Aim: To investigate whether there is any difference in regional brain volumes between AIS patients and age matched, sex matched control subjects.

Method and Materials: 20 adolescent idiopathic scoliosis (AIS) female patients (age ranged from 11 yrs to 18 yrs, mean age of 14.5 yrs) and 20 sex matched, age matched controls have undergone MRI brain examination performed with a 1.5T scanner (Sonata, Siemens Medical Solutions, Erlanger, Germany). A Magnetization Preparation Rapid Acquisition Gradient Echo (MPR) sequence was used. Volumes of neuroanatomical regions were quantitated automatically by using whole brain segmentation technique of atlas-based hybrid warping. The whole brain was classified into 100 fine anatomical regions.

The results were taken as significant when p value was less than 0.05.

Results: Significant unilateral regional differences were found in the following regions:

Left thalamus and left postcentral gyrus of AIS patients were significantly larger than the control subjects. Anterior and posterior limb of right internal capsule, right caudate nucleus, right cuneus and left middle occipital gyurs of AIS patients were significantly smaller than the control subjects. Some regions were bilaterally involved: Perirhinal and hippocampus regions were larger in AIS while inferior occipital gyrus and precuneus were smaller than the corresponding regions in the control subjects. In the midline, the volumes of corpus callosum and brainstem in AIS patients were significantly larger than the control subjects.

Conclusion: Our study found that significant differences in particular regional brain volumes exist between AIS patients and the controls. Most of these regions involved the brain unilaterally, indicating that there might be abnormal asymmetrical development of the brain in AIS. This is the first study of its kind to show the presence of L-R asymmetry of regional brain volume difference in AIS patients as compared to normal controls. The findings might also help to explain the reported poor performance in the combined visual and proprioceptive test, spatial orientation test, abnormal nystagmus response to calorie test, and impaired postural balance in AIS patients.