What is neurogenic bladder and how is it evaluated?

Neurogenic Bladder: Definition and Evaluation

Neurogenic bladder is a dysfunction of the urinary bladder caused by damage to the nervous system, resulting in abnormal bladder storage, emptying, or both, and requires comprehensive evaluation including risk stratification, detailed history, physical examination, and appropriate diagnostic testing to prevent complications and guide management. 1

Definition and Pathophysiology

Neurogenic lower urinary tract dysfunction (NLUTD), commonly known as neurogenic bladder, refers to abnormal function of the bladder, bladder neck, and/or sphincters related to a neurologic disorder 1. This condition results from damage to:

• Brain centers controlling micturition (pontine micturition center)
• Spinal cord pathways
• Peripheral nerves supplying the bladder
• Sacral micturition center (Onuf's nucleus between S2-S4) 2

Types of neurogenic bladder based on lesion location include:

• Autonomous bladder
• Spastic bladder
• Atonic bladder
• Cortical bladder 2

Common causes include:

• Spinal cord injury
• Multiple sclerosis
• Myelomeningocele
• Cerebrovascular accidents
• Other neurological conditions 3, 4

Initial Evaluation and Risk Stratification

Risk Classification

At initial evaluation, patients should be classified as either:

• Low-risk: No further evaluation needed
• Unknown risk: Requires further evaluation for complete risk stratification 1

Essential Initial Assessment

All patients with NLUTD should undergo:

1. Detailed history: Focus on:

   • Neurological condition and its stability
   • Urinary symptoms (incontinence, retention, frequency)
   • Previous UTIs
   • Cognitive ability
   • Upper and lower extremity function
   • Dexterity (affects ability to perform catheterization)
   • Mobility
   • Support system 1

2. Physical examination: Including:

   • Abdominal examination
   • External genitalia inspection
   • Neurological assessment
   • Assessment of hand dexterity 1

3. Urinalysis: To detect infection, hematuria, or other abnormalities 1

4. Post-void residual (PVR) measurement: For patients who spontaneously void 1

Optional Initial Studies

• Voiding/catheterization diary
• Pad test for incontinence assessment
• Non-invasive uroflow 1

Advanced Diagnostic Evaluation

For Unknown-Risk Patients

Further evaluation is required to complete risk stratification:

1. Multichannel urodynamic studies (UDS):

   • Essential for assessing lower urinary tract storage pressures
   • Provides accurate diagnosis
   • Helps assess prognosis
   • Guides treatment decisions
   • Should include detrusor leak point pressures when clinically relevant 1

2. Upper tract imaging:

   • Assesses for hydronephrosis, stones, or other abnormalities 1

3. Renal function assessment:

   • Blood tests to evaluate kidney function 1

Important Considerations

1. Timing of evaluation:

   • For patients with acute neurological events, risk stratification should be delayed until the neurological condition has stabilized
   • Spinal shock following SCI may last 3-6 months (up to 1-2 years)
   • UDS should be delayed until spinal shock has resolved 1

2. Cystoscopy:

   • Not recommended for routine initial evaluation
   • Only indicated for specific conditions:
     • Unexplained hematuria or pyuria
     • Suspected urethral pathology
     • Bladder stones
     • Known or suspected bladder cancer 1

3. Autonomic dysreflexia monitoring:

   • Patients at risk for autonomic dysreflexia must be hemodynamically monitored during urodynamic testing or cystoscopic procedures
   • If autonomic dysreflexia develops, the study should be terminated immediately, the bladder drained, and monitoring continued
   • Pharmacotherapy for managing autonomic dysreflexia should be readily available 1

Special Considerations

Patient Education

Patients must be educated about signs and symptoms requiring additional assessment:

• New or worsening autonomic dysreflexia
• New or worsening urinary incontinence
• New or more frequent UTIs, especially with fever or flank pain
• Upper tract findings (stones, hydronephrosis)
• Difficulties with catheterization
• Hematuria (may indicate bladder cancer or urinary lithiasis) 1

Follow-up Evaluation

• Low-risk patients with stable symptoms do not require surveillance upper tract imaging, renal function assessment, or multichannel urodynamics 1
• Patients should be monitored according to their risk level at regular intervals
• Risk stratification should be repeated if new or worsening symptoms develop 1

Pitfalls to Avoid

1. Performing risk stratification during periods of neurological instability:

   • Can lead to inaccurate assessment and inappropriate management 1

2. Routine cystoscopy in initial evaluation:

   • Unlikely to yield significant findings without specific indications 1

3. Inadequate monitoring during procedures:

   • Patients at risk for autonomic dysreflexia require continuous hemodynamic monitoring 1

4. Delayed recognition and management of autonomic dysreflexia:

   • Can lead to serious complications
   • Requires immediate intervention 1

5. Inadequate patient education:

   • Patients need to understand signs and symptoms requiring medical attention 1

By following this structured approach to evaluation, clinicians can effectively diagnose and risk-stratify patients with neurogenic bladder, leading to appropriate management strategies that minimize complications and optimize outcomes.