Author(s): Ashley Brown
Motion sickness describes the physiologic responses to travel by air, car, sea, train, and virtual reality immersion. Given sufficient stimulus, all people with functional vestibular systems can develop motion sickness. People vary in their susceptibility, however.
Risk For Travelers
Risk factors for motion sickness include age, sex, preexisting medical conditions, and concurrent medications. Children aged 2–12 years are especially susceptible, but infants and toddlers are generally immune. Adults >50 years are less susceptible to motion sickness. Pregnancy, menstruation, and taking hormone replacement therapy or oral contraceptives have also been identified as potential risk factors. People with a history of migraines, vertigo, and vestibular disorders are more prone to motion sickness.Some prescriptions can worsen motion sickness–associated nausea.
Clinical Presentation
Motion sickness typically occurs after a triggering motion or event. People with motion sickness commonly experience dizziness; headache; nausea, vomiting, or retching; sweating. For a complete list of motion sickness–associated signs and symptoms, see Box8-06.
Neurophysiology
When sensory input does not align with expected patterns (neural mismatch), patients suffer dizziness and nausea. Sensory conflict theory (the most widely accepted explanation for motion sickness) proposes that the condition is caused by conflict between the visual, vestibular, and somatosensory systems, and involves complex neurophysiologic signaling between multiple nuclear regions, neurotransmitters, and receptors. Medications used to prevent and treat motion sickness are thought to work by suppressing the signals that contribute to neural mismatch.
Nonpharmacologic Prevention & Interventions
Travelers can use nonpharmacologic interventions to prevent or treat motion sickness (seeBox8-07). Awareness and avoidance of situations that tend to trigger symptoms are the primary defenses against motion sickness.
Treatment
Medications used to treat motion sickness can vary in effectiveness and side effects; suggest travelers take a trial dose of medication at home before departure to find what works best for them. The most frequently used antihistamines to treat motion sickness include cyclizine, dimenhydrinate, meclizine, and promethazine (oral and suppository); nonsedating antihistamines appear to be less effective. Other commonly used motion sickness medications include anticholinergics (e.g., scopolamine [hyoscine, oral and transdermal]); benzodiazepines; dopamine receptor antagonists (e.g., metoclopramide, prochlorperazine); and sympathomimetics (often used in combination with antihistamines).
Complementary approaches with anecdotal evidence of effectiveness for preventing or treating motion sickness (e.g., acupressure and magnets, ginger, homeopathic remedies, pyridoxine [vitamin B6]) might be effective for individual travelers but cannot generally be recommended (see Sec. 2, Ch. 14, Complementary & Integrative Health Approaches to Travel Wellness). Clinical trials have shown that ondansetron, a commonly used antiemetic, is ineffective in preventing nausea associated with motion sickness.
Children & Motion Sickness
For children aged 2–12 years, dimenhydrinate (Dramamine), 1–1.5 mg/kg per dose, or diphenhydramine (Benadryl), 0.5–1 mg/kg per dose up to 25 mg, can be given 1 hour before travel and every 6 hours during the trip. Because some children have paradoxical agitation with these medications, encourage parents to try a test dose before departure. Oversedating young children with antihistamines can be life-threatening. Scopolamine can cause dangerous adverse effects in children and should not be used.
The following authors contributed to the previous version of this chapter: Stefanie K. Erskine
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