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MIGRAINE
Nin BajajNeurologist, Nottingham University Hospitals,Clinical Lead Neurology Derby Hospitals NHS Foundation Trust.
Migraine
• Isn’t just headache
• Aura + headache
• You can have aura + no headache
• Headache and no aura
• Aura with headache
Migraine- mechanisms• Missense mutations in the gene encoding the 1A subunit of the P/Q type
voltage-gated calcium channel are present for 55% of FHM • how the FHM mutations influence cellular excitability is obscure• mutations in CACNA1A are also associated with the episodic ataxia
syndrome EA-2, the spinocerebellar ataxia syndrome SCA-6, and idiopathic generalized epilepsy
• The second FHM gene to be described was ATP1A2 encoding the α 2 subunit of Na/K ATPase
• Other allelic conditions include alternating hemiplegia of childhood, basilar type migraine, and migraine without aura
• 3rd FHMgene is SCN1A encoding the pore-forming α1 subunit of neuronal voltage-gated sodium channel Nav1.1.
• Allelic conditions include generalized epilepsy with febrile seizures plus (GEFS) and severe myoclonic epilepsy of infancy
• Sporadic migraine- often a family history• May well be a channelopathy
Migraine- mechanisms
• TMS experiments demonstrate increased cortical excitability in CM and EM
• Topiramate, a GABA agonist, reduces cortical excitability• Brainstem PAG- Electrode stimulation or lesion in PAG
can induce migraine; mutation of PAG Ca channels may facilitate trigeminal nociceptive transmission- leading to throbbing facial pain; PET studies show increased PAG, locus caeruleus and dorsal raphe blood flow in a migraine attack; high PAG tissue iron levels in CM may be a surrogate biomarker of increased PAG metabolic activity;
Migraine- aura and CSD
• Leao 1940. Repetitive electrical stimulation of cortex in animal models showed period of electrical inactivity- spreading at 3 mm/min- CSD
• Speed of propagation of visual (and sendory aura) in migraine same speed
• Proven by BOLD fMRI in occipital cortex in visual migraine aura
Migraine- CSD
• CSD appears to trigger vasodilatation of meningeal blood vessels
• This in turn triggers pial nociceptive input to the trigeminal nucleus
Migraine- mechanisms and concepts
• Allodynia in CM
• Central or peripheral sensitisation
• Cross over with CPS
• Cross over with CFS
Migraine
• 5 basic kinds of aura
• Sensory- tingling, can be painful, can be just at night, can get a dead arm, patchy, variable, frequent, good days and bad days, often cheiro-oral
• Motor- weakness of a limb or limbs, can be clumsiness (dropping things)
Migraine
• Vertebrobasilar- unsteady, like a boat, mal debarquement, sometimes vertigo, worse on head turning or bending, can cause syncope
• Migrainous syncope- frequent blackouts, headache occurs before or after, can be prolonged apparent LOC
Migraine
• Visual- the commonest in younger patients, lights, colours, shapes, fortification spectra, scotomata, simple blurring
• Speech- slurring, reduced verbal fluency, word finding problems
Migraine
• Episodic Migraine and Chronic Migraine
• Low frequency EM (<10 attacks/month)
• High frequency EM (10-14 attacks/month)
• CM- >15 attacks/month
• CM- stress, stress, stress; poor sleep pattern, pain-killers,triptans, menstrual, weight gain, snoring, depression, age
Migraine
• Work-up
• MRI- exclude demyelination, vascular aetiology
• DDx over the years-
• Acoustic neuroma in vertebrobasilar migraine
• 2x pituitary tumours
• 2x MS patients
Migraine
• Treatment strategies
• EM- triptans, high dose aspirin
• Offer prophylaxis at 4-5 headache days/month
• CM- topiramate, zonisamide, amitriptyline, lamotrigine