Handbook of Genetic Counseling/Incontinence

Incontinence

General Information

• Refers to inability to retain urine in bladder
• Due to neurologic or mechanical disorder
• Normal bladder function
  • Detrusor muscle provides propulsive force for emptying bladder
    • Smooth muscle under parasympathetic autonomic control
    • Involves pelvic nerves from sacral spinal cord
  • Layer of smooth muscle of trigonal part of bladder acts as involuntary internal sphincter
    • Helps prevent incontinence even if no voluntary control
    • Innervated by motor fibers from T11 to L2
  • External sphincter and perineal muscles under voluntary control of pudendal nerves
  • Sensory tracts of pain, temperature, and distention pass from bladder to pelvic nerves to sacral spine to medulla of brain to cortical centers
• Infants and adults with spinal damage above S2 urinate spontaneously when bladder fills

Causes of Incontinence

• Detrusor instability
  • Bladder prone to uncontrollable contractions
  • Caused by damage to inhibitory neural pathways (70% of incontinence among elderly)
    • Cerbrovascualr accidents
    • Alzheimer's disease
    • Neoplasia
    • Hydrocephalus (?maybe?)
  • Could also be caused by bladder or pelvic infection or tumor, fecal impaction, uterine prolapse, and prostate hypertrophy
  • May be treated with Imipramine or calcium channel blockers
• Stress incontinence
  • Common in postmenopausal parous women
  • Structures of female urethra atrophy when deprived of estrogen
    • Pass urine under increased abdominal pressure during coughing, sneezing, climbing stairs
    • Physical activity may result in small amount of urine escaping
• Mechanical incontinence
  • Congenital anomalies, extrophy of bladder, patent urachus, and ectopic ureteral openings
  • Correctable by surgery only
  • May also be caused by prostate surgery, pelvic surgery, or irradiation of uterus or rectum
• Overflow or paradoxical incontinence
  • Large residual volumes of urine
  • Secondary to obstruction at bladder neck or urethra, or neurologic damage
  • May occur in diseases that produce autonomic peripheral neuropathy
    • Diabetes mellitus, uremia, hypothyroidism, chronic alcoholism, Guillain-Barre syndrome, collagen vascular diseases, and toxic neuropathy caused by carcinomas
    • Also may be due to prolonged distension of bladder
  • May be treated surgically if obstruction or with bethanechol chloride
• Psychogenic and functional incontinence
  • Occurs in children and some adults
  • May be to draw attention to themselves
  • May have psychological cause from abuse or other traumatic experiences
• Enuresis
  • Involuntary passage of urine at night during sleep
  • Considered normal under age of 2 years as neurological controls are still developing
    • Approximately 10% of children have some degree of enuresis beyond age of three
      • May be due to delay in maturation of bladder control
      • May be familial
    • Usually ceases by age of puberty unless disease interferes
      • Urinary tract infections, obstructive lesions, neurovesical dysfunction, and polyuric conditions that overload the bladder
      • Usually incontinent during the day also if one of these conditions

Reference

• "Dysuria, Frequency and Urgency, Incontinence, and Enuresis." Principles of Internal Medicine (1994): 240-241.

Notes

The information in this outline was last updated in 2002.