Outflow obstruction in neuropathic bladder dysfunction: the neuropathic urethra

Urethral pressure profiles were recorded in a series of patients with traumatic lesions of the spinal cord producing vesico-urethral dysfunction. Patients were classified into groups depending upon the relationship of the lesion to the sympathetic outflow to the bladder and urethra from the spinal cord. Using alpha-adrenergic blocking agents, the smooth muscle contribution to the maximum urethral pressure was ascertained in each group and differences in both the configuration of the profile, and the smooth muscle component, were found. Increases in the maximum urethral pressure in response to a change in posture were also investigated, and the extent of the increase found to vary according to the level of the spinal lesion in respect of the sympathetic outflow, and with the integrity of the sacral cholinergic reflex arcs. The hypothesis that these changes may be due to urethral "decentralisation supersensitivity" from alterations in circulating catecholamine levels is suggested.