Sound influence on vestibulo-spinal control

It has been known for a long time that the application of intense acoustic stimuli to the ear can induce reflex muscle responses. The classic physiology describes reflex responses of neck muscles aimed at turning the head towards the source of acoustic stimuli. It is well known Tullio phenomenon (1929) which is a rare but remarkable clinical entity consisting of a rotatory vertigo and unsteadiness evoked by extremely loud sounds (ipsilateral nystagmus ). The link between the vibratory energy and the vestibular response takes place in the saccule which is located between choclea and utriculus on one side and semicircular canals on the other side. The acoustic stimulation induces movements of the stapes footplate which excite macular receptors of the sacculus, due to their close proximity. Therefore, acoustic stimulation activates the vestibulo-spinal pathway by stimulating saccular maculae EMG/ABR recording from ipsi SCM showes a P13/N23 biphasic complex.