erectile dysfunction

ERECTILE DYSFUNCTION

No laughing matter..

ANATOMY OF THE PENIS

BLOOD SUPPLY OF THE PENIS

Is from the internal pudendal artery, which

enters the perineum through Alcock’s canal and

gives rise to 4 terminal branches

1. Dorsal art.

supplies penile skin and glans and contributes little to

erectile function

2. Cavernosal art.

within the corpora, branches into helicine arterioles

3. Bulbar art.

4. Scrotal art.


Intracavernosal drainage:

helicine arterioles drain into

vascular lacunar spaces of

corp. cavernosum which

empty into subtunical v.

emissary v., pierce tunica

albuginea deep dorsal v.

• Venous drainage is both intra + extra cavernosal


Extracavernosal drainage: is via 3 routes

1. Deep dorsal v. – drains distal corpora

into santorini’s vesicoprostatic venous

plexus

2. Cavernosal and crural v. – drains prox.

corpora into santorini’s plexus and int.

pudendal v.

3. Superficial dorsal v. – drains blood from

penile skin, glans and communicates

with deep dorsal v.

NERVE SUPPLY OF THE PENIS

Autonomic

Paraympathetic nerves from S2-4 nerve roots

primarily control erectile function while the

sympathetic nerves from T11-L2 control

detumescence and also contribute to ejaculation and

emission.

These autonomic nerve fibers form the pelvic plexus

of nerves and enter the penis within the cavernosal

nerves that course lateral and inferior to the

prostate.

N.B. It is these nerves that are preserved during nerve

sparing radical prostatectomy.


Somatic

Peripheral nerves (dorsal penile and pudendal n.) form

sensory and motor elements through a reflex arc in the sacral

spinal cord at Onuf's nucleus (S2-4).

Peripheral nerves containing sensory elements are also

responsible for erectile function, as they innervate the ischio

and bulbo cavernosus muscles of the penis


Central

Ultimate central nervous system control is likely

initiated in the hypothalamus in the medial pre-optic

area that integrates psychological and tactile stimuli.

TYPES OF ERECTION

Reflexogenic erection:

A genital stimulation leads to a

reflexogenic erection. Afferent signal pass

via the pudendal nerve to the sacral

erection center, this sends the efferent

signal via the inferior hypogastric plexus.

The reflexogenic erection is largely

independent of cortical influences, as this

kind of erection can remain intact after

cervical or thoracic spinal cord injuries.

Psychogenic erection:

The cortical processing of sensory, visual,

auditory stimuli or fantasies are triggers for an

erection.

The cortical centers influence the sacral erection

centers, which cause the erection via activation of

the inferior hypogastric plexus.

Nocturnal erection:

Occurs during the REM sleeping phase and can

be measured during sleeping studies (Nocturnal

penile tumescence = NPT).

Typical for the psychogenic impotence is the

existence of NPT, in contrast to serious

vascular erectile dysfunction.

Sympathetic centers mediate nocturnal erections,

the existence of NPT still cannot rule out damage

to the sacral parasympathetic erection center.

REVIEW MECHANISM OF ERECTION:

What happens to the penis during arousal?

Audiovisual or tactile stimuli activate

nuclei of spinal erection center T11-L2 and

S2-4

• Signals relayed via

cavernosal n. to erectile

tissue of corpora cavernosa

activating the veno-occlusive

mechanism

• This triggers increased arterial blood flow

into sinusoidal spaces, relaxation of

cavernosal smooth muscle, and opening of

vascular spaces

The result: Blood expands the sinusoidal spaces which

compresses the subtunical venous plexuses against the

tunica albuginea decreasing the venous outflow, and

further compressing the emissary veins

PHYSIOLOGY

Excitatory stimuli from the CNS produce erections

through a variety of neurotransmitters.

Many neurotransmitters including acetylcholine (ACh)

and vasoactive intestinal polypeptide (VIP) contribute

to erectile function.

The most important neurotransmitter in the corpora

cavernosa is nitric oxide (NO).

Following sexual stimulation, acetyl choline triggers

the release of nitric oxide from endothelial cells,

and diffuses into the corporal smooth muscle.

Nitric oxide (NO) is a gas that acts as a vasodilating

agent, inducing smooth ms relaxation via (guanylate

cyclase) the cGMP system.

Therefore, NO arteries dilate fills the corpora

spongiosum and cavernosa with blood = erection

cGMP is broken down by phosphodiesterase type 5 (PDE5).

When this occurs the Ca2+ increases in concentration in the cell, resulting in contraction of the smooth muscle cells and detumescence. N.B. Sildenafil ('Viagra') is a PDE5 inhibitor, and allows for

erections to be maintained in response to stimuli, but does not initiate erection.

ERECTION VS. DETUMESCENCE

Stimulation of the pelvic plexus and the cavernous nerves (Parasympathetic fibers ) through tactile sensory stimuli to the penis, releases acetylcholine, which enhances penile blood flow and smooth muscle relaxation, thus inducing erection

Sympathetic (adrenergic) fibers and norepinephrine neurotransmission help to maintain the penis in its flaccid state.

norepinephrine, activates alpha-adrenergic receptors that produce vasoconstriction of the penile vasculature and decompression of penile venules, which result in detumescence.

PHASES OF ERECTION

Phase Term Description

0 Flaccid phase Cavernosal smooth ms contracted; sinusoids

empty; minimal arterial flow

1 Latent (filling)

phase

Increased pudendal artery flow; penile

elongation

2 Tumescent phase Rising intracavernosal pressure; erection

forming

3 Full erection

phase

Increased cavernosal pressure (100 mmHg)

causes penis to become full erect

4 Rigid erection

phase

Further increases in pressure (to several

hundred mmHg) + ischiocavernosal muscle

contraction

5 Detumescence

phase

Following ejaculation, sympathetic discharge

resumes; there is smooth muscle contraction

and vasonstriction; reduced arterial flow; blood

is expelled from sinusoidal spaces

SO WHAT IS IMPOTENCE OR ERECTILE

DYSFUNCTION?

The persistent inability to achieve or maintain a penile

erection sufficient for sexual intercourse

ED affects about 10% of men aged 40-70 years,

and prevalence increases with age

Primary ED (ie, the man has never been able to

attain or sustain erections) is rare and is almost

always due to psychologic factors (guilt, fear of

intimacy, depression, severe anxiety) or

clinically obvious anatomic abnormalities.

Most often, ED is secondary (ie, a man who

previously could attain and sustain erections no

longer can). Over 80% = have an organic

etiology. However, in many men with organic

disease, ED leads to secondary psychologic

difficulties that compound the problem.

What is the aetiology of ED?

I.M.P.O.T.E.N.C.E

Inflammatory Prostatitis, urethritis

Mechanical Peyronie’s Disease, chordee

Psychological Depression, performance anxiety, stress, relationship

difficulties

Occlusive vascular Art: Hypertension, smoking, hyperlipidemia, DM.,

peripheral vascular disease

Ven: venous occlusion due to anatomical or

degenerative changes

Trauma Pelvic fracture, SC inj, penile trauma

Endocrine Hypogonadism, hyperprolactinemia, hypo +

hyperthyroidism

Neurologic Parkinsons, multiple sclerosis, spina bifida, pelvic

surgery, peripheral neuropathy

Chemical Anti-HTN, anti-arrhythmics, antidepressants,

anxiolytics, anti-androgens, anticonvulsants, alcohol,

marijuana, anti-parkonson drugs, LHRH analogues

Extra factors Prostatectomy, old age, CRF, cirrhosis

For details see: Siroky,

Mike B. Handbook of

Urology 2003

ED is more prevalent among patients with

atherosclerotic peripheral vascular disease,

hypertension, diabetes mellitus (75% of diabetic pts),

hypercholesterolemia, and heart disease and among

men who smoke cigarettes.

In the majority of impotent men, erectile impairment

has both a psychological and an organic basis.

ED caused exclusively by

emotional stress or psychiatric

disease = 10% - 50% of all

cases

Psychogenic EDCaused exclusively by

vascular, neurologic,

endocrine, or other physical

disease = 50% - 80%

Organic ED

How to diagnose & evaluate ED?

History

Examination

Investigation

HISTORY

Sexual

Some symptoms suggest psychogenic ED, and others suggest

organic disease.

A psychogenic cause is suggested by the sudden onset of ED

or the presence of ED under some circumstances but complete

erection at other times.

In contrast, gradual deterioration of erectile quality over

months or years with preservation of libido suggests organic

disease.

Psychological Evaluation

HISTORY

Medical

Inquiries should be made about: DM, HTN, smoking,

hypercholesterolemia, and hyperlipidemia as well as

about liver, renal, vascular, neurologic, psychiatric,

and endocrine disease.

Surgical History

Abdominal, pelvic, perineal

Drug History

Androgenic substances are associated with decreased

serum testosterone levels and decreased libido.

EXAMINATION

Full Physical

Body habitus, 2ndry sexual characteristics

CVS, abdomen, neurological (bulbocavernosus reflex

is used to assess integrity of S2-4)

External Genitalia

Penis: Phimosis, penile lesions

Testis: size, consistency

DRE

INVESTIGATION

LAB:

Recommended: Fasting glucose, lipid profile,

hormonal profile

Others: thyroid, PSA, prolactin

INVESTIGATION

Specialized Evaluations:

Indicated for failure of ttt, peyronie’s disease, 1ry ED,

history of surgery/trauma, complicated endocrine or

neuropsychiatric disorder

A. Vascular Evaluation

B. Neurologic Evaluation

C. Psychologic Evaluation

D. Hormonal Evaluation

1st line vascular evaluation: Intracavernosal

injection

Allows bypass of neurologic and hormonal influences,

directly evaluates penile blood flow

Alprostadil (10 – 20 μg) alone, or a combination of

papaverine + phentolamine (ie Bimix), or all three (ie

Trimix).

Compress needle site manually to prevent hematoma

2nd line vascular evaluation:

Duplex U/S: measures penile blood flow; most

reliable and least invasive assessment of ED

Color Doppler U/S: measures arterial peak systolic

velocity value (N:>35 cm/s) and end diastolic velocity

(N:<5 cm/s)

Cavernosography: measures penile blood flow

following intracavernosal inj of contrast and

induction of artificial erection. Can identify venous

leakage.

Venous leak (veno-occlusive

insufficiency).

Bilateral (a and b) Doppler

waveforms of the cavernosal

arteries at 25 min post-injection of

prostaglandin E demonstrate a

high peak systolic velocity (>40

cm/s), which excludes arterial

insufficiency as a cause of erectile

dysfunction in this patient.

However, a persistent diastolic flow

velocity of more than 5 cm/s is

suggestive of venous leak.

2nd line vascular evaluation:

Selective Penile Arteriography: to specifically assess a

defective/ruptured branch of cavernous art.

A. Arterial phase of right pudendal arteriography demonstrating obvious

extravasation (arrow) at right penile artery.

B. Venous phase image of right pudendal arteriography demonstrating

expansion of extravasation (arrow) and opacified penile veins.

TREATMENT

Psychosexual therapy

Aims to understand and address the underlying

psychological issues following proper evaluation

Instructs the pt on information regarding sex

education, partner communication and sexual

behavioral therapy

TREATMENT

Oral Medication

PDE5 (phosphodiesterase type-5) inhibitors (ex.

Sildenafil = viagra, tadalafil = cialis, vardenafil =

levitra)

Blocks the breakdown of cGMP, thus maintaining

erection

Sexual stimulation is still needed to initiate erection

Adverse Effects: headache, visual disturbance

Contraindication: pts on nitrates, recent MI, recent

stroke, unstable angina

TREATMENT

Androgen Replacement Therapy: indicated for hypogonadism. Available in oral, IM, patch & gel forms. In older men, PSA must be checked before and during ttt.

Intraurethral pellet therapy: using a synthetic PGE-1 pellet administered into the urethra. Unavailable in Egypt.

Intracavernosal therapy: Alprostadil/Caverjet(synthetic PGE1) enhances cavernosal smooth muscle relaxation. The needle is inserted at right angles into the corpus cavernosum on the lateral aspect of the penile shaft. A/E = priapism, pain, hematoma

TREATMENT

Alternative therapy

Vacuum erection device: uses vacuum chamber, pump and

constriction device to increase blood flow into the penis and

maintain rigidity via constriction band

TREATMENT

Alternative therapy

Penile prosthesis: may be semi-rigid, malleable or

inflatable.

Inserted surgically into the corpora to provide sufficient

size & rigidity for sexual intercourse. A/E = erosion,

infection, mechanical failure

…THANK YOU

erectile dysfunction

Health & Medicine