Object: Radical removal of meningiomas involving the major dural sinuses remains controversial. In particular, whether the fragment invading the sinus must be resected and whether the venous system must be reconstructed continue to be issues of debate. In this paper the authors studied the effects, in terms of tumor recurrence rate as well as morbidity and mortality rates, of complete lesion removal including the invaded portion of the sinus and the consequences of restoring or not restoring the venous circulation.
Methods: The study consisted of 100 consecutive patients who had undergone surgery for meningiomas originating at the superior sagittal sinus in 92, the transverse sinus in five, and the confluence of sinuses in three. A simplified classification scheme based on the degree of sinus involvement was applied: Type I, lesion attachment to the outer surface of the sinus wall; Type II, tumor fragment inside the lateral recess; Type III, invasion of the ipsilateral wall; Type IV, invasion of the lateral wall and roof; and Types V and VI, complete sinus occlusion with or without one wall free, respectively. Lesions with Type I invasion were treated by peeling the outer layer of the sinus wall. In cases of sinus invasion Types II to VI, two strategies were used: a nonreconstructive (coagulation of the residual fragment or global resection) and a reconstructive one (suture, patch, or bypass). Gross-total tumor removal was achieved in 93% of cases, and sinus reconstruction was attempted in 45 (65%) of the 69 cases with wall and lumen invasion. The recurrence rate in the study overall was 4%, with a follow-up period from 3 to 23 years (mean 8 years). The mortality rate was 3%, all cases due to brain swelling after en bloc resection of a Type VI meningioma without venous restoration. Eight patients--seven of whom harbored a lesion in the middle third portion of the superior sagittal sinus--had permanent neurological aggravation, likely due to local venous infarction. Six of these patients had not undergone a venous repair procedure.
Conclusions: The relatively low recurrence rate in the present study (4%) favors attempts at complete tumor removal, including the portion invading the sinus. The subgroup of patients without venous reconstruction displayed statistically significant clinical deterioration after surgery compared with the other subgroups (p = 0.02). According to this result, venous flow restoration seems justified when not too risky.