History and exam
Key diagnostic factors
common
motion stimulus for symptoms
Physical motion or visual motion can elicit symptoms. At least five episodes of motion sickness or visually induced motion sickness triggered by the same or similar motion stimuli is required to make a diagnosis of motion sickness disorder or visually induced motion sickness disorder.[1]
epigastric discomfort
Occurs in almost all people with motion sickness.
nausea
Occurs in almost all people with motion sickness and may continue after motion has terminated.
headache
May persist after motion has terminated.
vomiting
Vomiting may take place if nausea is severe. There may be possible relief of motion sickness symptoms after vomiting.
Other diagnostic factors
common
cold sweating
Frequently observed.
dry mouth
Frequently observed.
dizziness
Frequently observed.
yawning and sleepiness
Frequently observed.
pallor
Frequently observed.
uncommon
unsteadiness and incoordination
May persist after motion has terminated.
Risk factors
strong
childhood age
Individual susceptibility to motion sickness appears to develop sometime during childhood, peak at around the age of puberty, and thereafter decline through adulthood.[10][11] Children ages 2-12 years are particularly susceptible to motion sickness, while older adults (ages >50 years) are less susceptible.[9] Actual vomiting appears to be infrequent beyond teenage years.[12]
female sex
family history of motion sickness
One large-scale survey of motion sickness susceptibility in female twins concluded that approximately one half of the variation in motion sickness susceptibility is determined by genetic variation and that the decreasing relationship in adulthood may be due to individual differences in habituating exposure to, or avoidance of, motion.[47]
history of migraine
vestibulopathy
Acute vestibular disorder is characterized by intense vertigo, nausea, vomiting, and imbalance. Motion sickness is the model for the autonomic consequences of vestibular lesion. In the chronic phase, patients may continue to experience malaise and nausea when they have to navigate complex motion environments. This is usually attributed to maladaptive reweighting of sensory modalities due to reduced reliability of vestibular inputs. As a result, patients often become over-reliant on visual cues with increased susceptibility to visually induced vertigo and imbalance.[4][50]
spatial disorientation and space-motion discomfort syndromes
Conditions ranging from anxiety in drivers and pilots to vestibular disorders may give rise to symptoms of spatial disorientation, which are often poorly understood in clinical practice. Patients may experience dizziness, disorientation, and derealization when navigating complex environments. These symptoms have been characterized as visual vertigo and space-motion discomfort and may include an element of nausea induced by visual motion, although vomiting is rare.[4][54][55][56]
unpleasant odors/sight or smell of vomit
Environmental context, including the sight and smell of vomit, diesel fumes, and other unpleasant chemical and animal smells, lowers the threshold for the development of symptoms.
conflicting sensory inputs (e.g., reading in car, tilting trains)
Physiologic factors enhancing motion sickness usually involve what has been termed a “visuo-vestibular conflict” between sensory inputs.[10] The classic case is trying to read in a moving car. The vestibular ocular reflexes, which stabilize the eyes on external stationary objects, must be suppressed in some way by visually guided eye movements in order to maintain scanning fixation on the text, which is not moving relative to the head. A similar conflict arises in high-speed tilting trains (or in an airplane making a coordinated turn when it comes in to land or takes off). These are particularly nauseogenic if the passenger, who feels stationary in the cabin, views the external landscape, which appears to tilt.[27]
psychological factors
For example, anxiety.[28]
spatially loaded concurrent tasks
For example, map interpretation.[27]
weak
Asian ancestry
visual disorder
Experiments on visual plasticity found that wearing reversal prisms made participants very motion sick.[51] Optical correction that inadvertently induces anisometropia may induce motion sickness and secondary symptoms, due to conflicting right-left eye images.[52] Older people who may be unable to adapt readily to changes in magnification can become motion sick when using varifocal lenses.
smoking
Smokers are more susceptible to motion sickness when at their accustomed level of tobacco use than when they are nicotine-deprived.[53]
hormonal factors
Motion sickness susceptibility fluctuates with the menstrual cycle, with women becoming more susceptible about the time of menstruation. The variation in susceptibility is not sufficient to explain the sex differences in prevalence. Although never studied in detail, it is implicated that motion sickness susceptibility can fluctuate markedly with significant changes in hormonal status.[57] Nausea in pregnancy will interact synergistically with motion sickness. People on hormone replacement therapy or oral contraceptives are prone to motion sickness.[9] Hormonal imbalance in individuals with primary adrenal insufficiency has been shown to increase motion sickness susceptibility in women.[58]
neurologic disorder
Certain rare neurologic disorders may make the patient susceptible to motion. Although not yet proved in systematic clinical studies, this has been observed with tumors in the floor of the fourth ventricle and in some cases of periodic ataxia.
For acute episodes of motion sickness or visually induced motion sickness, symptom severity can be worsened by conditions like ocular motility disorders, visual-vestibular disorders, or vestibular disorders such as vestibular migraine, vestibular neuritis, or persistent postural perceptual dizziness.[1]
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