Definition and Causes:

Definition:

Migraines refer to certain types of headaches that may occur on one side of the head (left or right, front or back) or maybe all around the head, often throbbing/pounding and may or may not be preceded by a brief aura (transient neurological disturbance). Auras are most often visual disturbances (e.g. Zigzag lines, or colorful shapes), but may also be sensory (tingling or numbness on face or limbs) or cognitive (“fogged head” feeling).

Causes/Triggers:

While the precise cause of migraine is not completely understood, it is thought to be due to the interaction between nerves and blood vessels overlying the brain and head. In general, the brain tissue itself has no feeling, and in fact, neurosurgeons can perform brain surgery on awake patients. However, in susceptible individuals, certain brain cells (neurons) may be sensitive to certain stimuli (foods, stress, colds/flu, hormones). These neurons communicate with blood vessels in the head, causing them to swell which causes pain, the swollen blood vessels may eventually begin to throb; hence the throbbing pain that migraine patients experience.

The auras might stem from the overactive neurons stimulating various areas of the brain (for example the areas responsible for vision or sensation) hence causing the temporary neurological symptoms that patients experience as the “migraine aura).

Triggers:

A number of conditions/factors may trigger migraine as follows:

1. Hormonal changes

• May occur just before or during menstruation
• During or around the time of menopause
• Oral contraceptive pill could potentially trigger or exacerbate migraine. The pill can potentially increase the risk of blood clotting in migraine patients, particularly in smokers and those over the age of 35 years

2. Environmental and weather changes

• Rainy or hot, humid conditions
• Change in altitude
• Seasonal changes

3. Diet

• Poor diet, missing meals, hunger
• Chocolates, cheese, alcohol, processed meat (salami pepperoni, etc.)
• MSG seasoning (frequently used in the preparation of Chinese food)
• Aspartame – in diet products
• Citrus, tomato ketchup, dairy products, and nuts
• Caffeine – in excess: In some patients, it may help relieve the headache while in others it may trigger or worsen the headache

Notes: Not all of the above food types will trigger migraine in susceptible patients. It may only be 1 or 2 of these; however actually detecting which ones are causing the problem could be tricky, as it is not when the food is being eaten, but more so when it is digested. In addition, it’s not every time that the particular food is consumed that it will initiate the headache. Keeping a diary of foods and events on the day of the headache would be helpful in identifying triggers.

4. Lifestyle

• Stressful situations
• Sleep disturbance-usually sleep deprivation/disruption, but excess, sleeping can also be a trigger. Changing sleep patterns with shift work
• Fatigue
• Physical exertion-“exercise-induced migraine”. Some individuals may have the tendency to develop headaches during exercise (e.g. running, weight lifting)
• Exposure to:
  • Bright lights, computer screens, loud noises
  • Checkered patterns on floors, blinds, games (crosswords)
  • Odours such as perfumes, smoke

Symptoms:

Possible warning symptoms (auras):

• Auras are brief often lasting only a few minutes, although in some atypical cases may be longer. They may precede the actual headache and maybe:
  • Visual (blurring, flashing lights, colorful patterns, blind spots)
  • Sensory (numbness or tingling on the face, arms, body)
  • Motor (mild weakness on one side of the face, arm or leg)
  • Cognitive (difficulty speaking, concentrating)
• Headaches may occur as the auras subside, but in some cases may be delayed several minutes
• Some patients may experience the auras without the headaches – these have been referred to by several names including “migraine equivalent”, “painless migraine”, “ocular or optical migraine” if primarily visual disturbance

Headache symptoms:

• Usually begins as a dull headache in one location (example temples or forehead or around eyes)
• Progressively worsens and may begin to spread
• Severe throbbing pain along one or both sides of the head may ensue
• Pain in and around the one or both eyes (retro-orbital pain)
• Patients may experience:
  • Nausea with or without vomiting
  • Sensitivity to bright lights, sound, and even odours
  • Chill, increased sweating and decreased appetite have been reported
• Typically lasts from 3 hours-3 days, but maybe longer in some individuals and can even develop into a chronic migraine

Following a migraine attack, patients may experience symptoms of fatigue, restlessness, irritability and neck tenderness

Investigations and Treatment:

Patients suspected of having migraine headaches would be asked questions relating to the history of the headaches – new or longstanding as well as a family history of headache:

History:

• New or longstanding
• Intermittent or chronic
• Inquire about potential triggers
  • Food, lifestyle, stress, weather changes, etc.
• Location of headache
• Quality of pain- throbbing or not
• Preceded by aura or not
• Occupation (eg noise environment, or exposure to chemical and odours)

Physical exam might include:

• Vital signs
  • High blood pressure (hypertension) can be a cause of headaches
  • Temperature – fevers can trigger headaches
• Neurological exam
  • Checks for changes in speech, vision, sensation, strength, coordination, reflexes, and walking. Detection of abnormalities might help to signify abnormalities within the brain. This exam is usually normal in migraine patients

Investigations:

Patients with intermittent headaches, associated with nausea/vomiting, light/sound sensitivity, which improves with rest, sleep, or pain medications; such patients are otherwise normal between these episodes, with normal physical examination, may not require any specific investigations. However, if there is a suspicion or concern of some other underlying cause, they may be requested to have brain imaging.

Computed Tomography (CT) Scan:

• This device uses x-rays. Patients will lie on a table with the head placed inside of the scanner (resembles a large donut). Computer analysis of x-ray images produces detailed images of the brain can be obtained in this fashion. The scanning time is usually very rapid (less than 1 minute). In special circumstances, a dye might be injected into the veins just before the scan (CT with contrast). This can sometimes help to identify areas of infection (abscesses), inflammation, tumors, etc.

CT Angiogram (CTA):

• A CT scan completed of the brain after dye has been injected into the veins (CT with contrast), however, the computer analysis focuses on the arteries (a type of blood vessel) in and around the brain. This can be used to help identify aneurysms

Magnetic Resonance Imaging (MRI):

• This does not use x-rays. Instead, MRI uses magnetic fields over the body. The device looks like a long cylindrical tube. Patients will lie on a table that slides into the hollow tube. Computer analysis of magnetic fields within the machine can generate images of the internal structures of the body’s organs, including the brain. MRI of the brain will show the normal structures, plus any area(s) of brain injury caused by the inflammation, tumors, previous stroke, etc. Patients must lie still inside the MRI machine for about 30-60 min. In some circumstances, a dye may be injected into the veins (enhanced MRI) just before the scan to help improve the detection of abnormalities. Patients who complain of claustrophobia or discomfort may be given a mild sedative to help relax prior to MRI scanning

MRI Angiogram (MRA):

• An MRI scan completed of the brain after dye has been injected into the veins (enhanced MRI). However, the analysis focuses on the arteries (a type of blood vessel) in and around the brain. This can be used to assess for aneurysms

MRI Venogram (MRV):

• An MRI scan completed of the brain after dye has been injected into the veins (enhanced MRI). However, the analysis focuses on the veins (a type of blood vessels) in and around the brain. This can be used to assess for clots within the veins of the brain that can lead to headaches

Cerebrospinal fluid (CSF) analysis:

Lumbar Puncture/Spinal tap

• This procedure is not routinely used in the assessment of a migraine but may be used in some circumstances, eg suspicion of brain infection or leakage of blood from an aneurysm. The purpose is to extract a small amount of fluid called cerebrospinal fluid (CSF) from the patient’s spine in the low back (lumbar) area and send for analysis. During the procedure, the physician will clean and drape the lumbar area. A local anaesthetic is administered over the skin where the needle is to be placed. Since the spinal cord does not extend down into the lower lumbar region there is little or no chance of causing injury to the spinal cord
• The extracted CSF is sent to the laboratory for analysis and is checked for protein, glucose, red and white blood cells and infectious organisms such as bacteria or viruses. In some circumstances, CSF can be used to check for cancer cells (if required)

TREATMENT:

There is no specific cure but treatment may take a pharmacological (medication) or non-pharmacological (no-medication use) approach.

Non-pharmacological measures

• Identifying and avoiding the trigger. The patient is advised to carry a diary and begin logging the events leading up the migraine, for example – type of foods consumes, missed meal, weather changes, stress factors, sleeping pattern, menstruation, etc.
• If avoidable triggers identified that patient can try to eliminate these to reduce the chances of migraine episodes

Pharmacological measures

Immediate or abortive therapy

• Used on an as needed basis
• Best time to use would be at the onset of the headache and may not be as effective if used after the headache intensifies
• Better results if used in conjunction with other strategies, such as resting in a quiet, dark environment, i.e removing/minimizing the external stimuli
• Usual analgesics
  • Acetaminophen (Tylenol)
  • Ibuprofen (Advil, Motrin)
  • Naproxen (Aleve)
  • Aspirin
  • Ergotamine
• Triptan agents. Usually more effective than over the counter formulations. Used on an as needed basis

• CGRP receptor antagonists (gepants)
  • Ubrogepant (Ubrelvy)
  • Rimegepant sulfate (Nurtec ODT)
• Ergots
  • Ergotamine (older agent) Not to be used in conjunction with triptan agents
• Narcotics
  • Codeine
  • Morphine
  • Meperidine (Demerol)
• Other agents
  • Acetylsalicylic acid-Caffeine-Butalbital (Fiorinal)

Prophylactic therapy

• Used on a daily basis in patients with frequent attacks
• Effective if used daily as prescribed without skipping doses
• Usually reduces the frequency and severity of headaches
• Better results if used in conjunction with avoidance strategies, ie avoiding known or potential triggers such as stress, sleep deprivation, etc.
• Multiple classes of drugs used
  • Tricyclic antidepressants: e.g. amitriptyline (Elavil), nortriptyline (Aventyl)
    • Not used for anti-depressant effects
    • May help induce sleep, hence may be a good choice for those with sleep deprivation
  • Beta-blockers: e.g. propranolol (Inderal); nadolol (Corgard) etc.
    • Heart medication used to control heart rate and blood pressure
    • Maybe a reasonable choice in patients with high BP
  • Calcium channel blockers, e.g. verapamil (Isoptin)
    • Heart medication used to control blood pressure
    • Maybe a reasonable choice in patients with high BP
  • Selective calcium channel antagonist: flunarizine (Sibelium)
    • Used to prevent migraine headaches
    • Not effective in treating a sudden migraine attack
  • Anti-convulsants: e.g. topiramate (Topamax), divalproex (Epival)
    • Antiseizure drugs
    • Used also for mood stabilization /depression
  • Anti-CGRP monoclonal antibodies:
    • Erenumab (Aimovig)
    • Galcanezumab (Emgality)
    • Fremanezumab (Ajovy)
    • Eptinezumab (Vyepti)
  • Others

Note: While there are potential side effects from using these medications, there are also beneficial effects. Consequently, the treating physician will assess the side effect risks versus the benefits in controlling symptoms and improving quality of life (risk versus benefit ratio), before recommending treatment. If the patient has other medical conditions or using other medications, these are taken into account when prescribing medications. The patient is advised to take note of and report potential side effects to the treating physician.

Risk Factors and Prevention:

Risk Factors:

• Family history of migraines
• Occupation – shift work, noise environment, exposure to strong odours (e.g. hairdressers), excess use of computers
• Other lifestyle factors – stress
• Women are more likely to suffer from migraines

Outcome:

Although there is no cure for migraine, careful monitoring of symptoms, including keeping a diary of diet and events in the hours preceding the migraine may lead to the identification of potential triggers. Adjustment in behavior with avoidance of triggers may help control migraine frequency and/or severity. Both abortive (for immediate relief) and prophylactic medical therapy can help to decrease migraine attacks and improve quality of life.