We are reporting the cases of five patients who had occipito-atlantal
instability, a rare condition that may be due to either trauma or
congenital abnormalities. In three of the patients the instability was
secondary to trauma. The clinical and neurological manifestations were
varied and included cardiorespiratory arrest, motor weakness, quadriplegia,
torticollis, pain in the neck, vertigo, and projectile vomiting. All of the
patients underwent posterior arthrodesis of the occiput to the first or
second cervical vertebra. In the patients who had trauma-related
instability, surgery was performed when immobilization in a cast failed to
stabilize the spine; in the patients who had a congenital abnormality,
arthrodesis was indicated because of persistent symptoms and the potential
for catastrophe with minor trauma. Based on our experience, we recommend
surgical stabilization by posterior arthrodesis when this form of
instability of the cervical spine is diagnosed.