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What are nonpathologic causes of vestibular impairments?
1. Mal de debarquement, literally sickness disembarking,
This condition is a rare disorder that may occur after an intense motion experience.
Patients complain of vertigo and a sense of swaying or rocking and they may be observed to rock or sway while sitting quietly.
It is most often reported after a voyage on a cruise ship but may occur after flying in turbulence, as a pilot or passenger. It is more common in women than men and can last for months to years.
It recurs when the individual is re-exposed to the initial stimulus. Benzodiazepines may be helpful. Vestibular suppressants such as meclizine and scopolamine are not helpful.
Vestibular rehabilitation is contraindicated. Patients should be advised to avoid intense motion experiences until the symptoms subside, including head-shaking exercises, running, use of elliptical machines for exercise, and long car, train, or airplane rides.
2. Motion sickness
This condition happens often during a boat or car ride but also during sea voyages, air travel, and the initiation of space travel, probably occurs due to visual–vestibular conflict or, in the case of space travel, due to reinterpretation of signals from the otolith organs.
In land-based travel individuals may feel better by using a visual reference to confirm the sense of motion, such as looking at an object on the horizon. Motion sickness often causes nausea, vomiting, other vasovagal symptoms, decreased concentration, and difficulty thinking.
Medications that are useful include antihistamines, anticholinergic antimuscarinics, 5-HT3 serotonergic receptor antagonists, and stimulants. Antihistamines are the most common medication for treating motion sickness, have a longer duration of action, and are relatively safe.
Oral forms are used for prevention, while parenteral administration is used for treatment of motion sickness.
Medications with mixed antimuscarine and antihistamine effects include diphenhydramine and promethazine. Scopolamine is one of the most effective drugs to prevent motion sickness at dosages of 0.3 to 0.6 mg orally.
Intranasal scopolamine may be rapidly administered as a rescue therapy for motion sickness.
Stimulants, such as d -amphetamine or ephedrine, often in combination with scopolamine, are effective in preventing motion sickness.
Dextroamphetamine (5 to 10 mg) has been used effectively in combination with promethazine (Phen-Dex) or scopolamine (Scop-Dex) and can counter some of the sedating effects of antihistamines.
The 5-HT3 serotonergic receptor antagonists, such as ondansetron or granisetron, may be effective at preventing motion sickness and have few side effects.
3. Presbystasis
This condition also termed as disequilibrium of aging, is a multifactorial problem.
During the aging process the vestibular labyrinth loses hair cells, the otoconia may fracture and change shape, the vestibular nerve loses fibers, and the vestibular nuclei lose cells. In addition the brain shrinks and proprioception and tactile senses decrease.
A diagnosis of presbystasis is often given to a patient complaining of nonspecific dizziness who is over 65 years old when no specific cause is identified.
Although the patient may not have true vertigo, he or she may have slips, trips, and even falls.
This problem is compounded by polypharmacy, sleep disturbance, peripheral neuropathy, musculoskeletal problems including foot deformities, hip and knee pain and arthritis, visual decline (cataracts, age-related macular degeneration), and cognitive decline.
Patients may benefit from a review of medications and if possible decreased medication usage. They should have a through visual work-up by ophthalmology or optometry to improve vision with better eyeglasses and treatment of cataracts and other problems.
They should be worked up for foot deformities and counseled by podiatry about use of proper footwear.
Evaluation by orthopedics for hip and knee pain may be beneficial. Evaluation of cognitive function by neuropsychology and hearing function by audiology may be beneficial.
Referral to occupational therapy and physical therapy will be beneficial for functional assessment, functional skills training, strength training, assessment of need for home modifications, and training to avoid falls and how to deal with falls if they occur. Social service intervention may also be needed.
