ИСТИНА

OBJECTIVE: The transcallosal and the frontal transcortical approaches require traction of the frontal lobe and dissection of the corpus callosum or corticotomy and involve some postoperative consequences. The purpose of the proposed method is to remove the colloid cyst by the infratentorial supracerebellar approach and the posterior wall of the third ventricle without dissection of any neural structures. METHODS: 11 patients with a colloid cyst of the third ventricle were operated on by the proposed method. The mean patient age was 49 years at the time of diagnosis (range 18–63 years) and the mean cyst size was 10 mm (range 8–17 mm). In 10 cases there were no hydrocephalus (Evans index 0.26-0.30), in 1 case there was concomitant hydrocephalus (Evans index 0.42). In 1 patient, the colloid cyst was combined with breast cancer metastasis in the right cerebellar hemisphere. TECHNIQUE: With the infratentorial supracerebellar approach, the arachnoid of the quadrigeminal cistern is dissected. The pineal body is separated and displaced from the internal vein medially, and the posterior velum interpositum is opened. Perforation of the inferior layer of the tela choroidea just above the suprapineal recess allows opening of the third ventricle cavity. A foraminal region is exposed after a slight lateral displacement of medial surfaces of the thalamus along the third ventricle roof. RESULTS: All 11 patients had complete excision and showed regression of hypertensive-hydrocephalic syndrome. One patient in the early postoperative period had marked psycho-emotional and mnestic disorders, regressed after 4 days. In 4 patients, a mild increase in mnestic disorders was observed. CONCLUSION: The proposed approach through the infratentorial supracerebellar space and the posterior wall of the third ventricle may be used for removal of colloid cysts, especially in patients in whom the lateral ventricles are not enlarged.