title: Tonsillobiventral fissure approach to the lateral recess of the fourth ventricle.
abstract: OBJECTIVE Surgical access to the lateral recess of the fourth ventricle (LR) is suboptimal with existing transvermian and telovelar approaches because of limited lateral exposure, significant retraction of the cerebellar tonsil, and steep trajectories near brainstem perforator arteries. The goal in this study was to assess surgical exposure of the tonsillobiventral fissure approach to the LR, and to describe the relevant anatomy. METHODS Two formaldehyde-fixed cerebella were used to study the anatomical relationships of the LR. Also, the tonsillobiventral fissure approach was simulated in 8 specimens through a lateral suboccipital craniotomy. RESULTS The pattern of the cerebellar folia and the cortical branches of the posterior inferior cerebellar artery were key landmarks to identifying the tonsillobiventral fissure. Splitting the tonsillobiventral fissure allowed a direct and safe surgical trajectory to the LR and into the cerebellopontine cistern. The proposed approach reduces cervical flexion and optimizes the surgical angle of attack. CONCLUSIONS The tonsillobiventral fissure approach is a feasible and effective option for exposing the LR. This approach has more favorable trajectories and positions for the patient and the surgeon, and it should be added to the armamentarium for lesions in this location.
authors: Skull Base and Cerebrovascular Laboratory, Department of Neurosurgery, University of California, San Francisco, California.
authors: Ali
authors: A
authors: Tayebi Meybodi
authors: Skull Base and Cerebrovascular Laboratory, Department of Neurosurgery, University of California, San Francisco, California.
authors: Michael T
authors: MT
authors: Lawton
authors: Skull Base and Cerebrovascular Laboratory, Department of Neurosurgery, University of California, San Francisco, California.
authors: Halima
authors: H
authors: Tabani
authors: Skull Base and Cerebrovascular Laboratory, Department of Neurosurgery, University of California, San Francisco, California.
authors: Arnau
authors: A
authors: Benet
mesh_terms: D002102:Cadaver; D020546:Fourth Ventricle / Q000033:anatomy & histology / Q000601:surgery*; D006801:Humans; D008297:Male; D019635:Neurosurgical Procedures / Q000379:methods*; D055815:Young Adult
keywords: CMF, tCMF = cerebellomedullary fissure, transcerebellomedullary fissure; LR = lateral recess of the fourth ventricle; PICA = posterior inferior cerebellar artery; anatomy; biventral lobule; cerebellar tonsil; cerebellomedullary fissure; cerebellopontine cistern; inferior medullary velum; tela choroidea; telovelar approach; vascular disorders