What Do ECochG, VEMP, Caloric and vHIT Show in Hydrops?

No single test can completely confirm or rule out endolymphatic hydrops or Ménière’s disease. Instead, your doctor may recommend tests like ECochG, VEMP, caloric testing, and vHIT to assess specific parts of your inner ear’s function ^[1][2]. They provide complementary information to help characterize your condition, establish a functional baseline, or identify other possible issues. Because the inner ear’s environment fluctuates and these tests have varying sensitivities, you can have entirely normal test results even if you have the condition ^[3][4].

It is helpful to understand the difference between endolymphatic hydrops and Ménière’s disease. Endolymphatic hydrops is a structural or physiologic finding related to fluid in the inner ear. Ménière’s disease is a clinical syndrome diagnosed chiefly by your history of symptoms (such as the pattern of vertigo episodes), standard audiometry (hearing tests), and the exclusion of other causes ^[5]. These tests do not directly diagnose either condition, nor can they definitively rule out other disorders like vestibular migraine, which can coexist with Ménière’s disease ^[6].

When to Seek Immediate Care: Testing for Ménière’s disease is generally scheduled during routine care. However, if you experience sudden hearing loss over a few hours or days, new numbness or weakness, difficulty speaking, fainting, a severe new headache, or an inability to walk safely, seek urgent medical assessment. These can be signs of other serious medical emergencies.

What Each Test Measures

The inner ear consists of the cochlea (for hearing) and the vestibular system (for balance). The vestibular system has five distinct organs: three semicircular canals and two otolith organs (the utricle and saccule). No single test evaluates them all.

Electrocochleography (ECochG)

ECochG measures the electrical signals generated in your cochlea and auditory nerve in response to clicking sounds or tones ^[1].

• What it looks for: It evaluates a specific electrical relationship called the SP/AP ratio. This is an indirect electrophysiologic marker often associated with endolymphatic hydrops, though it does not measure fluid pressure directly ^[1].
• What it adds: An elevated SP/AP ratio may support the overall clinical picture of hydrops. However, sensitivity varies by protocol and study population. One meta-analysis found it detects abnormalities in roughly 48% of cases, meaning normal results are common ^[3].

Vestibular Evoked Myogenic Potentials (VEMP)

VEMP testing evaluates specific otolith pathways, which are the parts of the inner ear that sense gravity and linear movements ^[2].

• What it looks for: VEMPs use sound or vibration to trigger reflexes in your neck muscles (cVEMP, assessing the saccule and inferior vestibular nerve) or eye muscles (oVEMP, assessing the utricle and superior vestibular nerve) ^[2].
• What it adds: It provides functional evidence of otolith pathway involvement. While VEMP results can be highly specific in certain studies, pooled sensitivity is about 49% ^[7]. Responses are also influenced by age, hearing loss, muscle activation, and test protocols, meaning a normal result does not exclude disease ^[8].

Caloric Testing

Caloric testing evaluates your horizontal semicircular canals at very low frequencies ^[9].

• What it looks for: By introducing warm and cool air or water into your ear canal, the test stimulates a balance response. By tracking involuntary eye movements, the clinician can see if one ear’s low-frequency response is weaker than the other (canal paresis) ^[10].
• What it adds: It assesses low-frequency vestibular function. One meta-analysis noted altered caloric responses in approximately 64% of people with Ménière’s disease, though this depends on the specific study and population ^[5].

Video Head-Impulse Test (vHIT)

vHIT uses a camera to record your eye movements while the clinician performs quick, small movements of your head, evaluating the high-frequency function of the semicircular canals ^[9].

• What it looks for: It checks if your eyes can stay locked on a target during rapid head turns. If function is reduced, your eyes will temporarily slip off the target and make quick “catch-up” jumps (saccades) ^[10].
• What it adds: Endolymphatic hydrops often affects low-frequency balance (measured by calorics) while high-frequency balance (measured by vHIT) remains preserved ^[4]. An abnormal caloric test alongside a normal vHIT test may support the overall clinical picture, a pattern seen in about 47% of patients in one study ^[5].

Summary of Balance Tests

Preparing for Your Tests

When scheduling these tests, ask your clinic for specific preparation instructions. Caloric testing can cause temporary dizziness or nausea, so you may want to arrange for a ride home. Do not stop any medications, especially vestibular suppressants or dizziness medications, unless explicitly instructed to do so by the clinician ordering the test.

Why Are My Results Normal if I Have Symptoms?

It is common to experience significant symptoms but receive “normal” results on one or more of these tests. This can happen for several reasons:

• Fluctuation: Inner ear function can fluctuate in Ménière’s disease. Testing might capture a period of relatively normal function ^[11]. There is no universally established “best time” to take these tests, so follow your clinician’s scheduling advice.
• Varying Sensitivity: Test sensitivity differs among patients and changes over time ^[12]. Because these tests have limits in what they can detect, an abnormality may not be present or measurable.
• Protocol Differences: Technical factors, such as whether an ECochG electrode is placed closer to the eardrum or further out in the ear canal, can affect the results and interpretation ^[13].

Do You Need All of These Tests?

You do not necessarily need an abnormal result on all (or any) of these tests to be diagnosed with Ménière’s disease. However, your doctor might order a combination of them to:

• Establish a baseline: If you are considering ablative treatments (such as gentamicin injections or a labyrinthectomy), your care team may want functional baseline measurements of your ear before proceeding ^[14].
• Identify other conditions: Vestibular testing may prompt your doctor to consider or identify coexisting issues, though tests alone cannot definitively rule conditions like vestibular migraine in or out ^[5].
• Characterize function: Combining these tests helps characterize which specific pathways—cochlea, otoliths, or canals—are currently showing altered function ^[15].