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Brain abscess

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Title: Brain abscess  
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Subject: Abscess, List of MeSH codes (C10), Amoebic brain abscess, List of infections of the central nervous system, Spastic gait
Collection: Brain Disorders, Disorders Causing Seizures, Infectious Diseases
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Brain abscess

Brain abscess
Brain abscess in a person with CSF shunt.[1]
Classification and external resources
ICD-9-CM 324.0
DiseasesDB 6880
MedlinePlus 000783
MeSH D001922

Brain abscess (or cerebral abscess) is an abscess caused by inflammation and collection of infected material, coming from local (ear infection, dental abscess, infection of paranasal sinuses, infection of the mastoid air cells of the temporal bone, epidural abscess) or remote (lung, heart, kidney etc.) infectious sources, within the brain tissue. The infection may also be introduced through a skull fracture following a head trauma or surgical procedures. Brain abscess is usually associated with congenital heart disease in young children. It may occur at any age but is most frequent in the third decade of life.


  • Signs and symptoms 1
  • Pathophysiology 2
    • Bacterial 2.1
    • Other organisms 2.2
  • Diagnosis 3
  • Treatment 4
  • Prognosis 5
  • References 6
  • External links 7

Signs and symptoms

Fever, headache, and neurological problems, while classic, only occur in 20% of people.[2]

The symptoms of brain abscess are caused by a combination of increased intracranial pressure due to a space-occupying lesion (headache, vomiting, confusion, coma), infection (fever, fatigue etc.) and focal neurologic brain tissue damage (hemiparesis, aphasia etc.). The most frequent presenting symptoms are headache, drowsiness, confusion, seizures, hemiparesis or speech difficulties together with fever with a rapidly progressive course. The symptoms and findings depend largely on the specific location of the abscess in the brain. An abscess in the cerebellum, for instance, may cause additional complaints as a result of brain stem compression and hydrocephalus. Neurological examination may reveal a stiff neck in occasional cases (erroneously suggesting meningitis). The famous triad of fever, headache and focal neurologic findings are highly suggestive of brain abscess.



Brain abscess after metastasis treatment.

Anaerobic and microaerophilic cocci and gram-negative and gram-positive

  • Brain abscess at eMedicine
  • MR Diagnosis MedPix Imaging Brain Abscess

External links

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Death occurs in about 10% and people do well about 70% of time.[2] This is a large improvement from the 1960s due to improved ability to image the head, better neurosurgery and better antibiotics.[2]


There are few exceptions to this rule: Haemophilus influenzae meningitis is often associated with subdural effusions that are mistaken for subdural empyemas. These effusions resolve with antibiotics and require no surgical treatment. Tuberculosis can produce brain abscesses that look identical to conventional bacterial abscesses on CT imaging. Surgical drainage or aspiration is often necessary to identify Mycobacterium tuberculosis, but once the diagnosis is made no further surgical intervention is necessary.

Surgical drainage of the abscess remains part of the standard management of bacterial brain abscesses. The location and treatment of the primary lesion also crucial, as is the removal of any foreign material (bone, dirt, bullets, and so forth).

Secondary functions of HBOT include increased stem cell production and up-regulation of VEGF which aid in the healing and recovery process.[9]

Hyperbaric Oxygen Therapy (HBO2 or HBOT) is indicated as a primary and adjunct treatment which provides four primary functions Firstly HBOT reduces intracranial pressure.[8] Secondly high partial pressures of oxygen act as a bactericide and thus inhibits the anaerobic and functionally anaerobic flora common in brain abscess. Third, HBOT optimizes the immune function thus enhancing the host defense mechanisms and fourth HBOT has been found to be of benefit when brain abscess is concomitant with cranial osteomyleitis.

The treatment includes lowering the increased intracranial pressure and starting intravenous antibiotics (and meanwhile identifying the causative organism mainly by blood culture studies).


Ring enhancement may also be observed in cerebral hemorrhages (bleeding) and some brain tumors. However, in the presence of the rapidly progressive course with fever, focal neurologic findings (hemiparesis, aphasia etc.) and signs of increased intracranial pressure, the most likely diagnosis should be the brain abscess.

The diagnosis is established by a computed tomography (CT) (with contrast) examination. At the initial phase of the inflammation (which is referred to as cerebritis), the immature lesion does not have a capsule and it may be difficult to distinguish it from other space-occupying lesions or infarcts of the brain. Within 4–5 days the inflammation and the concomitant dead brain tissue are surrounded with a capsule, which gives the lesion the famous ring-enhancing lesion appearance on CT examination with contrast (since intravenously applied contrast material can not pass through the capsule, it is collected around the lesion and looks as a ring surrounding the relatively dark lesion). Lumbar puncture procedure, which is performed in many infectious disorders of the central nervous system is contraindicated in this condition (as it is in all space-occupying lesions of the brain) because removing a certain portion of the cerebrospinal fluid may alter the concrete intracranial pressure balances and causes the brain tissue to move across structures within the skull (brain herniation).

MRI (T1 with contrast) showing the ring-enhancing lesion. From a rare case report of an abscess formed as a complication of the CSF shunt. Jamjoom et al., 2009.[1]


  • Sinus and dental infections—Aerobic and anaerobic streptococci, anaerobic gram-negative bacilli (e.g. Prevotella, Porphyromonas, Bacteroides), Fusobacterium, S. aureus, and Enterobacteriaceae
  • Penetrating trauma—S. aureus, aerobic streptococci, Enterobacteriaceae, and Clostridium spp.
  • Pulmonary infections—Aerobic and anaerobic streptococci, anaerobic gram-negative bacilli (e.g. Prevotella, Porphyromonas, Bacteroides), Fusobacterium, Actinomyces, and Nocardia
  • Congenital heart disease—Aerobic and microaerophilic streptococci, and S. aureus
  • HIV infection—T. gondii, Mycobacterium, Nocardia, Cryptococcus, and Listeria monocytogenes
  • Transplantation—Aspergillus, Candida, Cryptococcus, Mucorales, Nocardia, and T. gondii
  • Neutropenia—Aerobic gram-negative bacilli, Aspergillus, Candida, and Mucorales

These organisms are associated with certain predisposing conditions:

meningitis generally predominate.

Other organisms

Bacterial abscesses rarely (if ever) arise de novo within the brain, although establishing a cause can be difficult in many cases. There is almost always a primary lesion elsewhere in the body that must be sought assiduously, because failure to treat the primary lesion will result in relapse. In cases of trauma, for example in compound skull fractures where fragments of bone are pushed into the substance of the brain, the cause of the abscess is obvious. Similarly, bullets and other foreign bodies may become sources of infection if left in place. The location of the primary lesion may be suggested by the location of the abscess: infections of the middle ear result in lesions in the middle cranial fossa and posterior cranial fossae;[5] congenital heart disease with right-to-left shunts often result in abscesses in the distribution of the middle cerebral artery;[6][7] and infection of the frontal and ethmoid sinuses usually results in collection in the subdural sinuses.


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