Defining Overactive Bladder As Hypersensitivity

Main Category: Urology / Nephrology
Article Date: 17 Feb 2008 - 0:00 PDT

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UroToday.com- Overactive bladder (OAB) has been defined by the International Continence Society (ICS) as urgency, with or without urgency incontinence, usually with frequency and nocturia, in the absence of infection, or other obvious pathology. Fully two-thirds of OAB patients do not actually experience incontinence. Urgency is defined by ICS as a sudden, compelling, difficult-to-defer desire to pass urine. It is the cornerstone symptom that drives the other symptoms of OAB (frequency, nocturia, urgency incontinence).

Yamaguchi and colleagues from throughout Japan explain that the ICS definition of urgency assumes an abnormal or pathologic bladder sensation that is distinguishable from the normal physiologic sensation of urge to void during a normal bladder-filling cycle. It is not always easy for patients to discriminate between urgency and normal urge, particularly between urgency and a strong desire to void. The authors took the novel approach of gathering diary information from 21 female patients with overactive bladder selected on the basis of high intelligence. They could understand and discriminate between urgency and urge. All had experienced urgency and normal urge and convinced the authors that they could distinguish the two. All completed a 7 day voiding diary.

All subjects were capable of differentiating urgency from urge sensation and all had sought medical care prior to entry into the study. Urgency episodes occurred less than once a day in 43% and some patients had days with no sensation of urgency. Even in cases where patients did experience urgency several times a day, most voiding occurred with a normal sensation of urge. The authors conclude that urgency does not seem to drive symptoms of frequency that are common in OAB. In contrast, urge sensation was markedly increased at any given bladder volume in their patients with OAB compared with normal subjects. Hypersensitivity was observed regardless of actual urgency episodes. Thus, they conclude, OAB may be more accurately defined as a hypersensitivity disorder rather than a syndrome characterized primarily by urgency as defined by ICS. Increased bladder sensitivity (hypersensitivity) appears to be a basis for inducing true urgency.

Yamaguchi O, Honda K, Nomiya M, Shishido K, Kakizaki H, Tanaka H, Yamanishi T, Homma Y, Takeda M, Araki I, Obara K, Nishizawa O, Igawa Y, Goto M, Yokoyama O, Seki N, Takei M, Yoshida M

Neurourol Urodyn. 26(s6):904-907, October 2007
Doi: 10.1002/nau.20482

Reported by UroToday.com Contributing Editor Philip Hanno, M.D

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