Increased bladder sensation without detrusor overactivity revisited: Use of a five-grade sensory measure

Increased bladder sensation (IBS) without detrusor overactivity (DO) is still a matter of debate, regarding its clinical relevance, urodynamic nature, underlying pathology, and management. Among these, we present our data focusing on the urodynamic nature of IBS without DO, by applying our five-grade sensory measure during urodynamics.

We enrolled 400 individuals who visited our laboratory for screening of lower urinary tract function, mostly with neurogenic etiologies. They included 74 control, 87 DO (irrespective of IBS), and 239 IBS (defined as first sensation <100 mL) without DO. During slow bladder filling, we instructed individuals to indicate their sensation in five grades: 1, first sensation to 5, strong desire to void. We also instructed individuals to report other sensations such as pain.

The five-grade measure could be performed in all participants without difficulty. None of the participants reported pain or any qualitatively different sensations. Although we defined DO irrespective of IBS, the sensation interval 0 (start) to 1 (first sensation) of subjects with IBS but without DO was significantly less than that of subjects with DO (P < 0.05).

The present study results showed that first sensation of subjects with IBS without DO was significantly less than that of subjects with DO (P < 0.05), while the bladder capacities of the two groups were the same. An extremely low-volume first sensation may suggest the possibility of IBS without DO.