Brain Abscess and Empyema Flashcards
Chapter 135
What is a focal, suppurative infection within the brain parenchyma, typically surrounded by a vascularized capsule?
Brain abscess
Term often employed to describe a nonencapsulated brain abscess.
Cerebritis
Predisposing conditions leading to a bacterial brain abscess.
Otitis media
Mastoiditis
Paranasal sinusitis
Pyogenic infections in the chest and other body sites Penetrating head trauma/neurosurgical procedure
Dental Infections
Pathogens implicated for immunocompetent individuals brain abscess
SEAS
Streptococcus spp (40%)
Enterobacteriaceae (25%)
Anaerobes (30%)
Staphylococci (10%)
Pathogens implicated for Immunocompromised hosts with underlying HIV infection, organ transplantation, cancer or immunosuppressive therapy
i CCANT protect myself
Candida spp.
C. neoformans
Aspergillus
Nocardia spp.
Toxoplasma gondii
Most common in Latin America and immigrants from Latin America
Taenia solium (neurocysticercosis)
Pathogen in India and East Asia
Mycobacterial infection
True or false, in 25% of cases, no obvious primary source of infection is found.
True. This is also called a CRYPTOGENIC BRAIN ABSCESS.
Where do otogenic abscesses occur predominantly in the brain?
Temporal lobe (55-75%)
Cerebellum (20%)
Abscesses that develop as a result of direct spread of information from the frontal, ethmoidal, or sphenoidal sinuses and those that occur due to dental infections are located in the _________.
Frontal lobes
In which age group is paranasal sinusitis associated with?
Young males in their second and third decades of life.
True or False. Hematogenous abscesses are usually multiple and occur in the territory supplied by the MCA (middle cerebral artery).
TRUE. Hematogenous abscesses are often multiple, and multiple abscesses often (50%) have a hematogenous origin.
Stages in the formation ob brain abscess
Early cerebritis stage ( Day 1-3)
Late cerebritis stage (day 4-9)
Early capsule formation (day 10-13)
Late capsule formation (day 14 and beyond)
Characterized by perivascular infiltration of inflammatory cells, which surround a central core of coagulative necrosis. Marked edema surrounds the lesion at this stage.
Early Cerebritis Stage
Characterized by pus formation leads to enlargement of the necrotic center, which is surrounded at its border by an inflammatory infiltrate of macrophages and fibroblasts. A thin capsule of fibroblasts and reticular fibers gradually develops, and the surrounding area of cerebral edema becomes more distinct.
Late Cerebritis
Characterized by the formation of a capsule that is better developed on the cortical than on the ventricular side of the lesion. This stage correlates with the appearance of a ring-enhancing capsule on neuroimaging studies.
Early Capsule formation.
There is a well-formed necrotic center surrounded by a dense collagenous capsule. The surrounding area of cerebral edema has regressed, but marked gliosis with large numbers of reactive astrocytes has developed outside the capsule .
Late capsule formation.
True or False. The classic clinical triad of headache, fever, and a focal neurologic deficit is present in >75% of cases.
False. Present in <50% of cases.
What is the most common symptom in patients with brain abscess?
Headache (occurs in >75% of patients)
_________ is the most localizing sign of a frontal lobe abscess.
Hemiparesis.
Abscess located in the ________ may present with a distubance of language (dysphasia)
Temporal lobe
_________ & ________ are signs of a cerebellar abscess.
Nystagmus and Ataxia
Appearance of brain abscess (cerebritis) on MRI.
Cerebritis appears on MRI as an area of low-signal intensity on T1-weighted images with irregular postgadolinium enhancement and as an area of increased signal intensity on T2-weighted images .
Appearance of brain abscess on T1-weighted MRI.
On contrast-enhanced T1-weighted MRI, a mature brain abscess has a capsule that enhances surrounding a hypodense center and surrounded by a hypodense area of edema.
Appearance of brain abscess T2-weighted MRI
On T2-weighted MRI, there is a hyperintense central area of pus surrounded by a well-defined hypointense capsule and a hyperintense surrounding area of edema.
True or False. CSF Analysis in patients with brain abscess is vital as it can change the therapy for the patient.
False.
CSF analysis contributes nothing to diagnosis or therapy, and LP increases the risk of herniation.
LP should not be performed in patients with known or suspected focal intracranial infections such as abscess or empyema;
Differential diagnosis in patients that have fever, headache, focal neurologic signs and seizure activity.
Brain abscess
Subdural empyema
Bacterial Meningitis
Viral meningoencephalitis
Superior sagittal thrombosis
Acute Disseminated encephalomyelitis
Emperical therapy of community-acquired brain abscess in an immunocompetent patients
3rd or 4th generation cephalosporin + metronidazole
Therapy for patients with penetrating head trauma or recent neurosurgical procdures.
Treatment should include ceftazidime as the third-generation cephalosporin to enhance coverage of Pseudomonas spp. and vancomycin for coverage of staphylococci.
Meropenem plus vancomycin also provides good coverage in this setting.
When will you refer to surgery for excision of a bacterial abscess via craniotomy or craniectomy?
Complete excision of a bacterial abscess via craniotomy or craniectomy is generally reserved for multiloculated abscesses or those in which stereotactic aspiration is unsuccessful.
Medical therapy alone is not optimal for treatment of brain abcess and is reserved for which group of patients (Give me 4)
- Neurosurgically inacessible
- Small < 2-3 cm
- Nonencapsulated cerebritis
- for patients whose condition is too tenuous to allow performance of a neurosurgical procedure
What is the minimum duration of treatment for bacterial abscess?
6-8 weeks of parenteral antibiotic therapy
Is prophylactic anticonvulsive therapy indicated in the management of brain abscess?
patients should receive prophylactic anticonvulsant therapy because of the high risk (~35%) of focal or generalized seizures. Anticonvulsant therapy is continued for at least 3 months after resolution of the abscess, and decisions regarding withdrawal are then based on the EEG.
If the EEG is abnormal, anticonvulsant therapy should be continued.
If the EEG is normal, anticonvulsant therapy can be slowly withdrawn, with close follow-up and repeat EEG after the medication has been discontinued.
What is the most common parasitic disease of the CNS worldwide?
Neurocysticercosis
T. solium
What is the most common manifestation of neurocysticercosis?
New onset partial seizures with or without secondary generalization.
_________ is a parasitic disease caused by T. gondii and acquired from the ingestion of undercooked meat and from handling of cat feces.
TOXOPLASMOSIS
True or False. It is when the cysticerci first lodges into the brain that the inflammatory response is greatly manifested and may even present with seizures.
False.
When the cysticerci first lodge in the brain, they frequently cause little in the way of an inflammatory response. As the cysticercal cyst degenerates, it elicits an inflammatory response that may present clinically as a seizure.
What is the most common finding and evidence that the parasite is no longer viable in neurocysticercosis?
Parenchymal brain calcification.
What are the MRI findings of Toxoplasmosis?
MRI findings of toxoplasmosis consist of multiple lesions in the deep white matter, the thalamus, and basal ganglia and at the gray-white junction in the cerebral hemispheres. With contrast administration, the majority of the lesions enhance in a ringed, nodular, or homogeneous pattern and are surrounded by edema.
True or False. Primary Toxoplasma infection is often asymptomatic.
TRUE.
What drugs are given in the treatment of neurocysticerosis?
Albendazole and Praziquantel.
The dose of albendazole is 15 mg/kg per day in two doses for 8 days.
The dose of praziquantel is 50 mg/kg per day for 15 days
Treatment for Toxoplasmosis.
Sulfadiazine, 1.5–2.0 g orally qid, plus pyrimethamine, 100 mg orally to load, then 75–100 mg orally qd, plus folinic acid, 10–15 mg orally qd.
Rationale of giving folinic acid in the treatment for Toxoplasmosis.
Folinic acid is added to the regimen to prevent megaloblastic anemia.
What is the duration of treatment for Toxoplasmosis?
Therapy is continued until there is no evidence of active disease on neuroimaging studies, which typically takes at least 6 weeks, and then the dose of sulfadiazine is reduced to 2–4 g/d and pyrimethamine to 50 mg/d.
What is the most common predisposing condition leading to subdural empyema?
Sinusitis, typically involved the frontal sinuses, either alone or in combination with the ethmoid and maxillary sinuses.
Most common causative organisms of sinusitis-associated SDE.
(Same with brain abscess for immunocompetent individuals)
SEAS
STREPTOCOCCI (aerobic and anaerobic)
ENTEROBACTERIACEAE
ANAEROBIC BACTERIA
STAPHYLOCOCCI
What are the organisms implicated in SDE following a neurosurgical procedure or head trauma?
Staphylococci
Gram-negative bacilli
Patients with SDE typically present with _______ and ________.
Fever and progressively worsening headache.
What is the most common focal neurologic deficit seen in SDE?
Contralateral hemiparesis or hemiplegia
What is the definitive step in the management of SDE?
Emergent neurosurgical evacuation of the empyema, either through craniotomy, craniectomy, or burr-hole drainage
Empirical Antimicrobial therapy for Community acquired SDE?
Third generation cephalosporin (cefotaxime, ceftriaxone), Vancomycin, Metronidazole
Antimicrobial therapy for patients with hospital-acquired SDE (may have infections due to Pseudomonas spp. or MRSA)
Carbapenem + Vancomycin
No need to add Metronidazole if meropenem is being used.
Duration of treatment for SDE.
Parenteral antibiotic therapy should be continued for a minimum of 3–4 weeks after SDE drainage. Patients with associated cranial osteomyelitis may require longer therapy.
True or False. Cerebral vein and sinuses have no valves and therefore blood can flow in either direction.
True
What is a common predisposing condition for septic thrombosis of the superior sagittal sinus?
Bacterial Meningitis
What conditions can contibute to cerebral venous sinus thrombosis?
Dehydration from vomiting
Hypercoagulable states
Immunologic abnormalities (like circulation antiphospholipid antibodies)
Which presents with headache, fever, nausea and vomiting, confusion, and focal or generalized seizures. There may be a rapid development of stupor and coma. Weakness of the lower extremities with bilateral Babinski’s signs or hemiparesis is often present.
Septic thrombosis of the superior sagittal sinus
What structures pass through the cavernous sinus?
oculomotor nerve,
the trochlear nerve,
the abducens nerve,
the ophthalmic and maxillary branches of the trigeminal nerve
Internal carotid artery
