Decision making.
BACKGROUND
The craniocervical junction is affected by numerous pathological processes. This involves congenital, developmental, and acquired abnormalities. It can result in neurological deficit secondary to neurovascular compression, abnormal cerebrospinal fluid dynamics, and craniovertebral instability. A physiological approach based on an understanding of the craniovertebral junction dynamics, the site of encroachment and stability was formulated in 1977 and has stood the test of time. The author has reviewed 5,300 patients with neurological symptoms and signs secondary to an abnormality of the craniocervical junction. This includes 2,100 children.
The factors that influence the specific treatment are: (1) reducibility of the lesion, (2) mechanics of compression and the direction of encroachment, (3) the presence of abnormal ossification centers and epiphyseal growth plates, and (4) the cause of the pathological process.
Instability at the craniocervical junction is considered when the predental space is more than 5 mm in children below the age of 8, when the separation of the lateral atlantal masses is more than 6 mm where the cruciate ligament is felt to be disrupted, and if there is vertical translation of more than 2 mm between the clivus and the odontoid process signifying occipital instability. The gap between the occipital condyle and the lateral atlas facet should never be visible on lateral cervical radiographs. Present day magnetic resonance imaging can visualize disrupted transverse cruciate ligament, alar ligaments, tectorial membrane, and bony malalignment. The primary aim of treatment is to relieve compression at the cervicomedullary junction. Hence, stabilization is paramount in reducible lesions to maintain neural decompression. Irreducible lesions require decompression at the site where the compression has occurred; these were divided into ventral and dorsal compression states. In the former compression state, the operative procedure was a ventral decompression through a palatopharyngeal route, LeForte dropdown maxillotomy, or the lateral extrapharyngeal approach. In dorsal or dorsolateral compression states, a posterolateral decompression is required. If instability is present after decompression, posterior fixation is mandated.
Menezes
Arnold H
AH
Department of Neurosurgery, University of Iowa Carver College of Medicine, University of Iowa, Iowa, IA, USA. arnold-menezes@uiowa.edu
D001268:Atlanto-Axial Joint / Q000002:abnormalities*; D001269:Atlanto-Occipital Joint / Q000002:abnormalities*; D002648:Child; D003657:Decision Making; D019299:Decompression, Surgical / Q000379:methods*; D006801:Humans; D007593:Joint Instability / Q000473:pathology / Q000517:prevention & control / Q000601:surgery; D008279:Magnetic Resonance Imaging; D019635:Neurosurgical Procedures / Q000379:methods; D013117:Spinal Cord Compression / Q000473:pathology* / Q000601:surgery