Toward the End of the Funnel: The Ventriculus Terminalis—The State of Art of an Ancient Entity with a Recent History

Purpose: The ventriculus terminalis (VT), also called the fifth ventricle, is a small cavity containing cerebrospinal fluid (CSF) that is in the conus medullaris in continuity with the central canal of the spinal cord. In adults, persistent VT is a very rare entity, and the diagnosis is incidental in most cases. Rarely, VT may become symptomatic for still-uncertain reasons but most often for its cystic dilatation. The management of these selected cases is still controversial and sometimes associated with unsatisfactory outcomes. Methods: We performed a critical review of the existing literature on the management of symptomatic VT in adults. The etiology, pathophysiology, and treatment of VT are presented and discussed, focusing on the best timing for surgery. Results: Conservative management, marsupialization, or the placement of a T drain have been reported. The existing classifications describe the most correct approach for each clinical presentation, but scarce importance has been given to the delay from symptoms’ onset to surgical treatment. Conclusion: Although different cases have been described in the literature, this rare pathology remains unknown to most neurosurgeons.