Cervical butterfly-block vertebra. A case report.

A new type of block vertebral malformation is described. A 42-year-old woman presented after an akinetic seizure. Routine cervical spine films, obtained because of a recent history of abnormal head posture, disclosed a vertebral anomaly. Computed tomography and conventional polytomography revealed that the lesion was composed of a butterfly vertebra as the upper portion of a pair of nonsegmented vertebrae. Vertebral fusion and segmentation anomalies are reviewed and compared with the specific features of this case.