Middle fossa transpetrosal-transtentorial approaches for petroclival meningiomas. Selective pyramid resection and radicality.

Forty-two patients with petroclival meningioma were operated upon by the middle fossa transpetrosal-transtentorial approaches since 1977. Half of those showed tumour extension into the middle fossa and one-third in the cavernous sinus. Seventeen (40%) had a large tumour of 40 mm in diameter or larger, and 8 of those had a broad attachment from the clivus to petrous pyramid of the temporal bone. The site of pyramid resection was selected from three types, depending on the tumour location and the patients' pre-operative hearing. There was no surgical mortality. Significant risk of lower cranial nerves palsy was minimal and useful hearing was preserved in 18 out of 21 patients. The follow-up, an average of 4 and a half years, showed tumours were completely eradicated in 32 patients (76%) and there was regrowth in 3 (7%). Thirty-four patients (81%) were independent, 3 disabled and only one died of rapid tumour regrowth. The most influential factor on surgical results was the extent to which the tumour had invaded the brain stem. The presence or absence of arterial encasement and of peritumoural oedema on MRI were important in the selection for radical surgery.