Migraine Flashcards
Pathophysiology of migraine
Peripheral sensitization: vascular mechanism
- incr blood flow in cerebral arteries, abnormal carotid artery blood flow, abnormal extracranial vascular response
Central sensitization: cutaneous allodynia symptoms (risk factor for transformation of episodic migraine to chronic migraine)
Phases of migraine
- Prodrome
- Aura
- Headache (ictal)
- Postdrome
- Interictal
Duration of migraine
(+ each phase)
Migraine (headache/ictal) phase: 4h-72h
- *All phases may last 7 days
- Premonitory: few hours to days
- Prodrome/postdrome: 48h or less each
- Postdrome: <12-24h
- aura: 5-60min preceding headache phase
Role of trigeminovascular system in migraine
Relays head pain signals to the brain
Periphery: trigeminal ganglion relay trigeminovascular nociceptive input from the meningeal vessels and dura mater to the CNS
Central: trigeminocervical complex receives peripheral trigeminovascular nociceptive pain signal from the trigeminal ganglion and relays it to the cortex via the thalamus, resulting in the experience of pain
=> Migraine may result as a result of a dysfunctional trigeminovacular system
Role of sensitization/hyperexcitability
Pain is experienced when trigeminovascular neurons are activated and relay the migraine pain signal from the periphery to the CNS
Repeated activation => state of hypersensitivity and sustained pain
S&S of prodrome
Patho of prodrome
- fatigue, yawning
- food cravings (changes in appetite)
- nausea and vomiting
- cognitive symptoms
- mood changes
- neck discomfort/pain
- photo/phonophobia
Activation of the hypothalamus involved in physiologic processes + neuropeptides involved in homeostatic functions
=> underlies burdensome non-pain symptoms
S&S of aura
Patho of aura
- Visual aura (scotoma - blind spots, fortification spectrum - zigzag, scintillation)
- Sensory disturbances (pins and needles, numbness)
- Speech disturbances
- Motor symptoms
Cortical spreading depression (CSD) in the cortex
Slow-spreading neuronal depolarization within the grey matter cause neuron hyperexcitation in the cortex and brainstem, which may inhibit cortical activity, causing changes to synaptic activity, extracellular ion concentrations, blood flow, and metabolism, thereby activating the trigeminovascular system, driving aura symptoms
What are some examples of positive and negative aura symptoms?
Positive symptoms:
- Scintillations (visual - flash of light)
- Pins and needles
Negative symptoms:
- Scotoma (partial loss of vision within a normal vision field)
- Numbness
S&S of headache (ictal)
Patho of headache phase
- mod-severe HA
- photo/phonophobia
- Nausea with/without vomiting
- cutaneous allodynia
- neck discomfort
- cranial autonomic symptoms - more a/w cluster HA
- cognitive symptoms
- fatigue
Neuropeptides (e.g., CGRP expressed in trigeminovascular and cranial parasympathetic systems) implicated in the sensitization of the central and peripheral trigeminovascular system, creating a state of hypersensitivity and contributing to pain + non-pain symptoms
Functional and anatomic abnormalities - a/w sensitization of primary nociceptors and central trigeminovascular system => mediate allodynia symptoms
Neural basis of photophobia - retinal and trigeminal nociceptive inputs converge in the thalamus + hypersensitive visual cortex
S&S of postdrome
Patho of postdrome
- photo/phonophobia
- nausea
- fatigue
- cognitive symptoms
- neck discomfort/stiffness
- difficulty concentrating
Unknown pathophysiology
S&S of interictal
Patho of interictal
- photo/phonophobia
- cognitive symptoms
- fatigue
Some regions of the brain (olfactory region, midbrain, hypothalamus, visual cortex) remain abnormally activated after HA cessation
Reduced cerebral bloodflow?
Main summary of headache patho:
Cortical spreading depression in the cortex – neurons depolarization, neurons hyperexcitation in the cortex and the brainstem, (inhibit cortical activity, activate trigeminovascular system), cause dilation of blood vessels, activation of nociceptors, activate ascending pain pathways
Migraine diagnosis (ICHD-3 criteria)
> = 5 migraine attacks during a lifetime that fulfills the following 4 criteria:
- duration 4h-72h
- > =2 of the following 4 characteristics
- unilateral
- pulsating
- mod-severe pain
- aggravation
- If no aura, >=1 of the following non-headache symptoms
- nausea and/or vomiting
- photophobia and phonophobia
- Not better accounted for by another ICHD-3 diagnosis
Episodic migraine
> = 5 migraine in lifetime, <15 MMD/MHD per month
Chronic migraine
> =15 MHD for >3 months, of which >=8 are MMD
Risk factors for progression of episodic to chronic migraine
- Baseline HA frequency
- Frequency in which individuals use acute meds
- Presence of cutaneous allodynia
- Presence of nausea
- Effectiveness of acute meds (less optimal response to acute med => more likely to progress overtime)
Episodic migraine without aura
At least 5 attacks fulfilling the following 4 criteria:
- duration 4h-72h
- > =2 of the following 4 characteristics
- unilateral
- pulsating
- mod-severe pain
- aggravation
- If no aura, >=1 of the following non-headache symptoms
- nausea and/or vomiting
- photophobia and phonophobia
- Not better accounted for by another ICHD-3 diagnosis
Episodic migraine with aura
At least 2 attacks fulfilling the following 3 criteria:
- At least 1 of the following fully reversible aura symptoms:
- visual
- sensory
- speech/language
- motor
- brainstem
- retinal
- At least 2 of the following 6 characteristics:
- at least 1 aura symptom spreads gradually over >=5min
- 2 or more aura symptoms occur in succession
- each indiv aura symptom lasts 5-60min
- at least 1 aura symptom is unilateral
- at least 1 aura symptom is positive
- the aura is accompanied, or followed within 60min, by headache
- Not better accounted for by another ICHD-3 diagnosis