ICL 4.4: Sexual Dysfunction

Question 1

what is sexual function?

Answer 1

brief description of physiology of erection and ejaculation

Question 2

what is the physiologic of erection?

Answer 2

endothelial cells release NO which when secreted goes into the smooth muscle fibers and causes GTP to be converted to cGMP via guanylate cyclase

cGMP activates protein kinase G which causes all the Ca+2 to go back into the ER which relaxes the smooth muscle fibers and allows the cavernous sinuses to open up and blood to pool in

Question 3

how do PDE-5 inhibitors effect erections?

Answer 3

they act on PDE-5 which normally breaks down cGMP

if cGMP is around longer then it’ll allow for longer relaxation of smooth muscle and longer erections

Question 4

which nerve roots are involved in erections?

Answer 4

parasympathetic outflow via S2, 3, 4

sympathetic inhibition via T11-L2

they meet in the hypogastric plexus and then from there on the nerve erigentis and cavernosal nerves also have a role to play

Question 5

what maintains a flaccid penis?

Answer 5

sympathetic stimulation leads to contraction of cavernosal muscle and maintains flaccid penis

Question 6

what is the neural pathway of erection?

Answer 6

erections can be mediated via

1. local stimuli (e.g. someone has cord transaction but sacral plexus is intact) OR
2. psychogenic stimuli (destruction of sacral spine or pelvic nerves)

parasympathetic outflow is via – sacral spine S2,3,4 –> pelvic splanchnic nerves –> inferior hypogastric plexus (sometimes called pelvic plexus) –> joined by nerves from sympathetic outflow T11-L2 via lumbar splanchnic nerves –> the inferior mesenteric and superior hypogastric plexuses, from which fibers travel in the hypogastric nerves to the inferior hypogastric plexus (pelvic plexus)

both sympathetics and parasympathetics play role in erections

Question 7

how do people with spinal cord injuries have erections?

Answer 7

if person has spinal cord injury they still have erections via smell, vision or thoughts – this will be via T11-L2 route, inhibition of sympathetic tone and release of NO via nNOS

if person has transaction of spine below L2 – their erections can be mediated mainly by local reflex arc via pelvic splanchnic nerves (nervi erigentes)

either way the inferior hypogastric plexus (Pelvic plexus) is the main integrating point for the autonomic supply to the penis.

Question 8

what are the causes of erectile dysfunction?

Answer 8

usually multifactorial

1. psychogenic: conflicts, performance anxiety
2. neurogenic: DM
3. vasculogenic: atherosclerosis, DM
4. endocrinological: hypogonadism
5. myogenic: atrophic muscle fibers from DM
6. miscellaneous: Peyronie’s disease, iatrogenic, drug abuse

Question 9

how does testosterone effect erections?

Answer 9

it doesn’t directly cause erections

it primes the tissues to respond properly to the stimuli

Question 10

which life stye factors effect ED?

Answer 10

1. smoking** (it’s vasculogenic and myogenic)
2. sedentary life style
3. alcohol
4. high cholesterol

Question 11

how is DM associated with ED?

Answer 11

ED risk increases three fold with DM

DM effects nerves, smooth muscles and vessels and that’s why it can cause ED

ED is the presenting symptom in 12% of men found to have DM

always check for HgA1c in at risk patients

50% of patients with DM will have ED within 10 years of diagnosis

proper control of HgA1c leads to improves ED, response to medical treatment so use it as an incentive for patients to keep A1c under control

Question 12

what do you do for an ED workup

Answer 12

1. AM testosterone levels
2. A1C
3. lipid profile

occasionally use penile doppler, angiogram, cavernous-gram

if they’re at risk for obesity, DM, CVD etc. you should do a full workup because ED is the tip of the iceberg that could be the start of underlying severe health issues

Question 13

how do you treat ED?

Answer 13

sildenafil aka viagra which is a PDE5 inhibitor

Question 14

what are the contraindications for PDE5 inhibitor use for ED?

Answer 14

1. nitrate group of medicines!! it can cause precipitous hypotension
2. retinitis pigmentosa (PDE5 is a retinol which can make their vision worse)
3. precaution with alpha blockers, aortic outlet obstruction, Macular degeneration, P450 inhibitors, Anti retroviral medications

Question 15

what are the proper uses of PDE5 inhibitors?

Answer 15

1. does not give spontaneous erections! they still need sexual stimulation

PDE5 only prevents breakdown of cGMP; you still need NO release, etc. for an erection

2. flushing, headache, palpitations are normal

Question 16

do PDE5 inhibitors cause heart attacks?

Answer 16

no! in fact, they dilate the coronary arteries and help with blood flow

but the sexual activity does uncover underlying heart conditions