To date, conventional urodynamic evaluation is not able alone to distinguish motor urgency with uninhibited detrusor contraction from sensory urgency. Transcutaneous electrical localization and reversible monolateral blockade of the 3rd sacral root was performed in 3 women with interstitial cystitis and in 2 men with idiopathic detrusor hyperreflexia by intranerve injection of 6 ml 0.5\% Bupivacaine solution. The paralysis of the detrusor was completely reserved in all patients within 6 hours of the blockade. Cystometry and cystography were performed at 10 min, 2 and 6 hour intervals after the injection. In patients with the urge syndrome resulting from interstitial cystitis, there was a small increase in bladder capacity during the blockade. In contrast, the bladder capacity increased considerably during blockade in patients with idiopathic detrusor hyperreflexia. These results allowed us to differentiate the forms of the syndrome described above.
