Bilateral telovelar approach: A safe route revisited for resections of various large fourth ventricle tumors
A 2-year-old girl presented with slight headache and gait disturbances, which had developed over the month prior to admission. MRI with contrast enhancement showed an irregularly shaped, avidly enhancing tumor mass, measuring about 40 mm in diameter and located in fourth ventricle. There was rostral extension into the cerebral aqueduct and also extension into the lateral recess accompanied by obstructive hydrocephalus []. For definite surgery, the patient was positioned in the left lateral decubitus position with the head well flexed. A standard external ventricular drain (EVD) was placed. The p-fossa access was achieved via an incision that was carried out in the midline, from about 1 cm above the inion to the level of C4 spinous process. A bilateral suboccipital craniotomy was performed as described earlier and the mid portion of the posterior arch of C1 was resected. Durotomy was performed and the underlying brain was exposed. CSF was released gradually after opening the cistern magna. A microscopic dissection was started. After opening the bilateral cerebellomedullary fissures both cerebellar tonsils were retracted upwards and laterally using a Leyla-type retractor equipped with Ruggles blades. The bilateral tela choroidea and inferior medullary velum were exposed. Then the tela choroidea was opened bilaterally to access the dorsal fourth ventricle. We stayed away from any resection involving or splitting the inferior vermis. Both PICAs and the veins of the bilateral cerebellomedullary fissures were preserved. Tumorous tissue in the fourth ventricle was immediately visible and adequately accessible. Careful establishment of a circumferential plane was achieved and internal tumor debulking was performed. Cutting the lateral margins of the inferior medullary velum created a wide operative field with easy visibility toward the aqueduct and the bilateral foramen Luschkae. At the end of the tumor dissection and removal, the caudal opening of the aqueduct and both foramina Luschkae were well visible. The case was closed as pointed out above. No new neurological deficit was encountered after this operation. The postoperative MRI revealed no residual tumor []. Histopathological analysis revealed a solitary fibrous tumor of the central nervous system WHO I with low mitotic index. Since a gross total resection was achieved, no adjuvant radiation was recommended. At 6 months follow-up, the patient was neurologically without deficit.