Relationships between the Vestibular system and Auditory system:

The effectiveness of facilitation of sensory integration through the vestibular system is a major component of Sensory Integrative Treatment. A related or associated alternative to the use of vestibular input may be the use of auditory input. In order to understand the effectiveness of this approach it is important to look at the similarities and relationships between the vestibular and auditory systems.

The vestibulocochlear system can be separated into three functional divisions. The semicircular canals respond to angular or phasic movement. The utricle and saccule respond to linear movement and static positioning. The cochlea and Organ of Corti provide hearing function. All of these components occupy the same anatomical region in the bony portion of the temporal bone. All share common fluids - the perilymph and endolymph.

The VIII cranial nerve (vestibulocochlear nerve) provides the sensory innervation for each of these areas by dividing into two branches, the cochlear nerve, and the vestibular nerve. However some of the nerve fibers from these two branches appear to be shared so that some auditory fibers are carried by the vestibular nerve and some vestibular fibers are carried by the cochlear nerve. Fibers from both systems synapse in the reticular formation of the midbrain enroute to the cortex and cerebellum (Moore 1973). Thus, the receptive systems for hearing and movement are highly interconnected at both anatomical and neurological levels.

Clinical evidence (Gilmor et al 1989; Tomatis 1981; Tomatis 1987 ) indicates that hearing deficits can upset equilibrium reactions and that balance and postural responses improve when precise listening skills are developed. Many children who have poor hearing and/or listening skills improve their functional use of hearing when vestibular input is used to facilitate movement.

FACILITATION OF SENSORY INTEGRATION THROUGH THE AUDITORY SYSTEM

Vestibular input provides an effective foundation for therapeutic learning for children with sensorimotor disorders. We might ask whether stimulation of the auditory portion of the auditory-vestibular system would create a similar impact on sensorimotor learning. If a similar effect can be identified, the use of specific types of sound could play a major supportive role in the treatment of children with sensory integrative dysfunction.