Name of the Procedure:

Caloric Vestibular Test
Common name(s): Caloric test, Binaural bithermal stimulation
Technical/medical terms: Caloric vestibular stimulation

Summary

The Caloric Vestibular Test is a diagnostic test that evaluates the function of the inner ear and vestibular system, which helps control balance. This test involves stimulating each ear canal with warm and cold water or air and observing the resulting eye movements (nystagmus).

Purpose

The primary purpose of the caloric vestibular test is to assess the functioning of the vestibular system within the inner ear. It helps diagnose balance disorders, dizziness, and vertigo, distinguishing between peripheral (inner ear) and central (brain) causes. It aims to ascertain whether both ears respond normally to stimulation and to identify any asymmetries in vestibular function.

Indications

• Persistent dizziness or vertigo
• Unexplained balance disorders
• Suspected vestibular dysfunction
• Evaluating the extent of inner ear damage following head injury
• Diagnosing Meniere's disease or vestibular neuritis

Preparation

• Patients may be advised to fast for a few hours before the procedure.
• Avoid caffeine, nicotine, and alcohol for at least 24 hours prior.
• Certain medications, especially those that affect the vestibular system, may need to be discontinued temporarily, as instructed by the healthcare provider.
• A complete medical history and possibly a physical examination will be conducted beforehand.

Procedure Description

1. The patient lies down on an examination table, with their head elevated to a 30-degree angle.
2. Each ear canal is irrigated with warm and cold water or air. Typically, warm water at 44°C and cold water at 30°C are used.
3. The temperature change in the ear canals stimulates the inner ear, inducing nystagmus (involuntary eye movements).
4. The healthcare provider observes and records the eye movements using a special camera or video goggles.
5. The procedure is performed four times: twice on each side, once with warm and once with cold irrigation.

Duration

Each irrigation takes about 1-3 minutes. The whole procedure generally takes around 30-45 minutes to complete.

Setting

The procedure is usually performed in an outpatient clinic or a hospital's ear, nose, and throat (ENT) department.

Personnel

• An audiologist or a vestibular therapist usually performs the test.
• An ENT specialist might be involved in the interpretation of the results and subsequent treatment planning.

Risks and Complications

• Transient dizziness or vertigo
• Nausea and/or vomiting
• Temporary discomfort or headache
• Rarely, ear canal irritation or infection

Benefits

• Accurate diagnosis of vestibular disorders
• Helps in formulating an effective treatment plan
• Can identify the specific ear affected by a vestibular problem
• Non-invasive and generally well-tolerated

Recovery

• Patients may experience dizziness or mild nausea immediately after the test, which typically resolves within a few minutes to hours.
• Resting quietly for a short period after the procedure is usually sufficient.
• Normal activities can typically be resumed soon after the test.
• Follow-up appointments may be scheduled to discuss results and potential treatments.

Alternatives

• Vestibular Evoked Myogenic Potentials (VEMP)
• Electronystagmography (ENG)
• Videonystagmography (VNG)
• MRI scans to rule out central causes of balance disorders
• Each alternative has its pros and cons, and selection may depend on the patient's specific condition and medical history.

Patient Experience

During the test, the patient might feel mild to moderate dizziness and some discomfort from the water or air in the ear canals. After the test, some transient dizziness or nausea may occur. Comfort measures include resting and taking deep breaths; medications may be provided for nausea if necessary. Pain is minimal, but the sensation of spinning could be unsettling.