What is a Migraine?
Migraine is a complex neurological disorder that affects multiple areas and functions of the brain.
Migraine affects over 13% of the global population with females 2 times more likely than males (~18 vs 10%) to suffer from the disease.
An individual is said to have migraine if within his/her lifetime there have occurred 5 or more attacks of headache, each lasting 4-72 hours, with attacks of typically one sided, throbbing head pain, severe enough to restrict routine daily activity, and accompanied by nausea or light/sound sensitivity.
Symptoms of Migraine
The headache may be preceded by a prodromal (warning) phase and followed by a postdromal (recovery) phase. Symptoms of these phases include hyperactivity, hypoactivity, mood changes such as depression and irritability, food cravings, increased yawning, fatigue, euphoria, and neck stiffness.
Typical migraine aura occurs before or during migraine and is experienced by about 25% of all migraine sufferers. The experience can be visual, sensory or result in problems with speaking or word finding.
Visual changes are the most common form of aura, occurring in more than 90% of those migraineurs with aura. There can be spots, zigzags or crescents, flashes of light, or losing sight partially or fully. The shimmering that occurs in aura when vision is obscured is referred to as a ‘scintillating scotoma’, where a scotoma is a blind spot in vision. Sensory changes are the second most frequent form of typical migraine aura. These may consist of tingling or numbness on one side of the face, body, or tongue.
A third form of typical aura results in problems with speech or language, such as being temporarily unable to speak, slurred speech, being unable to find the right word, or using the wrong word to express an idea. All 3 common types of aura are considered typical if any one of them lasts between 5 minutes to one hour.
Causes of Migraine
The aetiology of migraine is multifactorial and influenced by diet, lifestyle factors, and hormonal changes. Migraine has a clear tendency to run in families and this suggests a strong genetic component. The risk for the common forms of migraine-migraine with aura and migraine without aura-is increased when a first degree relative has migraine with heritability estimates of 50-65%.
The disorder likely reflects a genetically induced hypersensitivity involving neurons located within the central nervous system. If a genetically primed neuron is triggered by a change in the external environment (eg drop in barometric pressure) or internal environment (eg sudden drop in oestrogen level), that neuron may activate and trigger its neighbouring neurons to join in, including the pathways in the brain that conduct head pain to produce a migraine attack.
Chronic Migraine vs other migraines (Episodic)
Chronic Migraine
Chronic Migraine is defined as 15 or more headache days per month, of which at least 8 were migraine days. It affects between 5-8% of people with migraine. Episodic migraine is defined as 4-14 migraine days per month. It affects more than 90% of people with migraine.
Patients with chronic migraine represent the most severe, and disabled segment of the migraine spectrum. A patient with chronic migraine is a patient with migraine who has progressed to a very frequent headache pattern. When these patients are asked, ‘On how many days a month are you completely headache free?’, the answer will often indicate that the patient has more headache days a month than initially thought, as patients may not have been considering their milder headache days.
Other Migraines (Episodic)
These frequent headaches need not all have migrainous features (ie pulsating, one sided pain, light and noise sensitivity, and or nausea), and as noted can be somewhat milder in nature. Diagnosis by a Neurologist is an important step in management, for if the patient is incorrectly diagnosed with chronic tension type headache, then management will not be suitable.
Central sensitization of the pain systems likely plays an important role in the development of chronic migraine, and these patients have been shown to have diminished pain thresholds on sensory testing, as compared to subjects without this condition.
Risk factors for progression to chronic migraine include obesity, caffeine overuse, stressful life events, and acute medication overuse. Head and neck injuries can also cause rapid transformation of episodic migraine to chronic migraine.
What should be done to treat migraines, and when?
At our migraine clinic we advise our patients that the key to effective management of an acute migraine attack is early recognition and treatment. As a migraine evolves its responsiveness to treatment decreases. Medications developed specifically for acute migraine treatment, are far more effective if taken when the headache is still early, and mild to moderate in intensity, rather than later, when moderate to severe in intensity. Delaying taking acute migraine medication risks not resolving the headache completely, and this can be linked to the early recurrence of further severe headaches.
There are two types of migraine-Episodic migraine (high frequency or low frequency) and Chronic Migraine. Each of these subtypes are determined by the frequency of headache days. Chronic Migraine is defined as 15 or more headache days per month, of which at least 8 were migraine days. Episodic migraine is defined as 4-14 migraine days per month.
If your migraine is either chronic or high frequency episodic, preventative therapy is required to help you achieve remission back to low frequency episodic migraine. Preventative therapy for Migraines typically will involve non drug measures as well as medications.
Non drug treatment examples include an aerobic conditioning program, avoidance of triggers, eating healthy, regular spaced meals, allowing for relaxation time, and attention to good sleep hygiene. Medication treatment for chronic migraine or high frequency episodic migraine requires effective use of drugs for acute migraine treatment and medications for prevention.
