[A female child with Down syndrome complicated by spinal cord compression by atlanto-axial dislocation].

A 3-year-old girl with Down syndrome was admitted to our hospital, associated with hypotonia and dyspnea. She presented frog-posture and shallow breathing. The blood gas analysis revealed hypercapnic acidosis with pH 7.371, PO2 74.6 mmHg, PCO2 52.6 mmHg, and BE 3.5. The cervical X-ray films with flexion and extension of head showed anterior dislocation of the atlanto-axial articulation. Magnetic resonance imaging clearly showed a severe cord compression between C1 and C2. In children, spinal cord compression induced by dislocation of the atlanto-axial articulation is very rare. However, we should take into consideration of this insidious risk associated often with Down syndrome.