Causes of Dizziness & Imbalance
Benign Paroxysmal Positional Vertigo (BPPV)
Benign Paroxysmal Positional Vertigo (BPPV) is one of the most common types of dizziness. This disorder can be seen following head injury, vestibular neuronitis, Meniere’s disease, or can present alone. Simple everyday movements such as rolling over in bed, sitting up, or bending over can trigger vertigo (spinning sensation).
The vestibular system/inner ear is a complex structure which includes 3 semicircular canals and the utricle and saccule, which contain small crystals called canalith. If the canalith break loose they can float freely into the canals. The canalith are displaced with specific movements, such as bending over or rolling over in bed, and send an incorrect message to the brain resulting in vertigo/dizziness.
BPPV can be treated with repositioning maneuvers. Repositioning progressively moves the canalith out of the semicircular canals into the utricle. When the crystals are in the utricle, they cannot trigger dizziness.
BPPV can recur, therefore repositioning is sometimes repeated.
Vestibular Neuritis is an inflammation of the auditory/vestibular nerve usually caused by a virus. The inflammation can change or reduce the output of one or both of the balance portions of the inner ear to the brain. This inaccurate inner ear information results in severe dizziness and vertigo. Fortunately, vestibular neuritis usually subsides in time and usually does not recur. When the inflammation affects the auditory portion of the nerve, it causes hearing loss in addition to dizziness and is called labyrinthitis. Certain medications can help in the initial phases to decrease the severe symptoms. However, long-term use of medications can actually impede full recovery. Balance exercises (vestibular rehabilitation) can be the most effective treatment for the symptoms associated with vestibular neuritis.
Migraine- Associated Dizziness
Migraines are thought to be caused by vasoconstriction of cranial vessels or neuronal dysfunction. Changes in nerve cell activity and blood flow may result in symptoms such as visual disturbances, vertigo (spinning), motion intolerance, positional vertigo, photophobia (light sensitivity), misophonia (sound sensitivity), and nausea. Migraine associated dizziness may be due to the constriction of blood supply to the cochlear and/or vestibular system. Evaluation for migraine associated dizziness includes a hearing evaluation, a complete case history, videonystagmography (VNG), and a neurology consultation. Migraine medications have been shown to successfully reduce migraine associated dizziness.
Meniere's Disease (Endolymphatic Hydrops)
Meniere's disease is relatively rare compared to other more common disorders such as vestibular neuritis and benign paroxysmal positional vertigo. A typical Meniere's attack involves severe spinning vertigo with imbalance, nausea. and vomiting. Characteristically, the attacks are accompanied by fluctuations of hearing and sometimes tinnitus (ringing in the ears). Most patients with Meniere's Disease describe fullness in one or both ears. The attacks can last for hours but fatigue and nausea may persist for days. Meniere's Disease is caused by abnormal accumulations of fluid in the inner ear and increases of inner ear pressure. The diagnosis is often made with an accurate history, a hearing test, and specialized tests such as videonystagmography, vestibular evoked myogenic potentials, and videocochleography (VNG). The treatment consists of medications, a special low salt diet, and surgery (only rarely). Vestibular rehabilitation is considered to be helpful only in cases of persistent, non-fluctuating inner ear injury.
Ototoxicity is the term used to describe damage to the ear caused by toxic substances. This occurs when individuals come into contact with drugs or chemicals that are poisonous to the inner ear or to the nerve that supplies the inner ear (vestibulocochlear nerve). Because the inner ear is involved in both hearing and balance, ototoxicity can result in problems with either one or both of these senses. Symptoms vary considerably from drug to drug and person to person. They range from mild imbalance to severe vertigo and from tinnitus (ringing in the ears) to total hearing loss. If symptoms involve both the right and left inner ears, the patient may not have vertigo, but severe imbalance and blurred vision caused by poor stabilization of the eyes. This loss of vestibular function may cause the inability to tolerate head movement. The diagnosis is based upon the patient's history, symptoms, and test results. Tests that may be used to determine how much hearing or balance function has been lost include: videonystagmography (VNG), auditory brainstem response (ABR), and a hearing evaluation. The treatment consists of eliminating or reducing exposure to ototoxic substances and participating in a vestibular rehabilitation program to promote greater use of vision and muscle sensory information (proprioception). The goal of the treatment is to help the brain become accustomed to the changed information from the inner ear and to assist the individual in developing other ways to maintain balance.
Acoustic neuromas are rare. Only about 2,000 cases are diagnosed in the United States each year. An acoustic neuroma is a benign tumor on the vestibular portion of the eighth cranial nerve, which connects the inner ear to the brain. An acoustic neuroma may cause vertigo (spinning), unsteadiness, imbalance, or lightheadedness in addition to hearing loss and/or ringing in the affected ear. Most acoustic neuromas are removed by surgery. Other options, including various types of radiation therapy (often called radiosurgery), are available. Each type of treatment entails some risk of permanent change in hearing, balance, and facial motion. Some people may experience imbalance for several months after surgery.
A perilymph fistula is a tear or defect in the oval window or round window (the thin membranes between the middle and inner ears). When a fistula is present, changes in middle ear pressure will directly affect the inner ear stimulating the balance and/or hearing structures and causing dizziness, vertigo, imbalance, nausea, and vomiting. Individuals may experience ringing, fullness, and/or hearing loss. Symptoms typically worsen with changes in altitude such as elevators, airplanes, or travel over mountains. Additionally, strenuous activity or straining can trigger symptoms. Head trauma is the most common cause of perilymph fistula. However, other activities such as weight lifting or scuba diving can cause a perilymph fistula. Often a fistula can be diagnosed by applying pressure to the ear while measuring eye movements. Perilymph fistulas can heal spontaneously with rest, but sometimes surgery is required.
Superior Canal Dehiscence
Superior canal dehiscence is a balance disorder resulting from a hole in the bone overlying the superior (uppermost) semicircular canal within the inner ear. This abnormal opening can cause dizziness, nausea, and vestibular hyperacusis (vertigo and imbalance triggered by sound). Superior canal dehiscence is thought to result from a congenital condition in which the bone over the superior canal is thinner than normal and thus more vulnerable to damage from gradual erosion or from forces such as violent coughing or a blow to the head. The diagnosis of superior canal dehiscence includes a hearing evaluation, tympanometry, videonystagmography (VNG), vestibular evoked myogenic potentials (VEMP), and bone-imaging studies such as a CT scan. Treatment involves surgically patching the bone overlying the superior (uppermost) semicircular canal followed by vestibular rehabilitation therapy.
The proper function of the balance system requires not only the input for the inner ear, but also the appropriate nerve connections in the brain. If the areas of the brain that assist in balance do not get enough blood, even temporarily, dizziness can occur. Causes of vascular dizziness are varied. Arthritis in the neck can cause compression of arteries to the head, cholesterol plaques may narrow the arteries in the brain, and fluctuations in blood pressure may cause dizziness. Special testing such as videonystagmography (VNG), MRI, or Doppler tests may be needed to accurately diagnose these problems.
Natural Aging Process
Maintaining balance is a complex interaction which requires correct information from three sensory receptors, the inner ear, vision, and somatosensory input systems. All three signals must be correctly received by our central nervous system in order to maintain balance. If any component of this complicated system is compromised, the result is a loss of balance. The natural aging process may affect any one or all of these sensory receptors, as well as the central nervous system’s ability to interpret and react to them. Therefore, loss of balance and unsteadiness are common changes seen as a function of aging. Fear of falling is the number one health concern of individuals in their later years. The National Institute of Health statistics indicates that balance related falls account for 50% of accidental deaths in the population over 65. In addition, nearly 300,000 hip fractures and 3 billion dollars in medical expenses are due to balance related falls. Vestibular rehabilitation programs have been very successful in helping patients with fall prevention and improved balance and coordination. A complete case history and videonystagmography (VNG) evaluation are necessary to determine whether imbalance is due to the aging process or other medical conditions. They are also necessary to help ensure an appropriate treatment plan.
Information obtained from the American Institute of Balance at www.dizzy.com and Vestibular Disorders Association at www.vestibular.org