gms | German Medical Science

Objective: Lesions in the anterior vermis and the quadrigeminal plate are traditionally approached via the infratentorial supracerebellar route with the patient in a sitting position. A transtentorial interhemispheric route, originally proposed to access pineal lesions, might provide several advantages including an orthograde access to the pathology, avoidance of the veins on the cerebellar surface, early proximal control of afferent vessels, and the possibility to be executed with the patient in a prone position. The goal of this study was to investigate advantages and disadvantages of this approach in a consecutive microsurgical series.

Method: Consecutive case series of all patients with posterior fossa lesions operated between January 2011 and July 2013 via an interhemispheric transtentorial approach. Entry variables included demographic data, type and location of the pathology, type of patient positioning, type of perioperative cerebrospinal fluid drainage. Outcome variables included approach-associated morbidity, appproach-associated imaging alterations and whether the surgical goal was obtained (yes/no).

Results: N=7 patients (mean age 41 years, range 22 to 7 years, 2 females) were operated within 30 months. Pathological diagnosis was metastasis (n=3), pinealoblastoma (n=1), glioma WHO I (n=1) and cavernoma (n=2). The lesion was approached along the right side in 6 cases with the patients in the prone position in all cases. N=4 patients received a perioperative lumbar drainage, in n=2 patients the lateral ventricle was punctured. One patient already had an external ventricular drainage in situ. A complete resection of the lesion was possible in all patients. Postoperative imaging did not show signs of ischemia or contusions along the access route. In one patient bridging veins required an enlargement of the craniotomy. Complications included one wound infection (requiring removal of the bone flap) and one CSF fistula (treated with lumbar drainage).

Conclusions: The interhemispheric transtentorial approach to posterior fossa lesions is advantageous especially (1) when lesions are located far anterior in the upper vermis and in the lower part of the quadrigeminal plate, (2) when early control of the brainstem part of a space-occupying or a vascular lesion is desirable and (3) when the tentorium is steep. Contusional damage along the route of access is rare when adequate CSF draining measures are employed.