Analysis of bladder related nerve cuff electrode recordings from preganglionic pelvic nerve and sacral roots in pigs

Purpose: Electrical stimulation of appropriate lower urinary tract (LUT) ne rves may be used in bladder dysfunction to achieve continence and abolish h yper-reflexic detrusor contractions. It can also be used for consequent emp tying of the bladder. To control the time course of the described functiona l phases, knowledge of bladder sensory information is needed. We investigat ed if the latter could be extracted from the LUT nerve activity. Materials and Methods: In acute experiments using 10 pigs, tripolar cuff el ectrodes were placed unilaterally around the pelvic nerve and the S3 and S2 roots. The cuff electrode signals, filling rate and the bladder and rectal pressures were recorded during slow and fast bladder fillings/emptyings. Results: Two pigs were excluded from the analysis because of no observed ch anges in the nerve signals in one animal, and because of electrical noise p roblems in the other animal. Fast bladder pressure increases resulted in a sudden pelvic nerve signal rise in 6 out of 7 pigs (3 out of 6 for the S3 n erve signal). Slow bladder pressure increase was reflected in the recorded nerve activity only in 3 out of 8 and in 3 out of 7 pigs for the pelvic and S3 cuff signals respectively. In 2 animals small spontaneous bladder contr actions were clearly reflected in the pelvic nerve signal (contractions wer e observed only in 3 pigs). Except in one pig, there were no slow/fast blad der filling responses recorded in the S2 roots. It is shown that the record ed responses were afferent. Conclusions: Cuff electrodes can be used to record bladder afferent informa tion from the pelvic nerve and the sacral root S3 in pig. Pelvic nerve reco rdings were more selective than the sacral root recordings. Nerve activity increases were more distinct and repeatable during rapid bladder pressure c hanges and small spontaneous bladder contractions than during slow bladder fillings.