Chronic migraine

Chronic neurological disorder characterized by recurrent moderate to severe headaches often in association with a number of autonomic nervous system symptoms. The word derives from the Greek ἡμικρανία (hemikrania), “pain on one side of the head”, from ἡμι- (hemi-), “half”, and κρανίον (kranion), “skull”.

Chronic migraines (CM) affect approximately 2% of the population, resulting in significant disability, economic burden, and impairments in quality of life. Historical neurosurgical procedures, such as lesioning of the trigeminal dorsal root entry zone or neurolysis of the occipital nerve, have not gained favor because of procedural morbidity and poor durability, respectively. Occipital nerve stimulation is emerging as a potentially promising modality for the treatment of CM, with greater than 50% pain reduction in approximately 80% of patients in open-label trials and ∼40% of patients in randomized controlled trials. Mechanisms of neuromodulation remain unclear ¹⁾.

Migraine Classification

Typically the headache affects one half of the head, is pulsating in nature, and lasts from 2 to 72 hours. Associated symptoms may include nausea, vomiting, and sensitivity to light, sound, or smell. The pain is generally made worse by physical activity.

Up to one-third of people with migraine headaches perceive an aura: a transient visual, sensory, language, or motor disturbance which signals that the headache will soon occur.

Occasionally an aura can occur with little or no headache following it.

Migraines are believed to be due to a mixture of environmental and genetic factors.About two-thirds of cases run in families.

Changing hormone levels may also play a role, as migraines affect slightly more boys than girls before puberty, but about two to three times more women than men.

The risk of migraines usually decreases during pregnancy.

The exact mechanisms of migraine are not known. It is, however, believed to be a neurovascular disorder.

The primary theory is related to increased excitability of the cerebral cortex and abnormal control of pain neurons in the trigeminal nucleus of the brainstem.

Its molecular mechanisms remain poorly understood. There is some debate about whether migraine is a disease of vascular dysfunction or a result of neuronal dysfunction with secondary vascular changes. Genome-wide association (GWA) studies have thus far identified 13 independent loci associated with migraine. To identify new susceptibility loci, Gormley et al carried out a genetic study of migraine on 59,674 affected subjects and 316,078 controls from 22 GWA studies. We identified 44 independent single-nucleotide polymorphisms (SNPs) significantly associated with migraine risk (P < 5 × 10-8) that mapped to 38 distinct genomic loci, including 28 loci not previously reported and a locus that to our knowledge is the first to be identified on chromosome X. In subsequent computational analyses, the identified loci showed enrichment for genes expressed in vascular and smooth muscle tissues, consistent with a predominant theory of migraine that highlights vascular etiologies ²⁾.

see Migraine and Intracerebral hemorrhage.

see Migraine treatment.