What is an autonomic bladder?

Autonomic Bladder: Neurogenic Lower Urinary Tract Dysfunction

Autonomic bladder, more accurately termed neurogenic lower urinary tract dysfunction (NLUTD), refers to abnormal function of the bladder, bladder neck, and/or sphincters related to a neurologic disorder that affects the autonomic nervous system control of the lower urinary tract. 1

Definition and Pathophysiology

Autonomic bladder dysfunction occurs when neurological conditions disrupt the normal neural control of micturition, affecting:

• Storage phase (continence)
• Emptying phase (micturition)
• Coordination between smooth muscle of the bladder and voluntary control of the external urethral sphincter

The autonomic nervous system plays a crucial role in bladder function:

• Parasympathetic system: Controls bladder contraction (detrusor muscle)
• Sympathetic system: Controls bladder relaxation and sphincter contraction
• Somatic system: Controls voluntary external sphincter

Types and Classification

NLUTD patients should be risk-stratified based on their potential for upper urinary tract damage 1:

1. Low-risk

   • Normal bladder compliance
   • Low detrusor pressures during filling
   • Complete bladder emptying
   • No vesicoureteral reflux

2. Moderate to high-risk

   • High detrusor leak point pressures
   • Poor bladder compliance
   • Detrusor-sphincter dyssynergia
   • Vesicoureteral reflux
   • Incomplete bladder emptying

Common Symptoms

NLUTD can present with various symptoms:

• Storage symptoms:

  • Urinary urgency (sudden compelling desire to void)
  • Frequency (voiding more than 7 times during waking hours)
  • Nocturia (interruption of sleep due to need to void)
  • Urgency urinary incontinence

• Emptying symptoms:

  • Urinary retention
  • Incomplete bladder emptying
  • High post-void residual volumes

Diagnostic Approach

At initial evaluation, all patients with suspected NLUTD should undergo 1:

• Detailed history focusing on:

  • Cognitive ability
  • Upper and lower extremity function
  • Spasticity and dexterity
  • Mobility
  • Supportive environment
  • Prognosis of neurological condition

• Physical examination:

  • Abdominal exam
  • Rectal/genitourinary exam
  • Assessment of lower extremity function

• Basic testing:

  • Urinalysis to rule out infection
  • Post-void residual measurement in patients who spontaneously void

Management Approaches

Treatment depends on risk stratification, symptoms, and urodynamic findings 1:

1. Non-surgical options:

   • First-line: Pelvic floor muscle training for selected patients, particularly those with multiple sclerosis or cerebrovascular accident 1
   • Pharmacologic therapy:
     • Antimuscarinics or beta-3 adrenergic receptor agonists for storage symptoms 1
     • Alpha-blockers for emptying symptoms 2

2. Catheterization options:

   • Intermittent catheterization is strongly recommended over indwelling catheters due to lower rates of UTI and urethral trauma 1

3. Advanced interventions for refractory cases:

   • Botulinum toxin injections
   • Bladder augmentation
   • Urinary diversion

Complications and Special Considerations

1. Autonomic dysreflexia (AD): A potentially life-threatening condition in patients with spinal cord injuries above T6, characterized by sudden elevation in blood pressure, headache, and sweating. Bladder management with surgery (particularly augmentation) and indwelling catheters are associated with greater AD symptoms compared to clean intermittent catheterization or volitional voiding 3.

2. Recurrent urinary tract infections: More common with indwelling catheters than with intermittent catheterization.

3. Upper urinary tract deterioration: Can occur with high-pressure bladder storage, requiring regular monitoring in high-risk patients.

Follow-up and Monitoring

Follow-up should be based on risk stratification:

• High-risk patients require more frequent monitoring
• Patients who experience new or worsening signs and symptoms should be reevaluated and risk stratification repeated 1

Pitfalls and Caveats

• Avoid confusing autonomic bladder (neurogenic) with overactive bladder (non-neurogenic), which is defined as urinary urgency usually accompanied by frequency and nocturia, with or without urgency incontinence, in the absence of UTI or other obvious pathology 1
• Recognize that autonomic dysreflexia can be a medical emergency in patients with spinal cord injury
• Be aware that indwelling catheters carry higher risks of complications than intermittent catheterization
• Consider that abnormal autonomic function may be a biomarker for bladder dysfunction, with studies showing increased sympathetic activity in patients with overactive bladder 4, 5

Proper diagnosis, risk stratification, and management of autonomic bladder are essential to prevent upper urinary tract damage, reduce complications, and improve quality of life in affected patients.