INTRODUCTION AND HYPOTHESIS:Our objective was to compare autonomic nervous system function between women with an overactive bladder (OAB) and control participants during regulated bladder filling.
METHODS: Twenty-four women, nine with OAB and 15 without (control), were instructed to drink 1.5 l of water at a rate of 250 ml every 5 min during continuous electrocardiogram (ECG) monitoring. Participants were asked to indicate first sensations of filling (FSF), first desire to void (FDV), strong desire to void (SDV), and maximal bladder capacity (MC). ECG signals were used to assess heart rate variability, which were analyzed in time and frequency domains using the fast Fourier transform. The low-frequency (LF)and high-frequency (HF) spectral bands were used to asses sympathetic and parasympathetic pathways, respectively.
RESULTS: During the bladder-filling phase, women with OAB had significantly lower LF values (at the MC phase 5.4 ± 1.4 ms2/Hz vs. 6.4± 0.6 ms2/Hz in the control group, p = 0.02). In the control group, LF increased continuously, whereas in the OAB group, LF increased until the sensation of SDV and then abruptly decreased to baseline values. MC was lower in women with OAB (372 ± 153 ml vs. 592 ± 298 ml, p < 0.05, respectively).
CONCLUSIONS: Reduced sympathetic tone in women with OAB may explain their attainment of lower volumes of MC and their sensation of urgency. The rapid decrease in sympathetic neural activity that accompanies the sensation of an SDV may be related to the pathophysiology of the urgency symptom in these women.
Ben-Dror I, Weissman A, Leurer MK, Eldor-Itskovitz J, Lowenstein L. Are you the author?
Sackler Faculty of Medicine, School of Health Professions, Department of Physical Therapy, Tel-Aviv University, Tel-Aviv, Israel.
Reference: Int Urogynecol J. 2012 Apr 11. Epub ahead of print.
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