Neural axis abnormalities detected by preoperative magnetic resonance imaging in patients with type III idiopathic scoliosis

Abstract

We investigated the presence of neural axis abnormalities by magnetic resonance imaging (MRI) in patients with clinically and radiologically confirmed absolute flexible thoracic curves (King-Moe type III). Preoperative MRI scans of 84 patients (34 males, 50 females; mean age 14.1 years; range 11 to 17 years) with adolescent idiopathic scoliosis and a flexible thoracic curve (King-Moe type III) were prospectively evaluated to determine neural axis abnormalities. Clinical and radiologic indications for preoperative MRI examination were sought. All patients were treated with posterior fusion. All patients were intraoperatively monitored by means of motor evoked potentials by magnetic transcortical stimulation and somatosensory evoked potentials. The mean follow-up was 50.1 months (range 24 to 105 months). Neural axis abnormalities were detected in six patients (7.1%), including syringomyelia in five patients (5.9%) and diastometamyelia in one patient (1.2%). Of 84 patients, 51 patients (60.7%) had a relatively decreased spinal cord diameter, and an increased epidural distance. No clinical or radiologic indicators were found for preoperative MRI examination. No neurologic deficits developed during operation and in the postoperative period. The detection of neural axis abnormalities implies the necessity of intraoperative neurologic monitoring to minimize the risks for neurologic deficits. Where this is not available, preoperative MRI seems to be an essential tool in the prevention of surgery-associated neurologic risks.