Voiding Dysfunction Flashcards by Meghan May

Understand LUT antatomy

There are three pathways of urine

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What is the pontine micturition centers role in normal voiding

to coordinate contraction of the detrusor and relaxation of the sphincters; talks to PNS and SNS from lumbar and sacral area which innervates the bladder and the urethral spincter

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Role of CNS in the micturition

– Voluntary control over micturition

– Inhibition of reflex detrusor contraction

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Parasympathetic – facilitates micturition, how?

– Direct motor activation of detrusor contraction (acetylcholine; muscarinic receptors)

– Indirect facilitation of detruso rcontraction via stretch receptors

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Sympathetic – facilitates urine storage

– Inhibition of detrusor
» Direct (β3- adrenergic receptors)

» Indirect (via inhibition of parasympathetic stimulation)

– Contraction of “internal sphincter”/bladder neck (α adrenergic receptors)

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– Inhibition of detrusor
» Direct (β3- adrenergic receptors)

» Indirect (via inhibition of parasympathetic stimulation)

– Contraction of “internal sphincter”/bladder neck (α adrenergic receptors)

Sympathetic – facilitates urine storage

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– Direct motor activation of detrusor contraction (acetylcholine; muscarinic receptors)

– Indirect facilitation of detrusor contraction via stretch receptors

Parasympathetic – facilitates micturition

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Which part of the nervous system is under voluntary control?

Somatic – voluntary control
• Innervation of external urethral sphincter

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responsible for smooth muscle sphincter contraction and relaxation

sympathetic nervous system; alpha-adrenergic fibers

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Responsible for detrusor contraction and relaxation

cholinergic fibers; Parasympathetic Nervous System

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Striated muscle sphincter contraction and relaxation

Somatic nervous system

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Autonomic reflex between bladder and spinal cord promoting bladder emptying

Micturition Reflex

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Bladder fills with urine causing stretching of bladder wall

Stretch receptors activated and send signals back to spinal cord that :

Further activation of stretch receptors with :

promote detrusor contraction

further promotion of detrusor contraction

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CNS (cortex) sends inhibitory signals to __________micturition reflex in cognitively intact people (otherwise we’d peeing all the time like a baby)

“turn off”

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Micturition reflex can also be abolished by

external sphincter contraction (guarding reflex, voluntary/involuntary contraction of sphincter)

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When decision to urinate is made,______ removes the inhibitory signals and external sphincter relaxes to allow for micturition reflex to occur

CNS

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 Detrusor contraction via:

 Internal sphincter relaxation via:

– Parasympathetic innervation

– Sympathetic innervation

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have the potential to cause discoordination of these phenomena

• Damage to the brainstem/pons or spinal cord lesions below the brainstem

Detrusor contracts simultaneously with external sphincter (detrusor-sphincter dyssynergia)

Excessively high bladder pressures and trouble emptying bladder

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What promotes urine emptying?

Release of central inhibition of detrusor (brain decides “it’s time to pee”)

External sphincter relaxes

Detrusor contracts

Bladder neck/internal sphincter relaxes

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What promotes urine storage?

Descending signals from CNS inhibit detrusor

Detrusor at rest

Sphincters contracted

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= Gas pedal of car

= Brakes

Detrusor
Urethral sphincters

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________ = Car moving forward
________ ≈ detrusor contraction
________ ≈ relax urethral sphincters

• Voiding

– Foot on gas

– Take foot off brake

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_______ = Car stopping/stopped

_________ ≈ detrusor relaxed
_________ ≈ sphincter muscles active

Urine storage

– Foot off accelerator

– Foot on brake

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Failure to store urine

– Bladder (detrusor) – overactive (OAB) vs underactive

OAB/detrusor overactivity–>_________

Underactive detrusor with chronic urinary retention and bladder

overdistension–> _________

urge incontinence

overflow incontinence

– Urethral sphincter--\>stress incontinence • Incompetent/weakness This is what type of voiding dysfunction

voiding dysfunction; social or anxiety with extrinsic force on the bladder from raising abdrominal pressure

– Urethral obstruction: Anatomic causes

– Prostatic enlargement – Urethral stricture – Prior incontinence surgery

Failure to empty urine – Bladder (detrusor)

- weak/underactive/atonic/areflexic

Functional (hyperactive sphincter) – Neurogenic = – Non-neurogenic =

Functional (hyperactive sphincter) – Neurogenic = detrusor-sphincter dyssynergia – Non-neurogenic = dysfunctional voiding

Failure to store urine (car keeps moving when you want it to stop) – Intermittent stepping on accelerator ≈ \*Urge Incontinence – Brake malfunction ≈ \*Stress Incontinence

detrusor overactivity urethral sphincter dysfunction

Failure to empty urine (car won’t move forward) – Engine malfunction/failure to step on accelerator ≈ \_\_\_\_\_\_ – Something blocking the front of car ≈ \_\_\_\_\_\_\_\_\_\_ – Intermittent/continuous stepping on brakes ≈ \_\_\_\_\_\_\_\_\_\_

bladder dysfunction anatomic urethral obstruction hyperactive urethral sphincter (e.g. detrusor-sphincter dyssynergia)

Urinary Incontinence =

Failure to Store Urine

Two causes of urinary incontinence

• Due to Detrusor – Overactive bladder/Urge urinary incontinence (UUI) • Due to sphincter – stress urinary incontinence (SUI)

≈ Hyperactive/Irritable detrusor  “Bladder spasms”  Bladder decides “to go” independent of the brain’s control Urinary Urgency (gotta go in a hurry) Urinary Frequency (\>8 voids/24 hr) Nocturia (night time voiding) Urge incontinence (have to go so bad that you start leaking/voiding before reaching toilet)

Overactive Bladder

Causes of overactive bladders

* Inflammation/infection (e.g. UTI) * Bladder Irritants * Neurologic conditions – Spinal cord injury, stroke, multiple sclerosis • Metabolic conditions – Diabetes * Urethral obstruction – Enlarged prostate, prior surgery for incontinence

Etiology of overactive bladder

* 16.5% of Americans met the criteria for OAB – Telephone survey of \>5200 American adults * Estimated that 29.8 million adults aged ≥40 years in the United States have bothersome OAB symptoms – Internet survey of 20,000 American adults • Prevalence increases with age (not normal part of aging) – Age \<70: female \> male – Age \>70: female ≈ male

Behavioral therapies for OAB

Behavioral therapies – Fluid management – Pelvic floor exercises (Kegels) • Inhibit detrusor contraction by contracting urinary sphincter/pelvic floor

Why are anticholinergics such as **oxybutynin** and **tolterodine **recommend to tx overactive bladder?

• Block acetylcholine receptor in detrusor  Inhibit overactive detrusor contractions

Why do B-3 Adrenergic agonists work to treat OAB: Myrbetriq

Activates β-3 receptor in detrusor --\> Relaxation of detrusor

Cause of stress urinary incotinence (Incontinence with coughing, sneezing, exercise, heavy lifting (ie anything that increases intra-abdominal pressure)

Due to weakness of urinary sphincter and support structures of urethra and bladder neck

– Vaginal/pevic trauma: * Multiple vaginal deliveries * Pelvic surgery (incl prior incontinence surgery) * External trauma (e.g. car accident) * Often associated with vaginal prolapse – Lack of estrogen (i.e. menopause) – Neurologic (e.g spina bifida) – Radiation therapy  scarring – Obesity

All can cause or risk factor for stress urinary incontinence

How common is stress incontinence

* Approx 40% of healthy females aged 30-49 have experienced some degree of incontinence with exercise * Up to 25% of women may experience incontinence 3 months following their first vaginal delivery

Risk of incontinence increases with: – Number of children (vaginally \> C-section) – Age older than 45 yrs A 50 yr old with 3 children delivered vaginally has an almost \_\_\_\_\_risk of being incontinent

40%

Behavorial therapies for Stress incontinence

• Behavioral therapies – Pelvic floor exercises (Kegels) • Learn to contract pelvic floor/sphincter prior to activity (the knack) – Weight loss

What is duloxetine and why is it recommended for tx of stress incontinence

• Medication (technically no approved drug for SUI) – Duloxetine (selective serotonin and norepinephrine reuptake inhibitor) Increases neural output from spinal cord to external urinary sphincter Contraction of sphincter muscle

What are some causes of "failure to empty" that involved the detrusor

Due to Detrusor – Neurogenic – Myogenic – Psychogenic – Medication

What medications can affect the detrusor muscle and prevent it from emptying

* Anticholinergics * α-agonists * Narcotics

Urinary retention; what are some anotomic causes

– Anatomic • Prostate enlargement * Urethral stricture * Prior incontinence surgery

Urinary retention or failure to empty can be caused by spincter hyperactivity, what are two causes?

– Functional (sphincter hyperactivity) * Neurogenic (detrusor-sphincter dyssynergia) * Non-neurogenic (dysfunctional voiding)

Post-operative state: – Anesthetics (anticholinergic activity) still on board will:

Inhibit detrusor thus get retention of urine

Post Op – Increased sympathetic tone results in:

Inhibit detrusor Internal sphincter/bladder neck contraction

What are some signs and symptoms of urinary retention

Voiding difficulty/inability to urinate • Straining to urinate • Hesitancy • Intermittent stream • Weak urinary stream – Urinary frequency (from lack of bladder emptying) – Lower abdominal/suprapubic pain (acute) – “Overflow” urinary incontinence (chronic) – Suprapubic fullness/mass (distended bladder) – Hydronephrosis/renal failure

Management of Urinary retention:

Catheter drainage of bladder – Indwelling – Intermittent (ideal) * Treat UTI * Stop aggravating meds (e.g. anticholinergics) * Relieve any obstruction – α-blocker medication (reduce internal sphincter tone) – Surgery on prostate * Neuromodulation (for non-obstructive retention)

Parasympathetic nervous system activates the \_\_\_\_\_for micturition

detrusor muscle (via acetylcholine)

inhibits the detrusor (β3 -receptor activation, inhibition of parasympathetics) and activates the bladder neck/internal sphincter for urine storage

Sympathetic nervous system

Somatic nervous system controls the

external sphincter (voluntary control)

CNS tonically inhibits the micturition reflex; __________ initiates micturition

release of this inhibition

Failure to store (urinary incontinence)

 Due to hyperactive/overactive bladder  Urge incontinence  Due to weak overdistended bladder (ie urinary retention)  Overflow incontinence  Due to sphincter (weak/damaged)  Stress incontinence

Failure to empty (urinary retention)

 Due to bladder (weak/underactive)  Due to sphincter (hyperactive)  Neurologic disorder  Detrusor-sphincter dyssynergy  Non-neurologic  Dysfunctional voiding