Incidence of Intraspinal and Extraspinal MRI Abnormalities in Patients With Adolescent Idiopathic Scoliosis

Abstract

Study design: Retrospective study with follow-up.

Objectives: The purpose of this study was to determine the incidence of intraspinal and extraspinal MRI abnormalities in a consecutive series of patients with adolescent idiopathic scoliosis (AIS) and to describe the evaluation and management of these abnormalities.

Summary of background data: Indications for preoperative magnetic resonance imaging (MRI) in patients with AIS remain controversial. Previous studies have reported a wide range of abnormality rates; however, the majority of these studies focus on a nonconsecutive series of patients, and none of these studies report the incidence of extraspinal abnormalities.

Methods: We studied a consecutive series of patients with AIS managed with spinal deformity surgery. All patients underwent a routine neural axis MRI prior to surgery. MRI reports were reviewed, and intraspinal and extraspinal abnormalities were recorded. Additional chart review and follow-up was performed to determine the rates of evaluation and management for these abnormalities. Descriptive statistics were used to describe the incidence and types of abnormalities, as well as the rates of evaluation and management.

Results: This study included a consecutive series of 259 patients with AIS. MRI abnormalities were noted in 115 patients (44%). After excluding patients with degenerative changes, MRI abnormalities were noted in 64 patients (25%). The incidence of Chiari malformation was 4.2% and syringomyelia was 5%. Extraspinal abnormalities were noted in 10% of patients, and these findings ranged from benign cysts to malignant soft tissue tumor. Approximately 10% of patients needed additional evaluation because of their preoperative MRI findings, and 0.7% of patients required surgical management prior to spinal deformity surgery.

Conclusions: Significant MRI abnormalities were noted in patients with AIS, and some patients required further evaluation prior to surgery. Additional study including cost-effectiveness analysis is needed to better define the role of preoperative MRI in patients with AIS.

Level of evidence: Level II.

Keywords: Adolescent idiopathic scoliosis; Extraspinal abnormalities; Intraspinal abnormalities; Magnetic resonance imaging.