ACUTE FOCAL SUPPURATIVE INFECTIONS
- Brain Abscess
- Subdural Empyema
- Extradural Abscess
Brain abscesses may arise by_______________
- direct implantation of organisms,
- local extension from adjacent foci (mastoiditis, paranasal sinusitis), or
- hematogenous spread (usually from a primary site in the heart, lungs, or distal bones or after tooth extraction).
What are the predisposing conditions in brain abscess?
- acute bacterial endocarditis, which tends to produce multiple abscesses;
- congenital heart disease with right-to-left shunting and loss of pulmonary filtration of organisms;
- chronic pulmonary sepsis, as can be seen with bronchiectasis;
- and immunosuppression.
_____________are the most common offending organisms identified in nonimmunosuppressed
populations of brain abscess.
Streptococci and staphylococci
What is the Grossl appearance of brain abscesses ?
discrete lesions with central liquefactive necrosis
- surrounded by fibrosis and swelling ( Fig. 28-22 ).
What is the microscopic appearance of brain abscess?
- there is exuberant granulation tissue with neovascularization around the necrosis that is responsible for marked vasogenic edema.
- A collagenous capsule is produced by fibroblasts derived from the walls of blood vessels.
- Outside the fibrous capsule is a zone of reactive gliosis with numerous gemistocytic astrocytes.
What is the caused of marked vasogenic edema?
neovascularization around the necrosis
Cerebral abscesses are destructive lesions and patients almost invariably present clinically with progressive focal deficits in addition to the general signs of raised intracranial pressure.
CSF is ________________
The source of infection may be apparent, or it
may be a small systemic focus that is not symptomatic.
The increased intracranial pressure and
progressive herniation can be fatal, and abscess rupture can lead to ventriculitis, meningitis,
and venous sinus thrombosis.
With surgery and antibiotics, the otherwise high mortality rate
can be reduced to less than 10%.
- under increased pressure,
- the white cell count is raised,
- and protein concentration is increased,
but the glucose content is normal.
What is the caused of subdural empyema?
Bacterial or occasionally fungal infection of the skull bones or air sinuses can spread to the
subdural space, producing a subdural empyema.
The underlying arachnoid and subarachnoid
spaces are usually unaffected, but a large subdural empyema may produce a mass effect.
What is the reason for resulting venous occlusion and infarction of the brain in Subdural Empyema?
Further, a thrombophlebitis may develop in the bridging veins that cross the subdural space,
resulting in venous occlusion and infarction of the brain.
In the treatment of Subdural Empyema, including surgical
drainage, resolution of the empyema occurs from the dural side, and, if it is comp lete, what
may be the only residual finding.
Symptoms include those referable to the
source of the infection. In addition, most patients are febrile, with headache and neck stiffness,
and, if untreated, may develop focal neurologic signs, lethargy, and coma. The CSF profile of subdural empyema is
similar to that seen in brain abscesses, why?
If diagnosis and treatment are prompt, complete recovery is usual.
because both are parameningeal infectious processes.
Extradural abscess, commonly associated with ___________often arises from an adjacent
focus of infection, such as sinusitis or a surgical procedure. When the process occurs in the
spinal epidural space, it may cause spinal cord compression and constitute a neurosurgical