endolymphatic hydrops – The Ear Center of Greensboro

The clinical symptoms of Meniere’s disease are thought to be caused by an increase in the fluid pressure within the delicate membranes of the inner ear. The medical name for this condition is “endolymphatic hydrops“. 

The classic theory is that during a Meniere’s spell, the delicate membranes within the inner ear (cochlea) rupture. The mixing of inner ear fluids results in a sudden electrical discharge within the cochlea due to fluids with different electrolyte concentrations mixing together. The spell continues until the fragile membranes heal, and the body recovers its equilibrium. 

However, not all cases of Meniere’s Disease demonstrate the “membrane rupture” findings. It is possible that some, if not many, cases are due to a decrease in blood flow to the inner ear when the inner ear hydrostatic pressure prevents normal blood flow from reaching inner ear tissues. Meniere’s Disease may be due to vessel inflammation (vasculitis), aging and narrowing of blood vessels, and additional unrecognized factors such as problems with calcium channel metabolism, etc.

Unfortunately, the sudden disruption of the normal inner ear tissues leads to injury of the tiny hair cells that are responsible for hearing and balance. Injury of these cells causes permanent loss of hearing and unsteadiness associated with Meniere’s disease. Symptoms are thought to be worsened by:

  • stressful situations and fatigue 
  • excessive alcohol use
  • increase in dietary salt (sodium) intake
  • caffeine
  • smoking
  • food sensitivities (possibly)
  • increasing barometric pressure (low altitudes)
  • toxic exposure to chemicals (such as chlordane), fungal toxins, and carbon monoxide (possibly)

Natural History

In some patients, Meniere’s disease is only intermittently bothersome and takes an overall mild course. Such patients experience ear fullness, tinnitus, and fluctuations in hearing, but no vertigo (cochlear Meniere’s Disease).

Periods of increased symptoms, which are unpredictable and occur without warning, may be followed by long periods of improvement or even complete remission. However in some patients, the disease takes a much more serious course and is associated with frequent, disabling attacks of vertigo with nausea and vomiting, progressive loss of hearing, and constant roaring tinnitus. It is not possible to predict who will have a mild form of the disease and who will be severely affected. Some patients experience on fluctuations in hearing and tinnitus without having vertigo (Cochlear Meniere’s Disease).  Some patients that have vertigo, tinnitus, and fullness without vertigo have a condition called “atypical migraine variant” and do not have Meniere’s Disease. 

Currently, there are no blood, x-ray, or scan tests available that can
be used to specifically diagnose Meniere’s disease.

Some blood tests are available to help rule out autoimmune inner ear disease that may simulate Meniere’s Disease. The diagnosis is based on a combination of:

  • the patient’s history over time
  • symptoms during spells
  • hearing and balance testing
  • negative MRI/MRA brain scan results
  • clinical behavior over time

Diagnosis of Meniere’s Disease

The history and quality of symptoms are very important in making the diagnosis of Meniere’s disease. Vertigo, hearing loss, and tinnitus may not always be present at the same time. The pattern of symptoms may prompt additional evaluations such as for idiopathic sudden sensorineural hearing loss, atypical migraine variant disease, auto-immune inner ear disease, and superior semi-circular canal dehiscence syndrome.

High resolution CT scans may be performed to rule out superior semi-circular dehiscence syndrome (SSCDS). In SSCDS, there is an erosion of the normal bone that covers the top of the superior semi-circular canal.

On physical examination, the eardrums and neurological exam are usually normal, especially between the acute episodes of dizziness. During acute attacks, the eyes may exhibit a rapid beating motion called nystagmus. The eyes may be observed to be beating rapidly from side to side. The fast beating component generally goes toward the side opposite the affected ear. During an episode of nystagmus, the patient will often feel as if either the room is spinning around or that he or she is spinning, and the room is remaining still. Walking is difficult or impossible until the spell subsides. Nausea and vomiting can be severe.

Hearing Testing (Audiometry)

Special tests are necessary in order to help make a diagnosis. Basic hearing testing called an audiogram” is essential to assess and document hearing levels. Audiograms are often repeated to see if hearing levels are fluctuating. Audiograms are usually abnormal in Meniere’s disease. Early in the disease process, low frequency hearing loss is a common finding. Usually, hearing will decrease in only one ear. If the disease becomes bilateral, hearing loss may develop in the other ear over months to years. Moderate to severe hearing loss may occur in one or both ears.

Balance Testing (Electronystagmography & VEMP)

Evaluation of the inner ear balance system and its connections to the central nervous system are done by a test called “electronystagmography” (ENG). Eye motions related to the inner ear are measured by placing the head in various positions and by placing cold water in the ear canals. The affected ear will often show a balance weakness and decrease levels of function compared to the unaffected ear. If both ears are involved, both inner ear balance systems may show decreased activity. Balance tests are usually abnormal in Meniere’s disease with one or both ears demonstrating decreased inner ear function.

A new test, vestibular evoked myopotentials, VEMP, are now being used to test patients who are suspected of having Meniere’s Disease. VEMPs test otolith function and are measured on muscles. Classically, two muscles are used: (1) the sternocleidomastoid muscle (cervical VEMP or cVEMP) and (2) the inferior rectus muscle of the eye (ocular VEMP or oVEMP). Distension of the saccule of the inner ear in Meniere’s Disease is what is being indirectly measured and porvides diagnostic potential. 

Nerve Pathway Testing

The hearing nerve and hearing pathways within the brain can be measured by a special computerized test called an “Auditory Brainstem Response Test” or ABR. This test is also referred to in the medical literature as a BSER, BEAR, etc. Using headphones in a quiet room, rapid clicks of sound are placed in the ear canal. The clicks are heard by the ear and nerve impulses travel from the inner ear to the brain. The electrical impulses create brain waves that can be measured from the skin and analyzed by a computer. Interpretation of the brain wave patterns can help diagnose alterations in function of the hearing pathways within the ear and brain. Abnormalities can be seen with tumors of the hearing or balance nerves, multiple sclerosis, and other conditions that affect the nerve pathways. Usually, this study is normal in Meniere’s disease.

Inner Ear or Cochlear Testing

Several tests of inner ear function are available. One test called “Otoacoustic Emissions” or OAE is performed to evaluate the health of tiny inner ear hair cells (the outer hair cells). OAE’s are performed by placing a small sound probe with a delicate microphone in the ear canal. Sounds are presented to the ear and faint inner ear echoes are analyzed. This test takes only a few minutes to perform and is usually abnormal in the affected ear(s) in Meniere’s disease. 

A second test called “Electrocochleography” or ECOG is used to assess the electrical activity within the inner ear. Sounds are placed in the ear canal and measurements are made of the electrical activity generated by the conversion of sound energy to electrical energy in the inner ear. There are characteristic electrical abnormalities in endolymphatic hydrops.

Brain Imaging (MRI, MRA, CT Angiography)

An image of the brain and hearing/balance nerves can be made by performing a brain scan called a “Magnetic Resonance Imaging” (MRI) Scan. This study enables visualization of the structures of the inner ear and brain in order to rule out tumors, strokes, multiple sclerosis, hydrocephalus, congenital anomalies, and other abnormalities which can cause dizziness and imbalance. Unlike the other studies mentioned above, this study is performed at either a hospital or special MRI imaging center, rather than in a doctor’s office.

MRI scanning uses strong magnets and radio waves, rather than x-rays, to image the brain. Because strong magnets are used, MRI scans cannot be done if the patient has any metal materials in his/her body such as cardiac pacemakers, metal wires, screws or plates, metal fragments from injuries, or cochlear implants, just to name a few. If metal materials are present, a CAT scan, rather than an MRI scan, can be performed.

In order to be useful, the MRI must be performed using a special contrast substance called “gadolinium”. Gadolinium is not radioactive and does not contain any iodine dyes. During an MRI scan, gadolinium is routinely injected into a large arm vein after initial images are made. Gadolinium helps to uncover small, easily overlooked problems that may exist. Fortunately, MRI brain scans are usually normal in Meniere’s disease.

Other imaging tests such as “Magnetic Resonance Angiography” or “CT Angiography” may also be ordered by your surgeon.These are non-invasive tests like the MRI but use intravenous contrast and different software to make the images. They are also performed at a hospital or out-patient imaging center.

High resolution CT scans may be performed to rule out superior semi-circular dehiscence syndrome (SSCDS). In SSCDS, there is an erosion of the normal bone that covers the top of the superior semi-circular canal.

Blood Testing

Measurements of hemoglobin, blood sugar (glucose), cholesterol, immune system status, liver, kidney, thyroid function testing, and testing for infectious diseases such as syphilis, lyme disease, and infectious mononucleosis may be among the studies needed to rule out other conditions that may cause symptoms similar to those found in Meniere’s disease. Testing for food or environmental allergies may also be warranted. These tests are normal in Meniere’s disease.

There is no single study that diagnoses Meniere’s disease with absolute certainty. Ultimately, the patient and a skilled ear specialist must evaluate the history, physical examinations, entire clinical picture, and test results together in order to arrive at a diagnosis. If symptoms are not classic or the patient has had just one spell, it may take some time in order to arrive at a clear diagnosis. Occasionally, hair or blood samples are sent for toxicology screening if the possibility of exposure warrants the testing.

For more information from The Ear Center of Greensboro, use the link below.

http://www.earcentergreensboro.com/medical-education/menieres_disease.php

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