Brain control of the lower urinary tract

The knowledge on neural pathways involved in micturition and continence has been expanded greatly the last ten years. The aim of the present review is to summarize results obtained from animal and human experiments and to discuss the pathophysiology of relevant urological dysfunction. Four specific parts of the mammalian neural system are important for the control of micturition and continence: 1) ganglion cells in the bladder wall and sympathetic chain (autonomic) and dorsal root chain (sensory); 2) motoneurons and sensory interneurons in the caudal spinal cord; 3) the caudal brainstem; and 4) the cortical and subcortical areas. The parts 1) to 3) comprise the basic components of the micturition reflex and are interconnected via peripheral nerves and central fiber tracts. Normally, we are continent for urine continuously, except for the necessary emptying of the bladder five to eight times a day. Specific lesions of the neural pathways can result in distinct types of urological dysfunction: hypoactivity or hyperactivity of the micturition or continence pathways, and a loss of control of the beginning of micturition.