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Background Migraine is a common and disabling neurological disorder. Studies on the relationship between migraine and the autonomic nervous system ( ANS) have been inconclusive. Moreover, pediatric studies are extremely limited. Therefore, the present study investigated interictal ANS function in adolescent migraineurs. Methods We studied 21 patients with migraine and 26 healthy controls. Beat-to-beat blood pressure ( BP) and heart rate ( HR) were non-invasively and continuously measured in the supine and standing positions. ANS function was evaluated on power spectral analysis of HR variability and diastolic BP ( DBP) variability. Results Heart rate and systolic BP were not different between the two groups in either the supine or standing position. DBP did not differ between groups in the standing position, but was significantly higher in migraineurs in the supine position. The vasoconstrictor index was significantly higher in migraineurs. High-frequency ( HF) RR interval variability ( RR- HF) and the ratio of the low-frequency ( LF) to HF component of RR interval variability ( RR- LF/ HF) were not different between the two groups in both positions. The LF component of DBP variability ( DBP- LF) in the supine position was significantly lower in migraineurs, while DBP- LF during standing in migraineurs was significantly higher than in controls. Conclusion Migraineurs have significantly lower sympathetic vasomotor activity in the supine position, while sympathetic vasomotor activity was hyperresponsive during standing. [ABSTRACT FROM AUTHOR]

Background Postural tachycardia syndrome ( POTS) manifests as marked tachycardia while standing. We noticed two forms of circulatory response to orthostatic stress in POTS. We investigated cardiovascular and autonomic nervous response to orthostatic stress in the two forms. Methods We studied 79 patients with POTS and 38 healthy control subjects ( Ct). Beat-to-beat blood pressure ( BP) and heart rate ( HR) were non-invasively and continuously measured in the supine and standing positions. Autonomic nervous function was evaluated on power spectral analysis of HR variability and diastolic BP variability. We divided the subjects into two groups: standing-induced tachycardia ( SI group; increase in HR ≥35 beats/min) and supine tachycardia ( Su group; standing HR ≥115 beats/min with standing-induced HR increase <35 beats/min). Results The Su group had higher supine BP and HR compared with the other groups, indicating dominant sympathetic control of the heart in the supine position. While rising, the SI group had a higher increase in HR than the Ct group, indicating excessive withdrawal of vagal tone. The Su group had a smaller increase in HR and a greater decrease of systolic BP and cardiac index by standing compared with the SI group. These results suggest that compensatory mechanisms of sympathetic function during standing failed in the Su group, probably because of exhaustion by the nearly maximum effort to generate sympathetic drive even in the supine position with low central blood volume. Conclusion There is a difference between the two types of POTS, in the balance of resting autonomic function and hemodynamic response to standing. [ABSTRACT FROM AUTHOR]