The bladder cooling reflex and the use of cooling as stimulus to the lower urinary tract.

PURPOSE: We review the physiology of bladder cooling response in experimental animals and humans, and present its clinical usefulness. MATERIALS AND METHODS: We describe experimental studies of the bladder cooling response, and more recent clinical retrospective and prospective studies of the bladder cooling test in adults and children. RESULTS: Studies indicate the existence of a segmental spinal bladder cooling reflex that originates from specific cold receptors in the bladder and urethral walls supplied by unmyelinated C-afferents. The reflex is positive in neurologically normal infants and children until about age 4 years. It becomes negative with further maturation of the nervous system but may be unmasked by pathological processes that disturb the descending neuronal control of normal voiding. A positive test in a patient with an overactive bladder requires further neurourological evaluation. CONCLUSIONS: The bladder cooling response originates from cold receptors within the walls of the lower urinary tract. The cooling response represents a neonatal reflex that may be unmasked by central neuropathology, analogous to the appearance of the Basbinki sign in pyramidal tract lesions. The bladder cooling test is a simple and valuable tool to support the diagnosis of neurourological disorders.