The somatosensory pathways for erections originate in the penile skin, glans and urethra. Glans afferent sensory free nerve endings are 10-fold more than their corpuscular receptors, and are derived from Aδ and unmyelinated C fibers. The nerve endings coalesce to form the dorsal penile nerve along with other sensory nerve fibers. Through the pudendal nerve they enter the S2-4 nerve roots to terminate on spinal neurons and interneurons. The dorsal nerve is not purely somatic, however. Nerve bundles within the dorsal nerve contain nitric oxide (NO) synthase, found typically in autonomic nerves, and stimulation of the sympathetic chain can leak to evoked potentials from the dorsal nerve and vice versa (10-12).
Cavallini, G., Modenini, F., Vitali, G., & Koverech, A. (2005, November). Acetyl-L-carnitine plus propionyl-L-carnitine improve efficacy of sildenafil in treatment of erectile dysfunction after bilateral nerve-sparing radical retropubic prostatectomy. Urology, 66(5), 1080-5. Retrieved from http://www.sciencedirect.com/science/article/pii/S0090429505006515
An alprostadil cream that patients apply into the tip of the penis (the urethral meatus, the opening that urine passes through) is currently available in the UK and Europe. It is currently under review by the U.S. Food and Drug Administration (FDA). After application of the cream, an erection occurs within five to 30 minutes, and the erection lasts one to two hours in men who respond to the cream. Doctors recommend that one use the cream for a maximum frequency of two to three times per week and no more frequent than once every 24 hours. It has essentially the same contraindications and side effects as the other formulations of alprostadil. The cream may cause vaginal burning in roughly 4% of partners. Men should not use alprostadil cream for sexual intercourse with women of childbearing potential unless a condom is used. Researchers have performed controlled trial studies to evaluate the safety and effectiveness of this drug. Overall, 52% of men reported improvement in their erections compared to 20% of men receiving placebo. A later analysis demonstrated that 36% of men using the alprostadil cream had a clinically relevant improvement in vaginal penetration ability and 31% clinically relevant improvement in ability to have successful intercourse to ejaculation.
A physical exam checks your total health. Examination focusing on your genitals (penis and testicles) is often done to check for ED. Based on your age and risk factors, the exam may also focus on your heart and blood system: heart, peripheral pulses and blood pressure. Based on your age and family history your doctor may do a rectal exam to check the prostate. These tests are not painful. Most patients do not need a lot of testing before starting treatment.
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