Telovelar Approach to Fourth Ventricle Tumors: Highlights and Limitations

Objective: Fourth ventricle tumors have been traditionally approached by opening the cerebellar vermis. The "telovelar" approach is an alternative approach performed through the cerebellomedullary fissure to gain access to the fourth ventricle, avoiding neural tissue damage. We describe our experience with this approach and predictive factors for the extent of resection (EOR) and for outcomes. Methods: We retrospectively analyzed the data of patients who underwent resection of fourth ventricle lesions using a bilateral telovelar approach between June 1998 and June 2013. We evaluated EOR, clinical outcomes, complication rates, and postoperative cerebellar dysfunction. Univariate and multivariate analyses were performed to identify the predictive factors for EOR and outcomes. Results: Forty-five patients were included in this series. Complete resection was obtained in 40 patients (88.9%). One patient (2.2%) had lower cranial nerve palsy and died 2 months after surgery. Two patients (4.5%) had persistent deficits of the sixth cranial nerve. Two patients (4.5%) developed shunt dependency. Brainstem attachment, tumor size >4 cm, and location in the rostral one third of the ventricle were associated with a higher rate of subtotal resection and neurological worsening. Cerebellar mutism did not occur in any patient. Conclusions: Exposure of the fourth ventricle was satisfactory in all of the patients, and the floor of the fourth ventricle could be visualized early and be protected. EOR and outcomes were satisfactory in 90% of patients, including those harboring large tumors or lesions attached to the lateral or superolateral recesses of the ventricle. Deep rostral tumor attachment was the main limitation of the telovelar approach.