Background: The natural history of split spinal cord malformation (SCM) is still unclear. Knowledge of the characteristics of the osseous spur and its relationship with the spinal deformity may allow early identification of patients with a higher risk of a neurological deficit and enhance surgical decision-making.
Methods: Eighty-five consecutive patients with congenital scoliosis and type-I SCM who had undergone surgical treatment at our hospital from May 2000 to December 2013 were identified retrospectively. There were 22 male and 63 female patients with an average age of 13.9 years at the time of surgery. Preoperative clinical and radiographic data were collected to investigate the characteristics of the scoliosis and the osseous spur. Two groups were identified on the basis of whether the patients had intact neurological function (Group A) or a neurological deficit (Group B).
Results: There were 52 patients (61%) in Group A (intact neurological function) and 33 patients (39%) in Group B (neurological deficit). There were no significant differences in the demographic distribution, curve magnitude, or length and thickness of the osseous spur between the 2 groups. In Group A, the location of the osseous spur relative to the apex of the major curve was proximal in 13 patients (25%), distal in 28 (54%), and central in 11 (21%). In Group B, the osseous spur was proximal in 7 (21%), distal in 8 (24%), and central in 18 (55%). The 2 groups differed significantly with respect to the location of the osseous spur (chi square = 10.898, p = 0.004). Group-B patients had a higher proportion of patients with kyphotic deformity (42%) than Group A (10%). The ratio of the diameters of the hemicords (concave side divided by convex side) differed significantly between the 2 groups (0.98 for Group A versus 0.89 for Group B, p = 0.030).
Conclusions: The neurological status in patients with congenital scoliosis and type-I SCM appears to be closely related to the location of the osseous spur relative to the congenital scoliosis. An osseous spur at the apex of the scoliosis may be related to a higher risk of developing a neurological deficit, especially in patients with kyphotic deformity. Asymmetric splitting of the spinal cord may contribute to neurological deficits.
Level of evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.