Meniere’s disease is a malfunction of the internal parts of ear. High fluid pressure in the vestibular and cochlear systems malfunctions the whole apparatus resulting in multiple symptoms. Fluid pressure is not from an infection; its exact cause is unknown. The system may go back to normal once the pressure is normalized and the attack is over, but repeated attacks may cause permanent damage to many of its components.

What are the symptoms of Meniere’s disease?

It is an episodic disorder; attacks come and go, and each attack may last for hours to days. Typical symptoms of an attack are severe vertigo type dizziness, nausea and/or vomiting, an abnormal sound in the ear (tinnitus), fullness feeling in the ear, and hearing loss. A patient may not have all the symptoms, and each attack may not have every symptom either. Patient may feel exhausted for a few days after an attack is over.

 

What is the vestibular system?

Vestibular system is a structure deep in our ears. It is a complex, intriguing, and fascinating structure, and not completely understood. Following is a general introduction. To keep our balance in all kind of postures we assume or activity we perform, our brain always wants to know the direction and the type of movement (e.g., rotation or linear) and, in reference to our body, where our head is. The information from this system helps to maintain balance, especially if our vision is compromised.

A pair of three bony semi-circular canals or tubes is placed, one set on each side, deep inside the ear. These three tubes in a way are aligned with three axes, x, y, and z, acting as sensors. They are filled with jelly like fluid with one end slightly dilated. Close to that are two separate smaller but similar compartments, called utricle and saccule, with similar structural detail. Floor of each dilated area of the canals, utricle and saccule, is lined with thin hair like cells (or hair cells) in erect position. These hair cells can bend in different directions if there is a movement in the fluid. Suspended on top of these cells are tiny calcium carbonate crystals, like a weight. The crystals are bound together by glue like material, which keeps them together. 

Every head movement we make is either in x, y, or z-axis, or any of their combinations. Due to their inertia, every movement generates a tiny motion of the crystals suspended in the fluid, which creates a tiny wave in the fluid. The fluid movement creates tiny bend in the underneath hair cells. The mechanical movement of hair cells is converted in an electrical signal that travels to the brain. The receptors in semicircular canals sense movement, especially rotational movement. The utricle and saccule sense vertical and linear movements, probably also gravity. Because of exact replica of three tubes on either side, with opposite orientation, any movement of hair cells on one side is associated with a similar movement on the other, but in opposite direction. The system is placed at about 30-degree angle tilted upwards because in erect body posture our head is tilted forward by about 30 degrees from the earth’s horizontal plane. This way the x-axis of the system stays within earth’s horizontal plane.

It is a beautifully designed engineering marvel operating through multiple scientific principles including solid-state physics, fluid dynamics, electrochemistry, electronics, complicated biochemistry, and even much more that we do not yet understand. It is precise enough to sense every bit of head motion, but modulated enough to not overshoot or undershoot and send just the right signal to the brain. Constantly reading these signals, brain adjusts our posture, muscle tone, and the direction of gaze to let us flawlessly move around, dance, run, jump, or dive.

This system works well if both left and right sides are in sync. Any amount of asynchrony sends mixed messages. If a person is stationary and this apparatus sends an asymmetric signal, it is read as a sense of motion, a false sense of motion, which we call vertigo. The type and severity of vertigo depends upon the location and the extent of the problem. There are numerous conditions that may affect this system and cause vertigo, including Meniere’s disease.

 

What is cochlear system?

The cochlear system is designed to sense sound. The first receiver for sound waves is our tympanic membrane inside our ears. It is like a taut diaphragm of a drum, moving in certain ways depending upon the frequency and intensity of sound waves. It converts energy of sound waves to mechanical energy or movement. The tympanic membrane is attached to a tiny bone, which makes a joint with series of two more equally tiny bones, the tiniest in our body, in the middle ear. Their job is to either dampen or modulate the mechanical signal from the tympanic membrane. At the other end is another membrane, which is called inner tympanic membrane. This is where the cochlea starts. Inner tympanic membrane is the start of the middle tube of the cochlea.

The cochlea is a snail’s shell shaped bony structure deep inside our ears. Imagine a solid twisted tube-like structure like a snail’s shell. Also imagine a soft hose inside that hard structure. Now further imagine that the soft hose is actually 3 soft tubes joined together. The middle of these three tubes is the most important one, protected by a set of tubes from both sides. This middle tube is filled with a special fluid, the same type of fluid that fills the inside of vestibular apparatus. On the floor of this middle tube are tiny hair-like structures, and on top of these hairs is a thicker membrane. Hair cells are attached to the nerve endings that take electrical signal to the brain.

Similar to the vestibular system, the cochlear system basically is a complicated transducer, converting sound waves to mechanical energy, and then the mechanical energy to electrical. Sound waves ultimately move some of the hair cells in the middle tube. The location in the tube depends upon the frequency and intensity of sound waves. Very loud waves may damage hair cells instead of just moving them, resulting in permanent deafness.

 

What exactly happens in Meniere’s disease?

Vestibular and cochlear systems require a certain composition and pressure of the fluid in their inner tubes. Any change in either its composition, or the pressure, creates either abnormal or asymmetric signals in the vestibular system, or dampens the cochlear system, resulting in dizziness and hearing impairment. If system is pushed to the limit, permanent damage may occur resulting in constant dizziness, or deafness. In Meniere’s disease there is high pressure in the system. It is likely that the pressure rise is due to a change in fluid’s composition. To accommodate pressure fluctuations, nature has provided a bladder or a sac attached to this whole system, the endolymphatic sac, but somehow that fails too.

There is evidence of injury to small blood vessels and related structures resulting in malfunction of the normal equilibrium keeping the ear pressure normal.

 

How is Meniere’s disease diagnosed?  

It is diagnosed by history of its typical attacks with symptoms described above. Documenting temporary hearing loss during an attack, or progressive hearing loss after multiple attacks supports the diagnosis. Sometimes, an MRI of brain, especially during an acute attack of Meniere’s can reveal an abnormality in the affected ear, which can help to make the diagnosis.  

 

What is the difference between Meniere’s disease and Meniere’s syndrome?

If a patient has classical symptoms of Meniere’s and the diagnosis is supported by documentation of hearing loss, it is called Meniere’s disease. If patient has some of the symptoms, or the diagnosis is not yet supported by documentation of hearing loss, it may be called Meniere’s syndrome.

 

What conditions may look like Meniere’s disease?

Infection or inflammation in the system may cause similar symptoms, but usually these conditions are not difficult to diagnose. Sometimes there is a tumor, usually benign, affecting the nerves coming out of vestibular and cochlear systems. It can be a possibility in a patient with vertigo, tinnitus, and hearing loss, but then in case of a tumor symptoms may not resolve like they do in Meniere’s disease. If these symptoms are constant, not like episodes, or get progressively worse, an MRI of brain is required to rule out tumor around the nerves. A stroke may also have similar presentation with dizziness, and sudden hearing loss. If history is suggestive of a stroke, an MRI of brain is required to make a diagnosis.

 

What are the complications of untreated Meniere’s disease?

Many times, this condition is mild, but frequently it can lead to permanent hearing loss. Rarely, it can lead to sudden and sometimes violent falls or “drop attacks,” which can put patient at serious risk of injury. They are named as Tumarkin attacks.

 

How is Meniere’s disease treated?

First level of treatment is of symptoms, such as dizziness with a medicine like meclizine. If patient has too much vomiting, hydration may be needed. A brief course of prednisone may also help to stop an attack. Associated anxiety may also need treatment.

For prevention of further attacks, a diuretic or a water pill can be tried. Sometimes, decreasing salt intake can help. There is no specific medicine available that may control this disease.

Some cases may continue to worsen causing severe dizziness and hearing loss. These cases may require a surgical approach to treatment, which is usually accomplished by ENT surgeons. In more difficult cases, there is an option of destroying the hair cells on the diseased side, which may help with symptoms of dizziness. This may be done by injection of a toxic drug within the system, selectively destroying hair cells. Alternatively, vestibular system or the vestibular nerve can be surgically destroyed. Another approach is shunting the endolymphatic sac, to avoid high pressure in the system. Any patient having drop attacks confirmed to be caused by Meniere’s disease can benefit from surgical or ablative treatment.

 

Is there a cure for Meniere’s syndrome?

Not at this time.

 

Is Meniere’s disease a genetic disorder?

Not necessarily, most cases are sporadic, i.e., without family history.

 

What should I do to find out if I have Meniere’s disease?

It is diagnosed and treated by ENT doctors or neurologists, probably more so by ENT. This condition belongs to a sub-specialty of neurology called neuro-otology.  Not all neurologists feel comfortable treating it. Similarly, not all ENT specialists are comfortable with it either. A patient may have to explore the right doctor for its long-term management.  Usually primary care physicians have better understanding of who to consult in a particular area.

 

Where can I get more information about Meniere’s disease?

American Academy of Neurology

American Otolaryngology Society