Erectile Dysfunction

Definition
Erectile dysfunction (ED) refers to the condition in which the penis cannot achieve or maintain an erection sufficient for sexual intercourse. Some men may not achieve an erection, some may ejaculate prematurely, and some may experience pain during ejaculation.
The majority of cases are caused by insufficient blood supply to the penis.
The incidence increases with age—occurring in about 5% of men under 40 years old, and in approximately 37.5% of men between 40–70 years old.

This condition can be treated. If detected and treated promptly, there is usually no need for concern, since most cases are temporary. Persistent ED may indicate underlying psychological or physical problems. With age, changes in sexual function are natural: erections may take longer to achieve, may not be as firm as in youth, and often require more stimulation. Ejaculation may also feel different, with reduced semen volume.
Importantly, ED does not mean a loss of sexual desire or difficulty reaching orgasm.

Structure of the Penis

The penis is composed of three cylindrical chambers similar to sponges: two corpora cavernosa running along the top, and one corpus spongiosum running underneath surrounding the urethra.
When flaccid, the penis measures about 8.8 cm. Upon sexual stimulation, blood fills the spongy tissue, expanding up to seven times, increasing length and rigidity to about 12.9 cm. The erection remains as long as sexual arousal continues, but subsides when blood leaves the penis.

Mechanism of Erection

1. Sexual desire originates in the brain, triggered by visual, olfactory, auditory, tactile, or imaginative stimuli.
2. These signals are transmitted through the spinal cord to the penis.
3. The penile blood vessels dilate, allowing blood to flow into the erectile tissue.

If any part of this mechanism is disrupted, erectile dysfunction can occur.

Factors Required for Erection

• Healthy penile arteries: If arteries are narrowed or hardened (from smoking, diabetes, high cholesterol, or hypertension), blood supply will be insufficient.
• Peripheral nervous system: Required to sense and respond to physical touch.
• Spinal cord: Relays sensory input to the brain and transmits commands to the penis.
• Central nervous system: Processes stimulation from sight, sound, smell, imagination, and past experiences. Psychological health is crucial.

Symptoms of Erectile Dysfunction

• Inability to maintain erection throughout intercourse.
• Incomplete rigidity of the penis.
• Total inability to achieve erection.

If these symptoms persist for more than 2 months or occur repeatedly, medical consultation is recommended.

Causes of Erectile Dysfunction

ED usually results from multiple combined factors:

1. Age:
   • Ages 40–49: 20.4%
   • Ages 50–59: 46.3%
   • Ages 60–70: 73.4%
2. Socioeconomic factors: Men with higher education, stable income, and good occupations are less likely to experience ED compared to those with lower income.
3. Chronic diseases: Conditions affecting blood vessels, nerves, or muscles of the penis, e.g.:
   • Diabetes mellitus
   • Chronic kidney disease
   • Chronic alcoholism
   • Atherosclerosis
   • Cardiovascular disease (reduced penile blood flow)
   • Hypertension
   • Enlarged prostate (BPH)
     ED is found in about 70% of patients with such conditions.
4. Surgery/Trauma:
   • Pelvic or prostate surgery
   • Spinal cord, bladder, or pelvic fractures damaging erectile nerves
5. Medications: Some reduce libido or impair erection.
6. Lifestyle:
   • Smoking (ED in 45% vs. 35% non-smokers)
   • Alcohol (54% of drinkers vs. 28% non-drinkers)
   • Sedentary lifestyle increases risk
7. Psychological factors: Stress, anxiety, family/work pressure, fear of sexual failure, or relationship conflict. Psychological ED accounts for 10–20% of cases.

Mechanism-Based Causes

• Failure to initiate erection: Often from psychological issues, brain/nervous system disorders, or low testosterone.
• Failure of arterial inflow: Blood does not adequately enter the penis.
• Failure of venous retention: Blood enters but cannot be retained, common in older men with fibrotic vessels.

Causes by System

• Vascular: Diabetes, hypertension, hyperlipidemia, smoking, radiation therapy, long-distance cycling.
• Neurological:
  • Brain: Tumor, epilepsy, stroke, Parkinson’s, Alzheimer’s
  • Spinal cord: Trauma
  • Peripheral nerves: Diabetes, abdominal/prostate surgery
• Venous abnormalities: Common in elderly/diabetics.
• Hormonal: Low testosterone decreases libido (but not necessarily erection mechanism).
• Psychological: Depression, stress, chronic anxiety, or sexual trauma.

Severity Levels

• Mild: Intercourse usually successful.
• Moderate: Intercourse successful about 50% of the time.
• Severe: Intercourse rarely or never successful.

Diagnosis

• Medical history: Diseases, medications, frequency of sexual activity, erection, and ejaculation patterns.
• Physical exam: Assess penile function, hair distribution, possible hormonal causes.
• Laboratory tests: Liver, kidney, sugar, lipid profile, testosterone levels if libido is low.
• Nocturnal erection test: Normal nighttime/morning erections suggest psychological cause.

Treatment

1. Lifestyle modification: Healthy diet, low fat, reduce salt, quit smoking and alcohol.
2. Psychotherapy: For psychological ED.
3. Drug therapy:
   • Oral PDE5 inhibitors: Taken 30–60 minutes before sex, effective for 4–5 hours. Not for patients on nitrates (risk of severe hypotension).
   • Alpha-blockers (e.g., yohimbine).
   • Sublingual drugs (onset 10–25 minutes).
   • Testosterone therapy (for low testosterone).
   • Intracavernosal injection (erection in 5–20 minutes, lasts ~1 hour; risk of priapism, pain, bleeding).
   • Intraurethral suppositories (8–10 minutes onset, requires constriction band; may cause irritation/bleeding).
4. Vacuum devices: Create negative pressure to draw blood into penis, maintained with a constriction ring.
5. Surgery:
   • Penile prosthesis implant with pump.
   • Arterial bypass (for young patients with trauma).
   • Venous surgery (rarely performed).

Precautions: Certain heart conditions make sexual activity unsafe (recent MI or stroke, uncontrolled hypertension, severe valve disease, unstable angina, or advanced heart failure).

Prevention

• Regular penile exercise.
• Avoid alcohol and drugs.
• Quit smoking.
• Regular physical exercise.
• Manage stress and anxiety.
• Adequate rest.
• Annual health check-ups.