Telovelar surgical approach.

Abstract

Surgical access to lesions in the fourth ventricle may be achieved utilizing transvermian or transtelovelar trajectories. We performed a search of the PubMed database for studies describing the microsurgical details and evaluating the clinical utility of the telovelar surgical approach. The telovelar approach has proven to bea safe, effective, and versatile alternative to the transvermian approach. The operative strategy utilizes midline suboccipital craniotomy without or with C1 laminectomy, followed by cerebellar hemispheric and tonsillar retraction, and wide durotomy. Access is generouslyprovided to the fourth ventricle from calamus scriptorius to Sylvianaqueduct and foramen Luschkae bilaterally. Anatomic dissection studies evaluating and comparing the relative benefits of the operative exposure offered by these approaches have demonstrated improved access to thelateral recess gainedby thetelovelar trajectory and facilitated exposure of rostral reaches of the fourth ventricle by thevermian trajectory. In general, operative exposure may be significantly improved with tonsillar retraction or resection, bilateral telovelar opening, and performing C1 laminectomy in orderto improve access to the rostral fourth ventricle, which may be variably combined depending on location of pathology. Cerebellar mutism, a high incidence of which occurs with vermian approaches, is not commonly observed with use of the telovelar trajectory, though injury to the dentate nuclei may precipitate this syndrome. Deficits incurred with thevermian approach may include cerebellar mutism, dysequilibrium, truncal ataxia, posterior fossa syndrome, cranial nucleopathies and nerve palsies, and vascular injury to theposterior inferior cerebellar artery. The telovelar surgical approach has proven a safe and useful alternative to the transvermian trajectory. A significantly lower incidence of cerebellar mutism and cerebellogenic deficits representsthe principal advantage of the telovelar approach. Further studies are necessary in orderto prospectively evaluate and compare extents of resection, morbidity, and mortality utilizing the telovelar versus vermian approaches for microsurgically resectingfourth ventricular tumors.