Neurological examination may reveal a stiff neck in occasional cases (erroneously suggesting meningitis). Pathophysiology
Bacterial
Anaerobic and microaerophilic cocci and gram-negative and gram-positive anaerobic bacilli are the predominant bacterial isolates. Many brain abscesses are polymicrobial. The predominant organisms include: Staphylococcus aureus, aerobic and anaerobic streptococci (especially Streptococcus intermedius), Bacteroides, Prevotella, and Fusobacterium species, Enterobacteriaceae, Pseudomonas species, and other anaerobes. Less common organisms include: Haemophillus influenzae, Streptococcus pneumoniae and Neisseria meningitidis.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 and posterior cranial fossae; congenital heart disease with right-to-left shunts often result in abscesses in the distribution of the middle cerebral artery; and infection of the frontal and ethmoid sinuses usually results in collection in the subdural sinuses. Other organisms
Fungi and parasites may also cause the disease. Fungi and parasites are especially associated with immunocompromised patients. Other causes include: Nocardia asteroides, Mycobacterium, Fungi (e.g.
References
External links

NORD - National Organization for Rare Disorders, Inc. Chromosome 9, Trisomy 9p (Multiple Variants)
NORD - National Organization for Rare Disorders, Inc. Chromosome 9, Trisomy Mosaic