Definition
Definition
Collection of pus located inside the brain (intracerebral) complicating an infection.
Generalities
Brain abscess occurs either by continuity (following another abscess located nearby) originating from the otolaryngological system (sinusitis, otitis, dental abscess, mastoiditis), or at a distance (25%) and in this case, it is due to congenital cardiopathy (heart disease), infection of the endocardium (layer of cells covering the inside of the heart cavities), pulmonary or abdominal infection, bone infection, inflammation of the gallbladder, pelvic pathology, erysipelas of the face, scalp infection, bronchial dilatation, metritis, liver abscess, pyelonephritis, prostatitis. Finally, more rarely, it follows a surgical procedure (esophageal varices, esophageal dilation), telangiectasia, head trauma or a gunshot wound (migration of a bone fragment). Since the advent of antibiotics, brain abscess has become a rare pathology. In the neurosurgery departments of hospitals in developed countries, approximately 5 to 8 cases are observed each year. While the number is not really increasing in these countries, it is not the same in developing countries and particularly in children in disadvantaged socio-economic regions, especially since the patients have AIDS or have an immune deficiency. Males seem to be twice as affected as females and the age of exposure is between 2 and 30 years. Approximately 45% of brain abscesses occur in children under 25 years of age (this pathology is exceptional in children under 15 years of age). A survey over the last 2 years has made it possible to specify that approximately 50% of cases of brain abscesses were directly related to an infection of a neighboring region of the brain (ear, sinus): abscesses following damage to the inner ear are generally located in the temporal parts of the brain (temporal lobes: on the sides of the brain) or in the cerebellum (behind). In the case of sinusitis, brain abscesses are most often located in the frontal lobe (in front). With regard to newborns with meningitis, it is essential to consider a brain abscess, particularly when the germ in question is Gram negative (Citrobacter, Proteus sp). Still in children, cyanotic heart disease (deficit of tissue oxygenation) is recognized in 45% to 5% of cases of brain abscesses. Among these pathologies, we must mention tetralogy of Fallot which is the most frequently involved malformation. Other cyanotic pathologies include persistent foramen ovale, interatrial communication, transposition of the great vessels.
Symptoms
Symptoms
A brain abscess can develop either insidiously (and go unnoticed) or suddenly (fulminant abscess). In the majority of cases (about 75%), the clinical signs (symptoms) last about 15 days. These symptoms will depend on many factors such as the severity of the infection (virulence of the infectious agents), the subject's immunity and the location of the abscess. The signs described below affect only 1/3 of patients: Increased internal pressure in the skull (intracranial hypertension) causing nausea and vomiting in direct correlation with the brain abscess Hyperthermia (increased body temperature) in about half of patients (but in about 80% of children). Headaches in about 70% of patients. Headaches are characteristic of brain abscesses located in the frontal lobe. Epileptic seizures in approximately 25 to 50% of patients. Drowsiness, convulsions and other neurological abnormalities: these signs are directly related to the location of the abscess within the brain. There may also be hemiplegia (paralysis of half the body), hemianopia (loss or reduction of vision in one half of the visual field of one eye or most often both eyes), nystagmus (involuntary oscillating movements of low amplitude and rotation of the eyeball), ataxia (loss of coordination of movements), vomiting (in the case of cerebellar abscess), a change in personality. Edema of the back of the eye observed at the level of the papilla (circular area corresponding to the birth of the optic nerve). Edema is seen in only a few patients and is not directly related to the size of the abscess. However, there appears to be a close relationship between the size of the edema and vomiting and nausea.Please note:Brain abscesses occurring in the pituitary gland are manifested by headaches, visual field disturbances and endocrine (hormonal) disruption.
Pathophysiology
A brain abscess is not necessarily unique. It can be multiple, and in this case it is a metastatic abscess (coming from an infection via the blood). Brain abscesses due to a local cause are almost always unique. There is softening of the brain substance then necrosis (destruction) followed by the formation of a pocket of pus surrounded by a shell (rigid capsule) usually clearly visible by MRI. When the abscess occurs rapidly, its limits are clearer than when it occurs chronically. In both cases, there is the formation of an edema (additional fluid collection).
Medical exam
Labo
They show: Hyperleukocytosis (increased number of white blood cells in the blood) which is not specific and is not present in all patients. The sedimentation rate has the same characteristics. The PCR is also high but not specific. Blood cultures are systematic.
Additional examination
CT scan (with and without injection) and MRI can localize the abscess. The image obtained by MRI is typical and appears as a ring (for specialists: hypodense surrounded by regular annular contrast uptake. Variable hypodensity corresponds to the edema extending around the ring). This image should not be confused with a tumor, granuloma, cerebral infarction, toxoplasmic encephalitis, or a hematoma in the process of resorption. Scintigraphy using white blood cells labeled with indium 111 can confirm the diagnosis. However, the use of corticosteroids (cortisone) sometimes results in a false negative. Single photon emission thallium 201 CT is also useful. Lumbar puncture is contraindicated: in theory, it can reveal abnormal cerebrospinal fluid, but there is a major risk of morphological changes in the central nervous system during puncture. This is why a patient with a raised temperature and neurological signs (in focus) should not undergo a lumbar puncture.
Cause
Cause
The tissues constituting the brain are not particularly susceptible to infection. On the contrary, various studies have shown that the brain is generally resistant to infection. This is why for a brain abscess to develop in contact with an infectious focus, it requires another infectious focus nearby, among other things. The infection spreads continuously through bone tissue serving as a vector, or a vein. There are factors that promote this infection: polycythemia (increase in the number of red blood cells in the blood) and hypoxia (insufficient oxygenation of the tissues). This polycythemia causes a decrease in the speed of blood circulation (high viscosity) likely to prepare the brain tissue for tiny abscesses that cause an infection that occurs later. It is mainly patients with an immune deficiency (AIDS, alcohol, drug addiction, etc.) who are most exposed. The bacteria responsible are part of the following non-exhaustive list:
Treatment
Treatment
It involves antibiotic treatment combined with surgery. This involves puncturing and aspirating the abscess or sometimes excision, which is supplemented by the use of antibiotics, more specifically high-dose penicillin, generally in combination with a phenicol. Patients are then given anticonvulsant medication. The use of glucocorticoids (cortisone) as an adjunctive treatment is controversial. In fact, these molecules are likely to reduce the action of antibiotics on the central nervous system and to blur the information obtained by the scanner or MRI. Glucocorticoids are only used in patients with certain or suspected intracranial hypertension. In this case, mannitol or hyperventilation is used.
Evolution
Premature
When the abscess opens into a cerebral ventricle (cavity located in the center of the brain and containing the cerebrospinal fluid), we see a dramatic picture with delirium, convulsions, motor disorders and fatal progression within a few hours. In other cases, the progression can be towards purulent meningitis (inflammation of the meninges with the presence of pus) accompanied by convulsions and sometimes an irreversible coma. The severity of this pathology is directly related to the state of consciousness of the patient. Indeed, 5% of patients with obtundation develop towards death. 80% of patients with a deep coma have a fatal progression. Neurological sequelae are found in approximately a little less than half of patients. Epileptic seizures are observed in 90% of survivors.
Differential diagnosis
Related Terms and Articles
See also
- Abscess
- Arthrifluent abscess
- Brodie's abscess
- Caseous abscess
- Shirt button abscess
- Tooth abscess
- Metastatic abscess
- Abscess due to congestion
- Subperiosteal abscess
- Breast abscess
- Tuberous abscess
- Urinary abscess
- Velpeau's tuberous abscess
- Peritonsillar phlegmon
- Acute bacterial prostatitis
- Liver
- Spinal cord or spinal cord
- Mycosis fungoides
- Peritoneum
- pharynx
- lungs
- Breast (abscess)
- Testicle
- Perinephric phlegmon
- anus
- Aseptic abscess syndrome
- Extradural spinal cord abscess