Recurrent attacks of headache and neck pain caused by congenital aplasia of the posterior arch of atlas in an adult

Abstract

A 47-year-old Chinese woman, with a history of recurrent attacks of vertigo and vomiting for the past 5 years, presented with intermittent radicular pain in the left upper limb for the past 2 years. She also reported recurrent attacks of severe headache and neck pain for more than 10 years. The pain might be aggravated by coughing or sneezing and relieved after sleeping in the decubitus position. The MRI depicted Chiari malformation. A multidetector CT scan and three-dimensional CT reconstruction revealed partial aplasia of the left posterior arch of atlas of a small gap. The patient underwent plastic surgeries in Beijing. The disappearance of the recurrent pain syndrome was confirmed by follow-up after surgery.

Figure 1

Mid-sagittal T2-weighted MR image (A, B). Multidetector CT scan (C–F). Note the incomplete left posterior atlas arch in D and F. The right posterior arch of atlas is intact in C and E. Three-dimensional CT reconstruction (G–I). Note the partial aplasia of the left posterior atlas arch in G and I. CT reconstructed images (J–L).

Figure 2

Classification of posterior arch defects of the atlas. Type A: failure of posterior midline fusion with a small gap remaining. Type B: unilateral clefts. Defects may range from a small gap to a complete absence of the hemi-arch. Type C: bilateral defects with preservation of the most dorsal part of the arch. Type D: complete absence of the posterior arch with a persistent isolated tubercle. Type E: complete absence of the entire posterior arch, including the posterior tubercle. Over 97% of defects are type A. The incidence of the general population harbouring types B–E was estimated 0.69%.