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A. Normal Urinary Bladder Function [1] navigator

  1. Detrusor muscle provides contractile force for emptying urinary bladder
  2. Detrusor muslce receives parasympathetic innervation via S2-S4 spinal nerves
  3. Internal Urinary Sphincter
    1. Derived from bladder muscle layer beginning in urinary trigone
    2. Involuntary muscle innervated by motor fibers from T11-L2 (sympathetic system)
    3. alpha-1-adrenergic receptors regulate contraction
  4. External urethral sphincter and perineal muscles are voluntary from pudendal nerves
  5. Normal adult bladder holds about 400mL (13.5 ounces) without overdistension
    1. Sensations of fullness are neurally transmitted above this volume
    2. Transmission to spinal cord via alpha myelinated bladder afferents
    3. Sacral spinal cord relaxes sphincters above this volume unless cortical override occurs
    4. The pontine micturition area is the initial brain area involved
  6. Pontine CNS Control of Micturition
    1. Pontine signals permit one to voluntarily delay bladder emptying
    2. Two main signals are involved: detrusor relaxation and bladder outlet constriction
    3. Detrusor relaxation mediated through ß2-adrenergic receptors in bladder body
    4. alpha1-adrenergic stimulation leads to bladder neck constriction
    5. Pelvic floor muscles also constrict, preventing urinary leakage
    6. Hypogastric and pudendal nerves carry these inhibitory signals
    7. These are sympathetic nerves, which also block parasympathetic pelvic signals
  7. Bladder Emptying
    1. In appropriate circumstance, CNS releases inhibitory signals, allow bladder emptyping
    2. Normal emptying involves coordination of multiple systems
    3. Relaxation of bladder outlet, increase detrusor pressure, relax external sphincter
  8. Spinal cord injuries above S2 lead to spontaneous urination when bladder fills

B. Spastic Typenavigator

  1. Typically due to Upper Motor Neuron Dysfunction
    1. This leads to sphincter-detrusor dys-synergy
    2. This dys-synergy is uncoordinated sphincter-detrusor function
  2. Causes
    1. Multiple Sclerosis [1]
    2. Spinal Cord Damage
    3. Head Trauma
    4. Stroke
  3. Symptoms
    1. Frequent Reflex Voiding
    2. Small Volumes
    3. Urinary frequency with urgency
    4. "Urge inconcontinence"
    5. Rule out urinary tract infection (UTI)
  4. Treatment
    1. Medications: Muscarinic anti-cholinergics are first line
    2. Imipramine (Tofranil®), a tricyclic agent, may be helpful
    3. Other tricyclic antidepressant agents may be used but are not recommended
    4. Surgery: sphincterotomy
  5. Anti-Cholinergic Agents [3,4]
    1. Muscarinic antagonists
    2. Oxybutynin (Ditropan®, Ditropan XL®): 5mg po tid or 5-30mg qd, or patch (Oxytrol®) 2x/wk
    3. Patch form of oxybutynin may have less dry mouth but is probably not as effective as po
    4. Tolterodine (Detrol®, Detrol LA®): 2mg po bid or long acting 2-4mg po qd
    5. Propanthine (Pro-banthine®), hyoscyamine (Cystospaz M®), falvoxate (Urispas®) also
    6. Side effects include dry mouth, xerophthalmia, dyspepsia, constipation
    7. Side effects occur significantly less frequently with tolterodine than with oxybutynin

C. Flaccid Typenavigator

  1. Lower Motor Neuron Damage
    1. Peripheral Neuropathy
    2. Cauda equina lesion
    3. Diabetes mellitus
    4. Multiple sclerosis with spinal lesions
  2. Symptoms
    1. Large post-void residual
    2. Sensation relatively preserved
    3. Frequent urinary tract infections
    4. This increases overflow urgency and frequency
  3. Treatment
    1. Cholinergics (urocholine, Bethanechol®)
    2. Intermittent Catheterization
    3. alpha-1 adrenergic blockers are also helpful (terazosin or tamsulosin (Flomax®))
    4. Bladder myoplasty (skeletal muscle transplant) was very effective in 3 of 3 patients [2]

D. Sensory (Overflow) Typenavigator

  1. Unable to feel need to void
  2. Symptoms
    1. Large Post-Void Residual
    2. Overflow Incontinence
  3. Usually associated with Diabetes Mellitus
  4. Treatment
    1. Habit training to void periodically b. Cholinergics to increase squeeze may also be helpful
    2. May require self-catheterizations

E. Disinhibited Typenavigator

  1. Poor Voluntary inhibition of inappropriate voiding
  2. Reflexive Function otherwise normal
  3. Usually due to frontal lobe involvement in diffuse cortical lesions or hydrocephalus
  4. Rule out treatable causes

References navigator

  1. Andrews KL and Husmann DA. 1997. Mayo Clin Proc. 72(12):1176 abstract
  2. Stenzl A, Ninkovic M, Kolle D, et al. 1998. Lancet. 351(9114):1483 abstract
  3. Tolterodine. 1998. Med Let. 40(1038):101 abstract
  4. Oxybutynin Transdermal. 2003. Med Let. 45(1156):38 abstract