Accessory articulation of elongated anterior transverse process: a rare anatomical variant of the cervical spine depicted with CT and post-processing techniques.

There are several described anatomical variants of the cervical spine, ranging from common to extremely rare, which may have different clinical implications. We present the case of an extremely rare anatomical variant of the cervical spine, in a symptomatic patient, consisting of a unilateral accessory articulation between the 5th and 6th cervical vertebrae, due to elongated anterior transverse processes. Our search found only three cases in the English literature describing similar findings to the case here reported. Our case is, to our knowledge, the first report of this anatomical variant imaged with computed tomography including post-processing images (volume rendering technology and multiplanar reformations), which contribute greatly to a better understanding and depiction of the anatomical variant.