Disorders of Micturition

Question 1

Definitions

Answer 1

Urinary Incontinence
- Involuntary loss of urine
- Differentiate from inappropriate micturition
Urge incontinence
- Dt lower urinary tract irritation which produces
uncontrollable desire to void
Paradoxical incontinence
- Urine leaks 20 to bladder/urethral obstruction
Overflow incontinence
- When bladder cannot contract and will fill until
urine flows out passively
Reflex incontinence
- Dt UMN lesion causing bladder to fill/empty
without conscious control

Question 2

Physiology of Micturition

Answer 2

Functional unit: 
Detrusor muscle (reservoir) parasympathetic contracts, beta relaxes
Bladder outlet (Outlet) 
- Bladder neck - alpha contracts 
- Proximal urethra 

Nerves:
Sympathetic chain
Pelvic n.
Pudendal n.

Question 3

Micturition

Answer 3

Storage phase 
- Bladder relaxation and urethral 
contraction 
Voiding (emptying) phase 
- Bladder contraction and urethral 
relaxation

Question 4

Sm mm of bladder

Answer 4

Beta-adrenergic receptors (sympathetic)
Cholinergic receptors (parasympathetic)

Question 5

Bladder Outlet

Answer 5

Alpha-adrenergic receptors (sympathetic)
Cholinergic receptors (somatic)

Question 6

Storage Phase

Answer 6

Storage Phase
Bladder relaxes to accommodate urine
Sympathetic stimulation of Beta receptors in bladder wall
Alpha stimulation of internal urethral sphincter
Somatic stimulation of striated external sphincter
Reflex inhibition of parasympathetic

Question 7

Emptying

Answer 7

Parasympathetic stimulation of bladder
Detrusor contraction
Inhibition of somatic and sympathetic impulses to outlet Sphincter relaxation

Question 8

Disorders of Micturition

Answer 8

Many urinary diseases are associated with changes in pattern of micturition — not considered to be disorder of micturition
- Polyuria
- Pollakiuria or increased frequency dt bacterial cystitis, tumor, stones, polyps
Classification
- Voiding phase — urinary retention
- Storage phase — urinary incontinence

Question 9

Micturition Disorders

Answer 9

Distended bladder
— Usually a voiding phase disorder
Small or Normal-sized bladder
— Usually a storage phase disorder

Question 10

Voiding Phase Disorders

Answer 10

Disturbances of micturition reflex
UMN lesions (brain — C7) produce spastic bladders & Normal- hyperreflexic urethral sphincter
- Inability to void, distended bladder, difficult to express
- Micturition initiated by spinal reflexes
- Becomes automatic with time

Disturbances of micturition reflex
LMN lesions (sacral, cauda equina, pudendal)
- Flaccid, neuropathic bladder
- Detrusor atony
- Loss of coordinated bladder contraction/urethral relaxation
- Distended bladder, easy to express
- Overflow incontinence

Question 11

Excessive outlet resistance

Answer 11

May result in paradoxical incontinence
Mechanical — physical obstruction (stone, blood clot)
Functional — Failure of urethra to dilate
- Myogenic
- Neurogenic — reflex dyssynergia (failure of urethra to relax adequately with bladder contraction)

Question 12

Reflex Dyssynergia

Answer 12

o Aka idiopathic functional urethral 
outflow obstruction; detrusor reflex 
dyssynergia 
o Exclusion diagnosis 
Large breed dogs