Inter-critical and critical excessive daily sleepiness in episodic migraine patients.

The objective of this study was to determine the relationship between sleepiness and migraine in the intercritical period and to evaluate the time course of critical drowsiness during the attacks. One hundred patients fulfilling IHCD 2nd (2004) criteria for migraine without aura were compared to 100 healthy subjects. Habitual excessive daily sleepiness, evaluated by means of Epworth Sleepiness Scale, was not more frequent in patients with episodic migraine than in controls (12% migraineurs vs. 8% controls, NS). The analysis of critical sleepiness by means of Stanford Sleepiness Scale (SSS) revealed a beginning of sleepiness increase before the attack onset, starting 12 h before, a peak of SSS values at the migraine attack onset and then a gradual decrease to reach baseline values only 12-24 h later. Moreover, patients responding to symptomatic drugs showed a greater and faster decrease of critical sleepiness in comparison with non-responder migraineurs; this finding allows excluding the role of medications in promoting critical somnolence and together with critical drowsiness time-course supports the hypothesis that vigilance impairment could be related to migraine pathogenesis.