Brain abscess

A Brain abscess is an collection of pus in the brain. Symptoms are headache, lethargy, fever and neurological deficits. Bacteria are usually anaerobic. Diagnosis is by MRI.

CASES/YEAR
2,400 (US); 48,000 (Global)
CATEGORY
Localized Infections
AGENT TYPE
Mixed
OTHER NAMES
Cerebritis (focal infection without a capsule);
ACUITY
Acute-Severe
INCUBATION
Hours to months;
INITIAL SYMPTOMS
Headache, lethargy, fever, and neurological deficits; [Merck Manual, p. 1850];
PRECAUTIONS
COMMENTS
Predisposing conditions: otitis media, mastoiditis, sinusitis, penetrating head trauma, neurosurgical procedures, dental infections, infectious endocarditis, lung abscess, empyema, bronchiectasis, congenital heart disease, neutropenia, transplantation, and AIDS; Immunocompromised patients may contract brain abscesses caused by fungi and parasites: Toxoplasma gondii, Aspergillus, Nocardia, mycobacteria, and Cryptococcus neoformans. Neutropenia predisposes to brain abscesses caused by gram-negative bacilli, Aspergillus, Mucorales, and Candida. Neurocysticercosis and tuberculosis are important causes in some parts of the world. [PPID, p. 1248-53] Sources of brain abscesses: 90% from a focus of suppuration in another part of the body; 10% from head wounds or neurosurgical procedures; Patients with multiple abscesses may develop encephalopathy. [Cecil, p. 2458-9] The main findings are headache (>75%), fever (50%), focal deficit (>60%), and seizure (15-35%). Vomiting, papilledema, drowsiness, and confusion are signs of increased intracranial pressure. Meningismus indicates that the abscess has ruptured into the ventricle or subarachnoid space. Patients with a cerebellar abscess may present with nystagmus and ataxia. About 50% of patients have leukocytosis. Tumors are in the differential diagnosis, especially when fever is absent. [Harrison ID, p. 354-5] Mucormycosis and Aspergillosis may invade blood vessels and present with a stroke syndrome. [PPID, p. 1177]
DIAGNOSTIC
MRI and sometimes CT guided aspiration; No LP because of risk of herniation and CSF nonspecific; [Merck Manual, p. 1851] Gram stain; KOH prep; Stains for AFB and toxoplasma; Cultures (include mycobacteria & fungi); HIV status important; [ABX Guide]
SCOPE
Global
SIGNS & SYMPTOMS
  • >fever
  • E dysphagia
  • G nausea, vomiting
  • H leukocytosis
  • N confusion, delirium
  • N headache
  • N lethargy
  • N muscle weakness
  • N seizure
  • N stiff neck
  • *blindness
  • *brain abscess or lesion
  • *cranial neuropathy
  • *meningitis
  • *paralysis
  • *sepsis
  • *stupor, coma
ANTIMICROBIC

Yes

VACCINE

No

ENTRY
Inhalation, Ingestion, Needle (Includes Drug Abuse), Scalpel or Transfusion, Skin or Mucous Membranes (Includes Conjunctiva), Animal Bite, Swimming, Sexual Contact
SOURCE
Person-to-Person, Human Fecal-Oral, Fecally Contaminated Soil, Animal Excreta, Animal Tissue, Soil or Dust (Ingesting or Inhaling), Eating Contaminated Food, Eating Contaminated or Infected Meat, Eating Infected or Toxin-Containing Fish, Eating Contaminated Mollusks or Crustacean, Eating Unpasteurized Milk or Cheese, Eating Contaminated Produce, Waterborne (Ingesting, Inhaling, or Swimming)
RESERVOIR
Birds and Poultry, Cattle, Goats and Sheep, Cats, Dogs, Fish and Shellfish, Horses, Monkeys, Rabbits, Rodents, Swine, Human, Wild Animals
RISK FACTORS
  • AIDS patients
  • Cancer patients
  • Injection drug users
DRUG LINK
Merck Manual: Brain Abscess
REFERENCES FOR CASES/YEAR
1. (US) Annual incidence of about 0.3 to 1.3 per 100,000; [Harrison ID, p. 353] Calculate: 0.8 X 3000 = 2400 (US);
2. (Global) 20 X US cases/yr;