Postural Instability in Early-Stage Idiopathic Scoliosis in Adolescent Girls

Study Design. Cross-sectional study. Objective. To evaluate whether the amplitude of spine deformation in adolescent idiopathic scoliosis (AIS) is an important factor for postural control at disease onset. Summary of Background Data. AIS is related to disorders of postural control with potential involvement of vestibular, proprioceptive, and visual input. So far no assessment of postural control has been done in an AIS population at the onset of spine deformation. Methods. Sixty-five female patients with AIS (mean age: 11.4 +/- 2.3 years) were clinically and radiologically assessed at the time of diagnosis and evaluated in posturography, including static tests-with and without sensory conflict-and dynamic tests. Two groups were formed according to the mean Cobb angle of the primary curve. Results. The mean Cobb angle was 14.8 degrees +/- 5.1 degrees; 35 patients were included in group I with a Cobb angle of 5 degrees to 14 degrees, and 30 patients into group II with a Cobb angle of 15 degrees to 25 degrees. The latter group displayed higher body sways in static tests, characterized by a larger area covered by center of foot pressure in both eyes open and eyes closed conditions, and by higher lateral oscillations in only the eyes closed condition. Group II patients displayed poorer balance control, mainly in visual and somatosensory conflict conditions. Group II patients used fewer anticipatory strategies to stabilize body oscillations than Group I patients, especially in the more challenging sensory conflict and dynamic situations. Conclusion. Poorer postural performance, especially in sensory conflict situations, observed in patients with a Cobb angle greater or equal to 15 degrees, reflect less effective central information processing.