Erectile Dysfunction Flashcards
What is erectile dysfunction?
Failure to initiate an erection
OR
Failure to maintain an erection until ejaculation
What is an erection?
A physiological phenomenon in which the penis becomes firmer, engorged with blood and enlarged.
Under hormonal control, usually triggered by sexual arousal
What are the ‘corpora’ of the penis? What do they do?
2x corpora cavernosa
1x corpus spongiosum
Sponge-like erectile tissue that fills with blood during erection, making the penis firm
Describe the layout of the corpora within the penis?
Looking at a cross section, the corpora cavernosa are superior and lie side by side
The corpus spongiosum lies below and surrounds the urethra
There are 2 corpora spongiosa.
True or false?
False!
There’s one corpus spongiosum and two corpora cavernosa
Which ‘corpus’ does the urethra run through?
Corpus spongiosum
What is the nerve supply to the penis?
Pudendal nerve:
- parasympathetic
- sympathetic
Cavernous nerve
Which parasympathetic nerves supply the penis?
i.e. T1
S2-4
Which sympathetic nerves supply the penis?
i.e. T1
T11 - S2
What does parasympathetic stimulation do to the penis? How?
Causes an erection
Causes a release of NO into the penis arteries and smooth muscles
This stimulates arteriolar dilatation and trabecular smooth muscle relaxation
Blood flows into the corpora and causes rigidity, erection
What does sympathetic stimulation do to the penis?
Causes flaccidity
It causes arteriolar constriction, so blood can’t fill up the erectile tissue, no erection occurs
What is the trabecular smooth muscle in the penis?
The muscle that makes up the erectile tissue in the corpora
When it relaxes, the corpora fill with blood = erection
What is the blood supply to the penis?
Aorta branches into internal iliac artery
Internal iliac branches into internal pudendal
Internal pudendal has 3 branches:
- Bulbar artery
- Dorsal penile artery
- Cavernous artery
Which artery in the penis supplies the arterioles that dilate and cause erection?
Cavernous artery
What is the tunica albuginea?
Tough fibrous membrane covering the corpora cavernosa
Describe the physiology of an erection?
Central areas in the brain initiate desire for erection
Descending pathways carry stimulus to the parasympathetic nerves at S2, 3 + 4
Parasympathetic nerves cause release of NO
NO causes vasodilation of arterioles and smooth muscle
Muscles compress the veins of the corpora preventing blood flow out, maintaining the erection
Blood flows into corpora and causes an erection
What causes an erection to stop?
When parasympathetic activity reduces back to baseline
What are two types of causes of ED?
Organic: a physical problem preventing the erection
Psychogenic: a psychological cause prevents erection
How can you distinguish between organic ED and psychogenic ED?
Organic:
- gradual onset
- occurs in all contexts
- lack of morning erections
Psychogenic:
- sudden onset
- only in some contexts
- morning erections unaffected
A man presents with inability to attain an erection. His morning erections are unaffected.
Do you suspect organic or psychogenic?
Psychogenic, because his morning erections are unaffected
What are some organic causes of ED?
The big 3:
- Smoking
- Alcohol
- Diabetes
Endocrine disorders Neurological disorders Vascular disorders Anatomical problems Iatrogenic
What are some endocrine disorders that cause ED?
Hypogonadism: low testosterone
Hyperprolactinaemia: high levels of prolactin
Thyroid disease: hyper and hypo
What is prolactin?
A hormone involved in breast and milk development during pregnancy
What are some neurological disorders that cause ED?
Spinal cord lesions
MS
Autonomic neuropathy: affecting para and sympathetic nerves
What are some vascular disorders that cause ED?
Cardiovascular disease
Atherosclerosis
Hypertension
Hyperlipidaemia
Alarm bells should ring when you encounter a patient with ED caused by vascular disease (hypertension, atherosclerosis etc.). Why?
ED usually precedes a vascular event by 3 to 5 years
What anatomical problems cause ED?
Peyronie’s disease: fibrous plaque in the soft tissue of the penis, causes abnormal curvature of penis, pain and ED
Micropenis
What are some iatrogenic cause of ED?
Drugs:
- anti-hypertensives: B blockers
- antidepressants
- hormonal drugs
Surgery and radiotherapy
What causes psychogenic ED?
Disorders of sexual intimacy, lack of arousability
Situational: partner, stress, environment
Investigations of ED?
Full sexual and general history: is it psychogenic or organic?
Check general health: BP, HR, BMI
Examine genitalia: Peyronie’s disease, hypogonadism
Do a peripheral neuro and vascular exam
Blood tests
What blood tests would you do?
FBC U+E LFT Thyroid function test Testosterone levels Prolactin levels
What should you do initially to manage ED?
Treat the causes, if you can.
Provide counselling for psychogenic causes
Lifestyle advice: lose weight, control BP, diabetes, cholesterol
What is the first line therapy for treating ED?
Drugs!
Phosphodiesterase type 5 inhibitors
How do phosphodiesterase type 5 (PDE5) inhibitors work?
cGMP causes relaxation of smooth muscle in the penis
cGMP is degraded by PDE5 in smooth muscle cells
PDE5 inhibitors mean the cGMP is not degraded, so cGMP can cause smooth muscle to relax more
What are some examples of PDE5 inhibitors?
Sildenafil: Viagra
Tadalafil: Cialis
Do PDE5 inhibitors stimulate erections?
No, they simply make obtaining an erection easier. Sexual stimulation is still required
What are the 2nd line therapies for treating ED?
Vacuum constriction device: passive engorgement by vacuum
Intra-cavernosal injection: drug that relaxes smooth muscles allowing blood flow into corpora cavernosa
Intra-urethral therapy: a pellet that is inserted into the urethra
What is the 3rd line therapy for treating ED?
Implant!
Penile prostheses:
- Malleable implant: manually point up and down
- Mechanical implant: cylinders in corpora cavernosa that can be filled and emptied using a pump
What can you do to treat hypogonadism?
Testosterone supplements
How can you give testosterone supplements?
Not orally!
- transdermal patch
- buccal (cheek)
- nasal
- injections
- subcutaneous implants
Why can’t you give testosterone orally?
Because it is metabolised by he liver and won’t be effective
need to use a method that bypasses liver
What is priapism?
An erection that lasts over 4 hours
Becomes painful and there can be permanent ischaemic damage as a result
How do you treat priapism?
Aspirate corpora with needle
