[Clinicopathological study of meningiomas of the tentorium and its surrounding structures]

We report the clinical features, radiological studies, operative procedures and results, and follow-up data in 29 patients with meningiomas of the tentorium and its surrounding structures. The cases represented 22.5% of all the intracranial meningiomas operated on in a 15 year period and were divided into three groups, depending on their main attachments, tentorial, cerebellopontine angle (dorsal aspect of the petrous ridge) and others. Tumor size was generally large and 13 cases were larger than 5 cm. The most common tumor site was along or near the superior petrosal sinus and transverse-sigmoid junction in cases involving the tentorium, and medial to the porus acousticus in cases involving the cerebellopontine angle. Different operative approaches to these tumors were carried out, depending on their location. The tumors in the lateral or medial petrous ridge were approached mainly with a suboccipital craniectomy using a retromastoid incision. Total removal was carried out in 80% of the tentorial cases, in 46.2% of cerebellopontine angle cases, and in the 83.3% in the others. Total operative mortality rate was zero. Follow-up periods ranged up to 5 years 5 months in the tentorial cases, 4 years 6 months in cerebellopontine angle cases, and 7 years 1 month in the others. Long-term results were good in 21 cases (72.4%), fair in 3 cases (10.3%) and poor in 2 (6.9%). Three patients died due to tumor recurrence. One of them suffered lung metastasis, and two of them suffered extensive local recurrences. We recommend the retromastoid approach combined with the petrosal approach, if the CPA tumor is large enough and extends to the retroclival region.