The word “dizziness” is used to describe a wide range of symptoms from a true spinning sensation (vertigo) to loss of balance, unsteadiness, light headedness or motion sickness.
Dizziness is a very common health problem worldwide and can originate from a number of different sensory systems within the body including the vestibular system in the inner ear, the occulomotor feedback from the eyes and the movement sensors in the muscles and joints (somatosensory system).
Maintaining balance depends on at least two of these sensory systems functioning well. If one system is compromised, feedback from the other two systems helps to compensate and maintain balance. However, if the brain does not receive information form these systems, or if it is receiving contradictory information from these systems, you may experience loss of balance.
What Causes Balance Disturbance?
Inner ear (vestibular) dysfunction is a common cause of dizziness and can stem from a number of conditions which fall into two main categories.
Peripheral Vestibular Disorders:
Peripheral vestibular disorders stem from pathology of the inner ear vestibular organs or vestibular portion of the 8th cranial nerve. This kind of pathology decreases the reliability of the sensory feedback provided by the vestibular system regarding head position in space and movement. Common pathologies include;
• Vestibular neuronitis and labrinthitis
• Meniere’s disease
• Benign Paroxysmal Positional Vertigo (BPPV)
• Trauma or vestibular disturbance following surgery
Central Vestibular Disorders:
Central vestibular disorders involve the higher level structures of the vestibular pathway such as the cerebellum, midbrain and centres of cortical function. This kind of pathology affects how the information coming from the vestibular, visual and somatosensory systems are processed and integrated. Common pathologies include;
• Brainstem strokes
• Head trauma
• Vestibular migraine
• Multiple sclerosis
• Cerebellar degeneration
How Our Balance System Works:
Our balance systems help us stay upright and know where we are in relation to gravity. Balance is maintained through signals to the brain from your eyes, the inner ear, and the sensory systems of the body (such as the skin, muscles, and joints).
In the inner ear, the balance system consists of three semicircular canals which contain fluid and sensory hair cells that detect rotational movement of the head. These sensory hair cells send impulses to the brain for processing, to help us know where we are in space or if we are moving.
Located near the semicircular canals are the utricle and the saccule. The utricle is sensitive to change in the horizontal plane (i.e. side to side movement) and the saccule is sensitive to the change in the vertical plane (such as going up in an elevator).
Assessment of the vestibular system is often recommended when a person has:
• Rapid, involuntary eye movement (also known as nystagmus)
• Complaints of vertigo or dizziness
• Balance dysfunction
• Gait abnormalities
• Suspected pathology or disease of the vestibular system
Vestibular Rehabilitation Therapy:
Audiological, balance, and medical diagnostic tests help indicate whether you are a candidate for vestibular (balance) rehabilitation. Vestibular rehabilitation is a balance retraining program that promotes vestibular compensation that may decrease symptoms of dizziness and improve balance.