Abstract

Os odontoideum is defined as an odontoid ossicle process with smooth circumferential cortical margins that have no osseous continuity with the body of C2. The origins of Os odontoideum have much debate for both acquired and congenital causes. The incidence of Os odontoideum is unclear and difficult to investigate because symptoms not always occur. 11-year-old girl patient was presented with abnormal gait, abnormal speech, weakness of all limbs. All of these findings appeared for 3 years, and the presenting case was quite well before that time. The case was mentally normal. Physical examination revealed features of upper motor neuron deficit in the form of spasticity, hyperreflexia, and clonus. These signs were more marked in lower than the upper limbs. Vital signs were within normal limits. Palpation revealed midline tenderness all over the spine most marked down C1 to C2 with no step-offs renowned with intact cranial nerves. No evidence of sensory or motor deficits was noticed on the neurologic examination. Otherwise, no abnormalities were detected. Radiographic workup was done in the form of plain X-ray and magnetic resonance image (MRI). The computed tomography revealed Os odontoideum, as well as prominent ventricles. MRI revealed an evidence of the craniovertebral junction anomaly with most likely Os odontoideum as well as the backward displacement of the C2 vertebral body. Despite Os odontoideum is an infrequent lesion, its importance comes from associated injuries related to the cervical spine and vertebral artery injuries and should be considered in all age groups, more frequently in childhood, especially when the presenting symptoms are of upper cervical spine compression and its sequelae. Early diagnosis and proper management will prevent such complications to occur.