Investigations of micromotion characteristics of bladder wall strips and pressure wave phenomena in total bladders in vitro and in vivo indicate that m~cromotion phenomena occur in the bladder wall. Local contractions can occur without an increase in tension or pressure, because other pans are in antiphase. Local contractions stretch surrounding tissues, which can stimulate fast stretch receptors. Synchronisation of these micromotion phenomena appears to be possible. Hence, above threshold levels urge can theoretically occur, even in the absence of a pressure increase. This hypothesis could explain the weak relation between urge and pressure. The distinction between motor and sensory urge could be artifactual based on a misunderstanding of fundamental bladder wall processes.

(MMD) method, using eight electrodes mounted on a Silastic balloon; local displacements of the electrodes were recorded as changes in electrical resistance, which were used to compute changes in the distance between each pair of electrodes. RESULTSIn two of the six volunteers, micromotions were seen in the extraperitoneal (ventral) portion of the bladder. Women with increased sensation on filling cystometry had a significantly higher prevalence of localized activity than the control group during MMD recording. The localized activity was more sustained and at a higher frequency than in asymptomatic women. All nine women reporting urinary urgency during MMD recording had localized contractile activity, while only four had phasic increases in detrusor pressure during the episodes of urgency.

The passive behavior of the urinary bladder in the collection phase is described by a number of independent input–output relations characterizing the function of the bladder wall and the geometry of the bladder. Assembly of these relations yields a model characterized by twelve parameters. Two of these parameters can be determined from a static cystometrogram. Stepwise filling of the bladder gives a pressure-decrease curve which can be described by three exponential terms and a constant and yields nine of the desired parameters, or ten if two or more fillings are done on the same bladder.

Stepwise cystometry is a new method proposed to analyse the visco-elastic properties of the bladder. It is based on a mathematical analysis of the pressure decay after a stepwise filling. By assumption of a mechanical visco-elastic model of bladder tissue and a model of the geometry, the derived parameters are interpreted as elasticity and viscosity moduli. Static cystometry is involved in this new procedure. From analysis by stepwise cystometry it is concluded that static cystometry attained by following a slow-filling procedure is unacceptable in studying elastic behaviour.

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