Spontaneous atlanto-axial dislocation and trisomy 21: causal factors and management

Abstract

Spontaneous atlanto-axial (C1-C2) dislocation is an atlanto-axial instability, found in 10 to 30% of trisomy 21 patients, the majority of whom are asymptomatic. We report a case of a 21 years-old woman, with trisomy 21, admitted in our department presenting a spinal cord compression syndrome with right hemiparesis associated with a cervicalgia evolving for 3 months of admission without trauma. Standard cervical radiography showed a C1-C2 dislocation with posterior displacement of the odontoid process. A cervical computerized tomography revealed a C1-C2 dislocation with significant recoil of the odontoid process. A magnetic resonance imaging (MRI) confirmed the bulbo-medullar junction compression on the dislocation. It must be early detected. The surgical treatment consisted of a cervico occipital fixation. The laxity of the transverse ligament is one of the principal causes of C1-C2 dislocation; hypoplasia, malformation or complete absence of the odontoid process; are also predisposing factors. The treatment of choice is surgical also by arthrodesis of C1 to C4 + graft and enlargement of the occipital foramen or occipito-cervical arthrodesis by synthetic graft and Cotrel-Dubousset system or occipito-C4 + C1 laminectomy and enlargement of the occipital foramen.

Keywords

• atlanto-axial joint dislocation (c1-c2)
• trisomy 21
• down syndrome
• spinal cord compression
• neurosurgery