Analysis of the efficacy of microdissection of paravebous sinus meningiomas invading large venous sinuses

Abstract

Objective: The surgical management of paravebous sinus meningiomas that invade major venous sinuses remains controversial. The need for complete resection of all tumors and the need for venous sinus reconstruction after resection remains a point of debate. In this article, we attempt to illustrate the results of complete resection of the lesion (including the invading venous sinus portion) and the consequences of restoring or not restoring venous circulation in terms of tumor recurrence, mortality, and post-operative complications. Methods: The authors collected 68 patients with paravebous sinus meningiomas. 60 patients belonged to the parasagittal meningiomas: 23 were located in the anterior third, in close relationship with the anterior central vein, 30 in the middle third, in close relationship with the posterior central vein, and 7 in the posterior third. 3 remaining lesions were located in the sinus confluence area, and 5 in the transverse sinus. All patients underwent surgery. We use the following classifications depending on the degree of venous sinus involvement: type I, where the lesion was attached to the outer surface of the sinus wall; type II, where the tumor invaded the sinus wall but did not break through it; type III, where it invaded the ipsilateral wall; type IV, where it invaded the lateral wall and the roof of the sinus; type V: complete occlusion of the sinus without the involvement of the contralateral wall; and type VI: total occlusion of the sinus with the participation of the contralateral fence as well. For type I meningiomas, we treat them by stripping off the outer layer of the sinus wall. In cases of type II to VI invasion of venous sinuses, we employ two strategies: one is non-constitutional, i.e., we remove the tumor together with the affected venous sinuses but do not repair the venous sinuses. The other is reconstructive: after completely removing the tumor, suturing or repairing the venous sinuses. Results: Complete tumor resection was achieved in 97.1% (66/68) of cases, and sinus reconstruction was attempted in 38 of 45 cases (84.4%) with sinus wall and sinus cavity invasion. The recurrence rate of patients in this study group was 5.9%(4/68), with a follow-up period of 33 to 57 months. The recurrence rate was significantly higher in patients with incomplete resection than in patients with complete resection (P=0.0026, Fisher test). The overall mortality rate was 4.4%, and all cases were due to malignant brain swelling caused by the failure to perform venous reconstruction after resectioning the whole meningioma type VI. 7 patients had worsening symptoms of neurological deficits or complete loss of neurological function (10.3%), with a significantly higher incidence in patients without venous reconstruction than in the venous reconstruction group (P<0.0001, Fisher test). There was no statistically significant pre-operative and post-operative KPS score in patients with type I to V. Still, in patients with type VI (who did not receive venous reconstruction), the post-operative KPS score was significantly worse. Conclusion: The relatively low recurrence rate (5.9%) in this study suggests the importance of complete resection of the tumor (including the invasive venous sinus portion). Patients who did not undergo venous reconstruction exhibited significant clinical deterioration postoperatively compared with other subgroups, suggesting that venous sinus reconstruction is necessary.