Sagittal Alignment: Clue to the Presence of a Syringomyelia in Scoliosis

In a retrospective fashion, we reviewed standard spine scoliosis series (standing PA and LAT) of 93 patients with a diagnosis of scoliosis from two institutions. Nine patients had to be excluded due to inadequate imaging. The study group, consisting of thirty patients with scoliosis from TSRH with a MRI-proven syrinx, was compared to a controlled group, which consisted of fifty-four patients from the HSS with a diagnosis of adolescence Idiopathic scoliosis and a MRI-proven normal spinal cord. The groups were comparable for age (mean age: control 13 yr.; syrinx 12 yr.) and curve pattern yet different for Cobb angles (mean Cobb: control 50°; Syrinx 40°). Particular attention was paid to sagittal contour of the spine on the lateral x-ray, assessing presence or absence of Dickson’s apical lordosis. Apical lordosis was present in 97% of patient with scoliosis and a normal spinal cord. In contrast, 75% of patients with syringomyelia demonstrated absence of apical lordosis. The difference between the two groups was statistically significant (p< .0001). The difference was even more marked in single thoracic curves (i.e. King III). Patients with King III curves with absence of apical lordosis had 77% chance of having a syrinx in this study group. Furthermore, no patient with a King III curve with apical lordosis had a syrinx. Our results also confirmed that male patients with scoliosis and left-sided curves have a predisposition to having a syringomyelia (p< .0001). Sagittal plane deformity in scoliosis can be an indicator of the presence or absence of a syringomyelia. Our results reinforce the necessity of sagittal awareness when treating scoliosis and that if there is absence of apical lordosis then further imaging of the cord may well be indicated. One needs to be wary of a diagnosis of idiopathic scoliosis if there is no apical lordosis evident on lateral radiographs of patients with thoracic curves.