Effects of pedunculopontine nucleus stimulation on human bladder function

Area of Science:

• Neuroscience
• Urology
• Neurosurgery

Background:

• The pedunculopontine nucleus (PPN) is a deep brain stimulation (DBS) target for Parkinson's disease (PD).
• Previous reports suggest unilateral PPN stimulation may cause urinary dysfunction.
• The effect of bilateral PPN DBS on bladder function is not well understood.

Purpose of the Study:

• To evaluate the effect of bilateral PPN DBS on urodynamic parameters in PD patients.
• To investigate the mechanisms underlying PPN DBS effects on bladder control using probabilistic tractography.

Main Methods:

• Six male PD subjects with bilateral PPN DBS underwent urodynamic bladder filling assessments with stimulators ON and OFF.
• Diffusion-weighted and T1-weighted MRI scans were performed on two subjects.
• Probabilistic tractography was used to map white matter connections to the PPN.

Main Results:

• Bilateral PPN DBS did not induce detrusor overactivity or alter sensory thresholds during bladder filling.
• Maximal bladder capacity significantly increased with PPN DBS (199 mL ON vs. 131 mL OFF).
• Tractography revealed extensive PPN connectivity to cortical and subcortical bladder control regions, with pathways near the pontine micturition center.

Conclusions:

• Bilateral PPN DBS is safe for bladder filling parameters in PD patients.
• PPN DBS may improve bladder capacity through long-range neural connectivity or local effects.
• Further research is needed to elucidate the precise mechanisms of PPN DBS on bladder function.