Abnormalities in autonomic control have been documented in migraine even during the headache-free interval. It has long been recognized that spectral analysis of heart rate (HR) fluctuations can reflect the autonomic function, especially the sympathetic to parasympathetic balance. This technique is the basis for a quantitative approach to the investigation of migraine applied in the present study. A 24-hour Holter ECG recording was performed for each subject in a group of five migraine patients during the interheadache period. In addition, shorter 5-minute-long recordings of blood flow (BF) and blood pressure (BP) were made in these patients in both supine and standing positions. Short, 256-second subtraces were taken every 30 minutes along the 24-hour ECG signal and were submitted, as well as the BF and BP traces, to A/D conversion and computation of the power spectrum of fluctuations in HR, BF, and BP. Spectral analysis of fluctuations in these hemodynamic parameters was performed in the migraine patients before and during the treatment with verapamil and compared to that of a healthy control group. This procedure enabled us to assess the autonomic function, the sympathetic vs parasympathetic balance, and their response to a change in position, before and during calcium blockade. A characteristic autonomic abnormality is revealed in the group of untreated migraine patients in supine position: enhanced low frequency (LF) fluctuations reflecting increased sympathetic sensitivity during the inter-headache phase. An exaggerated sympathetic response is measured in the migraine patients during the transition from supine to standing position with a concomitant nonsignificant decrease in parasympathetic response.(ABSTRACT TRUNCATED AT 250 WORDS)

Migraine patients seem to suffer from a continuous autonomic imbalance. Sympathetic instability, expressed by enhanced low frequency fluctuations, which exists during the headache free intervals, was observed in our previous study by spectral analysis of heart rate (HR) fluctuations. Propranolol--a beta adrenoceptor antagonist, is widely used in migraine prophylaxis. In order to specify and quantitate propranolol efficacy in migraine, spectral analysis of heart rate fluctuations was performed on 10 migraine patients before and during the treatment with propranolol. They were compared to 10 healthy control patients and 6 migraine patients who were treated for several months with propranolol and then discontinued the medication. The analysis was carried out on a 24h Holter ECG recording, which was performed for each subject during a headache free interval. Short 256 sec subtraces, taken every 30 min from the 24h ECG signal, were submitted to A/D conversion, R wave detection and computation of heart rate power spectrum. Propranolol achieved a marked effect, when comparing the power spectra of HR fluctuations in treated versus untreated migraine patients. A strong reduction (to normal level) in the low frequency HR fluctuations in the range below 0.1 Hz., was apparent in patients treated with propranolol. Subjects who had received propranolol in the past and discontinued the drug, displayed a carry-over effect of reduced fluctuations even 2-3 months after its discontinuation. It seems that the propranolol efficacy in migraine is associated with the mechanism of stabilizing the fluctuations within the frequency band related to sympathetic activity, hereby moderating the vascular instability in migraine.

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