The spinning Go-Gos was not meant to throw you off. I imagined the drawing of rotating musicians would be a good intro for the topic of dizziness. I drew this back when the Go-Gos came out in the 1980s and I don't recall why I arranged them in a circle, only to say that it makes for great fun if you spin the drawing on its center axis. Chalk this up to a young guy’s creative impulses and his over-the-top fascination with the band. Anyway, we're here to talk about Meniere's.
Meniere's Disease is a mysterious, sometimes frightening disease that has affected millions of people. The cause of Meniere's is really not known. Meniere’s Disease typically involves a triad of symptoms: episodic dizziness (mainly vertigo or motion-sensation), fluctuating hearing loss usually in one ear, and fluctuating tinnitus (ear noises or ear-ringing), also usually in one ear.
There are two major organs of the inner ear (Figure 1): 1. The cochlea which is responsible for hearing, and 2. The vestibule, which is responsible for balance. Collectively, these are termed the labyrinth. There is a liquid which flows through the chambers and canals of the inner ear and bathes the receptor cells in both the cochlea and vestibule. The receptor cells connect to a single nerve cell (a neuron) which then travel from the inner ear to the brain. Those neurons from the cochlea collectively form the cochlear nerve and those from the vestibule form the vestibular nerve (do you see the crafty logic behind medical terminology?).
The vestibular nerve sends signals or messages to the brain indicating the latest position of the body. The eyes, muscles and joints also send positional messages to the brain. Thus, the inner ear is only one part of a system that helps with the body’s balance. The brain interprets these messages, and then sends out instructions to the body so that it can adjust and balance itself. The cochlear nerve sends signals generated from sound stimuli to the ear. The brain then interprets the meaning of these sounds.
Note: the “fluid” we are talking about is within the dense bony chambers of the inner ear. Fluid in the middle ear (the space between the ear drum (tympanic membrane) and the that bony inner ear) is entirely a different problem. Middle ear fluid occurs more commonly and is a cause of otitis media. Middle ear fluid also is a result of eustachian tube dysfunction.
There are two fluid-filled chambers in the labyrinth: the bony labyrinth is filled with perilymphatic fluid (perilymph) and the membranous labyrinth filled with endolymphatic fluid (endolymph). The two fluids have different properties and are separated from one another by the soft lining tissue of the membranous labyrinth. Figure 2 shows a cross-section of the bony labyrinth (imagine horizontally cutting through the right ear and then viewing it from above).
If the volume of liquid in the chambers and canals increases, the fluid pressure also increases, sending an incorrect message to the brain. This occurs within the membranous labyrinth, where too much endolymph is produced. This affects both the cochlea and vestibule. The fluid normally drains into the endolymphatic sac located in the mastoid bone which then absorbs and removes any excess fluid into the CSF (cerebral spinal fluid). In Meniere's disease, increased fluid pressure can cause a rupture of the membranes, causing endolymph to mix with perilymph, which then causes the symptoms of this disease. Thus, Meniere’s is also called endolymphatic hydrops. It is thought the production of the fluid is greater than the ability of the inner ear to drain it through the endolymphatic sac.
Meniere’s often presents with an “attack” of three symptoms (the triad): 1. vertigo (spinning or a sensation of movement when the body is stationary), sometimes with nausea and vomiting (a reaction to the vertigo), 2. hearing loss (sometimes experienced as a “muffled” sense of hearing) or ear fullness or stuffiness), and 3. tinnitus (ear ringing, usually of a lower frequency, much like the sound of a seashell held to your ear).
There are often no physical findings other than nystagmus (a rapid beating of the eyes) during an acute attack. The ears appear normal. An audiogram (test to evaluate hearing) done during an episode or if there is residual hearing changes will typically show reduced hearing (a low frequency sensorineural hearing loss) in the low frequencies of the involved ear.
Meclizine can alleviate and shorten the effects of the acute episode, but this should be used sparingly given its side-effects of sedation. It is a known as a vestibular sedative. There are other medications (i.e., ondansetron, promethazine) which can help control nausea and vomiting. Diuretics (i.e., hydrochlorothiazide and triamterene, usually started at a low dose) are used to increase endolymphatic fluid absorption and reduce the fluid pressure and often prescribed once a day to prevent or reduce the dizzy episodes. Antihistamines are sometimes used as there might be an allergy component to this. To reduce production of endolymphatic ear fluid, it is important to decrease salt in the diet; sodium intake should not exceed 2,000mg per day. I’ll admit this can be very bland, but the typical American diet is way too high in sodium. Many patients find it helpful to record daily sodium intake in a diary, since one can easily surpass 2,000mg. Also eliminate or reduce caffeine and alcohol intake, and do not smoke. Stress relief can also help. It is also important to stay well-hydrated, drink plenty of fluids, which sounds counter-intuitive, but it is believed it’s the excess dietary sodium that causes the fluid retention, not the oral intake of more water or fluids.
More invasive forms of therapy include a technique called intratympanic injection of either gentamycin or a steroid. This technique actually is trans-tympanic (across the tympanic membrane). Gentamycin is a strong antibiotic but has an ototoxic (“ear-toxic”) side-effect where it can kill off the receptor cells in the inner ear. It is thus considered an ablative therapy, utilizing the ototoxic properties of the drug. A small needle is placed through the tympanic membrane (after it has been anesthetized) and the gentamycin is injected into the middle ear space. It then gets absorbed through the round window (a membranous window within the bone of the cochlea) and enters the fluid within the inner ear. For some reason, gentamycin selectively kills the receptor cells more so in the vestibule rather than the cochlea, but a minority of patients can have toxic effects in the cochlea, and thus one of the risks of this treatment is permanent hearing loss. A steroid such as dexamethasone can also be delivered in the same way. Steroids are anti-inflammatory medications, and it is theorized there is an inflammatory reaction during acute episodes of Meniere’s. There is less of a risk for hearing loss; in fact, the other indication for intratympanic steroid injections is for the treatment of sudden-onset hearing loss.
There are other more involved surgical approaches for Meniere’s disease if these measures are unsuccessful. A small shunt can be placed through the endolymphatic sac, which drains endolymph into the mastoid (filled with air cells) which then drains into the middle ear and out through the eustachian tube. A labyrinthectomy is a surgery of last resort, where the bony labyrinth is drilled done, removing he membranous labyrinth. Needless to say, the ear will be deaf and patents will fell very off-balanced for a while until the remainder of their vestibular system adjusts. Candidates for surgery would often be referred to an otology subspecialist, one who has additional fellowship training beyond ENT residency and who specializes in more complex ear surgery