Transcranial Insertion of Atlas Facetal Screw for Atlantoaxial Fixation

Abstract

We evaluated the technical feasibility and potential advantages of transcranial insertion of an atlas screw for atlantoaxial fixation. From January 2016 to August 2018, the transcranial technique for atlas screw insertion was used in 6 patients. Conventional lateral mass atlantoaxial fixation was not possible because of the presence of a complex craniovertebral junctional abnormality and difficulty in direct exposure of the facet of the atlas. In all cases, severe basilar invagination and assimilation of the atlas was present. Of the 6 patients, 3 were male and 3 were female. The age range was 12-41 years (average, 23 years). The surgical technique involved a small suboccipital craniotomy in line with the facet of the axis. Extradural elevation of the cerebellum exposed the region of the occipital condyle and fused atlas. The screw was directed medially and inferiorly into the facet of the atlas. In all 6 patients, strong and successful atlantoaxial fixation was achieved. All patients showed clinical improvement after surgery. At an average follow-up period of 21 months, successful arthrodesis of atlantoaxial joint had been achieved in all 6 patients, with no complications. Transcranial insertion of atlas screw can be used as a salvage procedure when the conventional method of screw insertion is not possible because of technical difficulties.