Supraspinal Control of Urine Storage and Micturition in Men—An fMRI Study

Abstract

Despite the crucial role of the brain in the control of the human lower urinary tract, little is known about the supraspinal mechanisms regulating micturition. To investigate the central regulatory mechanisms activated during micturition initiation and actual micturition, we used an alternating sequence of micturition imitation/imagination, micturition initiation, and actual micturition in 22 healthy males undergoing functional magnetic resonance imaging. Subjects able to micturate (voiders) showed the most prominent supraspinal activity during the final phase of micturition initiation whereas actual micturition was associated with significantly less such activity. Initiation of micturition in voiders induced significant activity in the brainstem (periaqueductal gray, pons), insula, thalamus, prefrontal cortex, parietal operculum and cingulate cortex with significant functional connectivity between the forebrain and parietal operculum. Subjects unable to micturate (nonvoiders) showed less robust activation during initiation of micturition, with activity in the forebrain and brainstem particularly lacking. Our findings suggest that micturition is controlled by a specific supraspinal network which is essential for the voluntary initiation of micturition. Once this network triggers the bulbospinal micturition reflex via brainstem centers, micturition continues automatically without further supraspinal input. Unsuccessful micturition is characterized by a failure to activate the periaqueductal gray and pons during initiation.

Effects of pedunculopontine nucleus stimulation on human bladder function

“…Regions within the frontal cortex, including the SMA and the superior frontal gyrus, are considered important for exercising inhibition of the micturition reflex, since lesions in these areas tend to produce detrusor overactivity . The superior frontal gyrus has also been linked with decision‐making and social and motivational aspects of bladder function and the SMA with motor control, being typically activated during voiding and pelvic floor relaxation/contraction . The cerebellum is proposed to have a motor role during voiding and also to be involved in the processing of sensory information during bladder filling .…”

“…19 This is supported by evidence that cerebellar lesions have an effect on urinary storage and voiding processes. Michels et al 17 found that the cerebellum was activated during interruption of micturition. The ventral posterior thalamic nucleus is involved in interoception.…”

“…The ventral posterior thalamic nucleus is involved in interoception. 20 Relatively little attention has been paid to the precuneus and its significance in micturition control, however, its activation has been reported during void initiation 17 and bladder distension. 21 Overall, our tractography data suggest connectivity between PPN and sensorimotor components of the bladder circuitry, which may contribute to the observed effects of stimulation.…”

Urodynamic investigations in patients with spinal cord injury: should the ice water test follow or precede the standard filling cystometry?

“…15,18 The PMC in contrast induces the micturition reflex via one long descending pathway to the sacral spinal cord where the reflex is further mediated by segmental interneurons as an all-or-none response. 19 Only the latter reflex enhanced component but not the descending component from the PMC has been demonstrated to be susceptible to Matching of subjects between cohorts A and B was performed using propensity score analysis with a proportion of 1:2. Table 2 Outcome parameters comparing IWT performed before and after standard urodynamic Urodynamics in spinal cord injury: timing of ice water test M Kozomara et al modulation by recurrent inhibition.…”

Sacral Neuromodulation for the Treatment of Urinary Bladder Dysfunction: Mechanism of Action and Future Directions

“…Lesions rostral to the mesencephalic PAG result in the loss of control of the timing of micturition, but the micturition reflex remains intact. A pivotal role for the PAG and PMC in bladder control has been described in humans using positron emission tomography and functional magnetic imaging [20][21][22][23]. Afferent information from the bladder and urethra is relayed via the thalamus to the cingular and insular cortices.…”