Neuroselective measure of the current perception threshold of A-delta and C-fiber afferents in the lower urinary tract

Sensory dysfunction could be involved in various pathogeneses in the lower urinary tract including neurogenic bladder, overactive bladder, painful bladder syndrome and neuropathy as a result of endocrine disorders. The ability to diagnose sensory function more objectively is of increasing interest to clinicians. Afferent innervations of the lower urinary tract involve myelinated (A-delta) and unmyelinated (C) fibers. The Neurometer (Neurotron, Baltimore, MD, USA) is the only reported commercially available device to evaluate afferent function by selectively depolarizing different subpopulations of afferent nerves, with 250 Hz activating A-delta fibers and 5 Hz activating C-fibers, to determine their current perception threshold (CPT) as a quantitative measure. Recently, increased evidence has suggested that measurement of CPT values of A-delta and C-fibers in the lower urinary tracts is feasible and shows significant correlation with clinical symptoms and conventional urodynamic variables, as well as the efficacy of various treatments. However, there are still controversial issues in the wider use of this technology in diagnosis and assessment of the therapeutic effectiveness of sensory dysfunction in the lower urinary tracts. In order to resolve the remaining challenges in the CPT test of the lower urinary tract, recent efforts include development of a new balloon-type electro-catheter with dual electrodes as an alternative sensory test for the bladder or urethra, which allows simultaneous performance of conventional urodynamic tests and urine collection, and future standardized techniques available for comparison with validated control values.