[Cervical myelopathy in atlanto-axial dislocation: evaluation of 2 cases by nuclear magnetic resonance]

One patient with Down's syndrome and another who sustained acute cervical trauma developed signs of cervical myelopathy. In both, the cervical roentgenograms showed an atlanto-axial subluxation. Magnetic resonance imaging (MRI) of the cervical spine revealed a severe compression of the cord in the first case and a deformity of the C1 vertebral body, which caused a mild narrowing of the dural sac, in the second. Although MRI allowed an optimal visualization of the spinal cord and surrounding tissues, the images failed to correlate with the degree of severity of the presenting clinical signs and with the outcome.