Medically Fit For Exams
Medically Fit For Exams

Migraine

Definition

  • A headache typified by pulsation of pain, may be unilateral, often associated with gastrointestinal symptoms, lasting up to 3 days. Occur in attacks, with no symptoms between attacks.
  • May or may not have aura

 

Risk factors

  • Family history
  • Female
  • Stress
  • Depression
  • Smoking
  • Inactivity
  • Head trauma
  • Raised CRP
  • Overweight
  • Hypertension
  • Hypercholesterolaemia
  • Impaired insulin sensitivity
  • Stroke
  • Coronary heart disease
  • Hormonal changes, including pregnancy and menopause
  • Mitochondrial disorders (eg MELAS, CADASIL)
  • Genetic vasculopathies

 

Differential diagnoses

  • Tension headache
  • Cluster headache
  • Subarachnoid haemorrhage
  • Raised ICP/tumour
  • Temporal arteritis
  • Medication overuse headache
  • Meningitis

 

Epidemiology

  • More common in women, 2:1
  • Global incidence of around 15%
  • Chronic migraine affects 2%
  • Often begins in adolescence
  • 80% have migraine without aura
  • 15-20% have migraine with typical aura
  • Up to 5% have ‘silent migraine’ : aura with no headache

 

Aetiology

  • Strong genetic componenet: 70% have 1st degree relative also with migraine, risk increased 4x if family member has migraine with aura
  • Cause not well understood

 

Clinical features

  • Migraine can be with or without aura
  • IHS diagnostic criteria for migraine without aura:
    • A: At least 5 attacks fulfilling criteria below
    • B: Headache attack lasting 4-72 hours untreated/unsuccessfully treated
    • C: Headache has at least 2 of:
      • Unilateral
      • Pulsating
      • Moderate to severe pain intensity
      • Aggravated by routine physical activity/causes avoidance
    • D: At least one of:
      • Nausea and/or vomiting
      • Photophobia and phonophobia
    • E: Not attributed to another disorder
  • Migraine with aura diagnosed as above, but with addition of aura
    • Aura develops over a few minutes and doesn’t usually last over an hour
    • Aura is a neurological symptom, can be visual, auditory or motor, eg:
      • Scintillating scotoma (flickering/expanding area of lights, usually with jagged edges)
      • Tunnel vision
      • Homonymous hemianopia
      • Blindness
      • Parasthesia, usually follows visual aura, and spreads over the body
      • Feeling of heaviness in limbs
      • Aphasia
  • Aura is not the same as prodrome, which is experienced by up to 60% of sufferers in the build-up to a migraine:
    • Increased sensitivity to light, sound and smell
    • Lethargy/yawning
    • Food craving or anorexia
    • Mental/mood changes
    • Thirst and polyuria
    • Fluid retention
    • Constipation or diarrhoea
  • Migraine pain usually builds up over 1-2 hours
  • Throbbing, unilateral pain
  • Nausea + vomiting in 50-80%
  • Hemipariesis (defines Hemiplegic Migraine)
  • Triggers for migraine are less common than many believe, they include:
    • Alcohol
    • Hormone changes, eg menstruation
    • Change in habit, eg missing sleep, missing meals, lie-ins
    • Food (commonly cheese)
    • Relaxation after stress
    • Strenuous exercise

 

Pathophysiology

  • Not well understood
  • Best current theory is ‘Neurovascular theory’
    • Migraine initiated by complex series of neural and vascular events
    • Primarily neural, with vascular changes secondary
    • Extracranial vessels expand and become pulsatile during attack
  • Cortical spreading depression (CSD) is a leading theory of migraine with aura
    • Wave of neuronal excitation spreading from origin that is associated with aura
    • Causes glutamate release (excitatory neurotransmitter)
    • CSD activates trigeminovascular system, which leads to increased pain perception through production of certain chemokines such as substance P and NO
    • This produces vasodilation, and further pain
    • PET scans show reduced blood flow during aura, can lead to hypoxia
  • Number of other theories

 

Investigations

  • Migraine is a clinical diagnosis
  • Visual field testing
  • ESR + CRP
  • Neuroimaging in cases where tumour/brain pathology is suspected, or temporal arteritis
  • Investigations are to rule out other causes of symptoms

 

Management

  • Lifestyle modifications such as removing any triggers identified by a trigger diary
  • Maintain routine
  • Drug therapy can be abortive or preventative. Abortive methods are trialled first.
  • Abortive treatments:
    • First: Over the counter analgesia: aspirin or ibuprofen
      • Anti-emetic can be added if necessary for nausea/vomiting, eg domperidone, prochlorperazine
    • Then further NSAIDS, eg naproxen, tolfenamic acid, diclofenac with antiemetic eg metoclopramide, domperidone
    • Then try rectal diclofenac and domperidone
    • Then try triptans: sumatriptan (oral, nasal spray or subcutaneous), zolmitriptan (oral or nasal spray), rizatriptan, naratriptan, almotriptan, eletriptan, frovatriptan, ergotamine tartrate
    • Then try combinations eg triptan with naproxen
  • Preventative treatments to reduce number of attacks:
    • First line: beta-blocker, atenolol is most effective, or bisoprolol
    • Amitriptyline if comorbid tension headache, sleep difficulties, depression, chronic pain
    • Second line: topiramate and sodium valproate (antiepileptics)
    • Third line: other antiepileptics eg gabapentin

 

Prognosis

  • 7th leading cause of global disability
  • In UK 25 million days of work/school missed because of migraine
  • Increases risk of stroke and coronary heart disease by around 100%, more so for migraine with aura

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