Scientific research
2- Erectile Dysfunction
Practice Essentials
The National Institutes of Health (NIH) Consensus Development Conference on Impotence (December 7-9, 1992) defined impotence as "male erectile dysfunction, that is, the inability to achieve or maintain an erection sufficient for satisfactory sexual performance."
Signs and symptoms
The first step in the management of ED is a thorough history that includes the following:
- Sexual history
- Medical history
- Psychosocial history
A physical examination is necessary for every patient, emphasizing the genitourinary, vascular, and neurologic systems. A focused examination entails evaluation of the following:
- Blood pressure
- Peripheral pulses
- Sensation
- Status of the genitalia and prostate
- Size and texture of the testes
- Presence of the epididymis and vas deferens
- Abnormalities of the penis (eg, hypospadias, Peyronie plaques)
There is a strong correlation between hypertension and ED. There is also a correlation between benign prostatic hyperplasia and ED, though the causality is unclear.
Diagnosis
Laboratory testing for ED depends on information gathered during the interview; it is necessary for most patients, although not for all. Such testing may include the following:
- Evaluation of hormonal status (testosterone, serum hormone–binding globulin, luteinizing hormone [LH], prolactin, thyroid-stimulating hormone [TSH]) – Note that the American College of Physicians (ACP) does not recommend for or against routine use of hormonal blood tests or hormonal treatment in ED patients
- Screening blood studies (hemoglobin A 1c, serum chemistry panel, lipid profile)
- Prostate-specific antigen levels, if the patient is a candidate for prostate cancer screening (controversial)
- Urinalysis
Functional tests that may be helpful include the following:
- Direct injection of prostaglandin E1 (PGE1; alprostadil) into the corpora cavernosa (see the image below)
- Biothesiometry – Infrequently indicated
- Nocturnal penile tumescence testing – Once frequently performed, this is rarely used in current practice, though it can be helpful when the diagnosis is in doubt
- Formal neurologic testing – Not needed in the vast majority of ED patients, though it may offer some benefit to patients with a history of central nervous system problems, peripheral neuropathy, diabetes, or penile sensory deficit
Imaging studies are not commonly warranted, except in situations where pelvic trauma has been sustained or surgery performed. Modalities that may be considered include the following:
- Ultrasonography of the penis (to assess vascular function within the penis)
- Ultrasonography of the testes (to help disclose abnormalities in the testes and epididymides; rarely indicated)
- Transrectal ultrasonography (to disclose abnormalities in the prostate and pelvis that may interfere with erectile function)
- Angiography (in patients who are potential candidates for vascular surgery)
Management
Treatment options for ED include the following:
- Sexual counseling, if no organic causes can be found for the dysfunction
- Oral medications
- Injected, implanted, or topically applied medications
- External vacuum and constriction devices
- Surgery
Many patients with ED also have cardiovascular disease; thus, treatment of ED in these patients must take cardiovascular risks into account.
According to American Urological Association (AUA) guidelines, oral phosphodiesterase type 5 (PDE5) inhibitors are first-line therapy unless contraindicated. [1] Agents include the following:
- Sildenafil
- Vardenafil
- Tadalafil
- Avanafil
In patients with ED refractory to oral PDE5 inhibitors, one of these agents can be combined with an injection of PGE1. [2]
In a prospective, multicenter, single-armed study of ED patients who exhibited a suboptimal response to PDE5 inhibitors, the investigators found that percutaneous implantation of zotarolimus-eluting stents in focal atherosclerotic lesions was both safe and feasible and was associated with clinically meaningful improvement on subjective and objective measures of erectile function. [3]
Hormone replacement may benefit men with severe hypogonadism and may possibly be useful as adjunctive therapy when other treatments are unsuccessful. Replacement androgens are available in oral (rarely used), injectable, gel, and transdermal preparations.
Intracavernosal injection therapy may be considered and is almost always effective if the vasculature within the corpora cavernosa is healthy. Agents used include the following:
- Alprostadil (most common)
- Phentolamine
- Papaverine
The Medicated Urethral System for Erections (MUSE) involves the formulation of alprostadil (PGE1) into a small intraurethral suppository that can be inserted into the urethra. This may be useful for men who do not want to use self-injections or those in whom oral medications have failed.
External devices that may be used include the following:
- Vacuum devices to draw blood into the penis
- Constriction devices placed at the base of the penis to maintain erection
Selected patients with ED are candidates for surgical treatment. Procedures to be considered include the following:
- Revascularization (rarely indicated)
- Surgical elimination of venous outflow (rarely indicated)
- Placement of penile implant (semirigid or malleable rod implant, fully inflatable implant, or self-contained inflatable unitary implant) – Once the only effective therapy for men with organic ED, this is the last option considered in current practice
Suggested measures for preventing ED include the following:
- Optimal management of diabetes, heart disease, and hypertension
- Lifestyle modifications to improve vascular function (eg, not smoking, maintaining ideal body weight, and engaging in regular exercise)
