Sensory thresholds in the male urethra measured by electrical stimulation

The sensory pathways innervating the male urethra were investigated by recording the sensory thresholds with electrical stimulation. Twenty-six male subjects (age 16 to 73 years) were included in the study. Ring-electrodes mounted on a Foley catheter were used for stimulation in proximal and distal urethra. Square wave pulses (duration 0.5 ms) were delivered with a constant current stimulator at different frequencies and the lowest intensity felt by the subject was defined as the threshold. The sensory thresholds were in the order of 0.5 to 5 mA and decreased with increasing stimulation frequency. All patients described a qualitative difference in the experienced sensation when comparing proximal and distal urethral stimulation. The reason for this is discussed. The possible use of this method as an adjunct to the urodynamic investigation in diagnosing neurogenic lesions is proposed.