###### Created: 2023-10-14 14:10 ###### Areas & Topics: #medicine #neurology ###### Note Type: #permanent ###### Connected to: [[Headache]] - A migraine is a type of primary headache. - The term 'migraine' originally came from Galen in Ancient Greece as 'hemikrania' (meaning 'half-head') and was then bastardised over time to 'hemicrania' in Latin, then 'migrana' and finally 'migraine' in French, where the term has been adopted from now. - It is primarily characterised as a moderate-to-severe headache which is most often unilateral and causes nausea and sensitivity to light (photophobia) and/or sound (phonophobia) ### Aetiology - The exact cause and mechanisms underlying migraine aren't currently known. - There is evidence to suggest a strong genetic component related to developing migraine, - This is shown by the fact that a significant proportion of migraine sufferers have a first-degree relative who has the condition themselves, and through twin studies (especially when looking at monozygotic twins). - Despite this correlation though, no specific genes or loci have been associated with any type of migraine specifically as of yet. ### Triggers - Migraines have been shown to be precipitated or triggered due to presence of withdrawal of certain things - 76% of patients report having particular triggers to their migraines. Some more common and probable examples (i.e. examples which have more evidence to suggest they are a true trigger) include: - Stress (a very commonly reported trigger) - Disturbed Sleep - Hormonal Changes (e.g. menstruation, ovulation, pregnancy) - Dietary Factors - Skipped meals - Excessive Caffeine Intake - Alcohol Use (specifically wine) - Weather changes - Sensory Changes - Exposure to light - Heat - Odours - Neck Pain ### Pathophysiology - The mechanism of what goes in the build-up and instance of a migraine is still largely unknown - It was previously theorised that the headache part of the migraine was caused due to vasodilation of certain vessels in the brain and migraine aura was caused by vasoconstriction, however this has been disproven since. One idea regarding migraine pathophysiology is: - The trigeminal nerve (CN V) is an entirely sensory nerve which innervates the majority of the face and parts of the meninges (the pia and dura mater). - It is thought that opening of [[Pannexin-1]] mega channels and subsequent activation of [[Caspase]]-1 causes the eventual release of inflammatory mediators in the brain. - These mediators may then go on to stimulate these afferent nerve fibres in multiple different ways, leading to changes in the brain that lead to aura and headache in migraine. **Cause of Aura** - After nerve fibres and various structures are stimulated, it is generally thought that these changes in the brain lead to cortical and/or subcortical spreading depression (CSD), also known as the [[Cortical Spreading Depression of Leão (CSD)]]. - In patient's with aura, it is thought that CSD in the areas which are perceived consciously lead to aura, whereas Spreading Depression in subcortical or non-consciously perceived areas, such as the cerebellum, underlies migraine without aura. **Cause of Headache** - Pain in migraine is most commonly unilateral and towards the anterior surface of the head. - It is thought that inflammatory processes and stimulation of the ophthalmic division of the trigeminal nerve (V1), which supply this anterior area mainly, may cause the headache in migraine. - The course of trigeminal nerve fibres also go towards the posterior of the head and thalamus, so nociception in these areas could also explain migraine headache also being painful in other areas. ### Clinical Features - Unilateral/Asymmetric Headache (more commonly bilateral in children) - Pulsatile Headache (described as throbbing or banging) - Moderate to Severe Pain Intensity - Nausea and/or Vomiting - Photophobia (aversion to light), Phonophobia (aversion to sound) and/or Osmophobia (aversion to smells) - patients will typically want to go to a dark, quiet room during attacks - Sensitivity to Movement - patients will typically want to lie down or be still during attacks #### Aura - Aura is seen in 1/3rd of patients. - It typically lasts 5 to 60 minutes and precedes the onset of a migraine headache (the headache usually occurs within 60 minutes of the end of aura). - Aura symptoms are also typically fully reversible following the end of the migraine. - Aura is most commonly visual and presents as a hemianopic visual disturbance or [[Spreading Scintillating Scotoma]]. - It can also be sensory (numbness, pins and needles etc.) or present with speech and/or language symptoms such as dysphasia (issues forming speech). - More atypical symptoms of aura do exist and include focal neurological deficits such as motor weakness or double vision and decreased consciousness (these should be more thoroughly assessed and investigated to rule out potential underlying diagnoses). #### Prodrome and Postdrome - Prodromal symptoms can occur up to 1 to 2 days before the onset of migraine and can include fatigue, yawning, neck stiffness and poor concentration. - Postdromal symptoms will usually come on and last 48 hours following headache resolution, and can include fatigue, elated mood or depressed mood. ### Epidemiology - Migraine has a prevalence of around 1 in 7 people. - It is 2 to 3 times more common in women than men. - It most commonly occurs between 25 and 55 years old. ### Investigations - The diagnosis of migraine is an entirely clinical diagnosis based on the patient's symptoms and presentation, therefore thorough history taking and neurological exam are the main investigations. - Other investigations will be those which rule out other underlying causes of a patient's symptoms. ### Management ***Lifestyle Management*** - Ask the patient to keep a headache diary to track attacks and triggers - Ask the patient to avoid known triggers if possible and optimise factors including stress, sleep, diet etc. ***Acute Management*** - For treating migraines acutely, a triptan (see [[Triptans]]) alongside simple analgesia (either an NSAID or paracetamol) is first-line - You can consider also adding an anti-emetic (such as prochlorperazine or metoclopramide) if suitable Simple Analgesia - Ibuprofen 400mg (see [[Non-Steroidal Anti-Inflammatory Drugs (NSAID's)]]) - [[Aspirin]] 900mg (see [[Non-Steroidal Anti-Inflammatory Drugs (NSAID's)]]) - [[Paracetamol (Acetaminophen)]] 1000mg Triptans - Oral Sumatriptan 50 to 100mg (First Line) - Nasal Triptans (recommended by NICE to be used in adolescents aged 12 to 17, most likely because there is evidence to suggest that acute migraine may lead to dysmotility and reduced GI absorption and therefore nasal administration may be more effective) ***Prophylactic Management*** Preventative treatment for migraine should be offered if: - Migraines are significantly impacting a person's quality of life - There is a risk of medication overuse headaches due to use of analgesia during migraines - A person is contraindicated or cannot tolerate acute treatment First Line treatment options include: - Propanalol 80 to 160mg OD in divided doses - Topirimate 50 to 100mg OD in divided doses (should be avoided in women of childbearing age as it is teratogenic and can reduce the effectiveness of hormonal contraception) - Amitriptyline 25 to 75mg ON Additional Prophylactic Treatments - Behavioural Interventions - Acupuncture for up to 10 sessions over 5 to 8 weeks (if propanalol and topirimate are unsuitable) - Riboflavin 400mg OD (can be effective for some people in helping with migraines but should be carefully used in women planning pregnancy or already pregnant as riboflavin at high doses can be potentially teratogenic) N.B. You should advise patients that prophylaxis aims to reduce the severity and frequency of migraines but does not mean they'll be in total remission. Additionally, prophylactic treatment should only be started if the rewards from treating the migraines outweigh the risk of adverse effects. ***Menstrual-Related Migraine Management*** For women with menstrual-related migraines who don't respond to lifestyle or acute management, consider using: - Frovatriptan 2.5 mg BD (on the days migraine is expected or from two days before until three days after bleeding starts) - Zolmitriptan 2.5 mg BD or TDS (on the days migraine is expected or from two days before until three days after bleeding starts) N.B. Frovatriptan and Zolmitriptan are recommended as they have been shown to have a lower chance of causing a rebound headache and have longer half-lives, making them particularly effective for treating menstrual-related migraines compared to other triptans ### Prognosis - A good proportion of patient's will experience remission or reduction of migraine symptoms as time goes on. - Women tend to see improvements following menopause. - Women in pregnancy who have migraines are likely to improve in the second or third trimester. ### Resources BASH National Headache Management - https://bash.org.uk/wp-content/uploads/2023/02/01_BASHNationalHeadache_Management_SystemforAdults_2019_guideline_versi-1.pdf https://www.ncbi.nlm.nih.gov/books/NBK560787/ NICE CKS Migraines - https://cks.nice.org.uk/topics/migraine/management/adults/ ICHD 3 Migraines - https://ichd-3.org/1-migraine/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3444225/ PassMedicine - Extended Textbook - Migraine