Neuroimaging Findings in Patients with Medication Overuse Headache

AbstractMedication overuse headache (MOH) is a secondary headache syndrome defined as the deterioration of the headache associated with the overuse of analgesics. The prevalence of MOH is 1 –2% in the general population and even up to 50% in special clinics. Overuse of abortive medications is highly associated with chronic daily headaches and also a known risk factor for headache evolution. Possible mechanisms include neural plasticity changes such as sensitization and defective endo genous pain inhibition. Psychological studies have suggested dependence, even addiction, in patients with MOH. Neuroimaging studies have provided valuable information concerning MOH pathophysiology. Magnetic resonance imaging analyzed by voxel-based morphometry showed gray matter volume changes in b rain areas participating the pain modulations. Changes of brain function at similar areas have been revealed by positron emission tomography and functional magnetic resonance imaging studies. Many of these changes were correlated with either headache and/or analgesics parameters such as frequency an d duration. These changes are typically reversible after successful treatment. Though the cause or consequence debate remains unsettled, we are more in favor of these findings as maladaptive changes to the frequent headaches or medication overuse. Of these brain areas involved in MOH, orbitofrontal cortex is of interest in several ways. In an early positron emission tomography study, the hypometabolism p...
Source: Current Pain and Headache Reports - Category: Neurology Source Type: research