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MBBS IV - Junior Clerkship WCS > JC75 (Surgery) - Erectile dysfunction > Flashcards

JC75 (Surgery) - Erectile dysfunction Flashcards

1
Q

List the layers of the penis from outer to inner

A
  • Skin
  • Superficial Dartos fascia + superficial dorsal vein
  • Deep Buck’s fascia with deep dorsal vein and dorsal artery
  • Tunica albuginea: outer longitudinal and inner circular
  • Subtunical space
  • Corpus spongiosum and corpa cavernosa
  • Cavernosal arteries in corpa cavernosa, penile urethra in corpus spongiosum
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2
Q

Arterial supply of penis

A

Internal pudendal artery&raquo_space; dorsal and circumflex artery&raquo_space; Cavernous and Bulbourethral artery

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3
Q

Ligaments attached to penis

A

Fundiform ligament and suspensory ligament

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4
Q

Ligaments attached to penis

A

Fundiform ligament and suspensory ligament

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5
Q

Venous drainage of penis

A

Dorsal penis:
Subtunical plexus»emissary veins»Deep dorsal vein»Superficial dorsal vein»branch off:
- Saphenous vein»External iliac vein
- Dorsal venous complex»Peri-prostatic plexus»Internal iliac vein

Ventral penis:
Bulbourethral vein»circumflex veins to dorsal penis OR cavernous vein»Crural vein»Internal pudendal vein»Internal iliac vein

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6
Q

7 phases of penile erection and detumescence

Which phase is controlled by pudendal nerve and cavernous nerve?

A

Flaccid > Latent > Tumescence > Full erection > Rigid erection > Initial detumescence > slow detumescence

Phase 4 - Rigid erection, controlled by cavernous nerve and pudendal nerve

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7
Q

Physiology of penis blood flow in Flaccid/ Detumescence phase

A

Tonically contracted:
Arteriole wall smooth muscle + Smooth muscle separating sinusoids inside corporeal bodies

> > Minimal amount of arteriolar blood flow into corporeal bodies
Subtunical venous plexus and emissary vein drainage is normal
Low arterial inflow but good venous outflow = low blood stasis = flaccid

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8
Q

Physiology of penis blood flow in tumescence/ erect state

A

Smooth muscles Relaxed:
Arteriole wall smooth muscle and smooth muscle in-between sinusoids

> > Rapid arterial inflow into sinusoids
Sinusoid expansion/ Engorgement compresses on Subtunical plexus and tunica with emissary veins
Blood trapped inside corporeal bodies
Good arterial inflow with poor venous drainage = Blood stasis = erection

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9
Q

Innervation of penis

Sympathetic, parasympathetic, somatic

A

Sympathetic: T11-L2&raquo_space; pelvic plexus
Parasympathetic: S2-S4&raquo_space; pelvic plexus

Pelvic plexus&raquo_space; cavernous nerve (pass through postero-lateral aspect of prostate, commonly damaged in surgery)

Somatic: Onuf’s nucleus at S2-S4&raquo_space; dorsal nerve of penis > Ischiocavernosus (erection) and bulbocavernosus (ejaculation)

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10
Q

Effect of sympathetic firing on penile erection

A

Sympathetic firing (Norepinephrine)

  • Increase intracellular calcium&raquo_space; activate muscle contraction in arterioles and walls of sinusoids&raquo_space; Decrease arterial blood inflow&raquo_space; Decrease rigidity of corporeal tissue&raquo_space; Detumescence
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11
Q

Effect of parasympathetic firing on penile erection

A

Parasympathetic (Ach)

  1. Inhibits pre-synaptic sympathetic firing (blocks detumescence)
  2. Stimulates nitric oxide release from endothelium* most important*
  3. Influx of Potassium into neuron, blocking Ca influx and sequestration of Ca into ER

> > activate cAMP pathway by PGE1 and cGMP pathway by NO

> > arteriole and sinusoid wall relaxation/ vasodilation&raquo_space; Increase arterial inflow into corporeal tissue&raquo_space; Increase corporeal bodies engorgement and compression on Subtunical plexus and emissary veins &raquo_space; Tumescence

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12
Q

Molecular pathways for penile arteriole smooth muscle relaxation

A
  1. cAMP pathway activated by PGE1:
    PGE1 activates adenylyl cyclase&raquo_space; increase conversion of ATP to cAMP&raquo_space; cAMP activate PKA
    cAMP is degraded by phosphodiesterase-2,3,4
  2. cGMP pathway activated by NO:
    Activates guanylyl cyclase&raquo_space; Increase conversion of GTP to cGMP&raquo_space; activate PKG
    cGMP is degraded by phosphodiesterase 5
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13
Q

Which molecular target is most important in penile arteriole smooth muscle relaxation?

A

Phosphodiesterase 5 (PDE-5)

Most important in termination of cGMP- induced smooth muscle relaxation
Blocking PDE-5 = sustain penile arteriole relaxation = sustain erection

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14
Q

Role of Nitric oxide in penile erection

A

Produced by endothelial cells via NO synthetase

nNOS (nervous tissue) - initiate erection
eNOS (endothelium) - sustain erection
iNOS (all other cell types)

Release of NO from nerves = Non-adrenergic/ Non-cholinergic (NANC) neurotransmission

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15
Q

Outline the stimuli, neural pathway, vascular changes in penile erection

A

Stimuli:

  • Psychogenic, Tactile/ reflexogenic, Nocturnal (REM sleep)
  • Causes cavernous nerve to generate nNOS

Parasympathetic firing also generate eNOS

NO stimulate cGMP pathway&raquo_space; arteriole and intersinusoidal smooth muscles RELAX&raquo_space; arterial inflow into corporeal bodies&raquo_space; Blood engorgement and trapping in corporeal bodies

Ischiocavernosus muscle contraction compress base of engorged corpora cavernosa

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16
Q

List disease entities under male sexual dysfunction

A

Erectile dysfunction

Ejaculatory dysfunction:

  • Premature ejaculation
  • Anejaculation
  • Retrograde ejaculation

Reduced libido

17
Q

Erectile dysfunction

Clinical definition

A

Persistent inability to achieve/ maintain erection

Sufficient to permit satisfactory sexual performance

Not associated with anxiety, alcohol or fatigue

18
Q

Diseases associated with erectile dysfunction

A 
DM 
Dyslipidemia 
Obesity 
Metabolic syndrome 
Smoking 
Cardiovascular disease
Depression 
BPH

ED is a barometer of cardiovascular health, strong association with cardiovascular disease mortality

19
Q

Classify the causes of erectile dysfunction

A

** Multi-factorial in etiology in reality **

  1. Organic:
    - Vasculogenic: arterial or venogenic
    - Neurogenic
    - Endocrine
  2. Psychogenic
    - Generalized
    - Situational: partner, performance, distress related…
  3. Drug-induced
20
Q

Drugs associated with erectile dysfunction

A

Antiandrogens - 5-ARI, LHRHa

Antihypertensives - Thiazides, B-blockers
Antidepressants - SSRI, TCA
Antipsychotic - Neuroleptics
Recreational - Heroin, marijuana, methadone

21
Q

History taking for erectile dysfunction

  • Aims
A

Aims:

  • Find underlying causes
  • Find contra-indications for Tx
  • Find asso. medical illness
  • Readiness for invasive treatment
22
Q

Outline History taking for erectile dysfunction

A
  1. Sexual history:
    - Characterize ED
    - Severity
    - Libido, ejaculation, orgasmic responses
    - Any morning erection
  2. Medical history: CVD, Neurological, Urological
  3. Social: smoking, drinking
  4. Drug history: causative CVD drugs, nitrates, recreational/ hardcore drugs
23
Q

Compare psychogenic vs organic caused Erectile dysfunction

A

Psychogenic:

  • Sudden onset
  • Complete/ immediate loss of erection
  • Situational dysfunction
  • Waking erections present

Organic:

  • Gradual onset
  • Incremental progression
  • Global dysfunction
  • Waking erections poor/ absent
24
Q

Outline P/E for erectile dysfunction

A

General:

  • Stature- global
  • Gynecomastia - endocrine
  • Lower limb neurological exam, gait - neurological

Abdomen:

  • Secondary sexual characteristic
  • Femoral pulses and distal limb pulses - CVD

External genitalia:

  • Phallus deformity
  • Testes position, Genital/ perineal sensation
  • Bulbocavernosus reflex
25
Q

Outline a subjective clinical assessment tool for erectile dysfunction

A

International Index of Erectile Function (IIEF-5) Questionnaire

5 questions: e.g. rate confidence about getting an erection, how difficult to maintain erection to end of intercourse …etc

No ED: 22-25 
Mild ED: 17-21 
Mild to moderate ED: 12-16 
Moderate ED: 8-11 
Severe ED: 5-7
26
Q

First-line investigations for erectile dysfunction

A

Medical:

  • Fasting blood sugar
  • Lipid profile
  • Cardiovascular disease screen: CHD

Sexual characteristics:
- Testosterone/ LH levels

27
Q

Outline flowchart for ED risk stratification

A
28
Q

Indications for specialized testing of ED

A

Primary ED: no erection ever, endocrine cause likely

Young ED with pelvic/ perineal trauma

Complex psychiatric/ psychosexual disorder

Complex endocrinopathies

Medico-legal/ rape

29
Q

Treatment options for ED

Lifestyle, first-, second-, third- line

A

step-wise approach

Life-style:
- Stop smoking, better DM and CVD control, adjust inciting drug

First-line:

  • Oral PDE-5 inhibitor (Sildenafil/ Viagra)
  • Topical/ Intraurethral alprostadil
  • Vacuum constriction device
  • Low intensity SWL

Second line:
- Intracavernosal injection s

Third line:
- Penile prosthesis

30
Q

PDE-5 inhibitor

  • MoA
  • Examples
  • Effectiveness
A

MoA:
Inhibit PDE-5 from degrading cGMP pathway&raquo_space; Maintain penile arteriole and intersinusoidal smooth muscle relaxation

Examples: 
Sildenafil - Viagra 
Tadalafil - Cialis 
Vardenafil - Levitra 
Avanafil - Spedra

70% successful intercourse

31
Q

Compare Sildenafil, Vardenafil and Tadalafil

Onset 
Duration of effectiveness 
Starting dose 
Lead-time before sex 
Max dosing frequency
A
32
Q

PDE-5 inhibitors

Side effectives
C/I

A 
Headache 
Flushing 
Nasal congestion 
Abnormal vision (blue/ green vision) - Sildenafil, vardenafil only 
Back pain/ Myalgia - Tadalafil only

C/I:
Any NITRATE USE&raquo_space; cGMP accumulation&raquo_space; hypotension&raquo_space; death
MI, Stroke or arrhythmia in the last 6 months
Heart failure, CAD, Unstable angina
Resting hypotension under 90/50
Hereditary degenerative retinal disorders
Severe hepatic impairment Child-Pugh-C
end-stage CKD with dialysis

33
Q

PDE-5 inhibitor

Timing and daily dosage

A

Timing: 1 hour before sexual intercourse

Daily dosage: 1 dose maximum per day

34
Q

Intracavernosal injection

  • Drug of choice
  • MoA
  • Effectiveness
  • S/E
A

Alprostadil injection (Synthetic Prostaglandin E1)

MoA: smooth muscle relaxation via cAMP pathway, independent of NO release

Effectiveness: 80%, even for DM and post-RP

S/E: 
Painful erection 
Prolonged erection 
Priapism 
Penile fibrosis
35
Q

Vacuum constriction device

Disadvantages
C/I

A

Unnatural semi-erect penis
Inability to ejaculate
Bruising and numbness

C/I: anticoagulants

36
Q

Penile prosthesis

  • Indications
  • Main types
  • Advantage and disadvantage
  • Complications
A

Indications:
ED refractory to all other treatment
Patient preference for permanent solution

Types:
Malleables (Semi-rigid rods)
Inflatables

Adv: High success and satisfactory rates

Disadv: Cost, irreversible damage to corporeal bodies

Complications: infection, erosion, mechanical failure

MBBS IV - Junior Clerkship WCS (131 decks)

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