Clinical meaning
Neurogenic bladder refers to bladder dysfunction caused by neurological damage that disrupts the normal coordination between the detrusor muscle, the internal urethral sphincter, and the external urethral sphincter. Normal micturition requires intact neural pathways involving the pontine micturition center in the brainstem, the sacral micturition center at spinal cord levels S2 through S4, and both the sympathetic (T10-L2) and parasympathetic (S2-S4) nervous systems. The detrusor muscle is innervated primarily by parasympathetic fibers from the pelvic nerve; when these fibers are stimulated, the detrusor contracts and the internal sphincter relaxes, allowing urine to flow. The sympathetic nervous system promotes bladder filling by relaxing the detrusor and contracting the internal sphincter through the hypogastric nerve. The external urethral sphincter is under voluntary (somatic) control via the pudendal nerve. Upper motor neuron (UMN) lesions occur above the sacral micturition center, typically from spinal cord injuries at the cervical or thoracic level, multiple sclerosis, stroke, or brain tumors. UMN lesions produce a spastic (hyperreflexic) bladder with involuntary detrusor contractions, small bladder capacity, urinary frequency, urgency, and incontinence. The bladder contracts reflexively but without voluntary...