Duloxetine, a selective serotonin (5-HT) and norepinephrine (NE) reuptake inhibitor, has been shown to decrease SUI by increasing urethral sphincter contractility.[sup.5] The drug inhibits the pre-synaptic reuptake of 5-HT and NE at Onuf's nucleus in the sacral spinal cord.
Multiple factors may contribute to the risk of SUI following radical prostatectomy including age, preoperative continence status, surgeon experience, education level, concomitant pulmonary disease and need for adjuvant radiation therapy to the prostatic bed.[sup.11,12] The etiologies of SUI after prostatectomy include injury to the nerve, muscle fibers or support structures of the external urethral sphincter (EUS).[sup.13]-[sup.15] The somatic and autonomic neural innervation of the EUS arise from Onuf's nucleus of the sacral cord.[sup.16]-[sup.18] The post-synaptic autonomic neurons of the EUS have a high density of serotonergic and noradrenergic terminals.
External sphincter motor neurons originate from Onuf's nucleus
, located on the anterior horns of the sacral spinal cord at levels S2-S4, and send their axons into the pudendal nerve (and to a lesser degree, the pelvic nerve) that stimulate the striated muscle to contract via the release of acetylcholine (Darrah, Griebling, & Silverstein, 2009; deGroat, 2006).