What are the urinary bladder signs in a patient with D6 (sixth thoracic vertebra) spinal cord compression?

Urinary Bladder Signs in D6 Spinal Cord Compression

Patients with D6 (sixth thoracic vertebra) spinal cord compression typically present with neurogenic bladder dysfunction characterized by detrusor overactivity, urinary urgency, frequency, and incontinence due to loss of supraspinal inhibitory control.

Pathophysiology and Clinical Presentation

Spinal cord compression at the D6 level results in specific urinary bladder manifestations:

• Detrusor overactivity: The most common urodynamic finding, resulting in:

  • Urinary urgency
  • Frequency
  • Urge incontinence
  • Sudden or stress incontinence
  • New-onset enuresis
  • Nocturia 1

• Detrusor-sphincter dyssynergia (DSD): Uncoordinated contraction of the external sphincter during detrusor contraction 1

  • Leads to incomplete bladder emptying
  • High intravesical pressures
  • Risk of vesicoureteral reflux

• Autonomic dysreflexia: A potentially life-threatening complication 2

  • Characterized by sudden hypertension
  • Headache, flushing, sweating above the level of injury
  • Can be triggered by bladder distension or procedures

Diagnostic Findings

Urodynamic studies are essential for proper characterization of neurogenic bladder dysfunction in D6 cord compression:

• Cystometrography (CMG) findings typically show:

  • Reduced bladder capacity
  • Detrusor overactivity (in 45% of patients with cervical/thoracic lesions) 3
  • High detrusor pressures during filling phase
  • Low bladder compliance (C < 20 ml/cmH2O) in 64% of patients 4

• Pressure flow studies reveal:

  • Detrusor-sphincter dyssynergia
  • Incomplete bladder emptying
  • High post-void residual volumes

Associated Complications

Without proper management, D6 spinal cord compression can lead to serious urinary tract complications:

• Upper urinary tract damage:

  • Hydronephrosis (5% of patients) 4
  • Ureteropieloectasia (21% of patients) 4
  • Chronic pyelonephritis (10% of patients) 4
  • Renal calculi (24% of patients) 4

• Recurrent urinary tract infections:

  • 36.4% of patients develop bacteriuria 5
  • 15.9% experience 1-2 clinical UTI episodes per year 5
  • 5% have ≥3 clinical UTIs annually 5

Evaluation Algorithm

1. Initial assessment:

   • Evaluate for associated neurological deficits (lower extremity weakness, sensory changes)
   • Assess for orthopedic abnormalities (75% of patients with spinal dysraphism present with these) 1
   • Look for cutaneous markers of spinal dysraphism 2

2. Urodynamic testing:

   • Multichannel urodynamics to assess detrusor function and sphincter coordination 2
   • Measure detrusor leak point pressures when clinically relevant 2
   • Monitor for autonomic dysreflexia during testing 2

3. Upper tract imaging:

   • Renal ultrasound to assess for hydronephrosis or other complications 2
   • MRI of the thoracic spine to evaluate the extent of cord compression 1

Management Considerations

The management of neurogenic bladder in D6 cord compression requires a systematic approach:

• Risk stratification is essential once the neurological condition has stabilized 2
• Intermittent catheterization is the most common bladder management technique (used in 77.9% of spinal cord injury patients) 5
• Anticholinergic medications are used in 63.2% of patients to manage detrusor overactivity 5
• Regular follow-up with urine cultures, urinary system ultrasound, and urodynamic tests is necessary to prevent complications 5

Pitfalls and Caveats

• Avoid urodynamic testing during spinal shock phase (typically lasts 3-6 months but can extend to 1-2 years) 2
• Monitor for autonomic dysreflexia during urodynamic testing or cystoscopy in at-risk patients 2
• If autonomic dysreflexia develops during testing, immediately terminate the study, drain the bladder, and continue hemodynamic monitoring 2
• Long-standing untreated tethering can result in progressive musculoskeletal deformities and/or scoliosis 2