Association of Cobb angle progression and neuraxial abnormality on MRI in asymptomatic Adolescent Idiopathic Scoliosis

Abstract

Background: Detection of neuraxial abnormality in neurologically asymptomatic adolescent idiopathic scoliosis (AIS) is crucial prior to surgery. It can only be detected on magnetic resonance imaging (MRI), which was not routinely done in this group of patient. On the other hand, whole spine radiographs for measurement of Cobb angle have been routinely included during clinic follow-up. This study aimed to determine the correlation between Cobb angle progression and neuraxial abnormality finding on MRI in asymptomatic AIS.

Methods: A retrospective study was conducted in the Orthopaedic department of a tertiary hospital. Patients with asymptomatic AIS aged 10-20 years who attended scoliosis clinic from year 2007 to 2010 was reviewed. Patients who had whole spine MRI and two vertebral radiographs at least one year apart were further selected. Statistical analysis was done to see the association between Cobb angle progression and neuraxial abnormality on MRI.

Results: The mean age at first presentation was 14.4 years old. Female (n=249) to male (n=50) ratio was 5:1. Only 19 patients fulfilled the selection criteria. There were 5 patients (26.3%) who had neuraxial abnormalities. The mean curve progression was 7.05° (range from -5° to 28°). Patients with and without neuroaxial abnormality showed mean curve progression of 0.6° and 9.36° respectively. There was no significant association between Cobb angle progression and neuroaxial abnormality (p=1.000).

Conclusion: Cobb angle progression is not a reliable indicator for predicting neuroaxial abnormality in patients with asymptomatic AIS. However, this study stressed the need to perform MRI prior to operation to document any associated neuraxial abnormality in clinically asymptomatic AIS patients.