Voiding Dysfunction- Guralnick

Question 1

What innervates the detrusor muscle?

What innervates the internal sphincter?

What innervates the external sphincter?

Answer 1

Detrusor

• Hypogastric (sympathetic b3)
• Pelvic (parasympathetic)

Internal Sphincter

• Hypogastric (sympathetic a1)

External Sphincter

• Pudendal nerve (somatic)

Question 2

How does the central nervous system contribute to control of urination?

Answer 2

The pontine micturition center allows for voluntary control of urination and inhibits reflux detrusor contraction (detrusor automatically contracts when stretched).

Question 3

How does the sympathetic innervation of the urinary tract contribute to urinary control?

How does the parasympathetic innervation of the urinary tract contribute to urinary control?

Answer 3

Sympathetic

• Direct inhibition of the detrusor to store urine
• Indirect inhibition of the detrusor by blocking parasympathetic activation
• Contraction of the internal sphincter to store urine

Parasympathetic

• Direct activation of the detrusor to void urine
• Indirect activation of the detrusor in response to stretch reflex

Question 4

What is the micturition reflex?

How is it consciously altered?

Answer 4

When the bladder is filled, the detrusor is stretched, prompting contraction of the detrusor muscle to urinate.

Thanks to somatic control of the external sphincter and CNS inhibition of the micturition reflex, we have control over when we pee.

Question 5

What three things need to be coordinated to void the bladder?

What happens if these are not coordinated?

Answer 5

1. Detrusor contraction (parasympathetic)
2. Internal sphincter relaxation (sympathetic)
3. External sphincter relaxation (somatic)

Detrusor-sphincter dyssynergia; this condition can cause dysuria, high bladder pressures, and is usually caused by a brainstem/pons lesion.

Question 6

What are the three causes for incontinence?

Answer 6

1. Urge incontinence
   
   • caused by an overactive detrusor muscle, the muscle pushes out urine
2. Overflow incontinence
   
   • caused by an underactive detrusor muscle, the muscle is only able to stretch so much and the urine “overflows”
3. Stress Incontinence
   
   • caused by weak sphincters, increased pressure from coughing, laughing, etc overwhelms the resistance, and causes leak

A MIX OF SPHINCTER AND DETRUSOR PATHOLOGIES IS KNOWN AS MIXED URINARY INCONTINENCE

Question 7

What are three causes for urinary retention?

Answer 7

1. Weak, inactive Detrusor
   
   • weak detrusor does not provide the pressure needed to fully empty the bladder
2. Anatomic Urethral Obstruction
   
   • prostatic enlargment or urethral stricture blocks up the pipe
3. Functional Urethral Obstruction
   
   • hyperactive sphincter prevents urine emptying

Question 8

What are the symptoms of an overactive bladder (IE hyperactive detrusor)?

Answer 8

Urgency

Frequency (>8/day)

Nocturia (waking to pee)

Urge incontinence (can’t make it in time)

Question 9

What causes overactive bladder?

What is associated with overactive bladder?

Answer 9

Cause:

• Infection
• Irritants
• Neuro conditions
• Diabetes
• Urethral obstruction

Associations:

• Menopause
• Pelvic prolapse
• Obesity
• Pelvic floor dysfunction

Question 10

How is overactive bladder treated?

Answer 10

• Behavior Modification
  
  • fluid management
  • Kegels/ pelvic floor strengthening
• Medications
  
  • Anticholinergics to block detrusor activation
  • B-3 adrenergic agonist to relax detrusor
• Surgery

Question 11

What are risk factors for stress urinary incontinence?

Answer 11

Vaginal/Pelvic trauma (EG vaginal births)

Menopause

Neurologic problems (EG spina bifida)

Radiation therapy

Obesity

Question 12

How is stress incontinence treated?

Answer 12

• Behavior Modification
  
  • fluid management
  • Kegels/ pelvic floor strengthening
• Medications
  
  • Duloxetine blocks relaxation of external sphincter
• Surgery

Question 13

What 3 medications may cause urinary retention?

Why?

Answer 13

• Anticholinergics
• a-agonists
• Narcotics

All these medications can block the activation of the detrusor muscle.

Question 14

What are some symptoms of urinary retention?

Answer 14

• Straining to urinate
• Intermittant stream
• Frequnecy
• Suprapubic pain
• Hydronephrosis

Question 15

How can urinary retention be managed?

Answer 15

• Use catheter to drain bladder
• treat any UTI
• Stop any problematic medications
• Relieve any obstructions