Direct Bladder Contraction by Single and Multi-Electrode Stimulation

Detrusor sphincter dyssynergia (DSD) is characterized by the uncoordinated activity between contraction of the detrusor and relaxation of the external urinary sphincter, affecting 70%-84% of individuals with spinal cord injury (SCI). Current treatments include catheterization, medication, sphincterotomy, and neuromodulation. Here we divided the bladder in quarters and used point (0.78 mm²) electrical stimulation at 0.5, 1.0 and 2 mA to map those that evoked maximal contraction (9.88 mm²), as determined by vascular fiduciary markers before and after stimulation. A multi-electrode array was then used to reduce the electrodes size $(2000\mu \mathrm{m}^{2})$ which evoked a more efficient bladder contraction (16.51 mm²) and at a lower threshold (0.15 mA). The relative change of bladder size evoked by single electrodes was −7.3 %, whereas that evoked by the multichannel electrode was 12.9% (p = 0.007). This result defines the optimal targets sites and parameters that can be used to improve the neuromodulation treatment of DSD.