Caloric Test

What is Caloric Test?

If you’ve been experiencing dizziness, fatigue & asymmetrical nerve responses, & have already consulted with a doctor regarding your ailment (if you haven’t, then you immediately should) chances are you have been prescribed a Caloric Test.

Caloric Test is a part of Electronystagmography test, commonly known as ENG Test, & is an attempt to find out the degree to which the vestibular system is responsive & to ascertain the symmetry of nervous responses between the right & left ear.

Caloric Tests only consider the lateral semicircular canals, & do not assess vertical canal function &/or otolithic function.

Although it isn’t the best considering the advances medical science has made, a Caloric test is still doctors’ best bet to study the functions of each ear independent of the other.

Other popularly known tests like the Rotatory Chair test, assesses the function of both ears together & doesn’t provide any information on independent functioning of either ear.

Another test, VHIT is more of a compromise resorted to by doctors in the absence of evolved medical & computer equipment, & only helps determine the bad ear out of the two.

Developed by Audtro-Hungarian Otologist Robert Barany in 1906, the Caloric test was a breakthrough in medical sciences & paved the way for a Nobel prize for its founder.

His discovery began when one of his patients complained about the temperature of the water he was using to clean out the wax accumulated in his ears. Barany noticed that the patient’s eyes dilated in different directions in response to the pouring of hot & cold water respectively, also known as hot &/or cold irrigation.

This movement of the eyes in response to nerve stimulation is named ‘nystagmus’ & thus a test to determine the health of ears is called ‘electronystagmography’ test, commonly known as the ENG test, of which caloric test is a part.

Ofcourse, Caloric Tests have come a long way since their discovery in 1906, & are now done on sophisticated computerized systems.

The computer analyzes the caloric data, & computes peak slow-phase velocity to determine the working values corresponding to each ear.

Why are Caloric tests (ENG tests) performed?

Like all ENG (electronystagmography) tests, caloric tests are performed to check the function of your acoustic nerve, which is involved in aiding hearing & balance.

It is also used to evaluate the function of the areas of the brain involved in maintaining our balance.

Majorly, Caloric Test is used to evaluate:

Caloric Test is one of the most widely known & employed medical tests to assess the cause of vertigo (dizziness) in individuals suffering from it.

How is the Caloric Test carried out?

Caloric Tests are performed by inserting cold & warm water into the patient’s ears, one at a time, to stimulate the nerves of the ear. The aim of the test is to elicit a different nerve response to the pouring of water of different temperatures in the patient’s ear.

The test is carried out in different steps:

  • First, the eardrums are checked: Before the test begins, the test administrator first checks the patient’s ear drums thoroughly for any infection. This is essential since pouring hot & cold water into an already infected eardrum might worsen the patient’s condition further.
  • Then, the electrodes are placed: The electrodes are placed around the patient’s eyes & are connected to a computer. These electrodes are used to measure eye movement during the test.
  • Cold water is inserted into the ear canal: A tiny amount of cold water is then inserted into the ear canals, one at a time. This leads to a temperature change of the inner ear, & causes rapid side-to-side eye movements in the patient, called nystagmus.

The cold water causes the eyes to move away from the direction of the cold water, & then move back slowly.

  • Warm water is inserted into the ear canal: As in the case of cold water, a small amount of warm water is then inserted into the ear canal of the patient, & the eye movement is studied. Unlike in the case of cold water, this time around the patient’s eyes should move toward the direction of the warm water, & then move away from it slowly.

The procedure is performed one-by-one on each ear & the data is electronically recorded through computerized systems & studied to achieve the final results.

  • Eye movements are monitored: This step is performed through computers. The data from the electrodes in the previous step is recorded electronically & assessed to ascertain the health of each ear.

Based on the data obtained through the test, doctors can then identify the exact reason for your vertigo &/or hearing loss, through the electronically logged data.

Caloric Tests are the best bet to find out the cause of a patient’s vertigo, feelings of dizziness & imbalance arising out of the disorder.

How to prepare for the Caloric test?

There are certain foodstuffs & medications that can affect the results of your caloric test. Doctors generally recommend refraining from consuming these items 24 hours before you undergo the electronystagmography test procedure:

  • Large & heavy meals
  • Alcohol
  • Caffeine
  • Sedatives
  • Allergy medications

If you’re undergoing treatment for an already existing medical condition different from your vertigo & feeling of dizziness, it’s best to talk to your doctor if your medication could affect the results of your ENG test.

Always remember to NEVER stop taking any medications without consulting with your doctor first.

How to read Caloric Test results?

Normal results: If your doctor tells you that your caloric test results are normal, it means you have no damage to your acoustic nerve. It usually means your vertigo & feeling of dizziness are brought on by something other than your nervous system.

You should consult with your doctor for better diagnosis of your condition & consider some home exercises as well as significant changes in your lifestyle to deal with your condition.

Abnormal results: If your doctor finds out that your eye movements during the caloric test are abnormal, it usually is a sign of acoustic nerve damage, damage to the balance sensor in your ears &/or in severe cases, can even signal brain damage.

There could be several reasons for abnormal results, & you should consult your doctor to get a better diagnosis. Your doctor could help you find out the exact cause of your vertigo, & together with you can chart out a recovery & treatment plan.

Caloric Tests are a very useful way of finding out the reasons behind your vertigo & can help you deal with your condition & finding treatment options. Consult your doctor today before going for a Caloric Test.

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