eMedicine Specialties > Emergency Medicine > Infectious Diseases

Brain Abscess

Author: Lisa Elizabeth Thomas, MD, Staff Physician, Harvard Affiliated Emergency Medicine Residency, Brigham and Women's Hospital and Massachusetts General Hospital
Coauthor(s): Joshua N Goldstein, MD, PhD, FAAEM, Instructor in Surgery, Harvard Medical School; Attending Physician, Department of Emergency Medicine, Massachusetts General Hospital
Contributor Information and Disclosures

Updated: Sep 25, 2008

Introduction

Background

Although rare in developed countries, brain abscess is a serious, life-threatening emergency. Once having a dire outcome, morbidity and mortality have decreased because of advances in diagnostic modalities, antibiotic regimens, and earlier surgical interventions.1,2 However, changes in epidemiology, including new disease pathogens and predisposing factors, have renewed concern about the diagnosis and treatment of this condition.

Pathophysiology

Brain abscess is a focal infection, which begins when organisms are inoculated into the brain parenchyma, usually from a site distant from the central nervous system (CNS). Abscess formation occurs through several stages. Inflammation during the "early cerebritis" stage evolves into a necrotic collection of pus, eventually surrounded by a well-vascularized capsule after 2 weeks.3,4

The 3 mechanisms of entry into the brain are as follows:2,5,6

  • Direct extension: Infections stemming from the sinuses, teeth, middle ear, or mastoid may gain access to the venous drainage of the brain via valveless emissary veins that drain these regions. Because of improved antibiotic therapy for ear infections, this mechanism is decreasing in incidence, accounting for only approximately 25% of cases.2
  • Hematogenous: Seeding of the brain occurs from distant infection sites and often results in multiple brain abscesses.7 This remains an important cause of brain abscess.
  • Following penetrating head injury or neurosurgery: Previously low in incidence, more brain abscesses are developing after head trauma and neurosurgical procedures. A recent case series found that 37% of brain abscesses were associated with head penetration.2,8

Up to 25% of abscesses are cryptogenic and have no clear source.2,7

Frequency

United States

Brain abscess is rare in the general population; however, immunocompromised patients have increasing incidence of brain abscess, often with fungal or protozoan organisms.

In the United States, 1500-2500 cases are reported per year.7

Mortality/Morbidity

  • The mortality rate from brain abscess is currently approximately 10%.1,2,9
  • However, if the abscess ruptures into the ventricular system, the mortality rate may be 80%.2
  • Morbidity in survivors is generally due to residual neurologic defects, increased incidence of seizures due to scar tissue foci, or neuropsychiatric changes.7

Race

No compelling evidence exists for racial differences in the incidence of brain abscess.

Sex

Brain abscess occurs twice as often among men than women.2,4,10,11

Age

Traditionally, brain abscesses were disproportionately diagnosed in the young. However, with changes in vaccination practices, treatment of pediatric infections, and the AIDS pandemic, current literature suggests a shift in peak incidence toward the third to fifth decades of life.2,11,12

Clinical

History

  • Headache is the most common presenting symptom of brain abscess (50-90% of cases).2,11
  • Focal neurologic deficit (50%) may correlate with the local region of infection.6
  • Classic triad of headache, fever, and focal neurologic deficit is rarely seen (<5% of cases in a recent case series).2
  • Seizure (40%) and mental status changes (50%) are common.2,11
  • Nausea, vomiting, or stiff neck may be reported with increased cerebral edema due to the mass lesion.6
  • Sudden worsening of a preexisting headache accompanied with meningismus may be indicative of a catastrophic event—rupture of the abscess into the ventricular space.6

Physical

  • Fever is typically low grade, but presence or absence of fever does not aid in diagnosis, as it is present in less than half of all cases.6,11
  • Altered mental status ranges from subtle personality changes through drowsiness to full-blown coma.11
  • Nuchal rigidity occurs in about 25% of cases.11
  • Focal neurologic findings are commonly present6,11 and can signal increasing cerebral edema around the abscess.4
  • Seizures are typically generalized.11
  • Papilledema indicates the disease process is well advanced and increased intracranial pressure is present.11
  • Bulging fontanelles, irritability, and enlarging head circumference may be noted in infants.5

Causes

A wide variety of organisms can cause brain abscess, depending on the portal of entry, and up to one third may be polymicrobial.3,6   

  • Direct extension - Sinus, odontogenic, and otogenic sources are common.
    • Streptococcus species (aerobic and anaerobic) are most frequently isolated.
    • Other organisms include Bacteroides, Enterobacteriaceae, Pseudomonas, Fusobacterium, Prevotella, Peptococcus, and Propionibacterium.
  • Hematogenous spread - Pathogens depend on predisposing source. Some common examples are listed below.
    • Endocarditis -Streptococcus viridans, Staphylococcus aureus
    • Pulmonary infections -Streptococcus, Fusobacterium, Corynebacterium, and Peptococcus species
    • Cardiac defects with right-to-left shunt -Streptococcus species
    • Intra-abdominal infections -Klebsiella species, E coli, other Enterobacteriaceae, Streptococcus species, anaerobes
    • Urinary tract infections - Enterobacteriaceae, Pseudomonas species
    • Wound infection -S aureus
  • Penetrating head trauma, postoperative8
    • S aureus is most commonly isolated.
    • Enterobacteriaceae, other gram-negative bacilli, S epidermidis, Clostridium species, anaerobes, and Pseudomonas species may also be found.
    • Opportunistic infection is an increasing cause of brain abscess, as there are more patients with organ transplant, HIV, and immunodeficiencies. Common organisms include Toxoplasma gondii and   Nocardia, Aspergillus, and Candida species.4,5,6 Cases of Nocardia are increasing even in immunocompetent patients and have high mortality.2,4,13
    • Other predisposing risk factors include intravenous drug use, cardiac abnormalities (ie, prosthetic valve, septal defect), cyanotic congential heart disease (most common cause of multiple brain abscesses in children), diabetes, chronic steroid use, alcoholism, and neoplasm.2,7,11
    • Case reports of near drowning, foreign body aspiration, application of dental braces, and esophageal dilatation have also been associated with brain abscess.14,15,16,17
    • When there is no obvious source (up to 25% of cases), upper respiratory tract flora and anaerobes are often isolated.2 Several sources have identified a patent foramen ovale by echocardiogram in these cases and propose this as a possible mechanism for seeding oral flora to the brain.18
    • Several cases of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) causing brain abscess have been reported recently, so this must be considered when initiating empiric therapy in patients presenting with neurologic symptoms who also have risk factors for CA-MRSA.19,20

More on Brain Abscess

Overview: Brain Abscess
Differential Diagnoses & Workup: Brain Abscess
Treatment & Medication: Brain Abscess
Follow-up: Brain Abscess
References
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References

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  2. Carpenter J, Stapleton S, Holliman R. Retrospective analysis of 49 cases of brain abscess and review of the literature. Eur J Clin Microbiol Infect Dis. Jan 2007;26(1):1-11. [Medline].

  3. Lu CH, Chang WN, Lui CC. Strategies for the management of bacterial brain abscess. J Clin Neurosci. Dec 2006;13(10):979-85. [Medline].

  4. Mathisen GE, Johnson JP. Brain abscess. Clin Infect Dis. Oct 1997;25(4):763-79; quiz 780-1. [Medline].

  5. Sáez-Llorens X. Brain abscess in children. Semin Pediatr Infect Dis. Apr 2003;14(2):108-14. [Medline].

  6. Bernardini GL. Diagnosis and management of brain abscess and subdural empyema. Curr Neurol Neurosci Rep. Nov 2004;4(6):448-56. [Medline].

  7. Mamelak AN, Mampalam TJ, Obana WG, et al. Improved management of multiple brain abscesses: a combined surgical and medical approach. Neurosurgery. 1995;36(1):76-85. [Medline].

  8. Yang KY, Chang WN, Ho JT, et al. Postneurosurgical nosocomial bacterial brain abscess in adults. Infection. Oct 2006;34(5):247-51. [Medline].

  9. Sennaroglu L, Sozeri B. Otogenic brain abscess: review of 41 cases. Otolaryngol Head Neck Surg. Dec 2000;123(6):751-5. [Medline].

  10. Gallitelli M, Lepore V, Pasculli G, et al. Brain abscess: a need to screen for pulmonary arteriovenous malformations. Neuroepidemiology. 2005;24(1-2):76-8. [Medline].

  11. Seydoux C, Francioli P. Bacterial brain abscesses: factors influencing mortality and sequelae. Clin Infect Dis. Sep 1992;15(3):394-401. [Medline].

  12. Vidal JE, Oliveira AC, Filho FB, et al. Tuberculous brain abscess in AIDS patients: report of three cases and literature review. Int J Infect Dis 9(4):201-7. 2005;9(4):201-7. [Medline].

  13. Kennedy KJ, Chung KH, Bowden FJ, et al. A cluster of nocardial brain abscesses. Surg Neurol. Jul 2007;68(1):43-9; discussion 49. [Medline].

  14. Wolf J, Curtis N. Brain abscess secondary to dental braces. Pediatr Infect Dis J. Jan 2008;27(1):84-5. [Medline].

  15. Gaïni S, Grand M, Michelsen J. Brain abscess after esophageal dilatation: case report. Infection. Feb 2008;36(1):71-3. [Medline].

  16. Roberts J, Bartlett AH, Giannoni CM, et al. Airway foreign bodies and brain abscesses: report of two cases and review of the literature. Int J Pediatr Otorhinolaryngol. Feb 2008;72(2):265-9. [Medline].

  17. Katragkou A, Dotis J, Kotsiou M, et al. Scedosporium apiospermum infection after near-drowning. Mycoses. Sep 2007;50(5):412-21. [Medline].

  18. Khouzam RN, El-Dokla AM, Menkes DL. Undiagnosed patent foramen ovale presenting as a cryptogenic brain abscess: case report and review of the literature. Heart Lung. Mar-Apr 2006;35(2):108-11. [Medline].

  19. Enany S, Higuchi W, Okubo T, et al. Brain abscess caused by Panton-Valentine leukocidin-positive community-acquired methicillin-resistant Staphylococcus aureus in Egypt, April 2007. Euro Surveill. Sep 27 2007;12(9):E070927.2. [Medline].

  20. Sifri CD, Park J, Helm GA, et al. Fatal brain abscess due to community-associated methicillin-resistant Staphylococcus aureus strain USA300. Clin Infect Dis. Nov 1 2007;45(9):e113-7. [Medline].

  21. Hakan T, Ceran N, Erdem I, et al. Bacterial brain abscesses: an evaluation of 96 cases. J Infect. May 2006;52(5):359-66. [Medline].

  22. Kao PT, Tseng HK, Liu CP, et al. Brain abscess: clinical analysis of 53 cases. J Microbiol Immunol Infect. Jun 2003;36(2):129-36. [Medline].

  23. Marshman LA, Connor S, Chandler CL. Persistent absence of ring-enhancement on CT with an encapsulated brain abscess. Br J Neurosurg. Aug 2004;18(4):377-82. [Medline].

  24. Kastrup O, Wanke I, Maschke M. Neuroimaging of infections. NeuroRx. Apr 2005;2(2):324-32. [Medline].

  25. Lai PH, Hsu SS, Ding SW, et al. Proton magnetic resonance spectroscopy and diffusion-weighted imaging in intracranial cystic mass lesions. Surg Neurol. 2007;68 Suppl 1:S25-36. [Medline].

  26. Kimberly HH, Shah S, Marill K, et al. Correlation of optic nerve sheath diameter with direct measurement of intracranial pressure. Acad Emerg Med. Feb 2008;15(2):201-4. [Medline].

  27. Hasbun R, Abrahams J, Jekel J, et al. Computed tomography of the head before lumbar puncture in adults with suspected meningitis. N Engl J Med. Dec 13 2001;345(24):1727-33. [Medline].

  28. Boviatsis EJ, Kouyialis AT, Stranjalis G, et al. CT-guided stereotactic aspiration of brain abscesses. Neurosurg Rev. Jul 2003;26(3):206-9. [Medline].

  29. Unal O, Sakarya ME, Kiymaz N, et al. Brain abscess drainage by use of MR fluoroscopic guidance. Am J Neuroradiol. 2005;26(4):839-42. [Medline].

  30. Kurschel S, Mohia A, Weigl V, et al. Hyperbaric oxygen therapy for the treatment of brain abscess in children. Childs Nerv Syst. 2005;May 5:[Medline].

  31. Kutlay M, Colak A, Yildiz S, et al. Stereotactic aspiration and antibiotic treatment combined with hyperbaric oxygen therapy in the management of bacterial brain abscesses. Neurosurgery. Dec 2005;57(6):1140-6; discussion 1140-6. [Medline].

  32. Lee TH, Chang WN, Su TM, et al. Clinical features and predictive factors of intraventricular rupture in patients who have bacterial brain abscesses. J Neurol Neurosurg Psychiatry. Mar 2007;78(3):303-9. [Medline].

  33. Xiao F, Tseng MY, Teng LJ, et al. Brain abscess: clinical experience and analysis of prognostic factors. Surg Neurol. May 2005;63(5):442-9; discussion 449-50. [Medline].

  34. Demir MK, Hakan T, Kilicoglu G, et al. Bacterial brain abscesses: prognostic value of an imaging severity index. Clin Radiol. Jun 2007;62(6):564-72. [Medline].

  35. Prasad KN, Mishra AM, Gupta D, et al. Analysis of microbial etiology and mortality in patients with brain abscess. J Infect. Oct 2006;53(4):221-7. [Medline].

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Further Reading

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Keywords

brain abscess, intracranial abscess, intracerebral abscess, cerebritis, cerebral abscess

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Contributor Information and Disclosures

Author

Lisa Elizabeth Thomas, MD, Staff Physician, Harvard Affiliated Emergency Medicine Residency, Brigham and Women's Hospital and Massachusetts General Hospital
Lisa Elizabeth Thomas, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, and Phi Beta Kappa
Disclosure: Nothing to disclose.

Coauthor(s)

Joshua N Goldstein, MD, PhD, FAAEM, Instructor in Surgery, Harvard Medical School; Attending Physician, Department of Emergency Medicine, Massachusetts General Hospital
Joshua N Goldstein, MD, PhD, FAAEM is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American Stroke Association, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Medical Editor

Edward Bessman, MD, Chairman, Department of Emergency Medicine, John Hopkins Bayview Medical Center; Assistant Professor, Department of Emergency Medicine, Johns Hopkins University
Edward Bessman, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Barry J Sheridan, DO, Chief, Department of Emergency Medical Services, Brooke Army Medical Center
Barry J Sheridan, DO is a member of the following medical societies: American Academy of Emergency Medicine
Disclosure: Nothing to disclose.

CME Editor

John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Chief Editor

Jonathan Adler, MD, Attending Physician, Department of Emergency Medicine, Massachusetts General Hospital; Division of Emergency Medicine, Harvard Medical School
Jonathan Adler, MD is a member of the following medical societies: American Academy of Emergency Medicine and Society for Academic Emergency Medicine
Disclosure: eMedicine.com, Inc. Consulting fee Consulting

 
 
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