The ability of an individual to organize and integrate sensory information is essential to perform functional tasks. (2)
Balance, postural control, muscle tone,
equilibrium reactions, and the ability to focus cognitively are dependent on an organized
sensory system. Though all the sensory systems interrelate, it is significant that both
the tactile and vestibular systems are readily accessible for therapeutic intervention.
The two cannot be separated when performing or avoiding motor skills. Vestibular
stimulation has proven to be effective in treating individuals with sensory integrative
dysfunction. Sensory input in a therapeutic manner will result in other functions of the
somatosensory system experiencing a maturational change (1)
Many individuals seek out this stimulation through rocking and similar movements. Others manifest extreme and self-abusive behavior. This self-stimulating behavior is not only disruptive to others, but also interferes with focusing on meaningful tasks. Individuals may reject vestibular stimulation altogether which can negatively impact motor and academic learning. (1)
Vestibular stimulation is very powerful and can be detrimental if not done within the neurological limits of the individual. It can be simulating or inhibitory. Stimulation must be selective and easily modulated to be therapeutic.
Conclusions drawn from studies with infants accent the sensory organizing effects of vestibular stimulation. Infants treated with vestibular stimulation have been known to increase visual pursuit and visual alertness, experience increased relaxation and calming, and experience a decrease in crying. Rocking an infant, a simple form of linear vestibular stimulation, has shown to increase the length of quiet sleep time and increase weight gain. Vestibular stimulation as a supplement to environmental stimulation has proven to increase arousal, visual exploration, motor development, and reflex integration.(6)
Vestibular stimulation is imperative for skeletal muscle control as well as other essential functions in an individual. Lack of vestibular stimulation results in muscle debility; including the autonomic system or visceral muscles.(3) Vestibular input stimulates the autonomic system as evidenced by classic aversive responses to vestibular input, i.e. nausea, vomiting, dizziness or vertigo and other feelings of discomfort. (2,5)
Considerations when stimulating integration of the nervous system through vestibular stimulation are: (A) type of movement (i.e., linear vs. angular), (B) speed of movement (i.e. slow vs. fast), and (C) the presence of resistance to active movement to stimulate muscle receptors. (5) Linear vestibular stimulation in various positions is required to stimulate the otolith. Dynamic activity is imperative in the development of postural control. Sensory information is enhanced through active participation in an activity. The individual must be able to assume various positions and participate in weight shifting activities. (1)
Sensory disorganization may occur several hours after a treatment is completed. Treatment with linear stimulation has been shown to decrease aversive responses to vestibular stimulation. Providing stimulation slowly in a linear manner combined with resistive activities has proven to control adverse reactions to vestibular stimulation. (5)
Clinical therapists and researchers have known the effects of vestibular stimulation for years. Adapting therapeutic equipment to enable work in this area has taken creativity and perseverance. Most equipment combines a horizontal motion with a rounding, swinging, or tilting motion. This negates much of the therapeutic effect of the vestibular stimulation. To engage the individual actively while modulating the type and speed of stimulation has always proven to be a challenge.