Cutaneous allodynia may occur from a medical disorder, result from past trauma or injury, or present idiopathically. Anything that causes neuropathy may also have an association with allodynia. In migraine, cutaneous allodynia can occur when the secondary pain pathways of the trigeminothalamic system become sensitized during a migrainous episode. This reflects the perception of pain in response to non-noxious stimuli and may be considered a clinical marker for central sensitization. Cutaneous allodynia affects 63% of patients with migraines in the population and is associated with frequency, severity, disability, and associated symptoms of migraine. Allodynia has been identified as an independent predictor of an increase in number of migraine days and migraine chronification.
Poor sleep quality and sleep disorders are considered risk factors for migraine transformation. The CaMEO study showed that patients with chronic migraine more frequently reported sleep apnea or were more likely to be at high risk for sleep apnea than patients with episodic migraine. Patients with chronic migraine also showed poorer sleep quality compared with patients with episodic migraine, with higher rates of sleep disturbance, snoring, shortness of breath, somnolence, and poor sleep adequacy. The relationship between obstructive sleep apnea and migraine progression is not clearly understood, but some physiologic changes, such as fluctuations in intracranial and arterial pressure during snoring, hypoxia, hypercapnia, fragmentation of sleep, and increased muscle activation during awakening due to apnea, may underlie this relationship.
Genetic factors seem to be a component in determining the risk of developing episodic migraine with or without aura. However, the role of a genetic influence on the progression of episodic migraine into chronic migraine has not been elucidated. Few studies have specifically assessed genetics in chronic migraine and the relevance of their findings must be interpreted with caution.
Patients with chronic migraine significantly more often report comorbidities than patients with episodic migraine, such as psychiatric disorders, head and neck injuries, cardiovascular disease, metabolic syndrome, asthma, sleep apnea, and other pain syndromes. If untreated, these comorbidities can increase the risk for migraine chronification and migraine-related disability, leading to a decrease in quality of life and adversely affecting treatment outcomes.
Furthermore, in the CaMEO study, all comorbidity classes were associated with a statistically significant risk for progression to chronic migraine. However, the participants with the most comorbidities were approximately five times more likely to progress to chronic migraine than those with the fewest comorbidities.
Generally, other headache disorders are not as strongly associated with comorbidities as is chronic migraine.
Learn more about the risk factor for developing chronic migraine.
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Cite this: Jasvinder Chawla, Heidi Moawad. Fast Five Quiz: Overview of Chronic Migraine - Medscape - Jun 27, 2023.