Pathophysiological mechanisms in detrusor underactivity: Novel experimental findings

Underactive bladder (UAB) is a multifactorial symptom complex often related to detrusor underactivity (DU). Although recognized as a common cause of lower urinary tract symptoms and with significant effects on quality of life, UAB/DU is largely underresearched. Herein, we review up-to-date knowledge on the pathophysiological mechanisms of UAB/DU, with an emphasis on the relationship between UAB and bladder outlet obstruction (BOO). Original articles and reviews concerning UAB/DU were identified through a search of the PubMed/Medline and Scopus databases. DU can result from several pathological mechanisms, which can be categorized as idiopathic, neurogenic, myogenic, or functional. The main etiological factors of UAB/DU are aging, diabetes mellitus, neurogenic disorders, and BOO. Although conventional models focus primarily on efferent nerve and myogenic mechanisms, contemporary views highlight the importance of the afferent pathway. Specifically, recent findings in BOO showed that afferent dysfunction, such as altered expression of muscarinic and purinergic P2X(3) receptors or diminished urothelial ATP may play a role in the initial and reversible stages of DU, with potential diagnostic and therapeutic implications.