Basics
Description
- Suppurative infection involving the brain parenchyma
- May be a single or multiple lesions
Epidemiology
- Males more commonly affected (2:1 male-to-female predominance).
- Typical age of presentation is 4-7 years but varies according to predisposing factor.
- 85% of cases have a predisposing risk factor.
Incidence
~1,500-2,500 cases (adults and pediatric combined) occur per year with up to 25% being children.
Risk Factors
- Cyanotic congenital heart disease (tetralogy of Fallot is most common)
- Otorhinolaryngologic infections such as sinusitis, mastoiditis, and chronic otitis media
- Meningitis (especially in neonates)
- Penetrating head trauma
- Surgical manipulation of the brain (ventriculoperitoneal shunts, tumor removal)
- Congenital lesions of the head and neck
- Cystic fibrosis
- Dental infections
- Lung infections
- Patients who have traveled to endemic areas where neurocysticercosis (Latin America, parts of Africa, Asia, and the Indian subcontinent) is endemic
- Immunocompromised patients (congenital or acquired)
General Prevention
- During recreational activities, wearing helmets may prevent penetrating head trauma.
- Appropriate management of acute otitis media and acute sinusitis and timely recognition of treatment failure
Pathophysiology
- Microorganisms enter the brain parenchyma by contiguous or hematogenous extension.
- Location of brain abscesses:
- Cyanotic congenital heart disease patients tend to have abscesses within the middle meningeal artery distribution: frontal, parietal, and temporal lobes.
- Frontal abscesses are commonly seen with sinus and dental infections.
- Temporal, parietal, or cerebellar abscesses tend to occur with mastoiditis or otitis media.
- Brain abscesses can occur anywhere in the brain parenchyma, regardless of a predisposing risk factor, secondary to hematogenous metastasis.
Etiology
- Bacteria are the most common causes.
- Streptococcus milleri group and Staphylococcus sp. are the most commonly cultured microorganisms.
- Neonates may develop brain abscesses as a complication of Gram-negative meningitis (Proteus, Citrobacter, Enterobacter, and Cronobacter species).
- Polymicrobial infections occur in 30-50% of cases.
- Anaerobic organisms are found with increasing incidence with improved laboratory and culture techniques. Common pathogens include Bacteroides, Peptostreptococcus, Fusobacterium, Propionibacterium, Actinomyces, Veillonella, and Prevotella.
- Neurocysticercosis is caused by the parasite, Taenia solium. Fungi and protozoa can cause brain abscess in immunocompromised patients.
Diagnosis
History
The location of the brain abscess or abscesses will influence the clinical presentation.
- Classic triad of fever, headache, and focal neurologic findings occurs in <30% of cases.
- Fever, headache, and vomiting each occur in ~60-70% of cases.
- Headache is the most common complaint.
- Vomiting and mental status changes can be the presenting chief complaints.
- Neonates will often have a history of meningitis before developing a brain abscess.
- Questions should focus on acute or chronic otolaryngologic infections.
- A history of cyanotic congenital heart disease should be obtained, as well as partially repaired cyanotic congenital heart disease.
Physical Exam
- Neonates may present with a full fontanel, increasing head circumference, seizures, or vomiting.
- Older children may have signs of a focal neurologic deficit, hemiparesis, or even papilledema.
- Meningeal symptoms occur in ~30% of patients.
- Ataxia may be found with cerebellar lesions.
Diagnostic Tests & Interpretation
Lab
- Routine lab tests are not helpful and cannot rule out the diagnosis.
- <10% of blood cultures are positive.
- Peripheral WBC may be mildly elevated, but <10% will show band forms.
- ESR is a poor indicator of brain abscesses.
- Electrolytes may show low sodium, indicating syndrome of inappropriate secretion of antidiuretic hormone (SIADH).
- A lumbar puncture is contraindicated if any intracranial mass lesion is suspected, but if CSF is obtained:
- It may show a mild to moderate pleocytosis (20% of patients may have normal values).
- Opening pressure may be elevated.
- Glucose is decreased in 30% of patients.
- Protein is elevated in 70% of cases.
- CSF Gram stain and cultures are often negative.
Imaging
- CT with contrast and MRI scans are the studies of choice in diagnosing brain abscesses.
- Although CT can provide more rapid results, occult intracranial infections can be missed in up to 50% of cases.
- Cranial ultrasound may be useful in premature neonatal cases.
Alert
- Not all patients with brain abscesses have fevers.
- Pitfalls
- Failure to consider a brain abscess in a child with altered mental status, fevers, and meningismus or in a child with nonspecific symptoms but risk factors, such as cyanotic congenital heart disease
- Failure to recognize symptoms not typically seen in sinusitis, such as vomiting
Differential Diagnosis
- Infectious
- Meningitis
- Encephalitis
- Subdural empyema
- Epidural abscess
- Vascular
- Venous sinus thrombosis
- Migraine
- Cerebral infarct
- Cerebral hemorrhage
- Miscellaneous
- Primary or secondary tumor
- Pseudotumor cerebri
- Hydrocephalus
Treatment
Medication
- Broad-spectrum antibiotics that penetrate the CNS should be given at the time of diagnosis directed at most likely pathogens. The combination of a third-generation cephalosporin, vancomycin, and metronidazole provide good empiric coverage.
- Culture-directed antimicrobial therapy is recommended whenever possible. Typical antibiotic courses are 4-6 weeks.
- Consider neurosurgical and/or otolaryngology consultation.
- MRI or CT-guided stereotactic aspiration is encouraged to obtain cultures and identify the causative organism(s).
- Some patients are managed successfully with antibiotics alone, especially if there is a single, small (<2 cm) abscess.
- Antiparasitic medications (albendazole) with or without corticosteroids should be considered for treatment of neurocysticercosis.
- Antifungals should be considered for immunocompromised patients.
- Evaluation by cardiology, dental, otorhinolaryngology, and/or immunology may help identify predisposing factors.
Inpatient Considerations
Initial Stabilization
- If a patient is manifesting signs and symptoms of increased intracranial pressure (Cushing triad: bradycardia, hypertension, and abnormal respirations) or if the patient is unable to protect his or her airway, endotracheal intubation is indicated. Hyperventilation and mannitol should be considered.
- Electrolyte abnormalities such as SIADH may occur. Frequent monitoring of electrolytes is warranted.
- Seizures and focal neurologic deficits can occur early in presentation. They typically resolve with drainage of the lesion. Careful and frequent neurologic exams should be part of the hospital care.
Admission Criteria
- All patients with concern for brain abscess should be admitted for clinical monitoring, diagnostic evaluation, and treatment.
Discharge Criteria
- Generally, patients may be discharged home once their symptoms have resolved and antibiotic therapy is complete or can be completed at home.
Ongoing Care
Follow-up Recommendations
- Follow-up with neurosurgical, rehabilitation, and neurology clinics is usually required.
- Repeat imaging prior to cessation of antibiotic therapy should be done to document resolution of the abscess.
Complications
- Long-term complications arise from the location, size, and number of intracranial abscesses.
- Multiple abscesses, coma on presentation, <2 years of age, and rupture of abscess into the ventricle carry a higher mortality rate.
- 30-40% of patients have some morbidity associated with brain abscess; seizures, hydrocephalus, focal neurologic deficits (motor and sensory dysfunction), and behavorial or personality changes are potential complications. Mortality rates have decreased because of advances in imaging to assist in rapid diagnosis and surgical management.
Additional Reading
- Goodkin HP, Harper MB, Pomeroy SL. Intracerebral abscess in children: Historical trends at Children's Hospital Boston. Pediatrics. 2004;113(6):1765-1770. [View Abstract]
- Saez-Llorens X. Brain abscess in children. Semin Pediatr Infect Dis. 2003;14(2):108-114. [View Abstract]
- Yogev R, Bar-Meir M. Management of brain abscess in children. Pediatr Infect Dis J. 2004;23(2):157-160. [View Abstract]
- Herrmann BW, Chung JC, Eisenbeis JF, et al. Intracranial complications of pediatric frontal rhinosinusitis. Am J Rhinol. 2006;20(3):320-324. [View Abstract]
- Seydoux C, Francioli P. Bacterial brain abscesses: factors influencing mortality and sequelae. Clin Infect Dis. 1992;15(3):394-401. [View Abstract]
Codes
ICD09
- 324.0 Intracranial abscess
ICD10
- G06.0 Intracranial abscess and granuloma
SNOMED
- 441806004 Abscess of brain (disorder)
- 60404007 Cerebral abscess (disorder)
FAQ
- Q: Do all brain abscesses require surgery?
- A: No. Often times, brain abscesses will respond to intravenous antibiotics and will not require drainage. Close clinical and radiographic follow-up is imperative in these cases. Stereotactic aspiration of a brain abscess can be very helpful in identifying the microbiology of a brain abscess and help direct specific treatment.
- Q: What is the best imaging study to definitively diagnose a brain abscess?
- A: MRI