[Physiology and evaluation of overactive bladder]

Detrusor overactivity is a urodynamic observation characterized by involuntary detrusor contractions during the filling phase which may be spontaneous or provoked. There are certain patterns of detrusor overactivity. Phasic detrusor overactivity is defined by a characteristic wave form and may or may not lead to urinary incontinence. Terminal detrusor overactivity is defined as a single involuntary detrusor contraction occurring at cystometric capacity, which cannot be suppressed. Neurogenic detrusor overactivity is qualified as neurogenic when it is a relevant neurological condition (old term is "detrusor hyperreflexia"), idiopathic detrusor overactivity when there is no defined cause (this term replaces "detrusor instability"). In neurogenic patients, detrusor overactivity is secondary to various pathophysiologic factors: interruption of inhibitor pathways issued from cerebral regions, activation de novo of vesical C reflex mediated by unmyelinated capsaicin fibers, and ultrastructural modifications of bladder urothelium. Bladder overactivity treatment is necessary to avoid renal complications and improve quality of life of neurogenic patients.