II. Definitions

  1. Subdural Abscess (Subdural Empyema)
    1. Purulent collection between the Dura Mater and the acrachnoid membrane
    2. Most commonly a complication of Sinusitis or Mastoiditis

III. Epidemiology

  1. Subdural Empyema is most common in young males

IV. Pathophysiology

  1. Spread of infection from the sinuses directly into the subdural space (via bone haversian canals)
  2. Children are more prone to Subdural Empyema due to highly vascular sinuses
  3. Infections spread more rapidly through the subdural space than through the epidural or intracranial space

V. Risk Factors

  1. Prior Head Trauma
  2. Neurosurgery history

VI. Causes: Source

  1. See Brain Abscess
  2. Subdural Abscess (Subdural Empyema) is a spread of Sinusitis or Mastoiditis in 60-90% of cases
    1. Mastoiditis (due to Chronic Otitis Media)
    2. Sinusitis (most commonly frontal, but also ethmoid, sphenoid and Maxillary)
    3. Dental Infection

VII. Causes: Organisms

  1. See Brain Abscess
  2. Often polymicrobial infections
  3. Anaerobic Bacteria
  4. Aerobic streptococci
  5. Streptococcus Pneumoniae
  6. Staphylococci
  7. Staphylococcus epidermidis
  8. Haemophilus Influenzae
  9. Gram Negative Bacteria

VIII. Symptoms

  1. Recent Upper Respiratory Infection
  2. Severe Headache
    1. Typically unilateral in the region of abscess
  3. Photophobia
  4. Vomiting
  5. Seizures
  6. Fever
  7. Confusion

IX. Signs

  1. Fever
  2. Focal neurologic deficit
  3. Seizure
  4. Altered Level of Consciousness
    1. Associated with significant brain edema and with worse prognosis
  5. Comorbid Orbital Cellulitis may also be present

X. Imaging

  1. CT Head with contrast OR
  2. MRI Brain with gadolinium (preferred)

XII. Labs

  1. Complete Blood Count
  2. C-Reactive Protein
  3. Lumbar Puncture
    1. Indicated if Meningitis is suspected, but may be non-diagnostic in Subdural Empyema
    2. Contraindicated in focal symptoms/signs, CNS mass, Increased Intracranial Pressure (risk of Herniation)
    3. Obtain CNS imaging prior to Lumbar Puncture

XIII. Management

  1. See Brain Abscess
  2. Urgent Consultations (neurosurgery, infectious disease, otolaryngology)
  3. Initial Empiric Antibiotics
    1. Overall antibiotic course of 4-6 weeks is typical
    2. Cefotaxime 2 g IV q4 hours OR Ceftriaxone 2 g IV every 12 hours (or Pen G 3-4 MU q4h) AND
    3. Metronidazole 7.5 mg/kg every 6 hours AND
    4. Vancomycin for suspected Staphylococcus aureus
  4. Neurosurgical drainage
    1. Early intervention within first 72 hours may have greatest effect on outcome
    2. Craniectomy or burr hole drainage are most common
    3. Nonsurgical approach considered if clinically stable, <1 cm abscess and no midline shift
  5. Other adjuntive measures to consider (consult local expert opinion)
    1. Corticosteroids for brain edema
    2. Endoscopic Sinus Surgery may be considered
      1. Direct extension from sinus into subdural space through bony defect

XIV. Prognosis

  1. Mortality as high as 35% in Subdural Empyema

XV. Complications

  1. Associated with high morbidity and mortality
  2. Cognitive difficulties
  3. Hemiparesis
  4. Expressive Aphasia

XVI. References

  1. (2016) Sanford Guide, accessed 4/9/2016
  2. Marcom (2023) Crit Dec Emerg Med 37(7): 12-4
  3. Southwick in Calderwood (2016) UpToDate, accessed 4/9/2016
  4. Brouwer (2014) N Engl J Med 371:447 [PubMed]

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