Bladder Distension Increases Blood Flow in Pain Related Brain Structures in Subjects with Interstitial Cystitis

In healthy control subjects certain brain regions of interest demonstrate increased regional cerebral blood flow in response to painful stimuli. We examined the effect of bladder distension on arterial spin label functional magnetic resonance imaging measures of regional cerebral blood flow in regions of interest in subjects with interstitial cystitis.

A total of 11 female subjects with interstitial cystitis and 11 healthy controls underwent 3 brain perfusion scan studies using arterial spin label functional magnetic resonance imaging, including 1) with a full bladder, 2) with an empty bladder and 3) while experiencing heat pain. Regional cerebral blood flow was calculated using custom software and individual scans were spatially normalized to the MNI (Montreal Neurological Institute) template. Region of interest based, absolute regional cerebral blood flow was determined for each condition and for the within group/within subject regional cerebral blood flow distribution changes induced by each condition.

Bladder distension was associated with robust increases in regional cerebral blood flow in subjects with interstitial cystitis. The increases were greater than those in healthy controls in multiple regions of interest, including the supplemental motor area (mainly Brodmann area 6), the motor and sensory cortex, the insula bilaterally, the hippocampal structures bilaterally, and the middle and posterior cingulate areas bilaterally. During heat pain healthy controls had more robust regional cerebral blood flow increases in the amygdala bilaterally. At baseline with an empty bladder there was lower regional cerebral blood flow in the insula, and the mid and posterior cingulate cortex bilaterally in subjects with interstitial cystitis.

Compared to healthy controls, subjects with interstitial cystitis have limited differences in regional cerebral blood flow in baseline (empty bladder) conditions as well as during heat pain. However, they had robust regional cerebral blood flow increases in the full bladder state in regions of interest typically associated with pain, emotion and/or motor control, indicating altered processing of bladder related sensations.