1 year).