Commonly called “glaucoma of the inner ear,” Ménière’s disease is related to the inner ear (labyrinth) and the balance system is contains. The labyrinth contains three semicircular canals that together comprise a complex system of chambers and passageways in the temporal bone. Signals sent from the semicircular canals travel along the nerve pathways to the brain.
Inside these canals is a membranous sac filled with a fluid called endolymph. Surrounding the sac is another fluid, perilymph. These two fluids bathe the vestibular and hearing organs, enabling balance and normal hearing. When there is too much endolymph the condition is called Meniere’s disease.
This overabundance creates pressure, which builds until the sac bursts. Then the endolymph and perilymph mingle, sending an unbalanced message down the vestibular nerve to the brain. The resulting severe spinning, vertigo, nausea, hearing loss, tinnitus, and a feeling of fullness in the ear are the symptoms of Meniere’s disease.
As the disease progresses, hearing loss increases. In 85% of cases one ear is affected; both ears are affected in just 15% of cases. In half of all cases the attacks will subside after two years; in 70% of cases, they will disappear in eight years. However, in all cases hearing loss may become progressively worse.
Although the exact cause of Meniere’s disease is unknown, we do know that there are various triggers, including stress, allergies, excessive salt intake, caffeine, migraine headaches, and barometric changes in pressure. Common treatements of Meniere’s disease include prescribing a diuretic such as Dyazide, reducing dietary salt, and using of anti-vertigo drugs like Meclyzine (Antivert), Compazine, or Phenergan suppositories. One of the best drugs for stopping attacks of vertigo is sublingual Ativan (Lorazepan) three times a day. While these may help quell nausea and shorten the episodes, they cannot cure the disease.
Patients should also be skin tested for inhalant and food allergies, as 50% are found to have allergenic causes of Meniere’s that can be treated by injections. If migraine headaches are found to be the cause, they are usually treated with medication.
If medical treatment fails to stop vertigo, hearing loss, and ringing and pressure in the ear, surgery must be considered. In the past the only treatment was total destruction of the ear, which cured the vertigo but resulted in total hearing loss. In 1978 a different procedure was developed, one that cut the balance nerve to the brain yet preserved hearing and relieved vertigo in 95% of cases. But because it involved operating near the brain, only the most serious cases were treated in this way.
Development of minimally invasive procedures
With the advent of minimally invasive surgery for many surgical procedures, a search was made to find an effective office procedure to treat Meniere’s, one with minimal risk and discomfort. One such solution is the MicroWick, a procedure that is not only minimally invasive but can be implanted in the office and used for patient self-treatment at home. Patients place medication in their ear canal, and the MicroWick absorbs the medication and carries it to the inner ear. With the MicroWick two eardrop formulations are used: antibiotic and steroid.
For patients that have persistent vertigo attacks, gentamicin (an ototoxic antibiotic) is used as an eardrop in dilute concentrations three times a day. The patient is usually tested and seen once a week to titrate the amount. The results of this treatment are good: while some patients need to have repeat treatments, 81% are free of vertigo for four years after treatment. In some patients the inner ear is resistant to gentamicin and a vestibular neurectomy (cutting the balance nerve) or a labyrinthectomy is necessary. Fortunately, this happens in only 6% of patients
For patients whose main complaints are hearing loss, pressure, and tinnitus, dexamethasone is used in drop form. Dexamethasone is a powerful steroid that reduces inflammation, decreases allergic reaction, and may reduce fluid pressure in the ear. With this treatment, hearing is monitored at two-week intervals during the course of the four-week treatment. In many cases symptoms are relieved, and the risks and complications are minimal. Rarely does hearing worsen with this treatment, but occasionally after the MicroWick is removed the ear drum fails to heal and requires patching in the office.
If minimally invasive procedures fail to alleviate vertigo symptoms and hearing is still present, a vestibular neurectomy may be necessary.
The original approach, the retrolabyrinine approach (RVN), was improved in 1985 to become the combined retrolabyrinthine/retrosigmoid vestibular neurectomy (RRVN). RRVN offers immediate and permanent relief from the vertigo caused by Ménière’s disease in over 95% of patients, and preserves hearing in 99% of patients. The procedure involves making a small opening just behind the mastoid and exposing a small portion of the mastoid bone. This gives the surgeon quick access to the hearing and balance nerve, which he or she micro-surgically severs.
The surgery is delicate. The hearing nerve and balance nerve are close to the facial nerve, which controls facial movements and expression. To prevent facial nerve damage, a facial nerve monitor is often used. This device warns the surgeon when he or she is close to the facial nerve. In over 9,000 procedures utilizing this monitor, no facial weakness has occurred.
After the RRVN, a patient’s unaffected ear takes over the balance function, and vestibular and balance rehabilitation helps them recover quickly. While vertigo is usually cured, hearing sometimes continues to deteriorate do to the progression of the disease.
Source by Herb Silverstein, MD