Responsiveness of the autonomic nervous system during paced breathing and mental stress in migraine patients

Background Migraine is a stress-related disorder, suggesting that
there may be sympathetic hyperactivity in migraine patients.
However, there are contradictory results concerning general
sympathetic activation in migraine patients. To shed more light on
the involvement of the autonomic nervous system (ANS) in migraine
pathophysiology, we investigated cardiac and cardiovascular
reactions during vagal (paced breathing) and sympathetic activation
(mental stress test). Methods Heart rate variability parameters and
skin conductance responses were recorded interictally in 22
episodic migraine patients without aura and 25 matched controls
during two different test conditions. The paced breathing test
consisted of a five-minute baseline, followed by two minutes of
paced breathing (6 breathing cycles per minute) and a five-minute
recovery phase. The mental stress test consisted of a five-minute
baseline, followed by one minute of stress anticipation, three and
a half minutes of mental stress and a five-minute recovery phase.
Furthermore we measured blood pressure and heart rate once daily
over 2 weeks. Subjects rated their individual current stress level
and their stress level during paced breathing and during the mental
stress test. Results There were no significant differences between
migraine patients and controls in any of the heart rate variability
parameters in either time domain or frequency domain analysis.
However, all parameters showed a non-significant tendency for
larger sympathetic activation in migraine patients. Also, no
significant differences could be observed in skin conductance
responses and average blood pressure. Only heart rates during the
2-week period and stress ratings showed significantly higher values
in migraine patients compared to controls. Conclusions Generally
there were no significant differences between migraine patients and
controls concerning the measured autonomic parameters. There was a
slight but not significant tendency in the migraine patients to
react with less vagal and more sympathetic activation in all these
tests, indicating a slightly changed set point of the autonomic
system. Heart rate variability and blood pressure in migraine
patients should be investigated for longer periods and during more
demanding sympathetic activation.