Dizziness - a problem with the balance system

KOTA KINABALU: Few people realize that the balance system is responsible for every sense of motion that humans have.

Whether standing up, lying down, walking forward, riding in an elevator or driving a car, it is the balance system, together with input from your eyes that gives the brain a sense of where the person is in space.

Whenever a person complains of being “dizzy”, it is often a problem with the balance system that is responsible for that person’s symptoms.

As anyone who has ever had problems with their balance system can attest, the symptoms would affect every aspect of your life.

The clinical term for the balance system is the “vestibular” system. The vestibular system is housed within the inner ear and shares connections with the hearing (auditory) system.

The vestibular and auditory systems have several characteristics in common:

- Both systems are encased in the same part of the skull – just above and slightly behind each ear

- Both systems are fluid-filled organs

- Both systems have tiny hair cells within them that are forced to move by the motion of the fluid around them

- Both systems depend on the inner ear’s ability to convert the mechanical energy of the hair cells to electrical energy that can be used by the brain to gather information

It is common that if one of these systems is affected by illness, so might the other be affected. It is common for a “dizzy” patient to also have hearing loss and/or ringing or buzzing in the ears.

Similarly, a problem with the balance system may also cause abnormal eye movement as the brain tries to decipher why it is receiving inappropriate information.

The main difference between the vestibular system and the auditory system is that the vestibular (balance) system is a much more intricate structure than the auditory (hearing) system.

Each of the vestibular systems comprises five parts: the utricle, the saccule and three semicircular canals – each of which is responsible for detecting a specific plane of motion. Any or all of these parts could be affected by illness and cause balance problems.

It is important to understand that the brain relies on equal-butopposite input from each of your vestibular systems.

The vestibular systems are mirror images of each other. The benefit of this is that when one side of the vestibular system is sending excitatory information to the brain, the other side is sending an equal amount of inhibitory information to the brain.

If one of the vestibular organs is weak, it can’t send an equal amount of energy to the brain and the brain senses a mismatch in the information that it is receiving – the result is dizziness.

Dizziness is the second most common complaint heard by physicians. Dizziness that creates the sense that you or your surroundings are spinning or moving is called “vertigo”.

The most common condition that causes vertigo is BPPV (Benign Paroxysmal Positional Vertigo). It is a disorder of the balance system (clinically known as the vestibular system) that causes the patient to experience short bursts of extreme dizziness when there is a change in the position of the patient’s head.

Research indicates that up to 50% of patient’s who complain of dizziness have symptoms related to BPPV.

What is BPPV

Benign Paroxysmal Position Vertigo (BPPV) is a common disorder of the inner ear. Your balance organs, also known as your vestibular system, are housed in each of your inner ears.

They are mirror-images of each other and are designed to work together to give you the sensation of movement. Within each vestibular system are tiny rocklike “crystals” that are responsible for giving you a sensation of gravity.

Sometimes, these crystals become dislocated, causing pressure on other sensitive organs within the vestibular system. This causes brief episodes of severe dizziness that usually occurs with a change in your head position such as lying down or sitting up.

BPPV can be caused by head trauma, illness or for no apparent reason at all. However, the cure rate for BPPV is very high and often requires only one visit.

Common causes of balance disorders are aging, head trauma, inner ear infection, build-up of fluid within the inner ear (Meniere’s Disease), stroke, low or high blood pressure, viral infection, congenital birth defects, brain tumor, chronic illness and migraine.

One positive characteristic of BPPV is that it rarely requires medicine or surgery to correct. In fact, for most patients, a onetime, in-office treatment is all that is necessary for almost immediate relief of BPPV (if not immediate relief, maximum relief should occur within seven days of the treatment).

This treatment, known as “canalith repositioning maneuver”, requires your healthcare professional to move your head into a series of positions with the goal of forcing the otoliths back to where they belong in the utricle. The treatment is not painful and is highly successful.

Vestibulo-ocular reflex (VOR)

The VOR is also an integral part of the “balance” system because the brain relies on information from the ocular system as much as it relies on information from the vestibular system. The VOR is a reflexive eye movement that occurs in response to head movement. This reflex allows humans to focus on a stationary object while the head is in motion.

Dysfunction of the VOR often results in complaints of chronic unsteadiness, feelings of “motion sickness” and disorientation.

These complaints are common in elderly patients and are often attributed to a breakdown in neural firing of the VOR.

The diagnosis and treatment of vestibular disorders requires a network of medical professionals that often includes a primary care physician, an ear specialist, an audiologist and a physical or occupational therapist.

These professionals will likely use the “puzzle” approach to diagnosing the problem by putting together small pieces of information collected from physical examinations and from specialized testing of the vestibular system.

These tests can pinpoint whether the problem stems from the inner ear (which is often medically treatable) or if the problem stems from the brain. The end result of the assessment allows the appropriate recommendations to be made for treatment of the balance problem.

Because the vestibular system is such a complicated system, there is not a single test that can diagnose vestibular disorders. Rather, an assessment of the vestibular system requires a battery of tests – each stimulating a particular anatomical structure in an effort to tax that structure, probing for dysfunction.

I am feeling dizzy, what happens now?

There are many tests that can help your physician determine why you are feeling dizzy.

The tests described here are the most clinically useful in determining how well your balance organs are working.

V id eonys tag mo g rap hy (VNG) utilizes cameras that are imbedded into goggles to monitor and measure eye movements. Specifically, a VNG is a series of several tests that will help the medical professional to determine things like:

A. How well your eyes communicate with your balance system and your brain

B. Whether a change in position of your head causes dizziness or imbalance

C- Whether your balance organs are functioning equally when compared to each other while wearing the goggles, you will be asked to perform several tasks while watching either a video screen or a LCD screen. These tasks are very simple, but will yield important information to the medical professional about how well your eyes are communicating with your brain. The next step in the VNG process is for the examiner to assist you into several different postural positions. This helps to determine whether a change in the position of your head and/or body will evoke the unpleasant symptoms that you have described.

Video Head Impulse Test

(vHIT) is a maneuver performed to assess vestibular function. Clinicians, standing in front of the patient, deliver high velocity, low amplitude head rotations while asking the patient to fixate a target. Patients should be able to keep the eyes on the target during these impulses.

In patients with vestibular dysfunction, when the head moves, the eyes will move with the head, requiring a corrective movement back to the target (known as a “catch-up saccade”) that the clinician may be able to identify.

This saccade is interpreted as an indirect sign of vestibular deficit. The problem with this method is that it only evaluates the presence of catchup saccades, the results are subjective, non-quantified and abnormal responses are easily missed by the naked eye.

vHIT is an improvement of the Head Impulse Test. Speciallydesigned lightweight goggles with a high-frequency camera, an integrated inertial measurement unit (IMU) and a calibration laser are used to capture, record and analyze eye and head movements.

Auditory brainstem response (ABR) is an objective test of auditory function above the level of the ear (from the auditory nerve through the brainstem and to higher brain regions. Because the auditory (hearing) system and the vestibular (balance) system are housed within the same area of the skull, it is not unusual that if one system is affected, so might the other system be affected.

For the “dizzy” patient, ABR helps to rule out certain disorders of the brain that might effect the hearing and vestibular systems.

When sound enters the ear and stimulates the cochlea in the inner ear, the cochlea produces an electrical response to sound along the nerve pathways.

This electrical response can be measured on the skin through the use of electrodes placed on the forehead and behind each ear. Earphones are placed on the patient through which sounds are transmitted to the inner ear. The patient is instructed to simply relax until the examination is finished.