Congenital Partial Aplasia of the Posterior Arch of the Atlas Causing Myelopathy: Case Report and Review of the Literature

Abstract

This case illustrates a symptomatic congenital deformity of the posterior arch of the atlas due to a mobile, isolated fragment. These anomalies are exceedingly rare. To date, only 17 patients, including ours, have been described in the literature as having myelopathy related to an isolated posterior tubercle. Of these, only two patients had documented movement of this tubercle before our report. Recognizing the anomaly is crucial because treatment is relatively simple, produces resolution of symptoms, and prevents major neurologic deficits from occurring after trauma.