Migraines Flashcards
What is a prodrome
Warning phase where they know a migraine is going to occur:
-yawming, mood or appetite change
What happens in a migraine
1- aura= initial visual disturbance
2- unilateral throbbing headache. You get photophobia, nausea and vomiting
3) deep sleep and loss of headache
4) recovery- often get exhaustion
How are blood vessels like when the headache starts
Starts during vasoconstriction
What is the cortical spreading depression theory
Migraines have a neuronal origin
What is the third theory behind migraines
Overactivity of the V1 branch of the trigeminal nerve (ophthalmic division)
Neurones contain calcitonin gene related peptide (CGRP) a potent vasodilator and plasma CGRP increases in migraine
What is the role of 5HT1D in migraines and how can this be used to stop migraines
They increase vasodilation and inflammation
-5HT1D ragonists can be used to decrease release and decrease vasodilation and pain
Steps in managing mild and/or occasional attacks
1) Acute treatment analgesics/ NSAIDs and anti-emetics if nausea is troublesome. Combine with rest and sleep
2) Triptans 5HT1b and 5HT1D receptor agonists which cause constriction of cranial blood vessels and inhibition of neuropeptide release. Has cardiovascular risks
3) CGRP receptor antagonists in development but monoclonal antibodies against CGRP or the CGRP receptor are now developed and have few side effects
When are triptans contraindicated
What do they not stop
Ischaemic heart disease because it may cause chest pain due to coronary artery vasoconstriction
Will not prevent aura so take during headache attack
Migraine therapy for those with severe attacks and/or >2/month
-what to do in treatment resistant cases
1) abode known triggers such as stress of dietary factors
2) b blockers, calcium channel blockers, anti-epileptics (caution in pregnancy) or pre-menstrual oestrogen can be effective)
3) acupuncture or gabapentin in treatment resistant cases and Botulinum toxin type A is recommended for adults with frequent chronic migraine and patients with accompanying neck pain
4) CGRP receptor antagonists and monoclonal antibodies used when everything else has failed
What is emesis
Vomiting. It is a protective reflex to expel ingested toxins
Where is emesis generated and coordinated
Vomiting centre. a group of neurones in the medullary reticular formation
What receptors does the chemoreceptor trigger zone at the base of the fourth ventricle have
What is the major output transmitter
Dopamine D2,
5HT3,
opioid
acetylcholine
–Neurokinin
What area of the brain detects blood chemicals and why
area Postrema (has no BBB)
Which area via which cranial nerve plays a role in motion sickness and why
Vestibular system via the 8th cranial nerve
Rich in muscarinic cholinergic and histamine H1 receptors
How is gag reflex triggered and why
Vagal (10th cranial) nerve afferents activated when the pharynx is irritated, leading to the gag reflex.
The nucleus tracts solitaires has a high density of 5HT3 and NK1 receptors
How does nausea arise from irritation of GI mucosa by chemo, radiation, distention or acute gastroenteritis occur
Vagal and other gastrointestinal afferents respond to irritation via gut 5HT3 receptors
How does nausea arise from head injury or meningitis
Intercranial pressure receptors mediate nausea
How does nausea arise from sight or smell of vomit
Descending inputs from higher centres
How would you induce vomiting and when should you only do this
1) if the poison is likely still in stomach
2) if patient is not likely to inhale vomit (i.e. if respiratory reflexes are unimpaired)
- swallow an emetic such as ipecacuanha which directly activates chemoreceptor trigger zone
What anti nausea drugs can be used to stop nausea from any source
Neurokinin1 antagonist
What drugs can control vomiting
Cannabinoid agonists
Which drugs can be used for vertigo nausea
Histamine H3 antagonist
What drugs car effective against motion sickness
H1 and H3 antagonists
How can chemo induced emesis be controlled
Combo of corticosteroid and dopamine antagonist
But
5HT3 antagonists are effective
What can be used to reduce severe nausea
Combo of anti-emetics and mild sedation
What are corticosteroids not very effective for
control of acute vomiting
What are 5HT3 antagonists not very effective against
Non -chemo vomiting
