Vertebral artery tortuosity with concomitant erosion of the foramen of the transverse process of the axis. Possible clinical implications.

Thirty-six vertebral arteries were examined for the presence of tortuosity in their trajectory through the neck. Of these, 18 vessels (14 bilateral) showed various degrees of tortuosity of their proximal segment. Four arteries had marked kinking of the tortuous vessel at the foramina of the transverse process of the axis. These foramina presented with marked erosion of the underlying bone. Four other axes presented with moderate erosion of the F/Tp. The etiology and clinical significance of tortuosity of the vertebral artery, and erosion of the F/Tp of the axes, are discussed in light of the extreme range of rotation occurring at the C1-C2 segmental level.