Erectile dysfunction

• Overview:

  • The inability to attain +/- maintain erection sufficient for sexual performance
  • Common but treatable
  • Symptom not a disease
  • Associated with important conditions - cardiovascular disease
  • Attributable to a number of factors: neuronal, vascular, hormonal, metabolic
  • Risk factors similar to those for cardiovascular disease
• ED is an important marker of future cardiovascular risk

  Predate cardiovascular events by 3-5 years
• Risk factors:

  • Increased age
  • Sedentary lifestyle
  • Obesity
  • Smoking
  • Hyperlipidaemia
  • Hypertension
  • Diabetes
  • Metabolic syndrome
• Physiology:

  • Complex neurovascular phenomenon
  • Triggered by cognitive inputs to CNS
  • 3 cylindrical bodies of erectile tissue - corpus spongiosum + 2 corpora cavernosa
  • Arterial dilation - erectile tissue fills with blood
  • Trabecular smooth muscle relaxation
  • Activation of corporal veno-occlusive mechanism = compression of emissary veins = prevents venous outflow = erection
• Blood supply:

  • Arterial supply is by the dorsal penile artery, the deep penile artery and the bulbourethral artery - all from internal pudendal artery
  • Venous drainage via superficial and deep dorsal veins
• Innervation:

  • All innervation comes from S2-4
  • Parasympathetic innervation via cavernous nerves = erection
  • Sympathetic supply via pudendal nerve which gives off dorsal nerve of the penis = ejaculation
• Vascular causes:

  • Hypertension
  • Atherosclerosis
  • Hyperlipidaemia
  • Smoking
• Neurological causes:

  • Parkinson's disease
  • MS
  • Stroke
  • Spinal cord injury
  • Peripheral neuropathy
• Hormonal causes:

  • Hypogonadism (low testosterone)
  • Hyperprolactinaemia
  • Thyroid disease
  • Cushing's disease
• Drug induced:

  • Anti-hypertensives
  • Beta blockers
  • Diuretics
  • Antidepressants
  • Antipsychotics
  • Anticonvulsants
  • Recreational drugs
• Systemic disease causes:

  • Diabetes
  • Renal failure
• Structural causes:

  • Pelvic trauma
  • Penile trauma
  • Peyronie's disease - fibrous scar tissue
  • Prostate diseases
• Psychogenic causes:

  • Depression
  • Anxiety
  • Performance anxiety
  • Schizophrenia
• Ascertaining whether a patient is having normal or impaired nocturnal erections will help to distinguish between organic vs. psychogenic causes of ED.
• History:

  • Sexual
  • Onset and duration of symptoms
  • Explore - precipitating, predisposing and maintaining factors
  • Any previous investigations
  • Any previous management
  • Current emotional status
  • Any spontaneous/masturbatory/partner related erections
  • Sexual desire
  • Ejaculatory timing
  • Previous erectile capacity
• Other important areas in the history:

  • PMH - cardiovascular disease, previous surgery, diabetes, BPH
  • Medication history
  • Social history - alcohol, illicit drug use
• Validated questionnaires:

  • Sexual health inventory for men
  • International index for erectile function (IIEF)
• Predisposing factors:

  • Lack of sexual knowledge
  • Religious or cultural beliefs
  • Restrictive upbringing
  • Unclear sexual or gender preference
  • Previous sexual abuse
  • Physical or mental health problems
  • Drugs
• Precipitating factors:

  • New relationship
  • Acute relationship problems
  • Family or social pressures
  • Pregnancy and childbirth
  • Major life events
  • Drugs
• Maintaining factors:

  • Relationship problems
  • Poor partner communication
  • Lack of knowledge about treatment options
  • Ongoing physical or mental health problems
  • Drugs
• Examination:

  • Measure BP
  • Measure heartrate
  • Waist circumference
  • Calculate BMI
  • Check for gynaecomastia, sparse body hair and reduced muscle mass - testosterone deficiency
  • Further exams - genital exam, DRE
  • General clinical exam may identify stigmata of underlying cardiovascular, endocrine or neurological disease
• Blood tests to rule out common underlying organic causes:

  • FBC
  • LFTs
  • U&Es
  • TFTs
  • Lipid profile
  • Fasting glucose and/or HbA1c
  • Serum total testosterone (morning sample) - if reduced, prolactin will then be checked to screen for secondary hypogonadism (problem with pituitary)
  • PSA if clinically indicated
• Specialised tests:

  • In cases or complex or refractory ED done by urologists
  • Nocturnal penile tumescence testing (NPT) - used to distinguish between organic vs psychogenic ED - wear NPT device overnight to measure number, tumescence (amount of swelling) and rigidity of erections
  • Duplex doppler/angiography - if vascular cause suspected
• Management options:

  • Lifestyle modification
  • Endocrinology referral
  • Medication change/review
  • Psychosexual therapy
  • Pharmacological therapy
  • Vacuum erection devices
  • Intra-cavernous injection therapy
• Risk stratification:

  • ED may be marker for underlying coronary artery disease
  • Need thorough evaluation + identify risk factors
  • Can be stratified into low, intermediate, or high risk cardiac risk categories
  • Arrange referral to a cardiology or seek specialist advice if the man is at high cardiac risk, where sexual activity may be unsafe or PDE-5 inhibitor use is contraindicated - stop all sexual activity until review
• Modification of risk factors:

  • Smoking cessation
  • Minimal alcohol intake
  • Weight loss
  • Consider substitution or withdrawal of medication suspected to be the cause and review response in 2 weeks
• Patients may be referred for specialist counselling services if the cause of ED is considered to have a psychogenic component (either stand-alone or mixed) and if purely organic causes of ED have been ruled out.
• Phosphodiesterase-5 inhibitors:

  • Arrest PDE-5, allowing for prolongation of cGMP and subsequent relaxation of penile blood vessels = increased arterial blood flow
  • Different options with varying half life
  • take 15-1hr prior to sexual activity, take on empty stomach and avoid alcohol and fatty foods as reduces absorption
  • Not erection initiator - still need sexual stimulation
  • Contraindicated with concurrent nitrate use - severe hypotension
  • Caution in patients with CVD in previous 6 months
  • Side effects - headache, flushing, dizziness, dyspepsia and rhinitis
  • Arrange follow up at 6-8 weeks
• Types of PDE-5 inhibitors:

  • Sildenafil (Viagra) - shortest half life
  • Vardenafil
  • Avanafil
  • Tadalafil - longest half life
  • If a man presents with priapism (erection >4 hours) after use of PDE-5, urgent hospitalisation is required
• Patients may be referred to an endocrinologist for hormone replacement if a deficiency in reproductive hormones is found on laboratory testing (e.g. low testosterone).
• Vacuum erection devices:

  • Suction applied to penis
  • Effective at inducing erection irrespective of cause
  • May be useful combined with PDE-5s + injection therapy
  • Adverse effects - bruising, local pain, failure to ejaculate, skin necrosis
• Intra-cavernous injection therapy:

  • Alprostadil
  • Increases concentrations of cAMP = relaxation of smooth muscle
• Surgery:

  • Penile prosthesis insertion
  • Inflatable - presses a pump which fills a surgically implanted cylinder with fluid
  • Semirigid rods - penis remains rigid at all times
  • Last for 10-15 years