Surgical Treatment for Atlantoaxial Subluxation With Myelopathy in Spondyloepiphyseal Dysplasia Congenita

Abstract

A retrospective review of 21 patients with spondyloepiphyseal dysplasia congenita (SEDC), including 7 operated patients for atlantoaxial subluxation. To clarify the morphological findings of atlantoaxial subluxation in SEDC patients and to evaluate the operative procedures based on these image findings. The presence of atlanto axial sublucation with hypoplasia of the odontoid and/or lax ligaments leads to myelopathy in patients with spondyloepiphyseal dysplasia congenita. We retropectively reviewed the physical and morphological findings on atlantoaxial images and the clinical findings of myelopathy in 21 patients with SEDC. Myelopathy was found in 9 individuals with severe SEDC who presented with marked short stature and severe coxa vara; of these, 6 had gait disturbances. On the images of the 9 patients with myelopathy, the average sagittal canal diameter (SCD) at the level of the atlas was only 9.2 mm (range, 7-12 mm) with progressive atlantoaxial subluxation. The average atlantodental interval (ADI) was 3.5 mm (range, 2-6 mm) in the presence of a sagittal atlas diameter (SAD) of less than 27.1 mm (range, 22-36 mm). Surgery was performed for 6 of the patients with myelopathy. Since their SADs were small, and the average SCD, at 9.9 mm (8-14 mm), was narrow even at the position of extension (the position of reduction for atlantoaxial subluxation), C1 laminectomy was needed for all these patients, and occipital-cervical posterior fusion was performed. Stability was satisfactory in all cases and the operative outcome for myelopathy was excellent for 1 case, fine for 4, and fair for 2. A small SAD may limit the effectiveness of reducing atlantoaxial subluxation. Persistent narrowing of the SCD may require concomitant C1 laminectomy and occipital-cervical fusion.