The Tonsillouvular Fissure Approach: Access to Dorsal and Lateral Aspects of the Fourth Ventricle

• Published in: World neurosurgery 2018-06, Vol.114, p.e1107-e1119
• Main Authors: Aydin, Ilhan, Hanalioglu, Sahin, Peker, Halil Olgun, Turan, Yahya, Kina, Hakan, Cikla, Ulas, Baskaya, Mustafa K.
• Format: Article
• Language: English
• Subjects: Biventral lobule; Cerebellar tonsil; Cerebellomedullary fissure; Fourth ventricle; Microsurgical anatomy; Tonsillouvular fissure approach
• ISSN: 1878-8750; 1878-8769
• DOI: 10.1016/j.wneu.2018.03.157

Although approaches to the fourth ventricle (FV) have been studied well, approaches to the lesions located in the dorsal and lateral aspects of the FV have not been shown in anatomic or clinical studies. The aim of this study is to show for the first time in the literature the tonsillouvular fissure approach (TUFA) in anatomic dissections and its use in surgical series. For anatomic studies, 4 formalin-fixed human cadaveric heads infused with colored silicone and 10 cerebellar specimens were dissected in a stepwise manner. Records of 12 patients operated on via TUFA were also retrospectively reviewed. Neurosurgical anatomy and critical steps of TUFA were described in detail. Among 12 patients with lesions around the FV (4 cavernous malformation, 2 pilocytic astrocytoma, 2 hemangioblastoma, 1 B-cell lymphoma, 1 metastatic papillary carcinoma, 1 dermoid cyst, and 1 arteriovenous malformation), 11 gross total and 1 subtotal resection were achieved via TUFA without any mortality or morbidity. Comparative analyses of 4 surgical approaches to FV (TUFA, telovelar/cerebellomedullary fissure, supratonsillar/tonsillobiventral lobule fissure, and transvermian approaches) were also presented. TUFA provides a direct route and excellent surgical view to lesions around the FV, particularly on dorsal and lateral aspects, inferior vermis, and medial part of the dentate nucleus and cerebellar peduncles. It minimizes traversing the normal cerebellar tissue compared with a transvermian approach. •Microsurgical anatomy and surgical technique for TUFA are described in detail.•TUFA provides a direct route to and excellent surgical view of lesions around FV.•Smaller lesions on the dorsal and lateral aspects of FV are best candidates for TUFA.•Minimal traversing of neural tissue is required compared with transvermian approach.•For lesions with minimal or no representation in FV, TUFA is superior to telovelar approach.