Subthalamic stimulation improves sensory gating of urinary bladder afferents in Parkinson's disease

Objective: To investigate how subthalamic deep brain stimulation (STN-DBS) modulates the sensory processing of urinary bladder information in order to further elucidate the sensory gating mechanisms within this visceral pathway.

Background: STN-DBS does not only ameliorate motor symptoms in Parkinson's disease (PD) but also (i) improves dysuria and (ii) normalizes the perception of urinary bladder filling. A physiological explanation for this effect of STN-DBS has yet been elusive.

Methods: Nine PD patients with bilateral STN-DBS switched ON (STN-DBS ON) or OFF (STN-DBS OFF) were studied during dynamic bladder filling and an empty bladder condition (for control), while changes in regional cerebral blood flow (rCBF) were measured by positron emission tomography (PET).

Results: Urinary bladder filling led to an increased rCBF in the periaqueductal grey (PAG), the posterior thalamus and the insular cortex. A significant interaction between bladder condition and STN-DBS was observed in the posterior thalamus and the insular cortex, with enhanced modulation of these areas during STN-DBS ON compared to STN-DBS OFF. Furthermore, regression analyses revealed a modulation of the neural activity in the thalamus and the insular cortex by the PAG activity during STN-DBS ON only.

Conclusions: STN-DBS led to a significant enhancement of afferent urinary bladder information processing, thus facilitating the discrimination of different bodily states. Furthermore, this is the first imaging study which shows an effect of STN-DBS on sensory gating in PD patients and its neural basis.