Absent cervical pedicle.

Congenital defect of a cervical pedicle produces a rare clinical syndrome with a characteristic X-ray picture associated with vague clinical signs often accentuated after trauma. A careful analysis of the X-ray films, including oblique views, shows the congenital defect of the pedicle and the associated abnormalities which can all be attributed to a defect in the neural arch centre of chondrification. Further X-ray examinations including myelography with or without vertebral angiography as well as surgical exploration should be unnecessary. A case of absence of the right pedicle of the sixth cervical vertebra is described. The symptoms in this patient were not caused by the malformation, but by an associated enlarged seventh cervical transverse process which produced a thoracic outlet syndrome.