Intraspinal anomalies in infantile idiopathic scoliosis: prevalence and role of magnetic resonance imaging.

STUDY DESIGN: Retrospective case series of magnetic resonance imaging (MRI) findings in patients with presumed infantile idiopathic scoliosis (IIS).

OBJECTIVE: To identify the prevalence of intraspinal anomalies in patients with presumed IIS at a single, large volume institution and further define the role for a screening MRI.

SUMMARY OF BACKGROUND DATA: Idiopathic scoliosis in patients less than 10 years of age has been shown to carry a higher prevalence of concordant intraspinal anomalies, up to 20%, in juveniles, when compared to the adolescent age group. Few studies exist assessing the prevalence of intraspinal anomalies in the IIS patient population. Dobbs et al (2002) reported a 21.7% prevalence of neural axis abnormalities in 46 patients with presumed IIS across 3 combined spinal deformity clinics and recommended a screening MRI for all IIS patients with a curve >20 degrees.

METHODS: A retrospective review of the medical records of 54 patients at a single institution with a presumed diagnosis of IIS was performed. All patients satisfied the strict inclusion criteria of: curve > or =20 degrees, age <36 months at diagnosis, normal neurologic examination (i.e., normal tone, motor strength, reflexes, etc.), absence of any concomitant syndromes or congenital anomalies, and an MRI of the spine from skull to coccyx.

RESULTS: MRI revealed a neural axis abnormality in 7 (13%) of 54 patients who underwent an MRI. In this subset of 7 patients, 5 (71.4%) required neurosurgical intervention. Tethered cord requiring surgical release was identified in 3 patients, Chiari malformation requiring surgical decompression was found in 2 patients, and a small nonoperative syrinx was found in 2 patients.

CONCLUSION: This study represents the largest evaluation of intraspinal anomalies in IIS to date. Our patient population exhibited a smaller percentage (13%) of neural axis abnormalities than previously reported. On the basis of these findings, the close observation may be a reasonable alternative to an immediate screening MRI in patients presenting with presumed IIS and a curve >20 degrees.