Glossary

Central sensitisation

Increased pain sensitivity due to altered processing of sensory input in the brainstem (principally the trigeminal nucleus caudalis), which is hypothesised to account for many of the temporal and symptomatic features of migraine.

CGRP, calcitonin gene-related peptide

Neuropeptide synthesised and released from sensory nerves in the central nervous system and gastrointestinal system. Inflammatory substances in the CNS and activation of capsaicin receptors in the gastrointestinal system stimulate CGRP release. CGRP dilates microvasculature in the CNS and is considered to transmit nociceptive signals during migraine.

CGRPR, CGRP receptor

Formed by a combination of the ligand binding calcitonin-like receptor (CLR), receptor activity-modifying protein 1 (RAMP1), and CGRP receptor component protein (RCP).

CM, chronic migraine

A distinct and relatively recently defined sub-type of chronic daily headache. The International Headache Society defines chronic migraine as more than 15 headache days per month over a three-month period of which more than eight are migrainous, in the absence of medication over use.

CSD, cortical spreading depression

Propagating wave of depolarisation of neurones and glial cells that spreads across the cerebral cortex. The spreading of this wave is hypothesised to activate trigeminal nerve afferents, causing inflammatory changes in pain-sensitive structures that create migraine headache.

Drug–drug interactions

Modification of the effect of a drug when administered with another drug. In migraine, most acute treatments are 5-HT agonists which cause vasoconstriction and so when migraine-specific agents are co-administered with drugs with vasoconstrictive properties, or with drugs which inhibit the metabolism of the migraine-specific agents, there is a risk of interactions occurring which produce manifestations of excessive vasoconstriction.

Episodic migraine

A migraine sub-type, which is defined by the International Headache Society as less than 15 headache days per month.

HALT, Headache-Attributed Lost Time index

Adaptation of the Migraine Disability Assessment (MIDAS) instrument which estimates productive time lost due to the disabling effect of headache. There are different HALT indices which examine disability over different time periods; HALT-90 over 3 months, HALT-30 over 1 month and HALT-7/30 enquires into lost days in the preceding month and week.

Hemiplegic migraine

Temporary weakness on one side of the body which forms part of the migraine attack. This weakness can involve the face, arm or leg and be accompanied by numbness, or pins and needles.

HRQoL, health related quality of life  

An assessment of physical, mental, emotional, and social functioning. It goes beyond direct measures of population health, life expectancy, and causes of death, and focusses on the impact health status has on quality of life.

5-HT, 5-Hydroxytryptamine or serotonin

Monoamine neurotransmitter and vasoconstrictor primarily found in the gastrointestinal tract, blood platelets, and the central nervous system. Triptans are 5-HT1 agonists which relieve migraine symptoms, possibly by relieving swelling and narrowing blood vessels.

mAbs, monoclonal antibodies

Produced by hybridoma cells (fusion of a tumour cell with an antibody-producing cell) which divide indefinitely to produce antibodies specific to the antigen.

MOH, medication-overuse headache

Dull constant headache, often worse in the morning, caused by frequent use of abortive medications for migraine.

Paraesthesia

Abnormal or unpleasant sensation often described as numbness or a prickly, stinging, or burning feeling (‘pins and needles). Paraesthesia is a very common symptom of migraine.

Phonophobia

Increased sensitivity to sound, often an early symptom of migraine.

Photophobia

Increased sensitivity to light, one of the most common symptoms of migraine.

TGVS, trigeminovascular system

System of small sensory neurones that originate from trigeminal ganglion and upper cervical dorsal nerve roots which innervate cerebral blood vessels, pial vessels, dura mater, and large venous sinuses. The projections from upper cervical nerve roots and trigeminal ganglion converge at the trigeminal nucleus caudalis (TNC), which explains the distribution of migraine headache in the anterior and posterior part of the head and upper neck. Nociceptive information is also transmitted to the limbic system, which explains the emotional response in migraine headache.

TTH, tension type headache

Most common type of headache (normal, everyday headache). Like migraine, TTH are not caused by an underlying condition and there is an overlap in the triggers, as both may be brought on by stress or tiredness. TTH, however, generally only produce mild to moderate pain.

VNS, vagus nerve stimulation

Non-invasive vagus nerve stimulation can be achieved using a hand-held device that is gently pressed against the neck by a patient who self-administers a prescriptive dose of VNS therapy through the skin. The FDA has approved the use of VNS for the acute treatment of pain associated with episodic cluster headaches and it is also being evaluated in clinical trials for migraine.

YLDs, years lived with disability

Years Lived with Disability is a scale used to compare disease burden in populations. YLDs are calculated by multiplying the prevalence of a disorder by the short- or long-term loss of health associated with that disability (the disability weight).

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