Persistent proatlas with additional segmentation of the craniovertebral junction - The Tsuang-Goehmann-Malformation.

Case study description and analysis of a complex craniovertebral dysplasia in an 8-year-old male patient, in which conventional cervical spine radiographs demonstrated a regularly differentiated occipital base, as well as the presence of two lateral masses of the proatlas vertebra and two lateral masses of the atlas vertebra. Further assessment included computed tomography of the occipital base and the upper cervical spine as well as three-dimensional reconstruction. Malsegmentation of the fourth occipital vertebra can result in various anomalies that are known as 'manifestation of the proatlas'.