Sagittal plane deformity in the thoracic spine: A clue to the presence of syringomyelia as a cause of scoliosis

Study Design. A retrospective review of scoliosis radiographs of 93 patients with either idiopathic scoliosis or syringomyelia-associated scoliosis were assessed, defining their sagittal alignment. Objective. To validate an observation regarding the absence of Dickson's sagittal deformity of the thoracic spine in patients with syringomyelia-associated scoliosis. Summary of Background Data: Patients with adolescent idiopathic scoliosis have a classic sagittal deformity. Dickson described that patients with adolescent idiopathic scoliosis (AIS) have an associated lordotic deformity at the apex of their coronal deformity. Materials and Methods. Retrospective reviews of standard scoliosis series radiographs of 93 patients with idiopathic or syringomyelia-associated scoliosis from two institutions were compared. Particular attention was given to the lateral radiograph of the spine assessing presence or absence of Dickson's apical lordosis. Nine patients had to be excluded because of inadequate imaging. The study group consisted of 30 patients with scoliosis from TSRH with documented syringomyelia identified between 1985 and 1997. The demographic and radiographic features of this group were compared with those of a control group consisting of a consecutive series of 54 patients from HSS with adolescent idiopathic and normal MRI. The groups were comparable for age (mean age: control 13 y; syrinx 12 y) and curve pattern but differed in curve magnitude (mean Cobb: control 50°; syrinx 40°). Results. Apical lordosis was present in 97% of patient with AIS and a normal MRI but was absent in 75% of patients with syringomyelia-associated scoliosis (P < 0.0001). The results also confirmed that male patients with scoliosis and left-side curves have a predisposition to having a syringomyelia (P < 0.0001). Conclusions. Sagittal plane deformity in scoliosis can be an indicator of the presence of a syringomyelia. Our results reinforce the necessity of assessing sagittal plane deformity when treating scoliosis. If apical lordotic deformity is absent, a diagnosis of idiopathic scoliosis should be made with caution.