Session 8

Question 1

Describe the differences between the internal and external urethral sphincters

Answer 1

Internal - physiological sphincter, involuntary

External - anatomical sphincter, voluntary

Question 2

What what stage do we start to feel something is in the bladder?

Answer 2

~ 150ml

Question 3

Describe the nerve fibres controlling the detrusor muscle and internal urethral sphincter in the storage phase of the bladder

Answer 3

When there is little bladder wall stretch, stretch receptors in the detrusor muscle send signals along sensory neurones that enter at S2-3 and ascend up to T10-L2 to the sympathetic fibres. Sympathetic fibres (hypogastric nerve) cause relaxation of the detrusor muscle and contraction of the internal sphincter.

Question 4

Describe the nerve fibres controlling the external urethral sphincter in the storage phase of the bladder

Answer 4

Somatic motor neurones (pudenal nerve) in S2-4 controlled by the L centre in the brain stem cause contraction of the external sphincter

Question 5

Describe the spinal reflex controlling the detrusor muscle in the voiding phase of the bladder

Answer 5

When the bladder wall is stretched, sensory neurones send high frequency signals into S2-4 where it synapses with a parasympathetic nerve (pelvic nerve) which contracts the detrusor muscle.

Question 6

Describe the descending modulation of the bladder during the voiding phase

Answer 6

The M centre in the brain stem (controlled by the cerebral cortex (+/-) and high frequency sensory signals) stimulates the pelvic nerve. The M centre also inhibits the L centre and sympathetics the stimulate voiding.

Question 7

What happens to urination when there is a spinal cord lesion?

Answer 7

Loss of voluntary control - no descending modulation.

Question 8

What is urinary incontinence?

Answer 8

The complaint of any involuntary leakage of urine

Question 9

What are the types of incontinence?

Answer 9

Stress UI (most common)- on sneezing, coughing, exertion
Urge UI-involuntary leakage followed/accompanied by urgency
Mixed - associated with stress and urge
Overflow incontinence - retention of urine causing bladder of swell and leak

Question 10

What are risk factors for urinary incontinence?

Answer 10

Anything that weakens the pelvic floor muscles (e.g. Childbirth), obesity, age, UTI, menopause and family predisposition.

Question 11

What examinations can be done for urinary incontinence?

Answer 11

BMI, abdo exam, PR exam, vaginal exam

Question 12

What investigations can be done for urinary incontinence?

Answer 12

DIPSTICK, bladder diary, invasive urodynamics

Question 13

What are lifestyle interventions for urinary incontinence?

Answer 13

Modify fluid intake, weight loss, stop smoking, reduce caffeine intake

Question 14

What are management strategies for urinary incontinence that can’t be managed by surgery?

Answer 14

Indwelling catheter
Sheath device (condom catheter)
Incontinence pads

Question 15

What are specific treatments for stress UI?

Answer 15

Pelvis floor muscle training - 3x/day for 3 months
Duloxetine - increased activity of ext. sphincter during filling
Surgery females - low tension vaginal loops (permanent), intramural bulking (temporary)
Surgery males - artificial urinary sphincter, male sling procedure

Question 16

What are specific treatments for urge UI?

Answer 16

Bladder training - void at interval. Wait or leak in between, increase intervals
Anticholinergics - side effects on other M receptors
B2 adrenoreceptor agonist
Botulism toxin - inhibits ACh at pre synaptic NMJ