A review of the cases of thirty-five patients with os odontoideum, the
largest series reported to date, supports the concept that trauma is the
etiology of the abnormality. Most of the patients had roentgenographic
instability of the affected spinal segment, and were treated with spine
fusion. Eleven patients had lesions attributable to injuries received
before they were four years old, although surgical treatment usually was
delayed for one to eight years. Nine patients had documented
roentgenographic evidence of a normal odontoid process prior to the
development of the os odontoideum. Only one-third of the patients had any
signs or symptoms indicative of neural deficits, although most patients had
cervical pain. Surgical treatment alleviated the pain and instability.