Setting Patient is positioned in three-quarters prone. Retrosigmoid approach should be made under neurological monitoring and with neuronavegation to help achieve maximal safe resection. The skin incision is vertical, slightly curved, 5 mm medial to the mastoid notch. Craniectomy is superiorly limited by the transverse sinus and laterally limited by the sigmoid sinus. A C -shaped durotomy is made with its base protecting the sigmoid sinus. The lesion is removed in piecemeal fashion ( Fig. 1 ). The neurological monitoring helps.