The objective was to assess the impact of transcranial magnetic stimulation (TMS) on pain and the autonomic nervous system (ANS) in migraine. Fortytwo people [mean age 41.43±11.69 (SD) years, 36 females] were randomised into high vs. low TMS stimulation groups and received 2 brief pulses of TMS. Thirty-three (33/42) individuals had heart-rate variability assessed, before and after stimulation. No group effects were found. Pain decreased by 75%; 32% of people after 1 treatment reported no headache after 24 h. Mean heart rate decreased from 79.05±10.27 to 72.89±11.35 beats/min. The low-frequency (LF) and the high-frequency (HF) areas derived from power spectral analyses increased [mean 6522±1277 to 8315±1009 beats/min 2 (LF) (p=0.001) and mean 5600±1568 to 8755±3071 beats/min 2 (HF) (p=0.001)]. The LF:HF ratio decreased from mean 1.31±0.51 to 1.13±0.48 (NS). TMS produces immediate, sustained reductions in pain and modification of the ANS.

Individuals with spinal cord injury are prone to cardiovascular dysfunction and an increased risk of cardiovascular disease. Body weight-supported treadmill training (BWSTT) may enhance ambulation in individuals with incomplete spinal cord injury; however, its effects on cardiovascular regulation have not been investigated. The purpose of this study was to examine the effects of 6-mo of BWSTT on the autonomic regulation of heart rate (HR) and blood pressure (BP) in individuals with incomplete tetraplegia. Eight individuals [age 27.6 yr (SD 5.2)] with spinal cord injury [C4-C5; American Spinal Injury Association B-C; 9.6 yr (SD 7.5) postinjury] participated. Ten-minute HR and finger arterial pressure (Finapres) recordings were collected during 1) supine rest and 2) an orthostatic stress (60 degrees head-up tilt) before and after 6 mo of BWSTT. Frequency domain measures of HR variability [low-frequency (LF) power, high-frequency (HF) power, and LF-to-HF ratio] and BP variability (systolic and diastolic LF power) were used as clinically valuable indexes of neurocardiac and neurovascular control, respectively. There was a significant reduction in HR [61.9 (SD 6.9) vs. 55.7 beats/min (SD 7.7); P=0.05] and LF-to-HF ratio [1.23 (SD 0.47) vs. 0.99 (SD 0.40); P < 0.05] after BWSTT. There was a significant reduction in LF systolic BP [183.1 (SD 46.8) vs. 158.4 mmHg2 (SD 45.2); P < 0.01] but no change in BP. There were no significant effects of training on HR variability or BP variability during 60 degrees head-up tilt. In conclusion, individuals with incomplete tetraplegia retain the ability to make positive changes in cardiovascular autonomic regulation with BWSTT without worsening orthostatic intolerance.

No abstract

The evidence for deterministic chaos in normal heart rhythms is examined. Electrocardiograms were recorded of 29 subjects falling into four groups-a young healthy group, an older healthy group, and two groups of patients who had recently suffered an acute myocardial infarction. From the measured R-R intervals, a time series of 1000 first differences was constructed for each subject. The correlation integral of Grassberger and Procaccia was calculated for several subjects using these relatively short time series. No evidence was found for the existence of an attractor having a dimension less than about 4. However, a prediction method recently proposed by Sugihara and May and an autoregressive linear predictor both show that there is a measure of short-term predictability in the differenced R-R intervals. Further analysis revealed that the short-term predictability calculated by the Sugihara-May method is not consistent with the null hypothesis of a Gaussian random process. The evidence for a small amount of nonlinear dynamical behavior together with the short-term predictability suggest that there is an element of deterministic chaos in normal heart rhythms, although it is not strong or persistent. Finally, two useful parameters of the predictability curves are identified, namely, the 'first step predictability' and the 'predictability decay rate,' neither of which appears to be significantly correlated with the standard deviation of the R-R intervals.

Individuals with spinal cord injury (SCI) are prone to orthostatic intolerance and an increased risk of cardiovascular disease. The use of heart rate variability (HRV) and blood pressure variability (BPV) as indices of cardiovascular regulation would be valuable in this population; however, their reproducibility has yet to be tested in those with SCI. The purpose of this study was to examine the day-to-day reproducibility of resting HRV and BPV in individuals with SCI. Ten individuals (age 35.9 +/- 13.2 yrs) with chronic (5.4 +/- 7.7 years post injury) SCI (C4-T12; ASIA A-C) participated. On two occasions within a two-week period, 10-minute supine electrocardiogram and Finapres blood pressure recordings were obtained during spontaneous breathing. Computer software calculated frequency domain measures of HRV and BPV (Low frequency (LF) power, High frequency (HF) power, and LF:HF ratio). Intraclass correlations coefficients (R) were used as an index of day-to-day reproducibility, and analyses were conducted on all participants and only those with tetraplegia. For HRV, measures of heart rate, LF, and LF:HF were found to be highly reproducible (R = 0.82-0.88); however, the reproducibility of HF was found to be poor (all participants: R = 0.53, tetraplegia: R = 0.66). Measures of blood pressure as well as systolic BPV also showed high reproducibility (R = 0.72-0.93). Measures of diastolic BPV were less reproducible but still acceptable (R = 0.71-0.89) with the exception of LF:HF(DBP) (R = 0.51). In conclusion, despite the autonomic dysfunction associated with SCI, measures of HRV and BPV may still be used as reproducible indices of autonomic cardiovascular regulation in this population.