Patients with scoliosis have dysfunctional spinal muscles, preliminary study

Abstract

Etiology of idiopathic scoliosis is still unknown. Many theories have been introduced throughout the history to clarify the etiology of the scoliosis. Especially vague is the idiopathic scoliosis that apparently does not have any reasonable explanation. Due to the cosmetic appearance of the scoliotic spine, scoliosis has been mostly studied on its treatment. Because children’s vertebral column is flexible, uneven spinal muscle activity and forces may potentially play a role in the development of scoliosis. Some electromyographic (EMG) studies have reported higher activity in the convex side while other found no differences. Mixed findings may be due to fact that previous studies have analyzed absolute rather than normalized EMG results, although latter is commonly recommended. Do spinal muscles show uneven activity in scoliotic patients when examined using normalized EMG. We report results of six scoliotic patients. Multifidus (Mul), Lumbar erector spinae (Les) and thoracic erector spinae (Tes) EMG was recorded during walking and normalized to values of maximal voluntary contraction (MVC). At groups level, we found relatively little differences in the normalized EMG magnitude between concave (left) and convex (right) side; however, individual results reveal large side-to-side differences especially in the Les and Tes (Fig. 1). The peak normalized EMG values were relatively high often exceeding the 50% level of the MVC. Picture: Scoliotic spine and EMG of the spinal muscles.Download : Download high-res image (125KB)Download : Download full-size image During walking spinal muscles of the young scoliosis patients were activated asymmetrically in a patient-specific manner. While some patients showed relatively low normalized EMG values, others demonstrated high activity levels, indicating that substantial uneven forces are directed to the flexible vertebral column of these patients. Presumably, this influences the stability of the vertebra. It is evident that scoliosis already develops earlier than when it is actually diagnosed, suggesting that a large-scale EMG screening could help to detect abnormal spinal muscle function before scoliosis is manifested.