(Meniere's Disease; Endolymphatic Hydrops)
In Meniere disease, pressure and volume changes of the labyrinthine endolymph affect inner ear function. The etiology of endolymphatic fluid buildup is unknown. Risk factors include a family history of Meniere disease, preexisting autoimmune disorders, allergies, trauma to the head or ear, and, very rarely, syphilis. Peak incidence is between ages 20 and 50.
Patients with Meniere disease have sudden attacks of vertigo that usually last for 1 to 6 hours but that can (rarely) last up to 24 hours, usually with nausea and vomiting. Accompanying symptoms include diaphoresis, diarrhea, and gait unsteadiness.
Tinnitus in the affected ear may be constant or intermittent, buzzing or roaring; it is not related to position or motion. Hearing impairment, typically affecting low frequencies, may follow. Before and during an episode, most patients sense fullness or pressure in the affected ear. In a majority of patients, only one ear is affected.
During the early stages, symptoms remit between episodes; symptom-free periods may last > 1 year. As the disease progresses, however, hearing impairment persists and gradually worsens, and tinnitus may be constant.
The diagnosis of Meniere disease is made clinically. The simultaneous combination of fluctuating low-frequency sensorineural hearing loss, episodic vertigo, ipsilateral fluctuating aural fullness, and tinnitus is characteristic. Similar symptoms can result from vestibular migraine, viral labyrinthitis or neuronitis, a cerebellopontine angle tumor (eg, acoustic neuroma), or a brain stem stroke. Although bilateral Meniere disease can occur, bilateral symptoms increase the likelihood of an alternate diagnosis (eg, vestibular migraine). Vestibular migraine (also known as migrainous vertigo) is characterized by episodes of vertigo in patients who have a history of migraines or with other features of migraines, such as headache, photophobia and phonophobia, or visual aura; there is no loss of hearing.
On examination during an acute attack, the patient has nystagmus and falls to the affected side. Between attacks, the examination may be entirely normal. However, in long-standing or refractory cases with associated labyrinthine hypofunction, the Fukuda stepping test (marching in place with eyes closed, previously known as the Unterberger test) causes the patient to turn toward the affected ear, consistent with a unilateral labyrinthine lesion.
The Halmagyi head thrust maneuver, or head impulse test, is another technique that is used to show unilateral labyrinthine dysfunction. In the Halmagyi maneuver, the examiner has the patient visually fixate on a target straight ahead (eg, the examiner's nose). The examiner then rapidly rotates the patient's head 15 to 30° to one side while observing the patient's eyes. When vestibular function on the side to which the head has been rotated is normal, the patient's eyes remain fixated on the target. When vestibular function is impaired on the side to which the head has been rotated, the vestibulo-ocular reflex fails and the patient's eyes do not remain fixated on the target but instead transiently follow the head rotation and then quickly and voluntarily return back to the target (called delayed catch-up saccades).
Patients with symptoms suggesting Meniere disease should have an audiogram and an MRI (with gadolinium enhancement) of the central nervous system with attention to the internal auditory canals to exclude other causes. Audiogram typically shows a low-frequency sensorineural hearing loss in the affected ear that fluctuates between tests. The Rinne test and the Weber test may indicate sensorineural hearing loss.
Meniere disease tends to be self-limited. Treatment of an acute attack is aimed at symptom relief and done in a staged fashion; the least invasive measures are done first, and then ablative procedures are sometimes done if the measures fail.
Anticholinergic antiemetics (eg, prochlorperazine 25 mg rectally or 10 mg orally every 6 to 8 hours; promethazine 25 mg rectally or 25 mg orally every 6 to 8 hours) can minimize vagal-mediated gastrointestinal symptoms; ondansetron is a 2nd-line antiemetic. Antihistamines (eg, diphenhydramine, meclizine, or cyclizine 50 mg orally every 6 hours) or benzodiazepines (eg, diazepam 5 mg orally every 6 to 8 hours) are used to sedate the vestibular system. Neither antihistamines nor benzodiazepines are effective as prophylactic treatment. Some physicians also use an oral corticosteroid burst (eg, prednisone 60 mg orally once/day for 1 week, tapered over another week) or intratympanic dexamethasone injections for an acute episode.
A low-salt (< 1.5 g/day) diet, avoidance of alcohol and caffeine, and a diuretic (eg, hydrochlorothiazide 25 mg orally once/day or acetazolamide 250 mg orally 2 times a day) may help prevent or reduce the incidence of vertigo attacks and are commonly used first steps. However, there are no well-designed studies that clearly prove the efficacy of these measures for Meniere disease.
Although more invasive, endolymphatic sac decompression relieves vertigo in a majority of patients, spares vestibular function, and poses minimal risk of hearing loss. Thus this procedure is still classified as a vestibular-sparing treatment.
When vestibular-sparing treatments fail, an ablative procedure is considered. Intratympanic gentamicin (chemical labyrinthectomy—typically 0.5 mL of a 40 mg/mL concentration) is injected through the tympanic membrane. Follow-up with serial audiometry is recommended to monitor for hearing loss. The injection can be repeated in 4 weeks if vertigo persists without hearing loss.
Ablative surgery is reserved for patients with frequent, severely debilitating episodes who are unresponsive to less invasive modalities. Vestibular neurectomy (an intracranial procedure) relieves vertigo in about 95% of patients and usually preserves hearing. A surgical labyrinthectomy is done only if preexisting hearing loss is profound.
Unfortunately, there is no known way to prevent the natural progression of hearing loss. Most patients sustain moderate to severe sensorineural hearing loss in the affected ear within 10 to 15 years.
Meniere disease typically causes vertigo with nausea and vomiting, unilateral tinnitus, and chronic, progressive hearing loss.
Testing is with audiogram, and MRI is done to rule out other disorders.
Antiemetics and antihistamines can help relieve symptoms; some clinicians also use oral or transtympanic corticosteroids.
More invasive treatments for refractory cases include endolymphatic sac decompression, intratympanic gentamicin, and vestibular neurectomy.
Diuretics, a low-salt diet, and avoidance of alcohol and caffeine help prevent attacks.