Erectile dysfunction - Clinical review

An overview of diagnosis and management, including causes, investigations and treatment options.

Penile prosthesis: suitable for patients who fail on other treatments
Penile prosthesis: suitable for patients who fail on other treatments

Section 1: Epidemiology and aetiology
Section 2: Making the diagnosis
Section 3: Managing the condition
Section 4: Prognosis
Section 5: Case study
Section 6: Evidence base


Section 1: Epidemiology, aetiology and pathophysiology

Erection is a complex neurovascular event resulting from the relaxation of cavernosal arteries and smooth muscles of the corpus cavernosum in response to sexual stimulation and release of neurotransmitters. This, along with veno-occlusion, causes blood distension of the corporal sinusoid, leading to erection.

Erectile dysfunction (ED) is defined as the consistent inability to attain or maintain penile erections of sufficient quality to allow satisfactory sexual intercourse.

ED can affect the physical and psychological health of the patient and his partner and so can have an impact on their quality of life. However, ED should not simply be considered a QOL issue because it can be an early warning sign of cardiovascular disease.

Prevalence
ED is increasingly recognised as a public health problem.1 Prevalence increases with age, but ED is not simply a result of the ageing process.

Several population-based studies have considered the natural history and prevalence of ED.

NHSLS
One of these studies, the National Health and Social Life Survey (NHSLS), which defined various types of sexual dysfunction in men and women, documented an ED prevalence of 7% for ages 18-29 years, 9% for ages 30-39, 11% for ages 40-49 and 18% for ages 50-59.

MMAS
The Massachusetts Male Aging Study (MMAS) reported an overall prevalence of 52% ED in men aged 40-70 years. Specific prevalence for mild, moderate and complete ED was 17.2%, 25.2% and 9.6% respectively.2

Cologne Study
The Cologne Study assessed the prevalence of ED in men aged 30-80 years. Overall prevalence was found to be 19.2%, with prevalence increasing from 2.3% in 30 year olds to 53.4% in 80 year olds.3

Pathophysiology
The pathophysiology of ED can be broadly classified according to organic, psychogenic and mixed ED.

The psychogenic to organic sexual dysfunction ratio has been reported to be age-related, with 70% of men aged under 35 years having psychogenic ED and 85% of men aged over 50 years having organic ED. However, the condition is multifactorial in many patients.

The International Society for Impotence Research (ISIR) classification is shown in table 1.4

TABLE 1: ISIR CLASSIFICATION OF CAUSES
Organic
  • Vasculogenic
  • Neurogenic
  • Arteriogenic
  • Anatomical
  • Cavernosal
  • Endocrinological
  • Mixed
Psychogenic
  • Generalised
  • Situational

Risk factors
Risk factors for ED are similar to those of cardiovascular disease(CVD); obesity, diabetes mellitus, dyslipidemia, metabolic syndrome, sedentary lifestyle and smoking. As such, ED can be seen as a reflection of underlying CVD and should trigger further cardiovascular investigations.

Certain drug groups have been identified as possible causes of ED. These include thiazide diuretics, antidepressants (SSRIs), antipsychotics/neuroleptics, and recreational drugs including cocaine, heroin, marijuana, methadone, alcohol and anabolic steroids.

ED can result from various cancer treatments such as radiotherapy, brachytherapy, cryotherapy, high-intensity focused ultrasound and radical prostatectomy, which is associated with a 25-75% rate of ED.5


Section 2: Making the diagnosis

A detailed medical and sexual history is crucial in establishing a diagnosis of ED. This includes asking about sexual orientation, emotional status, problems with sexual arousal and desire, quality of erections, duration of symptoms, presence/absence of early morning erections, lifestyle (including alcohol, smoking and illicit drug use), and previous treatments.

The International Index of Erectile Function (IIEF) is a widely used, multidimensional self-report questionnaire that allows objective evaluation of male sexual function.

It is also useful, where possible, to involve the patient's partner in the initial consultations and follow-up appointments.

Important! Ask patients about sexual orientation, emotional status, sexual arousal and desire, quality of erections, duration of symptoms, early morning erections, lifestyle and previous treatments.

Presentation
Psychogenic and organic categories of ED differ in presentation and severity. 

Organic ED is typically more gradual in onset and progression, except when caused by immediate traumatic events. Erections, including early morning erections, are not routinely observed with organic ED.

Blood pressure
Physical assessment includes BP

Psychogenic ED is usually characterised by sudden onset, with complete and immediate loss of sexual function. The patient, with some exceptions, tends to have preserved early morning erections.

If the aetiology is organic, management would primarily address comorbid conditions contributing to the problem, for example Peyronie’s disease. If psychogenic ED is suspected, counselling is the mainstay of the treatment.

Examination of the patient is essential to look for unsuspected causes of ED such as penile curvature in Peyronie’s disease, genital lesions and other signs of cardiovascular, neurological and endocrine disease.

Investigations
Laboratory testing, including lipid profile, fasting glucose level or HBA1c, and morning total testosterone should be offered to all patients diagnosed with ED.

Other specialised tests, such as the nocturnal penile tumescence and rigidity test, intracavernosal injection test, duplex ultrasonography, arteriography and infusion cavernosometry or cavernosography, should only be used in very select cases.


Section 3: Managing the condition

Lifestyle modifications in patients with specific risk factors should be initially recommended.6 These modifications include weight loss, regular exercise, healthy diet, cessation of smoking and moderating alcohol consumption.

When lifestyle modifications do not suffice, pharmacological treatments may be necessary as outlined below.

PDE5 inhibitors
PDE5 inhibitors such as sildenafil, vardenafil, tadalafil and avanafil are considered first line therapy for ED.

Tadalafil (once daily 5mg) has recently been licensed for the treatment of ED and lower urinary tract symptoms.

Choice of drug will depend on the frequency of intercourse and the patient's circumstances.

Patients should be counselled regarding the treatment and whether it is short-acting (sildenafil and vardenafil) or long-acting (tadalafil), its possible disadvantages and how to use it.

Common side-effects associated with PDE5 inhibitors include headache, flushing and dyspepsia. Tadalafil has a higher incidence of back pain and myalgia than than the other PDE5 inhibitors.

Absorption of sildenafil and vardenafil can be delayed by fatty meals, while absorption of tadalafil is less affected by food.

Prostaglandins
The prostaglandin E1 analogue alprostadil 5-40 microgram can be administered as a second-line therapy in patients not responding to PDE5 inhibitors or who have contraindications to treatment with oral agents.

Two methods of administration are available - direct intracavernosal injection (Caverject) or intraurethral application of a small pellet (medicated urethral suppositories for erection, MUSE) with a dose of 250-1,000 microgram.

Side-effects associated with administration via intracavernosal injection include infection, bleeding and bruising at the injection site, dizziness, heart palpitations, flushing and a rare risk of priapism.

In patients taking anticoagulants, compression of the injection site for five to 10 minutes is advised to minimise bruising.

Side-effects of intraurethral injection of alprostadil include urethral, penile or perineal pain.

Vacuum devices
Vacuum devices produce an erection by creating a vacuum (physically engorging the corpora with venous blood) and using a rubber constricting ring at the base of the penis to maintain this state.

They are useful in patients with psychogenic or organic ED and can be used alone or in combination with other therapies (50-70% response rate).

Penile prosthesis surgery
Penile prosthesis surgery is third line and is suitable for patients with severe organic ED who do not respond to other treatments. Two main subtypes of prosthesis are available, malleable and inflatable.


Section 4: Prognosis

PDE5 inhibitors have revolutionised treatment of ED by decreasing reliance on more invasive options, with a response rate approaching 70-75% in ED of various aetiologies.

Possible reasons for failure include inadequate patient education, incorrect drug use, drug resistance over time, severe ED at presentation or ED after radical pelvic surgery.

However, third-line treatment in the form of penile prosthesis surgery is still associated with a high patient and partner satisfaction rate of more than 80%.


Section 5: Case study

A 60-year-old man presents to his GP after being newly diagnosed with diabetes mellitus. He also reports significant ED that has progressed over the past year and is affecting his quality of life as well as the relationship with his wife. He reports no early morning erections or spontaneous erections satisfactory for vaginal penetration. His history includes hypertension and obesity, he is a smoker and lives a sedentary lifestyle. His BP is moderately controlled (146/92mmHg) and his BMI is 32.

Physical examination is normal with normal genitalia and prostate examination, but a rotund abdomen that is non-tender.

The patient is prescribed PDE5 inhibitors to improve his erectile function after ensuring he has no contraindications.

He is also counselled on risk factors for erectile dysfunction. With obesity, dyslipidaemia and high blood sugars, it is likely that he has metabolic syndrome.

The patient is initiated on statin treatment for his dyslipidaemia, referred to a dietary controlled weight loss programme and encouraged to stop smoking.

Another possible cause of his ED is the combination of antihypertensive medications. These are changed from a thiazide diuretic and beta-blocker to an ARB.

On follow-up, the patient reports that his erections returned to normal within six weeks.


Section 6: Evidence base

Clinical trials

Guidelines

Key text

  • Wein AJ, Kavoussi LR, Novick AC et al. Campbell-Walsh Urology (10th edition). St Louis, WB Saunders, 2011.
  • Sanda MG, et al. Quality of life and satisfaction with outcome among prostate cancer survivors. N Eng J Med, 2008. 358:1250.

Mr Tamer El-Husseiny is specialist registrar in urology, University Hospital Coventry, and Mr Paul Anderson is consultant urological surgeon, Russells Hall Hospital, Dudley Group of Hospitals NHS Foundation Trust.

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References

  1. Laumann EO, Paik A, Rosen RC. Sexual dysfunction in the United States: prevalence and predictors. JAMA 1999; 281: 537.
  2. Feldman HA, Goldstein I, Hatzichristou DG et al. Impotence and its medical and psycho-social correlates: results of the Massachusetts Male Aging Study. J Urol 1994; 151: 54.
  3. Braun M et al. Epidemiology of erectile dysfunction: results of the 'Cologne Male Survey’. Int J Impot Res 2000; 12: 305.
  4. Lizza EF, Rosen RC. Definition and classification of erectile dysfunction: report of the Nomenclature Committee of the International Society of Impotence Research. Int J Impot Res 1999; 11: 141-3.
  5. Sanda MG, et al. Quality of life and satisfaction with outcome among prostate cancer survivors. N Eng J Med, 2008. 358:1250.
  6. Esposito K, Giugliano D. Lifestyle for erectile dysfunction: a good choice. Arch Intern Med 2012; 172: 295-6.

This is an updated version of an article that was first published in December 2013

Suggested further CPD activity

These further action points may allow you to earn more CPD credits.

  • Hold a meeting with your local urologist to discuss treatment options for men with ED.
  • Perform a search of patients with ED and determine the proportion who have had their cholesterol and testosterone levels checked.
  • Ensure that all patients with ED have had their weight and BP checked and documented.

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