Mechanism of Chronic Migraine

Abstract

Chronic migraine typically evolves from episodic migraine over months to years in susceptible individuals. Headaches increase in frequency over time, becoming less intense but more disabling and less responsive to treatment. Results of electrophysiologic and functional imaging studies indicate that chronic migraine is associated with abnormalities in the brainstem that may be progressive. Additionally, chronic migraine is associated with a greater degree of impairment in cortical processing of sensory stimuli than is episodic migraine, perhaps due to a more pervasive or persistent cortical hyperexcitability. These findings fit with the model of migraine as a spectrum disorder, in which the clinical and pathophysiological features of migraine may progress over time. This progression is postulated to result from changes in nociceptive thresholds and ensuing central sensitization caused by recurrent migraine in susceptible individuals, for whom a variety of risk factors have been described. This may lead to changes in baseline neurologic function between episodes of headache, evident not only in electrophysiologic and functional imaging studies, but also as an increase in depression, anxiety, nonhead pain, fatigue, gastrointestinal disorders, and other somatic complaints that may occur after years of episodic migraine. From the current research and migraine models, a conceptualization of chronic migraine, in which relatively permanent and pervasive central changes that warrant novel and tolerable treatments have occurred, is emerging. This model also implies that prevention of chronic migraine is an important goal in the management of episodic migraine, particularly in individuals who exhibit risk factors for chronic transformation.

Incidence and Risk Factors of Chronic Daily Headache in Young Adolescents: A School Cohort Study

“…Most of them (n = 57, 90.5%) completed a headache diary for 1 month. Their median headache frequency during the past 3 months was 16 days per month (IQR [15][16][17][18][19], and median PedMIDAS score was 9 (IQR 2-15). Five (7.9%) incident CDH subjects overused acute medications.…”

“…5,16 Higher headache frequency may indicate central sensitization of nociceptive neurons in the trigeminal pathway, thus paving the way to headache chronification and the development of CDH. 17 2. Migraine or probable migraine at baseline: CM represents a natural evolution from episodic migraine; a baseline diagnosis of migraine was therefore a sine qua non and predictor for CM and CDH in this study.…”

Amitriptyline and aerobic exercise or amitriptyline alone in the treatment of chronic migraine: a randomized comparative study

“…Chronic migraine is a disabling disease, with a negative impact on the individual's ability to perform daily activities 1 affecting 2% to 3% of the general population 2 and with the prevalence in Brazilian population of 5% 3 . The quality of life in patients with chronic migraine have significant impairments compared to the healthy population and also when compared to other chronic conditions 4 , and 85% of these patients have disabling attacks, justifying the introduction of prophylactic treatment 5 .…”

Expert Panel Consensus Recommendations for the Pharmacological Treatment of Acute Pain in the Middle East Region

“…The clinical implications of hyperalgesia and allodynia are important, since individuals who develop sensitization are at high risk of progressing from acute to chronic pain. 40,41 Persistent acute pain that becomes chronic is associated with several negative consequences, including significantly reduced quality of life, increased disability and risk of depression. 42 -44 Despite considerable conflicting data, which recent reviews have attributed to problems with study designs, it appears that the aggressive early treatment of acute pain may reduce the likelihood that chronic pain will develop.…”