Pathophysiology of detrusor overactivity

Detrusor overactivity is an “urodynamic observation characterised by spontaneous or provoked involuntary detrusor contractions during the filling phase”. The only clearly defined aetiological factor is “a relevant neurological condition”, leading to the definition of “neurogenic DO”. Neurological injuries or diseases may disrupt the normal voluntary control of micturition, causing the re-emergence of reflex micturition, resulting in DO. Many neurotransmitters are involved in detrusor overactivity genesis. Another recognised and debated cause of detrusor overactivity is certainly a bladder outflow obstruction. Morphologic bladder changes, including a progressive denervation may justify the occurrence of detrusor overactivity in patients with bladder outlet obstruction. Excluding relevant neurological diseases and local inflammations, infections, and tumours, and bladder outlet obstruction causes of detrusor overactivity may be congenital, behavioural/psychosomatic, aging-related, myogenic, secondary to pelvic floor disorders, and hypersensitivity disorders, and idiopathic. The three main proposed theories of detrusor overactivity are the myogenic theory, the neurogenic theory and the autonomous hypothesis. Unfortunately none is able to completely explain the mechanisms underlying non-neurogenic detrusor overactivity, opening the a wide and intriguing research field.