Brain activity on fMRI increased after treatment with onabotA in the right cingulate body, the left posterior cingulate, the left anterior cingulate, the right prefrontal cortex, the insula, and the pons micturition center. The few areas that showed decreased activity included the left cerebellum, left fusiform gyrus, and bilateral lentiform nucleus.
This showed that the injection of onabotA into the bladder has distinct effects on the activation pattern in brain regions associated with the sensation of bladder filling, urgency, and micturition, the authors concluded.
In particular, the amygdala/parahippocampal region (areas responsible for negative emotions and fear, in this case possibly secondary to incontinence) becomes less active after successful treatment of UUI, they found.
The entire micturition cycle, including the voiding phase, changed following treatment with onabotA, they noted. The strong impact on the voiding phase contrasts with other therapies used in overactive bladder, which could explain the different brain activation patterns seen in this study, said Dr. Khavari.
She speculated that this negative effect on the voiding phase could have a compensatory effect on the brain, causing an exaggerated activation pattern in order to allow for voiding, or an attempt of voiding.
In the next phase of this research, Dr. Khavari is working on optimizing a cap that can be individualized to deliver noninvasive transcranial magnetic stimulation to the superficial brain regions that control a patient's bladder.
The technique might work for patients with Fowler's syndrome, stroke, underactive bladder, and other causes of bladder dysfunction, she said.
Until 20 years ago, urologists had focused too narrowly on below the beltline and the bladders, she said.
"I had to train myself about brain imaging and MRIs," Dr. Khavari said. "We have to cross the disciplines to increase our understanding of all aspects of bladder control and to be the leaders in innovations in this field."