Vestibular mechanisms involved in idiopathic scoliosis.

Patients affected by idiopathic scoliosis (IS) show not only a spinal deformity, but also postural and oculomotor deficits suggesting that such syndrome can be related to a vestibular disfunction. It appears, however, that, in children, a slight unbalance in the activity of vestibular complex of both sides escapes the neuronal mechanisms responsible for vestibular compensation and leads to the spinal curvature which characterises IS. Such process could be reinforced by a disrupted integration of vestibular and visual signals at cortical level, leading to an altered perception of the vertical and to abnormal motor commands. In addition to the classical ascending and descending pathways arising from the vestibular nuclei, which utilize glutamate or GABA as neurotransmitters, labyrinthine afferents may also affect spinal, cerebellar and cerebrocortical structures, through the noradrenergic and serotoninergic systems, which originate from the locus coeruleus and the raphe nuclei, respectively. Due to the role of these neuromodulators in brain plasticity, a disruption in the activity of monoaminergic neurons could favour the development of postural and oculomotor deficits. An impaired release of monoamine at cerebrocortical level could also explain the cognitive deficits which may occur in IS patients.