Clinical features, pathophysiology, and treatment of medication-overuse headache.

Medication-overuse headache (MOH) is a chronic headache disorder defined by the International Headache Society as a headache induced by the overuse of analgesics, triptans, or other acute headache compounds. The population-based prevalence of MOH is 0.7% to 1.7%. Most patients with MOH have migraine as their primary headache and overuse triptans or simple analgesics. The pathophysiology of MOH is still unknown. As well as psychological mechanisms such as operant conditioning, changes in endocrinological homoeostasis and neurophysiological changes have been observed in patients with MOH. Recently, a genetic susceptibility has been postulated. In most cases, treatment of MOH consists of abrupt withdrawal therapy and then initiation of an appropriate preventive drug therapy. There is no clear evidence on which method of withdrawal therapy is the most efficacious. Withdrawal symptoms can be treated with steroids; however, not all data support this concept. As MOH can severely affect the quality of life of patients, it needs to be recognised early to enable appropriate treatment to be initiated.