Incidence of Neural Axis Abnormalities in Infantile Patients Diagnosed with Idiopathic Scoliosis: Is a Screening MRI Necessary?

*Washington University School of Medicine, St. Louis, MO, USA,¦ University of Iowa Hospitals and Clinics, Iowa City, IA, USA, "Johns Hopkins University, Baltimore, MD, USA

INTRODUCTION: Although the literature demonstrates approximately 20% incidence of neural axis abnormalities in juvenile idiopathic scoliosis patients with curves >20º, the incidence of neural axis abnormalities in the infantile idiopathic population is not well documented. The decision to obtain a screening MRI on these young children is also tempered with the necessity for IV sedation or even a general anesthetic to obtain the study.

PURPOSE: To determine the incidence of neural axis abnormalities in infantile idiopathic scoliosis patients without neurologic findings in a large, consecutive, multi-center series, to determine the need for a screening MRI in this age group.

METHODS: A multi-centered retrospective review evaluated 56 consecutive patients between 1993-2000 at 3 spinal deformity clinics with the following inclusion criteria: presumed idiopathic scoliosis at presentation; age 3 or less; scoliosis > 20º; no neurological findings; no associated syndromes; no congenital abnormalities. All patients were evaluated by a total spine MRI protocol for examination of neural axis abnormalities from the skull to the coccyx.

RESULTS: 11 of 56 (19.6%) of the patients were found to have a neural axis abnormality on their MRI. This included 5 with syringomyelia, 3 with Arnold Chiari malformations, 2 with tethered cords, and one with a spinal cord tumor. Of these 11 patients with abnormalities, 6 needed neurosurgical intervention for their abnormality for an incidence of 54.5%.

DISCUSSION: In two previous studies with a combined total of only 10 infantile idiopathic patients, 5 (50%) were noted to have a neural axis abnormality on MRI evaluation. The actual incidence appears to be closer to 20% in this significantly larger multi-center study.

CONCLUSIONS: The 19.6% incidence of neural axis abnormalities in the infantile idiopathic scoliosis group was found to be almost identical to that reported in the literature for the juvenile idiopathic patients. Due to this high incidence and the fact that 54.5% of the infantile patients with abnormal MRI's required neurosurgical intervention, a total spine MRI is recommended at presentation in patients with infantile idiopathic scoliosis >20º.