The bladder cooling reflex in man--characteristics and sensitivity to temperature.

The ice-water test is a simple supplementary urodynamic test that increases the precision of the diagnosis of overactive bladder subtypes. A similar bladder cooling reflex has recently been characterised in the cat and was found to originate from specific cold receptors in the bladder wall. In the present study, the threshold temperature of the human bladder cooling reflex was determined in patients with positive ice-water tests. Estimated threshold values were somewhat lower than those of the cat but still well above the temperatures required for cold stimulation of nociceptors. As in the cat, the strength of the cooling reflex varied inversely with the bladder temperature. These findings indicate that the human bladder cooling reflex is in principle organised in the same way as that of laboratory animals. The human bladder thus seems to be endowed with cold receptors with excitatory reflex connections to the detrusor.