Estimating bladder pressure from sacral dorsal root ganglia recordings

Individuals with dysfunctional bladders may benefit from devices that track the bladder state. Recordings from pelvic and sacral nerve cuffs can detect bladder contractions, however they often have low signal quality and are susceptible to interference from non-bladder signals. Microelectrode recordings from sacral dorsal root ganglia (DRG) neurons may provide an alternate source for obtaining high quality sensory signals for bladder pressure monitoring. In this study, penetrating microelectrode arrays were inserted in the S1 and S2 DRG in two cats to record afferent spiking activity at different bladder pressures. Multivariate linear regression models were used to estimate bladder pressure from the spiking activity of DRG neurons. The best estimates were obtained with populations of 5-10 units primarily from the S2 DRG, with root mean square errors of 3.0-3.2 cm H₂O (correlation coefficients of 0.5-0.9). This work demonstrates the feasibility of monitoring bladder pressure from DRG recordings.