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Orbitofrontal cortex involvement in chronic analgesic-overuse headache evolving from episodic migraine
Arnaud Fumal1, Steven Laureys, Laura Di Clemente
1Department of Neurology, University of Liège, Liège, Belgium. arnaud.fumal@ulg.ac.be
Brain : a Journal of Neurology
|December 7, 2005
Summary
Medication overuse causes reversible brain changes in migraineurs, except for persistent orbitofrontal cortex hypofunction. This persistent change may predispose some patients to recurrent analgesic overuse and chronic daily headache.
Area of Science:
- Neuroscience
- Neurology
- Medical Imaging
Background:
- Medication overuse transforms episodic migraine into chronic daily headache through unknown mechanisms.
- Understanding the brain alterations in medication overuse headache (MOH) is crucial for developing targeted treatments.
Purpose of the Study:
- To identify candidate brain regions involved in the transformation of episodic migraine to chronic daily headache due to medication overuse.
- To investigate the metabolic changes associated with analgesic overuse in migraine patients.
Main Methods:
- Utilized 18-fluorodeoxyglucose Positron Emission Tomography (18-FDG PET) to measure glucose metabolism.
- Assessed 16 chronic migraineurs with analgesic overuse before and after 3 weeks of medication withdrawal.
- Compared metabolic data with a control group (n=68).
Main Results:
- Before withdrawal, chronic migraineurs exhibited hypometabolism in the bilateral thalamus, orbitofrontal cortex (OFC), anterior cingulate gyrus, insula/ventral striatum, and right inferior parietal lobule, with hypermetabolism in the cerebellar vermis.
- Following medication withdrawal, most metabolic abnormalities resolved, except for the OFC, which showed further decreased metabolism.
- Orbitofrontal hypometabolism was more pronounced in patients overusing combination analgesics or ergotamine-caffeine preparations.
Conclusions:
- Medication overuse headache is linked to reversible metabolic changes in pain processing areas, similar to other chronic pain conditions.
- Persistent orbitofrontal hypofunction, observed after withdrawal, may indicate a predisposition to recurrent analgesic overuse and drug dependence in some migraineurs.