Microsurgical Resection of Dorsal Pontine Cavernous Malformation: The Telovelar Approach Augmented by the Tonsillouvular Fissure Exposure: 2-Dimensional Operative Video.

Surgical approaches to lesions of the fourth ventricle (FV) have been modified over the years to reduce the complications associated with splitting the inferior cerebellar vermis (ICV) and disrupting the brainstem and critical surrounding structures.1-4 Two common approaches to lesions of this region include the transvermian approach (TVA) and telovelar approach (TeVA).2 The TVA was initially considered the conventional route of access to lesions of the FV1 but has been associated with significant risks, including possible gait ataxia and dysarthria.3 The TeVA is advantageous, as it involves dissection along natural clefts and division of non-neural tissue and provides good exposure of the superolateral recess with modest exposure of the rostral FV. The TeVA approach can be augmented by opening the tonsilouvular fissures (TUFs). This added dissection allows greater lateral and superior exposure with less need for retraction. In this operative video, we demonstrate a case in which we augmented the TeVA with a TUF dissection to access a dorsal pontine cavernous malformation. We performed a midline suboccipital craniotomy with a C1 posterior laminectomy. TUF dissection was followed by division of the tela choroidea (TC), which allowed for more lateral exposure of the FV and excellent visualization of the cavernous malformation without the need to traverse neural tissue. TeVA augmented by TUF dissection provided adequate access to the dorsal pons for complete resection of the cavernous malformation. The patient consented to the procedure as shown in this operative video and gave informed written consent for use of her images in publication. Anatomic images provided by courtesy of © The Rhoton Collection. https://rhoton.ineurodb.org/. Video © Mayo Foundation for Medical Education and Research, 2021. Used with permission.