Urinary Session 8 Flashcards
Why are reflexes involved in micturition said to be modified?
Due to brain involvement
Which phase do sympathetic neurones control in micturition?
Storage phase
Which phase do parasympathetic neurones control in micturition?
Voiding
Which neurones control continence?
T10-L2
Which neurones control micturition?
S2-4
Why is the bladder described as an autonomic effector?
It has no inherent activity
Where does the bladder derive from?
Embryonic hindgut
What determines all activity in the bladder?
ANS
Is the bladder operated equally by the autonomic and somatic nervous systems?
Yes
Which two bi-stable states does the bladder occupy with no state in between?
Storage and voiding
What is detrusor muscle?
Plexiform network of smooth muscle cells arranged in inner longitudinal, middle circular and outer longitudinal layers
Why is detrusor muscle arranged in three different orientations?
Confer strength irrespective of direction of stretch so filling is uniform
Where does the neural supply of detrusor muscle come from?
Bilaterally from the spinal cord
Is bladder pain well or poorly localised?
Well
Why are there many different options for Tx of bladder function disorders?
Different anatomical components are supplied by different divisions of the nervous system
What causes detrusor muscle to be a mass contracting muscle?
Lack of gap junctions and peristaltic activity
Why is the submucosa in the bladder not a true submucosa?
Epithelium is non-secretory
Can mucus in the urine have originated from the bladder?
No, epithelium is non-secretory
Does the bladder vary much in size and shape between the two sexes?
No
What is micturition?
The desire to pass urine
How does the trigone differ from the surrounding detrusor muscle?
Endoderm derivative
Has very sensitive neurones which detect stretch to stimulate voiding
What neural control is the body of the bladder under?
Reflex via sympathetic and parasympathetic
Is the internal urethral sphincter a true sphincter?
No, it is physiological
Is the external urethral sphincter a true sphincter?
Yes, it is an anatomical sphincter
How is the external urethral sphincter formed?
In the urogenital diaphragm by pelvic floor muscles
What type of control is exerted on the external urethral sphincter?
Somatic - voluntary from cerebral cortex –> spinal cord
What are the layers of the bladder wall from lumen outwards?
Urothelium Lamina propria Submucosa Detrusor muscle Adventitia
What forms the mucosa of the bladder?
Urothelium
Lamina propria
Nerves
What can be said about the control of micturition?
It is entirely spinal
What type of receptor do pelvic nerves under parasympathetic control act on in the bladder?
M3
What type of receptors do hypogastric nerves under sympathetic control act on in the bladder and bladder neck?
Bladder: beta-3
Bladder neck: alpha-1
What receptor does the pudendal nerve under sympathetic control act on in the external urethral sphincter?
Nicotinic
Which receptors expressed in the urinary bladder are under stimulators action and which are under inhibitory action?
Stimulatory: M3, alpha-1, nicotinic
Inhibitory: beta-3
How is the ANS innervation of the bladder described with reference to its sympathetic and parasympathetic inputs?
Antagonistic pairing of inputs
Why is the continence phase not indefinite?
Bladder wall is permeable to toxins
How does damage to continence neurones lead to urinary incontinence?
Damage to neurones –> failure of storage –> decreased bladder capacity –> frequency of micturition
What are the neuronal events in the continence phase of micturition?
Cerebral cortex –> Pontine continence centre –> sympathetic nuclei in spinal cord –> detrusor muscle and external sphincter motor neurones in sacral cord –> continence
What is the action from the bilateral outputs of the Pons as they descend without crossing over from the Pontine continence centre?
Silence detrusor electrical activity
Relax detrusor via beta-3 in fundus
Increase urethral sphincteric pressure via alpha-1
How does the sympathetic nervous system spinal centre of continence act on the bladder?
Relaxes detrusor muscles via beta-3
Constructs bladder neck via alpha-1
How does the somatic nervous system spinal continence centre act in the continence phase?
Closes external urethral sphincter via ACh action at NMJ
Which spinal root values are in the sympathetic spinal continence control centre?
T10-L2
Which spinal nerve root values are involved in the somatic spinal continence centre?
S2-4
Where is the somatic spinal continence centre found?
Onuf’s nucleus in the ventral horn
What other sphincter is controlled by Onuf’s nucleus in the ventral horn?
Anal sphincter
What is the neural apparatus for urinary storage known as?
Continence circuits
What is the capacity of the bladder?
300-700 ml
At what volume will there be back flow of urine from the bladder into the ureters?
None, this does not occur
What does the trigone continuously monitor in the bladder?
Ionic composition of urine
Temperature
Volume via stretch
Describe the stress-relaxation phenomenon.
As the bladder fills rugae flatten so intra-vesical pressure is constant
What happens when the bladder fills by ~400 ml?
Afferent nerve in wall detect stretch and signal void via parasympathetic and some sympathetic nerves
How can a beta-3 agonist be used to treat urinary incontinence?
Increases capacity to store urine by activating receptors which cause relaxation of detrusor muscle in the fundus and body
What is the result of damage to micturition neurones?
Failure to pass urine –> urinary retention
When is urine passed involuntarily?
In overflow incontinence when bladder is overfilled
Disturbances to what lead to detrusor-sphincter dyssenergia?
Coordinated and opposite activity of bladder and external urethral sphincter
What is the micturition phase mediated by?
Voiding circuits
What are the neuronal events in control of the micturition phase?
Cerebral cortex –> M-region of Pons –> sacral levels of parasympathetic outflow –> detrusor muscle contracts and internal sphincter relaxes –> external urethral sphincter relaxes –> void acne
Where is the Pontine continence centre found?
L-region of Pons
Where do the ANS sacral nerves involved in controlling voiding centres arise from?
Lateral horn
What somatic spinal root values cause relaxation of the external sphincter?
S2-4 in the ventral horn
What neuronal activity causes increased detrusor activity?
Bilateral parasympathetic division of ANS from lateral horn of S2-4
How does the mediation of spinal control centres compare between the continence and micturition phases?
Continence: exclusively by sympathetic neurones of spinal cord
Micturition: exclusively by parasympathetic neurones of sacral spinal cord
What is another name for the M-region of the Pons?
Barrington’s nucleus
Why do sensation and voiding in the bladder not need to be under conscious control?
There is no sensory or motor representation of the bladder in the respective cortexes
What gives neural supply to the external urethral sphincter?
Perineal branch of Pudendal nerve, S2-4 from ventral horn
What can cause decreased compliance in the bladder leading to incomplete filling?
Scarring e.g. in TB or radiotherapy
What can increase the sensation of bladder filling when the volume does not correspond?
Stone
UTI
Tumour
What are the consequences of a lower motor neurone lesion affecting S2-4?
Decreased detrusor pressure
Decreased perianal sensation
Lax anal tone
What is the presentation of a pt with a lower motor neurone lesion of S2-4 likely to be?
Painless increasing waistline due to chronic retention +/- overflow incontinence is volume is large
What are the consequences of an upper motor neurone lesion affecting the spinal cord control of micturition?
Hypertrophical detrusor muscle –> increased pressure contractions –> dilated ureters due to high intravesical pressure –> decreased kidney function –> poor coordination of bladder with sphincters –> detrusor muscle dyssenergia
What storage lower urinary tract symptoms can pts present with?
Frequency
Urgency
Naturia
Incontinence
What voiding lower urinary tract symptoms can pts present with?
Slow stream Splitting/spraying Intermittency Hesitancy Straining Terminal dribble
What post-micturition lower urinary tract symptoms can pts present with?
Post-micturition dribble
Feeling of incomplete emptying
What is urinary incontinence?
Complaint of any involuntary leakage of urine
What are the effects of urinary incontinence on the pt?
Decreased QoL
Social exclusion
Sense of shame
What are the four types of urinary incontinence?
Stress
Urge
Mixed
Overflow
What is stress urinary incontinence?
Involuntary leakage on increase of intra-abdominal pressure e.g. effort, exertion, cough, sneeze
When does stress in continence most commonly arise?
After childbirth
What accounts for 50% of all cases of urinary incontinence?
Stress incontinence
How is stress urinary incontinence treated?
Pelvic floor muscle training
Duloxetine
Surgery
What is Duloxetine?
Combined NA and serotonin uptake inhibitor which increases activity of external urethral sphincter during continence stage
Why is Duloxetine not used as a first line Tx for stress incontinence?
Can cause severe nausea
What types of surgery can be used to treat stress incontinence?
Females: low-tension vaginal tapes, open retropubic suspension, classical sling
Males: artificial urinary sphincter, male sling
What temporary treatment can be used to treat stress incontinence when the pt plans to have further pregnancies?
Intramural bulking agents
What is urge urinary incontinence?
Involuntary leakage accompanied by/immediately preceded by urgency
How common is urge incontinence in urinary incontinence pts?
Accounts for 20% of cases
How is urge incontinence treated?
Bladder training with scheduled voiding Anticholinergics to act on M2&3 Beta-3 agonist Botulinum toxin to inhibit ACh release Surgery
What surgical procedures can be used to Tx urge incontinence?
Sacral nerve neuromodulation (stimulation via implant)
Remove detrusor muscle (autoaugmentation)
Use bowel to increase bladder volume
Urinary diversion
What is mixed urinary incontinence?
Involuntary leakage associated with urgency and exertion/coughing etc
When does overflow in continence typically occur?
At night when neural control of bladder is reduced
Why is overflow incontinence painless?
Bladder is under active
Describe faecal overflow incontinence.
Constipation causes soft stool to move around obstruction
What is overactive bladder syndrome?
Includes MUI and UUI and is characterised by urgency, frequency and nocturia
What are obstetric and gynaecological risk factors for urinary incontinence?
Pregnancy and childbirth
Pelvic surgery
Radiotherapy
Pelvic prolapse
Give some examples of predisposing risk factors for urinary incontinence.
Race
FHx
Anatomical/neurological abnormalities
Give some promoting risk factors for urinary incontinence.
Menopause Drugs UTI Increased intra-abdominal pressure Cognitive impairment Age Co-morbidities
Why is the menopause a promoting factor for urinary incontinence?
Drying vagina increases likelihood of developing UTI
How is the type of urinary incontinence identified by history?
Overactive bladder (MUI or UUI) will not be stimulated by coughing
Why is urine dipstick a mandatory investigation for urinary incontinence?
Identify UTI, haematuria (malignancy), proteinuria or glucosuria causing polyuria which will present as frequency
What are basic non-invasive urodynamics?
Measurements of fluid intake and exit over time or measurement of post-micturition residual volume by US
What optional investigations can be preformed in urinary incontinence?
Invasive urodynamics for pressure-flow studies
Pad tests
Cystoscopy
What general lifestyle interventions can be used to manage urinary incontinence?
Modify fluid intake Weightloss Smoking cessation Decrease caffeine intake esp. UUI Avoid constipation Fixed voiding schedule
What are the management options for urinary in continence pts who cannot have surgery and are not responding to conservative/medical Tx or have
Contained incontinence via indwelling catheter (urethral/suprapubic), sheath device (adhesive condom attached to catheter), incontinence pads
