Anatomical Aspects and Clinical Application of a Unilateral Uvulotonsillar Approach via a Minimally Invasive Open-Door Suboccipital Craniotomy to Remove Lesions of the Fourth Ventricle and Dorsal Brainstem

Abstract

Today, a median suboccipital craniotomy with access to the cavity of the fourth ventricle through the foramen of Magendie is widely used to remove neoplasms of the fourth ventricle and brainstem. However, according to modern literature, the median approach to the posterior cranial fossa is associated with a high risk of CSF leakage and pseudomeningocele. We propose a modified unilateral uvulotonsillar approach via a median suboccipital open-door craniotomy, which can potentially reduce the incidence of CSF leakage and preserve the ligamentous apparatus of the craniovertebral junction. Herein, we describe the implementation of this approach on cadaveric material and provide a clinical case. The material used for the study was 3 cadavers and 1 clinical case. Step-by-step dissection imitating the described approach was carried out. During the dissection, surgical landmarks were identified at the macro- and microstages, which should be considered when performing the proposed approach. A detailed description of the technique for performing open-door craniotomy, the features of the incision in the dura mater, unilateral dissection of the uvulotonsillar fissure, and the structures of the cavity of the fourth ventricle that could be visualized through this approach were described. This approach allows preservation of the normal anatomy of the craniovertebral junction and stable fixation of the bone flap. Unilateral dissection of the uvulotonsillar fissure provides adequate visualization of almost all parts of the rhomboid fossa, and the convenience of suturing the minimal arcuate incision in the dura mater potentially reduces the risk of CSF leakage.