Summary

Erectile dysfunction (ED) is the persistent inability to achieve or maintain an erection sufficient for satisfactory sexual performance. It is a vascular barometer for the entire body. Because the penile arteries are smaller (1-2mm) than coronary arteries (3-4mm), they clog up first. Therefore, ED is a predictor of Heart Attack and Stroke.

It is multifactorial, usually initiating with a vascular or neurological insult, but sustained by the "Psychogenic Loop" of performance anxiety.

Key Facts

• Prevalence: 52% of men aged 40-70 have some degree of ED.
• The "Calculus": Prevalence roughly equals Age (e.g., 50% at age 50).
• Silent Marker: Men with ED have a 50% higher risk of cardiovascular events compared to men without.

The "Brewer's Droop"

Shakespeare knew best.

"It provokes the desire, but it takes away the performance." - Macbeth.

• Mechanism: Alcohol is a CNS depressant. It numbs the sensation and dampens the reflex, even if it lowers inhibition.
• Chronic: Liver failure -> High Estrogen -> Low Testosterone -> Permanent ED.

H: Heart (The Sentinel)

The most important cause.

• Rule: ED is a vascular disease until proven otherwise.
• Protocol: Every man with ED needs a cardiovascular risk assessment (QRISK3 / Framingham).
• Statins: Statins may improve erectile function by fixing endothelial dysfunction!

Clinical Pearls

Quick Reference: The 4 Pillars

Pillar	Action
Vascular	"The Canary". Check the heart.
Hormonal	Check Testosterone.
Neuro	Check for Diabetes/MS.
Psych	Check for Performance Anxiety/Porn.

"The Penile Stress Test": Having sex is physically equivalent to walking 1 mile on the flat in 20 minutes (3-4 METs). If a man cannot do this without chest pain/breathlessness, he is not fit for sex (or Viagra).

"The Morning Glory": The presence of nocturnal penile tumescence (Morning Wood) is the single best differentiator between Organic and Psychogenic ED. If he wakes up hard, the plumbing works.

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Why the Penis Fails First

Size matters.

• Penile Artery Diameter: 1-2 mm.
• Coronary Artery Diameter: 3-4 mm.
• Carotid Artery Diameter: 5-7 mm.
• Concept: The same amount of plaque will block the tiny penile artery completely while only narrowing the coronary artery slightly.
• Timeline: ED typically precedes Angina/MI by 3-5 years. This is the "Window of Opportunity" to prevent the heart attack.

Anatomy: The Cavernous Nerves

The delicate wires.

• Origin: Pelvic Plexus (S2-S4).
• Course: They run postero-lateral to the prostate (at 5 and 7 o'clock).
• Risk: This proximity makes them extremely vulnerable during Radical Prostatectomy.

Physics: Laplace's Law

Why girth matters.

• Formula: Tension = (Pressure x Radius) / Wall Thickness.
• Concept: As the radius expands, the tension on the Tunica Albuginea increases exponentially. This tension compresses the subtunical veins, trapping the blood.
• Micro-Penis: Smaller radius = Less tension = Harder to trap blood (Venous Leak more common?).

Endothelial Dysfunction

• Nitric Oxide (NO) is made by the endothelium.
• In Diabetes and Hyperlipidemia, the endothelium is damaged -> Less NO -> Less relaxation -> No erection.

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The Mechanism

1. Stimulation: Brain sends signal via Cavernous Nerves (parasympathetic).
2. Release: Nerve terminals release Nitric Oxide (NO).
3. Chemistry: NO enters smooth muscle -> Activates Guanylyl Cyclase -> Increases cGMP.
4. Relaxation: cGMP lowers Calcium -> Smooth muscle relaxes.
5. Inflow: Blood rushes into the Corpus Cavernosum sinusoids.
6. The Trap: The swelling sinusoids compress the venous outflow against the Tunica Albuginea. (Veno-Occlusive Mechanism).
7. Result: High pressure, rigid erection.

Detumescence (Going soft)

• PDE5 Enzyme: Breaks down cGMP.
• Sympathetic Tone: Adrenaline squeezes the smooth muscle shut.

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B: Blood Compents (Hormonal/Metabolic)

• Diabetes: Double hit (Vascular + Neuropathy).
• Hypogonadism: Low Testosterone (Rarely the sole cause of ED, usually causes low libido).
• Hyperprolactinemia: Pituitary adenoma.

The Metabolic Syndrome

The Deadly Quartet.

• Definition: Abdominal Obesity + Hypertension + High Glucose + High Triglycerides.
• Impact: Each component damages the endothelium. Combined, they decimate it.
• Reversibility: Losing 10% body weight can restore erectile function in this group.

Diabetes: The Perfect Storm

Why Diabetics struggle.

1. Macrovascular: Atherosclerosis of iliac/pudendal arteries.
2. Microvascular: Fibrosis of the cavernosal sinusoids (they can't stretch).
3. Neuropathy: Autonomic nerves die (No signal).
4. AGEs: Advanced Glycation End-products stiffen the tissue.

• Result: ED in diabetics is earlier, more severe, and harder to treat (Viagra often fails).

Obstructive Sleep Apnea (OSA)

Hypoxia kills erections.

• Mechanism: Chronic hypoxia at night lowers testosterone and increases sympathetic tone.
• CPAP: Treating OSA with CPAP improves erectile function significantly.
• Screening: Ask "Do you snore?" (STOP-BANG score).

R: Reflex (Neurological)

• Spinal Cord Injury.
• MS.
• Pelvic Surgery: Radical Prostatectomy cuts the cavernous nerves (The "Nerual Sparing" debate).

Post-Prostatectomy ED

The cost of cure.

• Nerves: The Cavernous Nerves (NVB) run right along the surface of the prostate.
• Nerve Sparing: Robot-assisted surgery attempts to peel the nerves off, but "traction injury" (stretching) is common.
• Recovery: "Penile Rehab" (Daily Cialis + Pump) is used for 12 months to keep tissue oxygenated while nerves regrow (which takes 2 years).

E: Erection Chamber (Structural)

• Peyronie's Disease: Scar plaque causes curvature and pain.
• Venous Leak: The trap mechanism fails. Blood flows in but leaks out immediately. Common in young men with primary ED.

The "Venous Leak" Mystery

The Trap is broken.

• Demographic: Young men (Teenagers/20s) with primary ED (Never had a good erection).
• Mechanism: The outflow veins are too big or the valves fail. Blood flows in, but flows straight out.
• Diagnosis: Doppler Ultrasound (High inflow, High outflow).
• Treatment: Very difficult. Pills don't work well. Often need surgery/implant.

Peyronie's Disease

The Bent Nail.

• Pathology: Fibrous plaque in the Tunica Albuginea.
• Phases:
  1. Active Phase: Painful erections + Changing curvature. (No surgery yet).
  2. Stable Phase: Painless + Fixed curvature. (Surgery option: Nesbit Plication).
• Link: Dupuytren's Contracture (Hand) is often present (Collagen disorder).
• Xiapex: Collagenase injections dissolve the plaque (Limited availability).

A: Arterial (Vascular)

• Atherosclerosis (Smoking, HTN, Lipids).
• Cycling: Compression of pudendal artery by narrow saddle (pudendal entrapment).

Smoking: The Vasoconstrictor

One cigarette = 1 hour of constriction.

• Acute: Nicotine causes immediate spasm of the penile arteries.
• Chronic: Permanent endothelial damage.
• Recovery: Stopping vascular damage takes years to reverse, but the acute spasm stops within 24 hours.

The Cyclist's Syndrome

Pudendal Artery Entrapment.

• Mechanism: The narrow nose of a bike saddle crushes the pudendal arteries against the pubic bone.
• Symptom: Numbness in the perineum/penis after riding ("Sleepy Pee-Pee").
• Solution: "Noseless" saddles, Split saddles, or reducing ride time. Stand up every 10 mins to reperfuse.

K: Kinetic (Psychogenic)

• Performance Anxiety: Adrenaline kills erections (Sympathetic surge).
• Spectatoring: Watching oneself having sex rather than being in the moment.
• Depression: Loss of libido.

The "Porn-Induced" ED (PIED)

Rewiring the brain.

• Demographic: Young men who consume excessive pornography.
• Mechanism: The brain becomes desensitized to normal sexual stimuli. It requires hyper-stimulation (specific genres/acts) to get aroused.
• Reality: In real sex, the stimulation is lower, so the erection fails.
• Cure: "Dopamine Detox" (Abstinence from porn) for 3-6 months.

Post-Finasteride Syndrome (PFS)

The 5-ARI Risk.

• Drug: Finasteride/Dutasteride (used for Hair Loss / BPH).
• Effect: Blocks conversion of T to DHT.
• Syndrome: A small subset of men develop persistent ED and loss of libido even after stopping the drug. Mechanism unknown (Epigenetic?).
• Counselling: Warn young men before starting hair loss medication.

The "Hard Flaccid" Syndrome

Internet myth or reality?

• Symptom: Penis feels semi-rigid but cold/numb in flaccid state.
• Cause: Theorized to be chronic pelvic floor spasm (high tone).
• Treatment: Pelvic floor RELAXATION (Reverse Kegels), Stress management, Avoiding excessive masturbation.

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History: The "Big Three" Questions

1. "Do you get morning glory?"
   • Yes = Psychogenic (Hardware is fine).
   • No = Organic (Vascular/Neuro issue).
2. "Does it happen with masturbation?"
   • Yes = Psychogenic (Partner specific?).
   • No = Organic.
3. "Did it start suddenly?"
   • Sudden = Psychogenic or Trauma.
   • Gradual = Vascular (Atherosclerosis is slow).

The Erection Hardness Score (EHS)

Simple metric for notes.

• Grade 1: Larger but not hard (Tofu).
• Grade 2: Hard but not hard enough for penetration (Peeled Banana).
• Grade 3: Hard enough for penetration but not completely rigid (Unpeeled Banana).
• Grade 4: Completely rigid (Cucumber).

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The "Erection Diet"

Mediterranean works best.

• Foods: Nuts (Walnuts/Pistachios = Arginine), Olive Oil, Fish.
• Avoid: Processed sugar (glycation), Trans fats.
• Mechanism: Arginine is the precursor to Nitric Oxide.

The Pills: How to use them

Failure is often due to poor instruction.

Drug	Brand	Onset	Duration	Food Effect?
Sildenafil	Viagra	1 hr	4-6 hrs	Yes! Fatty meal stops absorption.
Tadalafil	Cialis	2 hrs	36 hrs	No. Can take with food.
Vardenafil	Levitra	30 mins	4-6 hrs	Slight.
Avanafil	Spedra	15 mins	6 hrs	No.
Note: Avanafil is the "fastest". Can take it 15 mins before. Good for rapid/unplanned intimacy.

Patient Instructions for Sildenafil

1. Timing: Take 1 hour before sex.
2. Stomach: Empty stomach (2 hours after eating).
3. Stimulation: "It is not magic." You still need foreplay. It effectively puts "fuel in the tank", but you still need to "turn the key".
4. Trial: Do not declare failure until you have tried 8 times at the maximum dose.

Safety Check

• Nitrates: GTN Spray, Isosorbide Mononitrate, Nicorandil. ABSOLUTE CONTRAINDICATION. Causes fatal hypotension.
  • Mechanism: Nitrates increase cGMP. Viagra stops breakdown of cGMP. Result = Massive accumulation of cGMP -> Total vasodilation -> Shock -> Death.
  • Poppers: Amyl Nitrate (recreational). Huge risk in MSM population.
• Alpha Blockers: Tamsulosin. Wait 4 hours between doses (Hypotension risk).

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Daily Tadalafil (5mg)

The game changer.

• Concept: Constant low level drug in system.
• Benefit: Removes "planning" sex. Spontaneity returns.
• Bonus: Also treats BPH symptoms (LUTS).

The BPH Connection

Killing two birds.

• Pathology: BPH and ED share mechanisms (Pelvic Ischemia / NO deficiency).
• Licence: Tadalafil 5mg is licensed for both.
• Strategy: Start Tadalafil 5mg daily early in men with LUTS + ED (instead of Tamsulosin, which causes dry ejaculation).

Low-Intensity Shockwave Therapy (Li-ESWT)

Regenerative Medicine?

• Mechanism: Sound waves cause micro-trauma, stimulating angiogenesis (new blood vessels) and stem cell recruitment.
• Evidence: EAU Guidelines list it as a potential cure for mild vasculogenic ED.
• Protocol: 6 sessions over 6 weeks. Painless.
• Caveat: Many private clinics sell this aggressively. Ensure it is a focused shockwave machine, not a radial one (massage gun).

Vacuum Erection Device (The Pump)

• Mechanism: Creates a vacuum -> Draws blood in -> Place constriction ring at base to trap blood.
• Pros: Non-drug. Safe.
• Cons: Penis feels cold/numb. Hinge effect (wobbles at base). Can't leave ring on >30 mins (gangrene risk!).

Patient Guide: The Pump

1. Seal: Use plenty of lube at the base to create a seal against the body.
2. Pump: Pump until rigid.
3. Slide: Slide the constriction ring from the tube onto the base of the penis.
4. Remove: Take the tube off. The ring holds the blood in.
5. Timer: MAX 30 MINUTES. Remove ring immediately if painful.

Intra-Urethral Alprostadil (MUSE)

• Method: Pellet inserted into urethra.
• Efficacy: Lower than injection (40%).
• Side Effect: ""Urethral burning"".

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ICI: Intracavernosal Injection

Caverject / Viridal.

• Drug: Alprostadil (Prostaglandin E1).
• Mechanism: Bypasses the nerves. Directly relaxes smooth muscle via cAMP (different pathway to Viagra).
• Efficacy: >80% (Works even if nerves are cut, e.g., post-prostatectomy).
• Technique:
  • Needle: Tiny (insulin needle).
  • Site: 10 o'clock or 2 o'clock position at the base.
  • Avoid: 12 o'clock (Nerves/Veins) and 6 o'clock (Urethra).
• Risk: Priapism (See below).

Trimix / Bimix / Quadmix

The Nuclear Option.

• Concept: If Alprostadil alone fails (monotherapy), we mix drugs.
• Ingredients: Papaverine (Non-specific PDE blocker) + Phentolamine (Alpha blocker) + Alprostadil (PGE1).
• Potency: Extremely strong. High risk of Priapism.
• Use: Only for salvage cases (e.g., severe diabetic fibrosis).

Patient Guide: Self-Injection

It sounds worse than it is.

1. Hygiene: Wipe the base.
2. Stretch: Pull the penis forward to make the skin taut.
3. Aim: 90 degrees. Into the side (Corpus Cavernosum).
4. Inject: Push the plunger slowly (5 seconds).
5. Pressure: Hold the site for 2 mins to prevent bruising.
6. Rotate: Left side one time, right side the next (prevents fibrosis).

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Penile Prosthesis

The bionic solution.

1. Malleable: Semi-rigid rods. Always hard, just bent up or down. Simple, durable.
2. Inflatable (3-piece): Cylinders in penis + Pump in scrotum + Reservoir in abdomen. Squeeze scrotum to inflate.
3. Inflatable (3-piece): Cylinders in penis + Pump in scrotum + Reservoir in abdomen. Squeeze scrotum to inflate.

• Satisfaction: Highest satisfaction rate of ALL ED treatments (>90%).
• Risk: Infection (Disaster - needs removal).

The Implant Procedure

The final solution.

• The destruction: The surgery destroys the natural cavernous tissue to make way for the cylinders. There is no going back.
• The "Oz" Effect: Men often feel they have lost length (about 1-2cm), but gain girth.
• Durability: Mechanical failure occurs in 5-10% over 10 years.

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The Ischemic Crisis

• Definition: Erection >4 hours.
• Pathology: Blood trapped. Oxygen used up. Ischemia -> Fibrosis -> Permanent ED.
• Action:
  1. Ice/Stairs: Cold/Exercise (shunts blood away).
  2. Aspiration: Butterfly needle into cavernosa -> Aspirate old dark blood.
  3. Phenylephrine: Inject alpha-agonist to constrict arteries.
  4. Surgery: Shunt procedures (Winter's / Al-Ghorab).

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Performance Anxiety

1. Failure once (Alcohol/Tired).
2. Anxiety about failing next time.
3. Adrenaline surge during foreplay.
4. Adrenaline constricts arteries.
5. Failure confirmed.
6. Anxiety increases.

Psychosexual Therapy

• Sensate Focus: Ban intercourse. Touch only. Remove the "goal" of erection.
• CBT: Challenge "Catastrophizing" thoughts.

The Partner's Perspective

It takes two.

• The Assumption: Partners often think: "He doesn't find me attractive anymore" or "He is having an affair".
• The Reaction: They stop initiating sex to avoid rejection.
• The Result: Total cessation of intimacy.
• Advice: Bring the partner to the consultation. ED is a couple's disease.

The Older Patient (>70)

Managing Expectations.

• Goal: "What do you want to achieve?" (Intimacy vs Intercourse).
• Physiology: Refractory period increases (may take 24 hours to get another erection).
• Partner: Is the partner willing/able? (Vaginal atrophy/pain).

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