Mechanisms of incontinence Flashcards
What is incontinence?
the lack of voluntary control of excretory functions
What clinical syndromes are disorders of micturition?
Inappropriate voiding
Inadequate voiding with urine overflow => dribbling
Increased urination frequency
Reduced bladder capacity
Incomplete voiding
Define enuresis
unconscious leakage of urine during sleep
Describe the clinical examination for disorders with micturition
History of voiding
Bladder size - palpation
Urethral sphincter tone - squeeze bladder to check for leakage
Integrity of detrusor/micturition reflex - squeeze bladder to stimulate urination
Perineal reflex - check for ‘winking’ around perineal region to check sacral nerve function
Full neurological assessment
What is the result of an upper motor neurone lesion?
spastic paralysis
hyper/normoreflexia
Slow muscle wastage
What is the result of a lower motor neurone lesion?
Flaccid paralysis
Hypo/areflexia
Rapid muscle wastage
Where are lower motor neurone lesions of the bladder?
Sacral spinal segment damage
Pelvic plexus
What is the results of lower motor neurones of the bladder?
Absent voluntary micturition
Atonic bladder
Atonic urethral sphincters
Absent detrusor reflex
Concurrent reduced perineal reflex and anal tone
Bladder flaccid and easily expressed
Where are upper motor neurone lesions of the bladder?
High spinal cord
brain dysfunction
What is the effect of an upper motor neurone lesion on the bladder
Absent voluntary micturition
Increased urethral tone
high volume urinary retention
Development of automatic bladder - no voluntary control
What are the anatomical disorders causing incontinence?
Ectopic ureter:
- Congenital malformation
- ureters enter directly into urethra
Acquired abnormalities of lower urinary tract:
- neoplasia
- calculi (bladder stones block urethra)
- Trauma
Describe the clinical findings and treatment of calculi/bladder stones blocking the urethra
Large bladder
does not release urine when squeezed
Need to relieve pressure via cystocentesis or catheter
Describe the effect of trauma on the lower urinary tract
Cannot urinate
Urine goes into abdomen
Bladder will be normal size
Will not be trying to urinate
Fluid in abdomen => very ill
Describe disorders of bladder function
Functional outflow obstruction - reflex dyssynergia
Initiation of detrusor reflex with reflex contraction of urethral sphincter - tries to urinate but cannot
Sphincter mechanism incompetence
Secondary detrusor muscle atony - stretch related injury => loss of contractility
Stretch injury
Urge incontinence:
- micturition reflex at low volume
- bladder mucosa irritation
Describe sphincter mechanism incontinence
Normal micturition reflex but sphincter too loss in between micturition reflexes => urine leaks when there is increased abdominal pressure e.g., when excited
Describe the signalment of sphincter mechanism incontinence
More common in female due to short urethra
More common in large/giant breeds
More common in spayed female (hormonal changes)
What are the treatment strategies for sphincter mechanism incompetance?
alpha adrenergic agonists e.g., phenylpropanolamine)
Oestrogens
Surgery - culposuspension:
- band around bladder and pulled up into abdomen stretches urethra
- urethra stretched => increased tone and decreased diameter
How does tail stretch injuries in cats cause bladder atony?
Sacral nerves stretch and pulled out of spinal cord (avulsion) => lost function
