| disease | Erectile Dysfunction |
| alias | Impotence |
Erectile dysfunction, also known as impotence, refers to the inability to achieve or maintain an erection sufficient for vaginal penetration or to sustain it until ejaculation. A survey conducted in the general population in the United States found that the incidence rate among adult males is 8%; in China, it is estimated to be around 10%.
bubble_chart Etiology
Erectile dysfunction is mainly divided into two categories: psychological and organic. Organic causes include neurological, vascular, endocrine, and structural issues. Previously, it was believed that 86-90% of cases were due to psychological disorders. Recent advances in scientific technology have revealed that organic erectile dysfunction accounts for more than 50%. Virag (1985) suggested that it accounts for 50%-80%. The Urology Research Institute of Beijing Medical University examined 503 cases of erectile dysfunction patients and found that organic factors accounted for 49.3% (248 cases). However, it is important to emphasize that all patients with erectile dysfunction have varying degrees of psychological disorders, and purely psychological erectile dysfunction generally accounts for less than half.
1. Psychological factors affecting erectile function Due to differences in individual psychological qualities, similar psychological stimuli may elicit different reactions. While psychological trauma does not lead to erectile dysfunction in most people, it can become a causative factor for some. Common factors include a lack of or incorrect sexual education, such as guilt and fear over masturbation and seminal emissions, viewing sexual behavior as dirty or vulgar, etc. Psychological trauma from sexual harassment in childhood, initial sexual intercourse failure, discord in marital relationships, excessive tension in social relationships, inappropriate settings for intercourse, fear of pregnancy and disease, etc., long-term anxiety can stimulate the sympathetic nervous system, releasing norepinephrine which causes vasoconstriction and a decrease in blood testosterone, leading to erectile dysfunction.
2. Qualitative factors affecting erection Systemic diseases in patients such as cardiovascular diseases (coronary heart disease, hypertension), respiratory diseases (lung cancer, pulmonary insufficiency), endocrine system diseases (hypospadias, cavernous body sclerosis), neuropsychiatric system diseases (spinal type, temporal lobe lesions, depression), blood and liver and kidney diseases, etc., are risk factors for impotence. Spinal cord, pelvic, and urethral trauma surgeries, drug effects (sedatives, anti-anxiety drugs, antihypertensive drugs, hormonal drugs, etc.), as well as smoking, alcoholism, and drug abuse can all lead to varying degrees of erectile dysfunction.1. Medical History Since sexual function involves issues concerning both partners, it is essential to patiently listen to the accounts of both the patient and their spouse when assessing the patient's sexual capabilities. For patients who find it difficult to express themselves, written or form-based methods can be used. The main content should include: ① The cause, duration, and severity of erectile dysfunction; ② Whether erections occur during nighttime, upon waking, masturbation, or visual stimulation; ③ Whether changes in sexual positions affect the hardness of erections; ④ Changes in libido and ejaculation; ⑤ Psychological trauma experienced in social or family contexts; ⑥ History of chronic diseases, medication use, and surgical trauma; ⑦ History of smoking, alcohol abuse, and drug use.
Based on the information obtained from the medical history, a preliminary impression can be formed to differentiate between psychological and organic erectile dysfunction. Psychological erectile dysfunction is more common in young adults, often with a history of psychological trauma, and manifests as sudden, intermittent, or situational erectile dysfunction. Normal erections may occur during nighttime or masturbation, with little change in libido or ejaculatory function, and no history of trauma, surgery, sexually transmitted diseases, or long-term medication use.
3. Laboratory Tests Routine blood and urine tests, as well as liver and kidney function tests, serve as screening measures. The following items should be emphasized:
Blood sugar and urine sugar: Diabetes often causes vascular and nerve damage, with approximately half of diabetic patients experiencing complications of erectile dysfunction. If necessary, a glucose tolerance test should be conducted to identify latent diabetes.
4. Special Tests
(1) Psychological Testing: The Minnesota Multiphasic Personality Inventory (MMPI), Derogatis Sexual Function Inventory, and California Personality Inventory are useful for distinguishing between psychological and organic erectile dysfunction, but they should not be considered definitive.
(2) Nocturnal Penile Tumescence (NPT) Test: In 1970, Karacan first used the physiological phenomenon of nocturnal penile erections to differentiate between psychological and organic erectile dysfunction. This test is less influenced by psychological factors and provides a more objective assessment of penile erectile function. In normal individuals, erections occur 4-6 times per night during rapid eye movement (REM) sleep, lasting 25-40 minutes. Rigiscan monitoring shows a hardness of 65-70%, but this test still has a 15-20% false-negative rate.
(4) Penile Blood Flow Testing: Vascular abnormalities in the penis are a significant cause of organic erectile dysfunction, involving impaired arterial blood supply and venous occlusion mechanisms.
Vasoactive Drug-Induced Erection Test: Currently, 30-60mg of papaverine, 1-2mg of phentolamine, or 20μg of prostaglandin E2 are commonly used, either alone or in combination. Injection of these drugs into the corpus cavernosum resulting in a rigid erection lasting more than 30 minutes indicates no significant vascular abnormalities, though false negatives are still possible. The reliability increases when combined with sexual stimulation. Possible complications include bruising, hematoma, and priapism.
Penile Doppler Ultrasound Monitoring: Determines the ratio of penile stirred pulse blood pressure to brachial stirred pulse blood pressure (PBI). A value less than 0.6 suggests a penile stirred pulse blood supply disorder. The absolute difference between the two systolic blood pressures should not exceed 4kPa (30mmHg).
Penile Flow Index (PFI): The penile flow index is calculated by measuring the acceleration of the radial stirred pulse, dorsal penile stirred pulse, and cavernous stirred pulse using a Doppler ultrasound probe. A PFI < 6 indicates normal penile blood supply.
Penile Stirred Pulse Blood Flow Volume Recording: The normal penile blood flow pulse volume waveform shows a rapid rise to a peak followed by a slow decline with a dicrotic notch. A rounded peak or a slow decline with the disappearance of the dicrotic notch suggests vascular pathology.
Color Duplex Doppler Ultrasound: This method detects the structure of the cavernous body, vascular diameter, blood flow velocity, and vasomotor function. It dynamically monitors the hemodynamic changes of the penile stirred pulse and venous blood flow during erection, as well as the cavernous resistance index. It is one of the most valuable non-invasive screening methods for vascular erectile dysfunction.
Cavernous Perfusion Test and Cavernosography (Dynamic Infusion Cavernosometry & Cavernosography, DICC): This typically monitors the induction flow (IF), maintenance flow (MF), and the pressure loss (PL) within 30 seconds after stopping the infusion. Higher MF and PL values indicate venous fistula disease-related erectile dysfunction. Normal PL should be < 3.3 kPa (25 mmHg) within 30 seconds, MF should be < 20-40 ml/min, and IF should be 80-120 ml/min. Cavernosography involves injecting a contrast agent to observe abnormal venous reflux during erection. Common abnormal refluxes include: deep dorsal penile vein to the prostatic plexus and internal pudendal vein, cavernous vein to the prostatic plexus and internal pudendal vein, and fistula disease between the penile cavernous body and the urethral cavernous body.
Internal Pudendal Stirred Pulse Angiography: For patients suspected of having penile stirred pulse blood supply disorders, bilateral internal pudendal stirred pulse angiography should be performed via the femoral stirred pulse before penile stirred pulse reconstruction surgery to observe lesions in the dorsal penile stirred pulse and cavernous stirred pulse.
Erectile Nerve Testing: Nerves play a crucial role in the erection mechanism, so routine testing of the nervous system related to erection is essential in disease cause diagnosis, especially for patients with a history of cranial, spinal, pelvic trauma, or diabetes.
Bulbocavernosus Reflex Latency Time (BCRL): This tests the conduction speed from the dorsal penile nerve (sensory afferent) to the sacral spinal cord, and then from the motor efferent nerve to the bulbocavernosus muscle, ischiocavernosus muscle, and anal sphincter. The normal range is 27-42 ms.
Urethroanal Reflex Latency Time (UARL): This tests the conduction speed of the autonomic nerves, with a normal range of 46-75 ms.
Pudendal Evoked Potential (PEP): This tests the conduction speed of the penile nerve along the spinal cord to the cerebral cortex, with a normal range of 36-47 ms.
Porst found that 66% of 130 patients with erectile dysfunction had the aforementioned nervous system abnormalities. In a study by the Urology Research Institute of Peking University, 39.6% (21 cases) of 53 patients with erectile dysfunction showed abnormalities.
Single Potential Analysis of Cavernous Electric Activity (SPACE): By observing the electrical activity of the cavernous muscle, the degree of degeneration of the autonomic nerves and smooth muscle can be understood. In a study by Stief on 112 cases of erectile dysfunction, 49% (55 cases) showed abnormal SPACE.
⑹ Corpus cavernosum biopsy: This remains controversial. Some scholars believe that the atrophy and disappearance of smooth muscle structure leading to functional decline is an important factor in causing erectile dysfunction. However, Mealeman and Jevtich argue that there are structural differences due to age, and there is no significant difference between normal individuals and patients.
bubble_chart Treatment Measures
Due to the unclear physiological mechanism of penile erection and the complex disease causes of erectile dysfunction, although there are many treatment methods for erectile dysfunction, the results are still not ideal. Therefore, a comprehensive analysis should be conducted before deciding on a treatment plan, and multiple approaches should be used to achieve satisfactory results.
1. Psychosexual therapy: Any type of erectile dysfunction should emphasize psychosexual therapy to achieve more effective results.
The human brain can send reinforcing impulses to the spinal erection center and can also send inhibitory messages to prevent the excitement of the erection center. Anxiety and tension generated by the brain are often the disease causes of erectile dysfunction. In the 1960s, Masters and Johnson, and in the 1970s, Kaplan made significant achievements in psychosexual therapy. Through a series of sensual focus training, the patient's tension is relieved, anxiety and fear are eliminated, confidence in restoring erectile ability is enhanced, and with the guidance of physiological knowledge and behavioral methods, the improvement rate of unselected erectile dysfunction patients reaches 30-55%.
2. Intracavernous drug self-injection: Initially, papaverine 30-60mg or phentolamine 1-2mg was used alone or in combination, achieving satisfactory results, but about 2-6% would experience priapism complications, which is concerning. Recently, prostaglandin E1 (prostaglandin E120-60μg) has been widely used, which can be rapidly metabolized in the body, significantly reducing the incidence of priapism, making it the most ideal drug. A report from Shanghai on 1500 patients showed that 86% could complete sexual intercourse after injection of papaverine and phentolamine, while priapism, local pain, skin static blood, foreskin edema, and cavernous fibrosis each accounted for 2%, and there was a phenomenon of drug escalation. However, PGE1 had no priapism, but 18% of patients experienced local pain at the injection site. Stief (1991) used PGE1 10μg and CGRP5mg in combination, and the efficacy was significantly higher than single injection, but the lack of toxicological research on CGRP limits its application. Recently, linsidomine (SIN-1), an NO donor, has been applied. Stief first applied it to intracavernous injection; in 40 patients who did not respond to papaverine and phentolamine or had persistent erection, SIN-1 was used instead, and 33 cases achieved complete or almost complete erection. However, Turss believes that although SIN-1 is more complete, its efficacy is not as good as papaverine and phentolamine (except for neurogenic erectile dysfunction). In a 10-year summary of 4000 cases of erectile dysfunction treatment, Porst observed the effective rates of various drugs: SIN-1 only 17.3% (13/75), papaverine 39% (370/950), papaverine + phentolamine 61% (152/250), PGE172% (2304/3200), and considered the latter two effective for all types of dysfunction, while SIN-1 is only effective for psychogenic and neurogenic erectile dysfunction. Melman reported that forskolin, due to its ability to activate adenylate cyclase and increase intracellular cAMP levels, causing smooth muscle relaxation, is a promising clinical drug in animal experiments. Schmidt, Cavallini, and others reported the use of nitroglycerin, yohimbine, and minoxidil, which have skin-penetrating effects and can achieve erection effects when applied to the surface of the penis.
3. Intraurethral Administration Starting in 1996, synthetic prostaglandin E1125-1000μg (alprostadil, urethral suppository) was used for intraurethral administration to treat erectile dysfunction, with a one-time success rate of 65% (compared to 19% for placebo). Possible side effects include penile pain, urethral pain, testicular pain, and dizziness. There are no reports on whether this Yaodui has any effect on early pregnancy, so contraceptive measures are necessary.
4. Oral Medications: Divided into Hormonal and Non-Hormonal Categories:
Hormonal medications are suitable for endocrine erectile dysfunction. Primary hypogonadism, such as Klinefelter syndrome, is treated with testosterone replacement therapy using testosterone enanthate, testosterone undecanoate, triolandren, etc. Secondary hypogonadism, such as Kallmann syndrome, is treated with human chorionic gonadotropin and LHRH biopump to promote the development of Leydig cells and seminiferous epithelium, achieving therapeutic goals.
Non-hormonal medications mainly include yohimbine, an α2adrenergic receptor antagonist, which acts on the central and peripheral nervous systems, but its efficacy remains controversial. The dopamine receptor agonist apomorphine (apomorphine), used in oral form by Heaton, improved 70% of non-organic erectile dysfunction cases.
In 1998, the phosphodiesterase type V (PDE3) inhibitor (Viagra) was introduced, which relaxes cavernous smooth muscle through the NO-cGMP pathway to treat erectile dysfunction, with an improvement rate of 78%, compared to 20.5% for placebo. However, it may cause side effects such as dizziness, headache, flushing, nasal congestion, gastrointestinal symptoms, and visual disturbances; it should not be used with NO agents like nitroglycerin. Patients with heart disease should use it with caution.
Subsequently, the oral α-receptor blocker phentolamine began to be used domestically and internationally, with an efficacy rate of 36-50%, compared to 13.4-26% for placebo, and is effective for mild grade II erectile dysfunction.
5. Vacuum Constriction Device (VCD): Designed by Lederer in 1917 and improved and popularized by Osben in the 1970s. It uses negative pressure to enlarge the penis, with an elastic ring placed at the base of the penis to prevent venous return, maintaining an erect state. This device is suitable for elderly patients with organic sexually transmitted diseases. Nadig observed 196 patients, with 75% experiencing penile numbness, 28% having reduced orgasmic ability (2.5% unable to achieve orgasm), 12% experiencing ejaculation difficulties, and 3-11% having painful orgasms.
6. Surgical Treatment: Suitable for venous and arterial erectile dysfunction.
Penile venous surgery includes deep dorsal vein ligation, penile crural vein ligation, ischiocavernosus muscle plication, urethral spongiosum stripping, and internal iliac vein ligation.
Statistics from 15 authors reporting on 602 cases of various venous surgeries, with follow-ups ranging from 1 to 72 months, showed success rates ranging from 0 to 88%, with an average of 37.4%. Wespes reported 20 cases in 1985, with follow-ups of 3-24 months and a success rate of 80%; in 1990, he reported 67 cases with follow-ups of 24-72 months, with the success rate dropping to 46%. The Urology Research Institute of Beijing Medical University reported 57 cases, with follow-ups of 1-3 months and a success rate of 47.4%; follow-ups of 6-24 months showed a success rate of 28.1%. Therefore, venous surgery is not an ideal treatment method, possibly due to the complex causes of erectile dysfunction, as patients often have issues beyond just venous problems, including psychological, arterial, neurological, and penile tissue structural pathologies.
The penis stirred pulse surgery mostly adopts the inferior epigastric stirred pulse and the dorsal penis stirred pulse for end-to-side or end-to-end anastomosis; for those with poor dorsal penis stirred pulse conditions, the deep dorsal vein of the penis stirred pulse can be used for Virag I (without ligating the deep dorsal vein of the penis above the anastomosis), Virag II (ligating the deep dorsal vein of the penis above the anastomosis), and the dorsal penis stirred pulse and deep dorsal vein with the inferior epigastric stirred pulse for a trifurcation anastomosis (Hauri method). Eight authors reported 884 cases of penis stirred pulse reconstruction, with a success rate of 50-80%, averaging 71.5%. The Urology Research Institute of Beijing Medical University performed 8 surgeries, with a short-term success rate of 75% and a long-term follow-up rate of 50%.
Penile prosthesis implantation is an effective treatment for erectile dysfunction, suitable for patients with organic and certain psychological erectile dysfunction who have not responded to other treatments. The prostheses mainly include semi-rigid rod penile prostheses (small-carrion, flexirod, silicone-silver prostheses), inflatable three-piece prostheses (AMS 700CX), inflatable two-piece prostheses (mentor GFS, uni-flate 1000), and inflatable single-piece prostheses (AMS hydroflex, flexi-flateⅡ). Surgical complications and mechanical failures account for about 7-25%, infections about 1-8%, perforations 1.6%-6.7%, pain 0.4%-5.7%, and prosthesis size discomfort about 0.7-2%.
