Urology - Erectile dysfunction Flashcards
What is erectile dysfunction (ED)?
This is the inability to achieve or maintain an erection sufficient for sexual performance.
How common is ED?
ED is extremely common across multiple geographical regions. It is twice as common in hispanic populations.
What is the aetiology of ED?
Impaired local regional blood flow is a common characteristic and arteriogenic is the most common cause. It accounts for 40% of cases of erectile dysfunction, with diabetes being the second most common at 30%.
Other common causes are:
- pelvic surgery/ radiation
- prostate cancer and resultant treatment
- CNS disorders - e.g. AD, PD, stroke, MS
What is the aetiology of diabetic ED?
ED occurs in >50% of men with diabetes and occurs at an earlier stage than in non diabetic men. It is multifactorial and linked to the duration of disease, age and degree of glycaemic control. Autonomic neuropathy may also play a role as do associated atherosclerosis, hyperlipidaemia and HTN.
Diabetes causes microangiopathy through oxidative stress which impairs endothelial/ erectile function.
How are normal erections achieved? What mediators are important?
Penile erection depends on a complex intracellular cascade that results in cavernosal smooth muscle relaxation, increased cavernosal blood flow, occlusion of venous outflow followed by rigidity.
Nitric oxide is an important mediator. It is released from presynaptic nerve fibres and endothelial cells and is responsible for initiating and maintaining vascular smooth muscle relaxation. Diffusion of NO activates guanylate cyclase which converts GTP into cGMP. This triggers intracellular calcium sequestration by the endoplasmic reticulum. Smooth muscle relaxation occurs as intracellular calcium concentration decreases.
Adrenergic stimulation activates PDE-5 which converts cGMP to 5-MP that allows calcium levels to normalise.
Remember, parasympathetic “points”, sympathetic “shoots”
What are the 3 ways that penile erection can be initiated?
1) Psychogenic erections - occur in response to afferet sensory stimulation (T11-12 and S2-4) to trigger central dopaminergic erection from the preoptic area.
2) Reflexogenic erections - these are often preserved in men with spinal cord injuries above the sacral level, and occur due to genital stimulation. They are mediated by spinal reflexes and autonomic nuclei.
3) Nocturnal erections - these occur during REM sleep and probably occur due to suppression of inhibitory sympathetic outflow by the pontine reticular formation and the amygdala.
Is ED classified in any way?
There are 2 classification systems used for ED. The first one is by the international society for impotence research that classifies based on the cause into either (i) organic, (ii) psychogenic generalised and (iii) psychogenic situational (e.g. partner related).
Clinically, ED can be classified based on the underlying aetiology into:
- ageing
- psychological disorders (e.g. depression, anxiety)
- neurological disorders
- hormonal disorders
- vascular disorders
What are primary preventative strategies for ED?
The main primary prevention of ED is a reduction in modifiable cardiac risk factors such as diabetes, blood pressure, cholesterol, obesity and smoking.
Is there any secondary prevention for ED?
There is growing evidence that dietary modification, weight loss and exercise can be useful in improving ED.
What are the key diagnostic factors in ED?
Presence of risk factors - key risk factors include: coronary artery disease, peripheral arterial disease, psychosexual/ relationship problems, excess alcohol intake, HTN, high cholesterol, radical pelvic surgery, neurological disease etc
Abnormalities of the penis on examination is uncommon, as is abnormal androgenisation.
Other diagnostic factors that are common include premature ejaculation, abnormal prostate exam, and psychosocial stressors.
What differentials should be considered in ED?
1) Premature ejaculation - men are still capable of maintaining an erection but ejaculation occurs sooner than expected or desired
2) Priapism - pathological condition of sustained erection after sexual activity
What is the diagnostic approach for ED?
1) History - distinguish between ability to obtain an erection vs maintain an erection; clarify if morning erections occur or if erections following self stimulation; interview the partner
2) Risk factors - e.g. CAD, PAD, HTN, diabetes, cholesterol etc
3) Standardised questionnaires - most common is international index of erectile dysfunction (IIEF) or sexual health inventory for men (SHIM)
4) Physical examination - identify any cardiovascular, endocrine, neurological causes; examine genitals for abnormalities; assess degree of androgenisation; DRE in men >50
5) Laboratory testing - tailored to the patients history, e.g. HbA1c, fasting lipids, TSH and PSA.
What is Peyronie’s disease?
This is an inflammatory condition characterised by the formation of fibrous, non compliant nodules in the tunica albuginea, which can impede tunical expansion during erection leading to deformity or bending.
Management of ED in men without Peyronie’s previous pelvic surgery or psychosexual problems
1st - treat the underlying cause:
- PDE-5 inhibitors in HTN
- testosterone replacement + sildenafil in hypogonadism
- sildenafil in diabetes
Adjunct - psychosocial/ couples therapy
2nd - PDE 5 inhibitors, sidenafil (regardless of the cause)
3rd - intracavernous injection, alprostadil or papaverine
4th - intraurethral suppository
4th - penile vacuum pump
4th - alprostadil (topical)
5th - penile prosthesis
In what group of patients is sildenafil contraindicated?
Sildenafil is contraindicated in patients who:
- take organic nitrates
- severe cardiovascular disease
- MI within 90 days
- CVA within 6 months
- ACCS
- Heart failure NYHA class II or greater
- uncontrolled arrhythmias
