Surgical Treatment of Tentorial Meningiomas: An Outcome Analysis

Introduction: Tentorial meningiomas are notorious for their critical location. Selection of a suitable approach that exposes the multicompartmental growth of tumor is important for a complete and safe resection. This paper discusses about various operative approaches and their overall surgical outcome.

Methods: We retrospectively reviewed our 41 patients of tentorial meningiomas. They were classified according to modified Yasargil’s classification. The symptomatic improvement and recurrence free survival were analyzed at follow up.

Results: Tumors were found nearly equally distributed at all location groups. Tumors along the lateral tentorial hiatus were operated via subtemporal or transylvian approach. Tumors along the posterior tentorial hiatus, tentorial membrane or torcula were operated by occipital-interhemispheric- transtentorial, infratentorial-supracerebellar or a combined approach. Tumors along petrous attachment were operated by a retromastoid-suboccipital or a combined presigmoid-retrosigmoid approach. Seventy six percent had total excision (Simpson grade 1 and 2). Group II tumors had the highest total resection rate (100%). On histopathological examination, 32 (78%) were WHO grade 1 meningioma and others were WHO grade 2. Headache and diplopia were the symptoms that significantly improved post operatively (p = 0.0001). Two patients (4.8%) developed post-surgical infection, one patient (2.4%) developed CSF leak, three cases (7.3%) experienced new hydrocephalus, and six cases (15%) developed new cranial nerve palsies. In four patients the diplopia improved in the follow up period. There was no mortality in this series.

Over a median follow up of 65 months, 13 patients (31.7%) had recurrence. The recurrence rate varied with Simpson grade of excision and the tumor location. Tumor recurrence occurred earlier and at a higher rate (75%) in Simpson grade IV excision, followed by grade III (50%), grade II (26%) and grade I (12.5%). Recurrence rate was significantly less in group III locations (12.5%) compared with the other groups (36%) (p = 0.0002). Three cases (7.3%) required further treatment with re-surgery, and eleven cases (26.8%) required gamma knife radiosurgery (GKRS) after initial resection. The median RFS period in all cases was 149 months. The median RFS in group III and IV locations (149 months) was better than other groups (89 months) (p = 0.30); however the overall recurrence rate was much lower in group II and III tumors (p = 0.005). The median RFS for Simpson’s grades I, II, III, and IV was 247, 149, 60 and 33 months, respectively (p = 0.001). Similarly, there was a significant difference in RFS in patients undergoing gross total excision (Simpson Gr 1 and 2 excision) when compared with patients undergoing subtotal excision (Simpson 3 & 4 excision) (p = 0.003). WHO grade 1 tumors had higher median RFS as compared with Grade 2 tumors (p = 0.03). In multivariate analysis, the Simpson’s grade of excision and WHO grade of tumor were the only significant factors affecting recurrence (p = 0.002 and 0.004 respectively).

Conclusion: Gross total excision is the key to achieve an improved recurrence free survival. A careful preoperative planning is necessary to choose the right approach based on the location and extension of the tumor for a safe and complete resection.