Brain Abscess

Aka: Brain Abscess, Intracranial Abscess, Cerebral Abscess, Subdural Empyema, Subdural Abscess, Central Nervous System Abscess, CNS Abscess

1. See Also
   1. Epidural Abscess
   2. Intracranial Mass
   3. Bacterial Meningitis
   4. Bacterial Meningitis Management
   5. Neisseria Meningitidis
   6. Viral Meningitis
   7. Aseptic Meningitis
   8. Encephalitis
   9. Brain Abscess
   10. Viral Meningitis
   11. Aseptic Meningitis
   12. Encephalitis
2. Epidemiology
   1. Peak Incidence in children: Ages 4 to 7 years old
3. Pathophysiology
   1. Frontal, temporal, and Parietal Lobes are most commonly affected
4. Causes: Source
   1. Unknown primary source of abscess in 20-40% of cases
   2. Direct Spread
      1. Subdural Abscess (Subdural Empyema) is spread of Sinusitis or Mastoiditis in 60-90% of cases
         1. Mastoiditis (due to Chronic Otitis Media)
         2. Frontal Sinusitis or Ethmoid Sinusitis
         3. Dental Infection
      2. Retained Foreign Body such as bullet fragments (abscess development may be years later)
      3. Neurosurgery (abscess development may be >1 year later)
      4. Epidural Abscess (rare)
         1. Skull Osteomyelitis
         2. Orbital Cellulitis
         3. Acute Sinusitis
         4. Otitis Media
   3. Hematogenous spread
      1. Lung Abscess or empyema in host with chronic lung disease (e.g. Cystic Fibrosis, Bronchiectasis)
      2. Esophageal procedures (e.g. esophageal dilation, Varices management)
      3. Cyanotic Congenital Heart Disease
      4. Bacterial Endocarditis
      5. Pulmonary AV Malformation with right to left shunt
      6. Skin Infections
      7. Intraabdominal and pelvic infections
      8. Dental Infection
5. Causes: Organisms
   1. Strepotococcus esp. viridans (60-70%)
   2. Staphylococcus, esp. Staphylococcus aureus (10-14%)
   3. Other source site-specific organisms (in addition to Staphylococcus and Streptococcus species)
      1. Actinomyces (lung)
      2. Bacteroides (sinus, dental, ear) in up to 20-40% of cases
      3. Clostridium (penetrating Head Trauma)
      4. Enterobacteriaciae, Gram Negative Rods (ear) in up to 25-33% of cases
      5. Enterobacter (urine, penetrating Head Trauma, neurosurgery)
      6. Fusobacterium (sinus, dental, lung)
      7. Haemophilus (sinus, dental)
      8. Pseudomonas (ear, urine, neurosurgery)
   4. Immunocompromised patients
      1. See Brain Lesion in HIV
      2. Aspergillus
      3. Coccidioides
      4. Cryptococcus
      5. Listeria
      6. Nocardia
      7. Toxoplasma gondii
      8. Other fungus (e.g. Candida)
   5. Immigrants
      1. Cysticercosis (most common)
      2. Entamoeba histolytica
      3. Schistosoma
6. Symptoms
   1. Often initially subacute (results in delayed diagnosis typically >1 week)
   2. Headache (69%), typically unilateral in the region of abscess
   3. Neck Stiffness (15%), associated with posterior abscess (e.g. occiput)
   4. Vomiting (suggests Increased Intracranial Pressure)
7. Signs
   1. Fever (45%)
   2. Focal neurologic deficit (50%, delayed finding >1 week after Headache onset)
      1. Oculomotor findings (CN 3 or CN 6) suggests Increased Intracranial Pressure
   3. Seizure (25%)
   4. Altered Level of Consciousness (associated with significant brain edema and with worse prognosis)
8. Imaging
   1. CT Head with contrast OR
   2. MRI Brain with gadolinium (preferred)
9. Differential Diagnosis
   1. See Intracranial Mass
10. Diagnostics
    1. Lumbar Puncture
       1. Contraindicated in focal symptoms/signs, CNS mass, Increased Intracranial Pressure (risk of Herniation)
       2. Obtain CNS imaging prior to Lumbar Puncture
11. Labs
    1. Serology
       1. Blood anti-Toxoplasma IgG
       2. CSF anti-cysticercal Antibody
    2. CT-guided or neurosurgery obtained fluid
       1. Gram Stain
       2. Acid-fast stain and modified acid fast (Mycobacteria, Nocardia)
       3. Fungal stains
       4. Aeorbic and Anaerobic Bacterial cultures
       5. Mycobacterial culture
       6. Fungal Culture
12. Management
    1. See Toxoplasmosis
    2. Bacterial cause (initial empiric therapy, including for Subdural Empyema)
       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
       4. Add Vancomycin for suspected Staphylococcus aureus
    3. Nocardia initial empiric therapy
       1. Trimethoprim-Sulfamethoxazole (or Linezolid 500 mg IV or oral every 12 hours) AND
       2. Imipenem 500 mg IV every 6 hours (or Meropenem 2 g IV every 8 hours)
       3. Add Amikacin 7.5 mg/kg every 12 hours, if multiorgan involvement
    4. Post-Trauma or Post-Surgical
       1. Vancomycin 15-20 mg/kg every 8-12 hours (or Linzeolid 600 mg q12h) AND
       2. Cefepime 2 g IV every 8 hours (or Meropenem 2 g IV every 8 hours)
13. References
    1. (2016) Sanford Guide, accessed 4/9/2016
    2. Southwick in Calderwood (2016) UpToDate, accessed 4/9/2016
    3. Brouwer (2014) N Engl J Med 371:447 [PubMed]