Our aim was to check for possible differences in voiding detrusor pressures between women with and without detrusor instability (DI) who had no bladder outflow obstruction. For this purpose, 60 women were studied who voided with a rise in detrusor pressure, all of them having been assessed by symptom analysis, physical examination, medium-fill water cystometry, pressure/flow study and pelvic floor surface electrode EMG recording. Thirty had idiopathic DI, and the other 30 had stable bladders. Half of each group of 30 had a continent urethral closure mechanism, whilst the other half had stress urinary incontinence. In all patients, cystography showed the bladder neck closed at rest, and there was always perineal EMG relaxation at start flow. Maximum cystometric capacity was lower in the women with DI, who had higher values of maximum detrusor strength and shortening velocity, peak flow rate (corrected for volume), and voiding detrusor pressures. In some patients, these higher pressures showed as a response to a pseudo-dyssynergic contraction of the pelvic floor muscles. In the majority of cases, the greater detrusor strength in the unstable patients may have produced a higher bladder neck pressure rise during the onset of micturition contraction, and thus, as a response, higher voiding detrusor pressures. It seems possible that the higher bladder neck pressures in the patients with DI were related to an enhanced muscular tension at the bladder neck region. Thus, a positive feedback of enhanced afferent signals from tension receptors may have reinforced the detrusor contraction. A mechanism of this kind would most likely allow an unstable bladder to maintain its enhanced contractile capability.
|Number of pages||6|
|Publication status||Published - 1999|
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