Cervical Myelopathy Caused by Hypoplasia of the Atlas and Ossification of the Transverse Ligament. Case Report.

Abstract

A 79-year-old Japanese female presented with symptomatic cervical myelopathy caused by a hypoplastic posterior arch of the atlas and ossification of the transverse ligament. Neuroradiological examination demonstrated a hypoplastic posterior arch of the atlas and ossification of the transverse ligament. The cervical spinal cord was compressed at the level of the atlas by both the hypoplastic posterior arch of the atlas and the ossification of the transverse ligament. The patient underwent C-1 laminectomy, which arrested the progressive myelopathy and resulted in a good recovery. Atlas hypoplasia with ossification of the transverse ligament may be associated with Asian ethnicity.

Atlas Hypoplasia and Ossification of the Transverse Atlantal Ligament: A Rare Cause of Cervical Myelopathy

“…Although in other very rare instances, as in our case, ossification of the transverse atlantoid ligament was implicated [1, 3, 4]. …”

“…This is the fourth such case in the literature, with two being identical to ours having both lesions concurrent [3, 4], while the more recent case had a further additional hypertrophied odontoid process contributing to the myelopathy [1]. …”

“…Although the majority of anomalies at the level of atlas reported in the literature are defects of either arches of atlas [4], these rarely lead to cord compression, since they usually either increase the canal space (essentially acting as an autolaminectomy) or leave it unaltered with a few exceptions [6]. In contrast to these anomalies, hypoplasia of an intact posterior arch of the atlas does in fact decrease canal dimensions [7].…”

“…In contrast to these anomalies, hypoplasia of an intact posterior arch of the atlas does in fact decrease canal dimensions [7]. It should be stressed that hypoplasia of an intact arch of the atlas is an entity distinct from arch clefts with a different pathogenesis that may involve premature fusion of synchondroses, or facetal hypertrophy from abnormal rotator mechanics [4]. …”

“…The syndromes reported include Down syndrome, Turner syndrome, achondroplasia, and gonadal dysgenesis among others [8]. Anomalies of the atlas also show evidence of familial clustering and ethnic predisposition [4, 9]. Although believed to be a disease exclusive to the Far East, two recently reported cases were Caucasian [6, 10], showing that although predominantly affecting Asian males, it is not exclusive to a specific race or sex.…”