Overactive bladder as a dysfunction of the autonomic nervous system - A narrative review

Overactive bladder (OAB) is a common condition with increasing prevalence. However, its aetiology is not fully understood. The main symptoms are sudden urge to urinate, with or without incontinence; increased daytime frequency; and nocturia. OAB-like symptoms can be caused by a number of diseases, including urinary tract infections, neurologic and metabolic diseases, and neoplasms. The final diagnosis is made after excluding all the abovementioned factors. Autonomic nervous system (ANS) dysfunction has also been identified as a possible cause of so-called 'idiopathic OAB'. In order to check this hypothesis, many studies have measured ANS activity in patients with OAB by means of dynamic pupillometry, heart rate variability and sympathetic skin response. These non-invasive, fast and reliable tests assess ANS function - both sympathetic and parasympathetic - indirectly. ANS activity depends on many factors, such as age, gender, baseline level and a number of environmental stimuli. An imbalance between the sympathetic nervous system and the parasympathetic nervous system can lead to homeostatic disruption and the subsequent development of many diseases, including OAB. This narrative review summarizes the most important studies concerning the putative influence of the ANS on OAB symptoms.