Balance and Fall Prevention

Sensory Input

The ability to maintain balance depends on information that the brain receives from three different sources the eyes, the muscles and joints, and the vestibular organs in the inner ears. All three of these sources send information in the form of nerve impulses from sensory receptors, special nerve endings, to your brain.

Input from the eyes
Nerve endings or sensory receptors in the back of the eye (retina) called rods and cones are sensitive to light. When light rays strike them, their nerve fibers send impulses to the brain with visual cues that aid in balance. For example, if a person is walking down the street, buildings appear to be aligned straight up and down.

Input from the muscles and joints
The input received by the brain from the muscles and joints comes from proprioceptionsensory receptors that are sensitive to stretch or pressure in the tissue that surrounds them. As the legs, arms, or other parts of the body move, the receptors respond to the stretch of the muscles surrounding them and send impulses through many sensory nerve fibers to your brain.

Especially important are the impulses that come from your neck, which indicate the direction the head is turned, and the impulses that come from the ankles, which indicate the body's movement or sway relative to the ground while standing.

Input from the vestibular system
The inner ear or labyrinth is a complex series of passageways and chambers within the bony skull. Within these passageways are tubes and sacs filled with a fluid called endolymph. Around the outside of the tubes and sacs is a different fluidthe perilymph. Both of these fluids are of precise chemical compositions, and they are different. The mechanism in your inner ear that regulates the amount and composition of these fluids is important to the proper functioning of your inner ear.

Each inner ear has a hearing (auditory) componentthe cochlea, and a balance (vestibular) componentthe vestibular apparatus, consisting of three semicircular canals and a utricle and saccule. Each of the semicircular canals is located in a different plane in space. They are located at right angles to each other and to those on the opposite side of the head. At the base of each canal is a swelling (ampulla) and within these ampullae are located the sensory receptors for each canal.

Inside each fluid-filled semicircular canal is a sensory receptor (cupula) attached at its base. With head movement in the direction in which this canal is located, the endolymphatic fluid within the canal, because of inertia, lags behind. When this fluid lags behind, the sensory receptor within that canal is bent. The receptor then sends impulses to the brain about movement.

When the vestibular apparatus on both sides of the head are functioning properly, they send symmetrical impulses to the brain. That is, the impulses coming from the right side conform to [agree with] the impulses coming from the left side.

Integration of Sensory Input

All of the sensory input concerning balance, from the eyes, from the muscles and joints, and from the two sides of the vestibular system, is sent to the brain stem, where it is sorted out and integrated with contributions from other parts of the brain.

Motor Output

Motor output to the eyes
The motor impulses that go to the eyes coordinate their movement to produce clear vision during active head movements (e.g., while running or watching a tennis match) or passive head movements (e.g., while sitting in a moving car).

Eye movement during head motion is controlled automatically by the vestibular system. When the head is not moving, the number of impulses from the right side is equal to the number of impulses coming from the left side. When the head turns toward the right, the number of impulses from the right semicircular canals increases and the number from the left decreases. This difference controls eye movements and allows for clear vision as the head is turning.

Motor output to the muscles and joints
The motor impulses that are sent from the brain to the other muscles of the body control their movement so that balance is maintained whether a person is sitting, standing, or turning cartwheels.

For example, when a person is turning cartwheels, some of the impulses that leave the brain stem go back to the cerebral cortex, carrying information to the thinking centers that acknowledge that it's okay to see trees whirling in circles. With practice at this and similar new activities, the brain learns to "read" different kinds of sensory input as normal.

This is exactly what happens as a baby learns to balance through practice and repetition. The impulses from the sensory receptors to the brain stem and then out to the muscles form a pathway. With repetition, it becomes easier for the impulses to travel over the same network or pathway, until maintaining balance during any activity becomes automatic. Physiologists say that these nerve pathways become "facilitated." This is the reason why dancers and athletes practice their activities over and over again.

Even very complex movements become almost automatic over a period of time. Anyone who has learned to ride a bicycle, swim or ski can relate to this idea.

This is also the basis for physical therapy in treating people with a damaged vestibular system the exercises mimic the movements that make them feel dizzy and lose their balance. After a time, the brain "learns" that the input from this activity is "normal" for the damaged system, and the side effects of dizziness and balance decrease.

In effect, balance becomes the "sixth sense."

Vestibular Rehabilitation Therapy (VRT)

Why is therapy needed?

If the brain cannot rely on the information it receives from the vestibular system, a person's ability to maintain posture and coordinate balance can become overly dependent on vision or on the information received from the muscles and joints (proprioception).

This can lead to developing new patterns of movement to compensate for the change and to avoid head movements that are apt to create symptoms of dizziness and nausea. For example, a person might adopt an exaggerated hip sway as a method of balancing, might swivel the entire body rather than just the head in turning to look at something, or might always look down at the floor to avoid what appears as a confusing swirl of activity.

Unfortunately, these types of adaptation can result in headache, neckache, muscle stiffness, general fatigue, and a decrease in the ability to retrain the brain to adjust to the vestibular problem, hence making the symptoms much worse.

The goal of VRT is to retrain the brain to recognize and process signals from the vestibular system in coordination with information from vision and proprioception. This often involves desensitizing the balance system to movements that provoke symptoms.

What happens during vestibular therapy?

A qualified therapist will first perform a thorough evaluation. This includes observing posture, balance, movement, and compensatory strategies.

Using the result of this evaluation, the therapist will develop an individualized treatment plan that will include exercises to be performed both in the therapy department and at home and that combine specific head and body movements with eye exercises. Many times, treatment may also include increasing activities and exercise in order to strengthen muscles and increase tolerance for certain stimuli.

Some of the exercise and activities may at first cause an increase in symptoms, as the body and brain attempt to sort out the new pattern of movements. But with time and consistent work, the coordination signals from the eyes, proprioception, and vestibular system will occur.

How does therapy help?

In most cases, balance improves if the exercises are correctly and faithfully performed. Muscle tension, headaches, and fatigue will diminish, and symptoms of dizziness, vertigo, and nausea will decrease or disappear. Many times, vestibular VRT is so successful that no other treatment is required.

If you have experienced any of the above-mentioned conditions or symptoms, you may be a candidate for conservative therapy at our office. Give us a call to find out today (888) 595-7282 .

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