Anatomical risk factors for the complicated postoperative period in the surgery of extracerebral tumors of the posterior cranial fossa

Tumors of the base of the posterior cranial fossa are among the most difficult for surgical treatment in neurosurgery. Numerous studies are being conducted on the factors that determine clinical manifestations and treatment outcomes. The aim of the study was to study the linear and angular parameters of the posterior cranial fossa in patients with extracerebral neoplasms and to evaluate their effect on the results of surgical treatment. Craniometric study of linear and angular parameters of the posterior cranial fossa was performed in 115 patients with sub-tentorial extracerebral tumors. A computer program was used to determine the longitudinal, transverse and height diameters of the head, the length, width and height of the posterior cranial fossa, the sagittal diameter of the foramen magnum, the length of the clivus, the length of the posterior part of the skull base, the basilar angle, the Boogard's angle, the posterior angle of the base of the skull, angle of the cerebellar mantle, angle of inclination of the clivus, angle of inclination of the scales of the occipital bone and angle of convergence of the pyramids of the temporal bones. These parameters were determined on magnetic resonance tomograms in the sagittal projection on the median section and in the axial projection, on the section passing at the level of the internal auditory canals. The main group consisted of 15 patients who developed vascular complications after surgery, the second comparison group included 100 patients with uncomplicated postoperative course. The predominant head shapes according to the transverse-longitudinal index in both groups were brachycephalic (53.3 and 54%, respectively). There was no acrocephaly (high and narrow head forms) among patients with complications, while in the control group this type was registered in 12% of cases. Certain craniometric prerequisites for a complicated course of the postoperative period have been identified, allowing a more selective approach to the tactics of treating these patients. The risk group includes patients with large values of the basilar angle and the angle of inclination of the scales of the occipital bone, having a narrower and elongated shape of the posterior cranial fossa.