The Management of the Venous Sinuses During Surgery for Posterior Fossa Meningiomas.

OBJECTIVE

To define, from a series of surgically treated meningiomas of the posterior fossa with dural attachment above the dural sinuses, the best management of the sinus invasion according to the pattern of venous circulation.

METHODS

Seventy-five patients with posterior fossa meningioma whose dural attachment involved the major venous sinuses were included in the study. We considered tumor location and dural attachment, pattern of venous sinus circulation, degree of sinus involvement and its management, entity of surgical resection, complications, and recurrences.

RESULTS

The resection of the involved sinus segment (Simpson I) was performed in 15 patients (20%) (10 with complete occlusion and pattern of circulation of types A and B and 5 with narrowed sinus and type B circulation); 42 cases (56%, all of type 1) were treated by coagulation and/or removal of the outer dural layer (Simpson II). In 14 (19%) the intrasinusal fragment was left (Simpson III), and in 4 (5%) the resection was partial, with residual intradural tumor (Simpson IV). No postoperative complications secondary to venous obstruction occurred. Eleven patients (15%) experienced tumor recurrence and were reoperated on. Only 4 of them with extensive dural invasion had further recurrence.

CONCLUSIONS

In patients with posterior fossa meningiomas, we suggest to safety resect the involved sinus segment only when completely occluded. If the sinus lumen is not invaded or the tumor lies on the side of the unique or dominant transverse sinus, it should be preserved. This results in no or negligible risk of venous infarction and rather low recurrence rate.