Introduction: The aim of this study is to evaluate the efficiency and safety of the telovelar approach for removing 4th ventricular lesions through identifying and preserving important neurovascular structures.

Methods: Patients and methods: This is a combined retrospective and prospective study on forty children (=12 years) suffering from fourth ventricular tumors using the telovelar approach from 2006-2013

Results: Results: This approach provided adequate exposure in all cases and the narrow working angle was efficiently compensated by changing the angle of the microscope and operating table. The brainstem and posterior inferior cerebellar artery (PICA) were early identified and preserved in all cases. Potential tumor attachment was observed at the floor of the fourth ventricle in twenty two (55% ) cases. Out of brain stem cases which constitute five cases , 16 of the remaining 17 cases (94%) had focal attachment at any area of the caudal fourth ventriclular floor e representing an inverted triangle with the obex inferiorly and the level of lateral recesses bilaterally and two cases (11,7%) was attached at any area of the lateral aspect of the rostral fourth ventricular floor which was the only point point of attachement in one of them . None of these tumors infiltrated the area of the cerebral aqueduct . Gross total excision was achieved in 45% of cases and near total excision (leaving < 1.5 cm2) was possible in 25% due to focal tumor attachment at one or more of the previously mentioned areas .. However, debulking was only possible in 30%, because in other cases, the tumor either originated from the brain stem or was attached extensively to the floor.

Conclusions: Conclusions: The main advantage of the telovelar approach is the early identification and preservation of the brain stem and PICA and in addition it allow for assessment of potential tumor attachment at the aforementioned areas. The pathological nature of the tumor and the degree of brain stem infiltration were the key factors that determined the degree of tumor excision.

Patient Care: By early identification of neurovascular structure during fourth ventricular surgery

Learning Objectives: enhance safety and efficieny of fourth ventricular tumour surgery

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