Motion sickness almost invariably presents as a syndrome, comprising multiple symptoms (Table 1, Figure 2). Initially signs of discomfort such as epigastric sensations, mild dyspepsia, headache (predominantly frontal), drowsiness, tiredness, yawning, shivering, cold sweating, hot flashes, pallor, increased salivation, strangury (painful urination) and lacrimation may precede outright motion sickness (malaise). The complex of drowsiness and mood changes seen in motion exposed persons has also been named >Sopite syndrome< [27].

Characteristic neuromotor symptoms are swaying, poor coordination, tremble and muscular weakness [28], effects putting sailors at an increased risk of injury, falling, and submersion.

Gastrointestinal manifestations include loss of appetite, gulping, nausea and vomiting, but may also comprise bowel movements.

 

 

 Fig_2_Pathogenesis_Motion_Sickness_2


 

 

Fig. 2  Pathophysiology and symptomatology of motion sickness. Sensory input from different sources may trigger and modulate motion sickness, which may manifest in an great variety of symptoms in multiple organ systems involved. Vegetative, gastrointestinal and neurological symptoms are commonly recognized by motion sickness patients. (Adapted from: Wolffgram T. Motion- and seasickness (Kinetosis) – Update on pathophysiology, prophylaxis and therapy. Medizinische Welt 2000;132: 21-27)

 

 Impact on mental function may be discrete at onset with reticence, low mood, fatigue, malaise, decreased vigilance and low level of concentration, the latter being supported by impaired performance in psychometric testing including reduced short term memory [29]. More advanced symptoms comprise increasing indifference, vertigo and visual disturbances. Aggravation towards apathy with severely impaired decision-making capabilities is seen in severely affected subjects. On rare occasions mental impairment may proceed until loss of consciousness or delirium.

Even moderate impact on decision-making capabilities may lead to faulty navigation and hence poor vessel guidance by crews of seagoing vessels, potentially facilitating accidents and major incidents. The skipper or captain of a ship should diligently take this >human factorall hands on deck<.

 In severe motion sickness repeated vomiting and associated fluid loss may occur. If not compensated by fluid and electrolyte substitution, this may result in hypotonic dehydration and metabolic alkalosis, further adding to the malaise and rendering the patient apathetic and weak. Vomiting may also contribute to a loss of body heat. Due to impaired vasoconstriction and thermoregulation seasick sailors immersed in cold water are significantly more prone to core cooling [1;2], which may reduce their survival time.

A diagnostic scale for the assessment of motion sickness has been devised first by Graybiel et al. [30], predominantly accounting for gastrointestinal symptoms occuring at different stages of the condition. The Graybiel scale (Table 1a) assigns points to various symptoms ranging from mild accessory phenomena such as epigastric awareness (1 point), to severe nausea including retching or vomiting (16 points). The latter indicates full-blown motion sickness, whereas malaise is differentiated into four different grades ranging from mild (1-2 points) to severe (sum of points from 8 to 15 points).

 

 

Table 1a: Cardinal symptoms of motion sickness and criteria for grading motion sickness severity (Graybiel-Scale) [30]

 

 Severity: I= Slight, II= Moderate, III= Severe. AQS= Additional Qualifying Symptoms. Scores in the 8-15 points range indicate severe malaise.

 

Category

Pathognomonic

(16 Points)

Major

(8 Points)

Minor

(4 Points)

Minimal

(2 Points)

AQS

(1 Point)

Nausea syndrome

Vomiting or Retching

Nausea II, III

Nausea I

Epigastric dyscomfort

Epigastric awareness

Skin colour

 

Pallor III

Pallor II

Pallor I

Flushing

Cold sweating

 

III

II

I

 

Increased salivation

 

III

II

I

 

Drowsiness

 

III

II

I

 

Pain

 

 

 

 

Headache

CNS

 

III (with eyes open)

II ( with eyes closed

 

Dizziness/Vertigo

 

 

 

 

 

 

Motion Sickness Grading according to sum of points

Full-blown Motion sickness

Severe Malaise (M III)

Moderate Malaise A (M IIa)

Moderate Malaise B (M IIb)

Mild Malaise (M I)

 

16 points

8-15 points

5-7 points

3-4 points

1-2 points

 

 

 Further diagnostic scales for motion sickness assessment have been developed and validated since, including the MSAQ [[v]], which differentiates four different symptom groups (gastrointestinal, central, peripheral, and Sopite-related. Table 1b). This approach captures mood-changes (annoyance, uneasyness) as well as drowsyness and fatigue (“Sopite syndrome”, sopire (lat.)-> to put to sleep; [[vi]] http://en.wikipedia.org/wiki/Sopite_syndrome), thereby extending the range of relevant motion sickness symptoms when compared to the classic Graybiel Scale.

 

 Table 1b: Motion Sickness Assessment Questionnaire (MSAQ). Courtesy Dr. Peter J. Gianaros, Pittsburgh [31]

 

 

 

Instructions. Using the scale below, please rate how accurately the following statements describe your experience, where 1 = not at all and 9 = severely.

 

 

(not at all) 1——2——3——4——5——6——7——8——9 (severely)

 

1. I felt sick to my stomach (G)

2. I felt faint-like (C)

3. I felt annoyed/irritated (S)

4. I felt sweaty (P)

5. I felt queasy (G)

6. I felt lightheaded (C)

7. I felt drowsy (S)

8. I felt clammy/cold sweat (P)

9. I felt disoriented (C)

10. I felt tired/fatigued (S)

11. I felt nauseated (G)

12. I felt hot/warm (P)

13. I felt dizzy (C)

14. I felt like I was spinning (C)

15. I felt as if I may vomit (G)

16. I felt uneasy (S)

 

 

Investigator use: G; Gastrointestinal; C: Central; P: Peripheral; SR; Sopite-related.

The overall motion sickness score is obtained by calculating the percentage of total points scored: (sum of points from all items/144) × 100. Subscale scores are obtained by calculating the percent of points scored within each factor: (sum of gastrointestinal items/36) × 100; (sum of central items/45) × 100; (sum of peripheral items/27) × 100; (sum of sopite-related items/36) × 100.

 

 

Being exposed to sea-motions while working or cruising on ships usually leads to habituation (adaptation) within 2-5 days, accompanied by a decline in symptoms in subjects prone to seasickness. Habituation may outlast the end of the cruise for a few weeks, however sleep deprivation or heavy alcohol consumption may increase motion sensitivity again at any given time.

Surprisingly, a good indicator for individual habituation to sea motion stimuli seems to be the sensation of a swaying type of vertigo, experienced not at sea but on dry land [33]. This phenomenon is harmless and usually ceases 1-2 days after the end of the journey, however rare cases of chronic vertigo have been reported after ocean cruises. This so called mal-de-debarquement-syndrome is observed mainly in middle-aged women and may prove refractory to pharmacotherapy and physiotherapy [34].

 


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