Orbitofrontal Cortex (OFC) Influence on Addictive Medication Overuse Headache (MOH) Deriving From Migraine

Medication Overuse Headache

Orbitofrontal cortex, Medication Overuse Headache, Chronic headache, withdrawal

Medication Overuse Headache (MOH) is an illness affecting about 1,5 % of the general population. It is characterized by chronic headache occurring for at least 15 days a month, by a use of antimigraine drugs during at least 3 months for more than 10 days a month (for ergots, triptans, opiate derivates and combined analgesics) or for more than 15 days a month (for simple analgesics). The chronic headache must have occurred during the period of antimigraine drug abuse and the headache must have returned to its episodical pattern after withdrawal of antimigraine drugs. But, about 50% of the MOH patients will relapse during the first year following the antimigraine drugs withdrawal. The pathophysiology of MOH is still largely unknown, and the role of antimigraine drug abuse in the transformation from migraine through MOH is not fully understood.

We recently explored cerebral metabolism in these MOH patients using (18F)FDG-PET (Fluoro Dexoxy Glucose Positon Emission Tomography) comparing them with controls. Results showed a hypometabolism in the OFC, which persist immediately after the antimigraine drugs withdrawal. A similar pattern is observed in varied substance related disorders and should be a marker of addictive behaviour. It can be linked with difficulties in the decision-making process, which can be explored by the Iowa Gambling Task (IGT) test. Several questions are still unanswered. What will this abnormality become in the long term ? Is it predictive of susceptibility for relapse? Can it be linked to a specific psychological profile (addictive behaviour)?

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