The Neuroanatomical Correlates of Bladder Filling: An Activation Likelihood Estimation Meta-Analysis of Functional Neuroimaging Studies.

BACKGROUND: Urinary continence relies on a complex interplay between urine storage and voiding involving both spinal reflex circuits and supraspinal brain areas to coordinate volun-tary control over emptying. Despite a vast number of studies on the pathophysiology of neurogenic bladder and urge incontinence, less is known about the central correlates of bladder filling. METHODS: An ALE (activation likelihood estimation) meta-analysis including a total count of 14 studies investigating 243 participants under different conditions of bladder filling during functional neuroimaging was performed to demonstrate the neuroanatomical correlates of bladder filling. The literature search and reporting were conducted according to the PRISMA-P 2020 guideline. Data analysis was performed using the GingerAle software version 3.0.2 and was displayed with the Mango software 4.1 on an anatomical MNI template. RESULTS: Synthesizing studies on the functional neuroanatomy of urine storage, bihemispheric clusters of activation in the thalamus, the insula and the cingulate were observed. CONCLUSION: The present ALE meta-analysis indicates that the supraspinal representation of urine storage involves areas of autonomous-homeostatic processing which allow for the perception of the usually unconscious inner state of bladder filling and enable postponing and voluntary voiding.