Apomorphine-induced yawning in migraine patients: enhanced responsiveness.

Migraine patients usually exhibit hypersensitivity to dopaminergic agonists, but the tests used (such as the so called "piribedil test") preferentially assess the sensitivity of the peripheral dopaminergic receptors. Apomorphine-induced yawning may be useful in the evaluation of central dopaminergic receptor sensitivity. Nine migraine patients were included in an age- and sex-matched control study. They had been without treatment for 1 month and free of a migraine attack for at least 7 days. Apomorphine hydrochloride (5 micrograms/kg) was administered subcutaneously, and yawning was recorded by two observers. The cumulative number of yawns as a function of time was studied. The comparison of the regression graphs showed a significant difference between migraine patients and controls. Migraine patients exhibited enhanced responsiveness to apomorphine challenge. This finding supports the hypothesis of a constant central dopaminergic hypersensitivity.