Our sense of balance is a complex system, which combines information from our visual system, vestibular system, and somatosensory system. Visual information, of course, is perceived through our eyes and with respect to balance it helps us to see upcoming obstacles, survey the surface that we are standing or walking on, or determine whether we are standing still or moving. Our vestibular system detects head movement in any direction: up and down, side to side, forward or backward, or any angular movement of our head. Finally, somatosensory information is detected by nerve receptors throughout our body in skin, muscles, tendons, and joints. With respect to balance, we use information from our feet, ankles, knees, hips, waist, and neck.
Our brain receives input from all these systems and integrates it to help us perform tasks ranging from the mundane, such as walking down the street, to more complex tasks, such as climbing a ladder or participating in athletic activities. When we experience a problem with our balance system, those activities, which may be easy under ordinary circumstances, may become challenging or impossible. Often people with major balance problems have difficulty performing household or occupational responsibilities and need to seek medical attention to determine the cause of their problem and take corrective measures.
Dizziness is a general term, or an “umbrella” term, for many different, specific symptoms. People may use the word dizziness to mean imbalance, unsteadiness, lightheadedness, vertigo, blacking out, staggering, disorientation, or weakness. Some of the symptoms most commonly experienced by individuals with inner ear-related balance problems are as follows:
Vertigo: a sensation that you or your surroundings are moving. This is most often described as a sensation of spinning, though others experience a feeling of swaying or rocking. Vertigo may be accompanied by nausea, vomiting, excessive sweating, or a need to use the bathroom. Vertigo tends to come in attacks or episodes rarely lasting for more than 12 hours.
Imbalance: difficulty maintaining balance, particularly when standing and walking. Also referred to as unsteadiness, there is no sense of spinning or motion, but the individual may tilt or list to one side or need to hold on to the wall or furniture as they move around. They would feel normal or near-normal when sitting or lying down.
Lightheadedness: The feeling of nearly passing out or losing consciousness. This may be present regardless of whether the individual is lying down, sitting, or standing.
Anatomy of the Inner Ear of Balance
Our ear is generally and accurately thought of as our organ of hearing. When we talk about our inner ear, however, there are six separate groups of nerve endings, only one of which is devoted to hearing. The other five organs are devoted to our sense of balance. Each inner ear houses three “semicircular canals,” which detect head motion in different angles of motion (roll, tilting the head to either side; pitch, tilting the head forward or backward; and yaw, shaking the head side to side). Additionally, there are two “otolith organs,” which detect motion in an up/down plane, as in an elevator, a forward and backward plane, as when walking, or a side to side plane, as when we step to the side of something.
Our entire inner ear is a complex cavity filled with fluid. The nerve endings in each inner ear organ sit within this fluid. When the fluid moves the nerve endings sensitive to head motion, a neurological signal is generated, which is sent out of the ear on one of the two branches of the vestibular nerve. (The audio-vestibular nerve, or the eighth cranial nerve, has three branches: the auditory nerve, the inferior vestibular nerve, and the superior vestibular nerve. These branches merge into one nerve outside of the inner ear).
Information from our inner ears travels through our central nervous system to our brain as well as to our eye muscles, neck muscles, leg muscles, and other muscles throughout our body. It is used for reflexive muscular contraction, as when our body reacts automatically when we slip on ice, and for the purposeful, coordinated movements involved in walking, climbing steps, or sitting up in bed.
Within our central nervous system, the information from each inner ear is compared with the other ear and with the information from our other balance senses: vision and somatosensory. Each sense complements the others to allow us to move quickly and easily through our everyday environments, performing all the tasks of daily life.
Many people experience motion sickness on a boat in rough seas or in airplane that has encountered air turbulence. Other people have motion sickness in boats or airplanes even under ideal conditions or if they try to read in the car. In extreme cases, some people have motion sickness even when they move their head quickly or when they are driving. Motion sickness occurs when the information from the three balance senses (vestibular, visual, and somatosensory) is not integrated smoothly or properly. For example, when someone is sitting a boat, even if it is sitting at the dock, the inner ear will sense the motion of the boat in the water. The eyes may also detect the motion of the boat. However, the muscles in the feet, legs, and other areas of the body are detecting a solid, stable surface (the deck of the boat). This conflict may lead to motion sickness and its symptoms of nausea, vomiting, sweating, and fatigue.
Migraine is a common condition that can affect people of all ages and races. When it presents with headache, the diagnosis may be simple. However many patients have symptoms related to migraine without getting the typical throbbing, debilitating headache most often associated with the condition. These symptoms can involve visual distortions (sparkles or “floaters”), swaying or spinning sensations, fatigue, motion intolerance, and head or ear pressure. A patient with migraine may report that they “just don’t feel right” much of the time but often have difficulty being more specific. In women, symptoms may be related to their menstrual period.
Migraine can often be successfully treated with dietary changes, as migraine may be triggered by certain foods or drinks. In others, prescription medication may be necessary to relieve the symptoms.
Inner Ear Balance Problems
The inner ear is sensitive to motion of the head and the two ears interact with one another in a push-pull system. That is, one ear senses motion toward that side as the other ear senses motion away from that side. For example, when we turn our head to the left, the left inner ear senses motion toward the left as the right inner ear senses motion away from the right.
Most often, an inner ear-related balance problem occurs when one ear becomes weaker than the other due to infection, trauma, or illness. This weakness means that the two ears can no longer work together as equal partners and the result is a breakdown of our balance system.
Labyrinthitis or Vestibular Neuritis
These are viral infection of the inner ear, which are likely to cause permanent damage to the balance organs. Labyrinthitis also affects the hearing organ, while vestibular neuritis affects only balance. While our immune system is usually able to kill the virus, the permanent damage caused to our balance organs is likely to result in vertigo for several hours followed by lingering unsteadiness. This unsteadiness may gradually resolve on its own or physical therapy may be necessary. Most individuals recover to normal or near normal in a few weeks or months.
Benign Paroxysmal Positional Vertigo (BPPV)
The most common cause of vertigo and dizziness in individuals over the age of 50, this type of vertigo is caused by changes in head position. Most commonly, an individual experiences a 30-second attack of strong vertigo when he lies down in bed or bends to tie his shoes. The vertigo may last more or less than 30 seconds, and the head movement triggering the attack may vary.
BPPV is caused when small crystals in the inner ear fluid lodge in part of the balance system. These crystals form a vital purpose under ordinary circumstances but when they break away they cause the inner ear fluid to continue to move even after the individual has stopped moving. In many cases, this condition can be successfully treated by an audiologist or physician, though it may take two or more treatments. These treatments involve specific movements of the head to remove the crystals from the inner ear.
Meniere’s disease is a disorder of the inner ear caused by excess pressure in the endolymphatic fluid compartment. It is often related to excess sodium in the inner ear, though its exact cause is not known. The symptoms of Meniere’s disease are episodic vertigo, fluctuating hearing, pressure in the ear, and tinnitus.
Treatment of Meniere’s disease may involve dietary changes, such as minimizing salt, caffeine, alcohol, and nicotine. In more extreme cases, surgery may be required. This surgery sometimes involves destroying the malfunctioning portions of the inner ear.
An acoustic neuroma is a benign (non-cancerous) tumor, which results from abnormal growth of the cells that line the audio-vestibular nerve. This condition rarely causes vertigo but over time may cause a sensation of imbalance as it presses on the nerve. Most often the individual will have hearing loss and tinnitus in the affected ear, and many report that they have strong headaches on the side of the affected ear. This growth would need to be removed surgically.
The inner ear is a fluid-filled cavity within the temporal bone of the skull. If a leak of this fluid occurs, dizziness and hearing loss may occur. A leak most often occurs in or near the natural openings to the inner ear such as the oval window or round window of the cochlea. This leak may occur naturally or result from straining or trauma. Some people are born with a condition called Enlarged Vestibular Aquaduct Syndrome (EVAS), a condition in which a small tunnel connecting the fluid of the inner ear with the fluid in and around the brain is too large. This condition may cause similar symptoms.
A perilymphatic fistula or EVAS can often be detected on a CT scan and may heal on its own. In most cases, however, surgery is required to repair the leak.