Motion sickness

Question 1

Briefly describe the pathophysiology of motion sickness

Answer 1

• Conflicting motion stimuli fed by vestibular labyrinth, eyes and proprioreceptors to the vestibular nuclei
• Stimuli goes through cerebellum to vomiting centre in medulla oblongata and other areas in CNS

Question 2

Which age group(s) is/are likely to develop motion sickness?

Answer 2

Children 2-12 yo

Question 3

Patient factors that may contribute to motion sickness

Answer 3

• Menstruation
• Pregnancy
• History of migraines
• Sleep deprivation
• Tobacco smoking

Question 4

Early signs of motion sickenss

Answer 4

1. Pallor
2. Restlessness
3. Cold sweat

(late stages: nausea and vomiting)

Question 5

Key treatment principle of motion sickness

Answer 5

Prevention

Question 6

Three general non-pharmacological principles to prevent motion sickness

Answer 6

1. Reduce vestibular motion: choose locations of vehicle that minimise motions
2. Synchronise visual and motion: view outside, choose window seat, or close eyes while holding head still
3. Actively synchronize the body with motion: such as actively tilting head

Question 7

State the mechanism of action of cinnarizine. Describe its dosing regimen for motion sickness

Answer 7

• MoA: Antihistamine-1, with anticholinergic effects
• Dosing: 25 mg at least 30 min before travel, then q4-6h

Question 8

State the mechanism of action of promethazine. Describe its dosing regimen in motion sickness

Answer 8

• MoA: H1 antihistamine with strong anticholinergic effect
• Dosing: 25 mg 30-60 mins before travel, then q8-12h

Question 9

State the mechanism of action of scopolamine patch. Describe its dosing regimen in motion sickness

Answer 9

• MoA: Antimuscarinic with anticholinergic properties
• Dose: 1 patch at a hairless area behind the ear 5-6h before travel, then q72h (one patch lasts 72h)

Question 10

State the mechanism of action of dimenhydrinate. Describe its dosing regimen in motion sickness

Answer 10

• MoA: H1 antihistamine with anticholinergic effect. Metabolised to diphenhydramine
• Dosing: 50-100 mg 30-60 mins before travel, then q6-8h

Question 11

State the mechanism of action of diPHENhydramine. Describe its dosing regimen in motion sickness

Answer 11

• MoA: H1 antihistamine with anticholinergic properties
• Dose: 25-50 mg at least 30 mins before travel, then q4-6h

Question 12

Describe the dosing regimen of ginger pills in motion sickness

Answer 12

2-3 tablets at least 30 mins before travel, then 1 tab q2h

Question 13

What kind of symptoms should you refer a patient to the doctor in nausea and vomiting?

Answer 13

1. Severe abdominal pain
2. Blood in vomitus
3. Head injury, or other neuropathy (e.g. numbness, visual disturbances)
4. Signs and symptoms of dehydration

Question 14

Describe the dose of domperidone for NNV. State the forensic classification and the indication for supplying domperidone if applicable, as well as the maximum supply

Answer 14

• Dose: 10 mg TDS (max 30 mg/day)
• Forensic classification: POM w exemption for 14 days for gastric symptoms (e.g. bloating, belching) or nausea (not vomiting) for patients at least 12yo
• Max supply: 14 days (42 tabs)

Question 15

Besides ginger, what is/are the complementary treatment(s) that can be used to prevent motion sickness?

Answer 15

Sea band (attached to P6 of meridian system, somewhere around the wrist area)

Question 16

Non-pharmacological management for patients who experiences mild headache at high altitudes?

Answer 16

1. Sleep upright
2. Stay hydrated
3. Rest
4. Avoid alcohol
5. Descend if symptoms persist for 24h