Congenital defect of the atlas and axis. A cause of misdiagnose when evaluating an acute neck trauma.

Congenital absence of the posterior arch of the atlas (C1) is rare and even more presenting with a double spinous apophysis of the axis (C2). It is important to keep in mind these cervical congenital abnormalities when evaluating an acute neck trauma because of the possibility of making an erroneous diagnosis of a fracture. This case report is about a 13-year-old boy in the context of a traffic accident who presented both abnormalities, a combination that to our knowledge has not been reported previously in the literature.