[Untreated os odontoideum may cause tetraplegia]

This review summarises the present, limited, knowledge of os odontoideum (OO). The prevalence is unknown, and the aetiology is widely debated, though irrelevant to management of the disease. Surgery of symptomatic patients is advocated, as there is more uncertainty about the treatment of asymptomatic patients. Diagnosis is obtained with plain X-ray. However, nowadays MRI and CT scanning are recommended for further clarification and judgement of the severity. Knowledge of OO is important to minimise misjudgement and consequently inappropriate treatment. It is recommended, that patients are examined by highly specialised spine doctors before further cervical manipulation due to the high risk of instability with potentially severe consequences.