[An unusual anomaly : cervical spondylolysis in an adult].

A case of spondylolysis with exceptional involvement of the cervical spine is reported. The lesion turned out to be a defect in the pars interarticularis of a cervical vertebra. Such cases generally involve the sixth vertebra. Spondylolysis is asymptomatic more often than not. Positive diagnosis is supported by an analysis of the anatomic structures on radiographs and CT-scans. Differential diagnoses include congenital lesion (articular dysplasia) is always found, there is no argument allowing the assertion that cervical spondylolysis is a congenital condition rather than secondary to stress fractures.