In addition to motor symptoms, patients with Parkinson's disease (PD) show deficits in sensory processing. These deficits are thought to result from deficient gating of sensory information due to basal ganglia dysfunction in PD. Deep brain stimulation of the subthalamic nucleus (STN-DBS) has been shown to improve sensory deficits in PD, e.g. STN-DBS normalizes the perception of urinary bladder filling in patients with PD. This study aimed at investigating how STN-DBS modulates the processing of urinary bladder information to elucidate the (patho-)physiology of sensory gating mechanisms in PD. 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 PET. Urinary bladder filling led to an increased rCBF in the periaqueductal grey (PAG), the posterior thalamus, the insular cortex as well as in the right frontal cortex and the cerebellum bilaterally. 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. Thus, STN-DBS led to a significant enhancement of afferent urinary bladder information processing. The data suggest that STN-DBS facilitates the discrimination of different bodily states by supporting sensory perception and the underlying neural mechanisms. Furthermore, this is the first imaging study, which shows an effect of STN-DBS on sensory gating in PD patients and its neural basis.

Detrusor hyperreflexia is a relevant clinical symptom for patients suffering from Parkinson's disease. In a series of 16 patients, we demonstrated that subthalamic deep brain stimulation has a significant and urodynamically recordable effect leading to a normalization of pathologically increased bladder sensibility.

Subthalamic nucleus deep brain stimulation (STN-DBS) is an effective therapy for off-period motor symptoms and dyskinesias in advanced Parkinson's disease. Clinical studies have shown that STN-DBS also ameliorates urinary bladder function in Parkinson's disease patients by delaying the first desire to void and increasing bladder capacity. This study aimed at investigating the effect of STN-DBS on the neural mechanisms underlying cerebral bladder control. Using PET to measure changes in regional cerebral blood flow (rCBF), 11 patients with bilateral STN-DBS were studied during urodynamic bladder filling in STN-DBS ON and OFF condition. A filled bladder led to a significant increase of rCBF in the anterior cingulate cortex, which was further enhanced during STN-DBS OFF. A significant interaction between bladder state and STN-DBS was observed in lateral frontal cortex with increased rCBF when the bladder was filled during STN-DBS OFF. The data suggest that STN-DBS ameliorates bladder dysfunction and that this modulation may result from facilitated processing of afferent bladder information.

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