Erectile Dysfunction
The inability to get or keep an erection firm enough for sexual intercourse, often indicating underlying vascular or metabolic issues.
Emergency Management: Priapism (an erection lasting >4 hours, often a complication of injection therapy or trazodone) requires emergency corporal aspiration and injection of phenylephrine (100-500 mcg) to prevent irreversible penile fibrosis and permanent ED.
Erectile dysfunction (ED) is defined as the consistent or recurrent inability to attain and/or maintain a penile erection sufficient for satisfactory sexual performance. It must be present for a minimum of 3 to 6 months to establish the diagnosis.
Detailed Overview
Penile erection is a complex neurovascular event that relies on the intact functioning of the autonomic and somatic nervous systems, arterial blood flow, and the veno-occlusive mechanism of the corpora cavernosa. ED is rarely a primary disease; it is most often a symptom of underlying systemic conditions, particularly endothelial dysfunction and cardiovascular disease. ED shares the same risk factors as coronary artery disease and often precedes clinical cardiovascular events by 3 to 5 years, acting as an early warning sign.
Epidemiology & Demographics
Highly prevalent, affecting over 150 million men worldwide. The prevalence strictly correlates with age, affecting approximately 40% of men at age 40 and up to 70% of men at age 70.
Etiological Mechanism
ED can be categorized into vasculogenic (most common, due to atherosclerosis), neurogenic (e.g., radical prostatectomy, spinal cord injury), hormonal (hypogonadism), psychogenic (performance anxiety, depression), and iatrogenic (medication-induced).
Primary Causes
Atherosclerosis and Endothelial Dysfunction
Diabetes Mellitus (neurovascular damage)
Prostate surgery or pelvic irradiation
Medications (e.g., SSRIs, Beta-blockers, Thiazides)
Testosterone Deficiency
Normal erection requires nitric oxide (NO) release from parasympathetic nerve endings and endothelium in the corpora cavernosa. NO stimulates guanylate cyclase, converting GTP to cGMP. cGMP causes smooth muscle relaxation, allowing rapid arterial inflow into the cavernous sinusoids. The expanding sinusoids compress the subtunical venules against the tunica albuginea, creating veno-occlusion and trapping blood. In organic ED, endothelial dysfunction reduces NO bioavailability. Atherosclerotic plaques reduce arterial inflow. Structural changes (fibrosis) in the corpus cavernosum prevent adequate expansion and veno-occlusion (venous leak).
Diagnostic Criteria & Guidelines
Diagnosis is clinical, based on patient history using standardized questionnaires like the International Index of Erectile Function (IIEF-5). Organic ED is characterized by gradual onset and loss of nocturnal erections. Psychogenic ED often has sudden onset, situational occurrences, and preserved nocturnal erections.
Phosphodiesterase type 5 (PDE5) inhibitors are first-line. Sildenafil 50 mg PRN (taken 1 hour before intercourse on an empty stomach); Tadalafil 10-20 mg PRN (lasts 36 hours) or 5 mg daily. Contraindicated in patients taking systemic nitrates (e.g., Nitroglycerin) due to risk of fatal hypotension. Optimize underlying conditions (glucose control, statins, BP control).
Second-Line & Adjunctive Therapy
Intracavernosal Injections: Alprostadil (PGE1) 10-20 mcg injected directly into the corpus cavernosum using a 29g needle. Intraurethral Suppositories (MUSE): Alprostadil 500-1000 mcg inserted into the urethra. Vacuum Erection Devices (VED).
Surgical & Procedural Management
Penile Prosthesis Implantation. Inflatable Penile Prosthesis (3-piece is the gold standard) is highly effective and offers the highest patient and partner satisfaction rates for medical-refractory ED.
Patient Counseling & Advice
Educate that PDE5 inhibitors are not magic pills; they require sexual stimulation to work. Explain proper timing and food interactions (especially for Sildenafil). Reassure that ED is common and highly treatable. Stress cardiovascular screening.
Follow-Up & Monitoring Schedule
Re-evaluate at 4-6 weeks after initiating PDE5 inhibitors to assess efficacy, side effects, and proper usage. Screen annually for cardiovascular disease progression.
Preventive Strategies
Maintenance of a healthy lifestyle (diet, exercise) and strict management of hypertension, hyperlipidemia, and diabetes. Avoidance of excessive alcohol and tobacco.
Highly treatable. Over 70% of men respond well to oral PDE5 inhibitors. For non-responders, injection therapies or surgical prostheses offer >90% success rates.