The origin of the AIS is unknown. Several studies in AIS have shown disturbances of orthostatic postural control and somatosensory modality. The orthostatic postural control is the ability to organize the upright position on the earth-vertical, by multisensory central integration, especially somatosensory information. Our hypothesis is that the somatosensory disturbances in the AIS involve change in the organization of orthostatic postural control, around an erroneous central representation of verticality. Our objective is to test, in the AIS, the existence of a disturbance of the somatosensory modality in orthostatic postural control by measuring the Subjective Postural Vertical (SPV).

Uncontrolled preliminary study on 8 adolescents with SIA (7 girls, 13.8±0.83 years, 38.8±10.4°angle). Test=SPV measurement, vision obscured, head-trunk-members strapped, sitting on a seat, fixed to a German vertical wheel athletic gymnastics (external diameter: 1.90 m), with electronic inclinometer that measures the rotational tilt of the seat, with reference to the gravitational vertical. From 45° inclination, the subject is tilted (1°/sec) and evaluates the alignment with the vertical gravitational.

AIS SPV=7.48±4.86° with a tilt predominance to the right. It is impossible to realize statistical evaluation in this preliminary study. Our results are comparable with those reported in pusher patient.

This preliminary study shows a disturbance in the assessment of SPV in the AIS. Disorders of the central integration of somatosensory modality could explain this result.

The authors are grateful to the Harps Association's members, for their helpful comments.