Detrusor instability and bladder outlet obstruction

Detrusor instability is found in a high percentage of children with voiding disorders and in elderly patients both with and without bladder outlet obstruction. An assumption that outlet obstruction leads to detrusor instability has arisen largely from the findings that prostatectomy results in a marked reduction in the incidence of instability. However, studies have shown that the incidence of instability is related to age both by virtue of a decreasing incidence in childhood and an increasing incidence in later life. In later life the increase reflects advancing age and is not related to the severity of any coexisting outlet obstruction. The reduction in instability following prostatectomy may be due to an interruption of sensory afferent impulses due to resection of prostatic, urethral, and bladder neck nerve tissues. In children, instability is likely to represent delayed maturation of cerebral control over the micturition reflex, or to be due to neurological disease such as meningomyelocele. More data are required for all groups of patients, both children and adults, to determine the influence of the relief of obstruction on the incidence of instability. Furthermore, additional data are required on the incidences of instability and obstruction in the “normal” population.