Evidence for autonomic nervous system dysfunction in females with idiopathic overactive bladder syndrome

Micturition and continence are largely under the control of the autonomic nervous system (ANS). In this study, we analyzed ANS function using autonomic cardiovascular (CV) testing in females with idiopathic overactive bladder syndrome (iOAB) versus control females. Our hypothesis was that ANS dysfunction could comprise part of the pathophysiology of iOAB.

Twenty-three females with iOAB and 29 controls were enrolled into this prospective study. Patients performed CV autonomic testing, including two sympathetic tests (hand grip exercise and cold pressor test), two parasympathetic tests (deep breathing and 30:15 ratio), and two mixed tests (Valsalva manoeuvre and blood pressure [BP] response to standing). Patients with iOAB also underwent conventional urodynamic studies in order to define iOAB as either with or without demonstrable detrusor overactivity (DO).

Both groups were similar with respect to age and menopausal status. Females with iOAB had significantly more positive tests than controls (P < 0.0001), particularly for sympathetic tests (P < 0.0001). Among the iOAB group, the sympathetic tests (P = 0.03) were significantly more often positive in patients without DO (based on cystometry) compared to patients with DO, with the results being particularly significant for the cold pressor test (P = 0.02). No differences were found among iOAB sufferers with respect to a past history of enuresis.

These results suggest ANS dysfunction, predominantly a sympathetic ANS dysfunction, is associated with iOAB, specifically in patients with iOAB without DO.