Generality
Motion sickness is a general term that indicates a combination of unpleasant symptoms - such as dizziness, nausea and vomiting - that occur following repetitive or irregular body movements. It is a neurological disorder that derives from the contrasting interpretation of the signals coming from the vestibular (inner ear), visual and proprioceptive apparatus.
Symptoms
To learn more: Kinetic symptoms
The symptoms of motion sickness are variable and usually begin with nausea and discomfort perceived at the level of the upper abdomen, associated with a growing sense of malaise. These symptoms can be followed by a second series of more serious manifestations, including:
- Pallor;
- Sweating;
- Dizziness;
- Profuse salivation;
- Vomiting (often intense and persistent).
Some people also experience other symptoms, including:
- Headache;
- Drowsiness;
- Extreme tiredness, weakness and a sense of fainting.
" Mal de debarquement " or earth-sickness
Landing disease is a rare condition that generally manifests itself after a trip on a ship or plane. Unlike the symptoms of motion sickness, the person suffering from it perceives a continuous sensation of rocking or swaying, as if it were still on the means of transport. At the end of the journey, this disorder can persist even for a long time before it is resolved.
When to consult a doctor
If the symptoms persist after completing a journey, it is necessary to ascertain their origin: the doctor's consultation allows the exclusion of other possible causes at the origin of the manifestations, such as an infection of the inner ear (labyrinthitis). No special investigations are necessary to formulate the diagnosis: the doctor will collect information on the symptoms and the situations that led to the problem, in order to provide the patient with some useful tips to avoid subsequent episodes of motion sickness.
Risk factors
All people, if subjected to a stimulus of sufficient intensity, can develop the symptoms of motion sickness. Some subjects, however, are particularly sensitive to these stimuli, therefore more exposed to motion sickness; It is the case of:
- children aged between 2 and 12;
- women, especially during pregnancy;
- people suffering from migraines: they are particularly susceptible to the onset of the disorder during a headache attack and vice versa.
Other factors predisposing to motion sickness are:
- Excessive heat;
- Annoying noises;
- Poor ventilation in the means of transport.
Causes
Motion sickness is a disorder that involves the sense of balance and movement, regulated by a complex interaction of three main pathways of the nervous system:
- Signals from the inner ear (detection of movements, acceleration and gravity);
- Eyes (vision);
- Proprioceptors (these are special receptors sensitive to changes in body postures).
In particular, it is believed that motion sickness is triggered by a conflict between the stimuli coming from the systems responsible for controlling vision and balance (vestibular apparatus): the brain, consequently, receives a set of conflicting information that can trigger the symptoms of motion sickness.
Motion sickness may arise due to uneven body movement, regardless of its nature. It can commonly occur when traveling by car, plane, train or ship . Other types of movement, such as riding, taking a lift, riding on a swing and swinging in a swing, can also cause disturbance. Less common causes of motion sickness include some activities that do not involve traveling, such as watching a movie recorded with a shaky camera. Some people have reported the symptoms of motion sickness even after playing with a video game in which the graphics alternated quickly, like in car racing or flight simulators. Motion sickness also occurs in these cases because the realism of computer graphics can produce the same mismatch between visual stimuli and information provided by the vestibular system.
The vestibular apparatus
The vestibular system is a complex combination of nerves, small canals and fluids, located at the level of the inner ear; from this location information is transmitted to the brain about changes in position with respect to the terrestrial field and movements in a linear sense (without changes in direction) or angular. These details allow the body to maintain balance and balance.
Many experts believe that motion sickness is caused by a conflict of information between the senses. The brain constantly processes and updates information on the position, acceleration and balance of the body, perceived by the eyes and the vestibular system. However, if the messages from these two senses are discordant, the brain can "go haywire" and cause the symptoms of motion sickness. For example, if you travel by car, the disorder may arise because the brain processes information from the eyes - which informs you that you are traveling at more than 30 km / h - along with that of the vestibular system, which tells the brain that one is seated, therefore standing still. This lack of correspondence between the received stimuli can trigger the symptoms of motion sickness, such as nausea and vomiting.
Treatment
The treatments for motion sickness can range from simple advice for self-management to actual drug therapy. In fact, mild symptoms can be improved with some behaviors that can be easily adopted by the subject, such as fixing the horizon or being distracted by listening to music. The most serious manifestations may make it necessary to take some useful drugs to prevent and combat the disorder. When drug therapy is undertaken, the doctor should make sure that patients understand the risks and benefits, the profile of unwanted side effects and potential drug interactions.
Some medications can aggravate motion sickness:
| Class of drugs | Examples |
| Antibiotics | Azithromycin, metronidazole, erythromycin, trimethoprim-sulfamethoxazole |
| pesticides | Albendazole, thiabendazole, iodoquinol, chloroquine, mefloquine |
| Estrogen | Oral contraceptives, estradiol |
| Cardiovascular | Digoxin, levodopa |
| Narcotic analgesics | Codeine, morphine, meperidine |
| Non-steroidal analgesics | Ibupropofen, naproxen, indomethacin |
| Antidepressants | Fluoxetine, paroxitene, sertraline |
| Asthma medications | Aminophylline |
| Bisphosphonates | Alendronate sodium, sodium ibandronate, risedronate |
drugs
Several drugs can be used for the treatment of motion sickness. Usually, it is advisable to resort to pharmacological therapy before a long journey, rather than waiting for the disorder to manifest: the onset of motion sickness symptoms, such as vomiting, could in fact hinder the adequate absorption of the active ingredient, compromising its effectiveness. Motion sickness medications can cause drowsiness: drivers, pilots, ship crew members and anyone working with heavy equipment should refrain from hiring them.
Scopolamine (also known as hyoscin) is a muscarinic antagonist, commonly prescribed for the management of motion sickness: it works by blocking some of the nerve signals sent by the vestibular system, which can cause nausea and vomiting. Scopolamine is available by mouth or as a transdermal patch. To be effective, it must be taken before leaving on a trip, in order to prevent the symptoms before they occur. In the form of a patch, scopolamine can be applied behind the ear about 6-8 hours before travel. The effects last up to 3 days.
Undesirable reactions common to scopolamine include:
- Drowsiness;
- Blurred vision;
- Dry mouth;
- Dizziness;
- Constipation.
More rare side effects include:
- Nausea and vomit;
- Disorientation, particularly in older people.
Because of these side effects, scopolamine should never be taken if you are planning to drive a vehicle. The scopolamine must be used with extreme caution in children, in elderly subjects and in case of:
- Epilepsy;
- Kidney or liver problems;
- Heart problems;
- Some problems in the digestive system, such as gastro-oesophageal reflux;
- Asthma, glaucoma or urinary retention.
Antihistamines are often used to treat allergy symptoms, but they can also control nausea and vomiting. These drugs are less effective in the treatment of motion sickness than scopolamine, but may cause more limited adverse reactions (headache, blurred vision, drowsiness and dry mouth). Antihistamines (such as promethazine, dimenhydrinate, meclozine and cinnarizine) are taken orally, one or two hours before the trip. If the journey is quite long, it may be necessary to have a dose every eight hours.
To learn more: Medicines for the cure of motion sickness »
Prevention
Preventive measures for travelers
You can try to alleviate the symptoms of motion sickness by using non-pharmacological interventions for the correct management of the disorder:
- Minimize head and body movements . If possible, choose a seat in the vehicle where you can experience minimal movement. Leaning against the backrest of the seat and using a cushion or a headrest can help to keep the position of the head still.
- Fix the vision on a stable object . Reduce sensory input, for example by keeping your eyes on the horizon. Do not read or play, as they can make motion sickness worse. Closing the eyes can help relieve symptoms.
- Take some fresh air . If possible, open the windows to maintain good ventilation. Do not smoke and avoid sitting near smokers.
- Food and drinks . Avoid eating large meals or drinking alcohol before traveling.
If you suffer from motion sickness while traveling by plane, you may want to follow these tips:
- Sit towards the front of the aircraft or in a place near the wing.
- Eat light meals within 24 hours before traveling.
If possible, in anticipation of a trip, book in advance the places where the movement can be felt to a lesser extent:
- By ship, request a cabin in the front or center of the ship. When you are on the bridge, keep your eyes fixed on the horizon or on a distant and immobile object.
- By train, take a seat near the front and next to a window.
- In the car, drive or sit in the front passenger seat.
Deepening: Car sickness and movement-related disorders: what to do to prevent them
Alternative therapies
Ginger ( Zingiber officinale )
Ginger is a remedy used in the herbalist tradition against nausea and vomiting. Taking supplements that contain ginger extract can help prevent the symptoms of motion sickness, but not all research confirms an obvious benefit applied to this specific condition. Before taking a ginger supplement, it is still useful to check with your doctor the absence of any interactions with other regularly taken medicines. For example, ginger can increase the risk of bleeding when combined with anticoagulants such as warfarin (Coumadin) or aspirin.
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