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Motion Sickness

BASICS

Description

  • Physiologic response to sensory conflict among visual, vestibular, and proprioceptive inputs
  • Triggered by motion patterns that differ from past experience or expectation
  • Requires actual movement (not “cybersickness” or “virtual reality sickness”)
  • Systems affected: nervous, gastrointestinal

Synonyms: car sickness, sea sickness, air sickness, space sickness, physiologic vertigo, kinetosis

EPIDEMIOLOGY

  • Female > male
  • Prevalence: 25% (air), 29% (sea), 41% (road)
  • Vomiting: 0.5% (air), 7% (sea), 2% (road)

ETIOLOGY & PATHOPHYSIOLOGY

  • Mismatch between vestibular and visual sensations
  • Rotary/vertical/low-frequency motions produce more symptoms than linear/high-frequency
  • Neurotransmitters involved: dopamine, acetylcholine, histamine, norepinephrine, GABA
  • Genetics: heritability 55–75%

RISK FACTORS

  • Travel by car/plane/boat/amusement rides
  • Moving visual stimuli
  • Poor ventilation
  • Emotions (fear, anxiety)
  • Zero gravity
  • Pregnancy, menstruation, OCP use
  • Migraine history (especially vestibular migraine)

Pediatric

  • Rare <2 years; peaks 6–12 years
  • Antihistamines may cause excitation

Geriatric

  • Increased resistance with age; higher risk for anticholinergic side effects

Pregnancy

  • Increased risk; most treatments considered safe (meclizine, dimenhydrinate, scopolamine, diphenhydramine, promethazine)

ASSOCIATED CONDITIONS

  • Migraine
  • Vestibular syndromes

DIAGNOSIS

History

  • Nausea, vomiting, stomach awareness, diaphoresis
  • Pallor, hypersalivation, yawning, hyperventilation
  • Anxiety, malaise, lethargy, confusion, dizziness

Physical Exam

  • No specific findings

Differential Diagnosis

  • Mountain sickness
  • Vestibular disease
  • Gastroenteritis
  • Metabolic/toxic disorders
  • Concussion, hypoglycemia

Diagnostic Tests

  • Not usually needed
  • Consider pregnancy test or glucose if indicated
  • Online questionnaires (e.g., Motion Sickness Susceptibility Questionnaire) available

TREATMENT

General Measures

  • Avoid triggers: travel in inclement weather, strong motion
  • Improve ventilation
  • Eat before travel: light, bland, low-fat/acid
  • Increase airflow to face
  • Positioning: recumbent/supine, eyes on horizon/still distant objects
  • Avoid reading/moving objects
  • Habituation: graded exposure to triggering stimulus
  • Seat choice: airplane (over wing), car (front seat), boat (center, face waves), bus/train (front, face forward)

First-Line Medications

  • Scopolamine patch (Transderm Scop): 2.5 cm² patch behind ear, apply ≥4 (preferably 6–12) hours before travel, change q3 days
  • Promethazine: 25 mg PO q12h, start 30–60 min before travel (children: 0.5 mg/kg PO q12h, max 25 mg BID)
  • Dimenhydrinate (Dramamine): 50–100 mg PO q4–6h (children: age/dose adjusted)
  • Meclizine: 25–50 mg PO q24h (adults/adolescents >12)
  • Diphenhydramine: 25–50 mg PO q6–8h (dose adjusted for children)

Contraindications/precautions: glaucoma, urinary/pyloric obstruction, elderly, young children, pregnancy

Adverse effects: drowsiness, dry mouth, blurred vision, confusion, constipation, urinary retention

Interactions: sedatives, alcohol, anticholinergics

Second-Line

  • Benzodiazepines (diazepam, lorazepam): not first-line due to sedation, addiction
  • Diazepam 2–10 mg PO q6–12h
  • Lorazepam 1–2 mg PO q8h

For Migraineurs

  • Rizatriptan (serotonin receptor agonist)

COMPLEMENTARY & ALTERNATIVE

  • Acupressure: PC6/Neiguan point—limited evidence for motion sickness, but helpful in other types of nausea
  • Ginger: 1–1.5 g per 24h (250 mg QID), 4 hours before travel—effective for general nausea

ONGOING CARE

Diet

  • Light meal before travel, avoid empty stomach/alcohol

PROGNOSIS

  • Symptoms resolve when motion ends
  • Resistance increases with age

COMPLICATIONS

  • Hypotension, dehydration, depression, panic, syncope

ICD-10

  • T75.3XXA: Motion sickness, initial encounter

Clinical Pearls

  • Scopolamine patch is first-line for prevention—apply at least 4 (preferably 12) hours before travel
  • First-generation antihistamines are also effective; sedating, administer 30–60 min before departure
  • Nonsedating antihistamines, ondansetron, ginger root: not effective for motion sickness
  • Acupressure bands: effective for postop/chemotherapy-induced N/V, not consistently for motion sickness