Download Slide 1

THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
The Diagnosis and
Management of Brain
Abscesses
Stephen Aston
Stephen Aston is a Specialist Registrar in Infectious Diseases at the
Tropical and Infectious Diseases Unit, Royal Liverpool University Hospital.
Following general medical training in Birmingham, he spent time working
on clinical trials in vaccine development in Oxford and the 2009-10
influenza pandemic in Liverpool, before taking up his current post.
He is particularly interested in immune responses to severe bacterial
infections and how this informs vaccine development.
Edited by Prof Tom Solomon and Dr Agam Jung
This session provides a review of brain abscesses, including
a brief description of aetiology and pathogenesis, later
focusing on current investigation and best practice in
management.
Learning Objectives
THE DIAGNOSIS AND
By the end of this session you will be able to:
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
• Describe the stages of development and pathogenesis of
brain abscesses
• Identify the typical spectrum of pathogens implicated in the
aetiology of brain abscess
• Define the nonspecific nature of the clinical features of brain
abscess
• List the appropriate investigation of possible brain abscess
and to identify the important radiological features on CT and
MR scanning
• Develop a management plan for patients with brain abscess,
including antimicrobial treatment, surgical interventions and
adjunctive therapies
Introduction
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
Brain abscess is fortunately a relatively uncommon condition, with an
incidence of approximately 1 in 100,000 per year.
Prior to pioneering advancements in neurosurgical techniques in the late
19th century, brain abscesses were invariably fatal. The development of
effective anti-microbial agents following the Second World War secured
further improvements in prognosis.
With the inception of modern neuroimaging techniques allowing earlier
diagnosis, mortality rates have fallen further, presently between 5 and
15%. However, debilitating sequelae such as seizures, paresis and
cognitive impairment remain common.
This session outlines the pathogenesis, aetiology and typical clinical
features of brain abscess. Approaches to diagnosing the condition are
described before reviewing current management strategies.
MRI (T1 + contrast) showing a
small ring-enhancing lesion
Stages of Development and Pathogenesis of
Brain Abscesses I
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
Brain abscesses occur at focal points of bacterial multiplication
within the brain parenchyma; they begin as a localised area of
cerebritis and later progress into a collection of pus surrounded
by a vascularised capsule.
By virtue of the impermeability of the blood-brain barrier, the
brain parenchyma is relatively resistant to the establishment of
focal bacterial infection. An area of necrosis caused by for
example micro-infarction or hypoxaemia is necessary to act as a
nidus for bacterial multiplication.
Several stages of development en route to the formation of a
mature encapsulated brain abscess following bacterial ingress
have been defined by neuroimaging studies
Stages of Development and Pathogenesis of
Brain Abscesses II
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
1. Early Cerebritis
Days 1-3: Perivascular inflammation,
characterised by neutrophil infiltration,
occurs around the site of focal infection
with a surrounding area of oedema.
2. Late Cerebritis
Days 4-9: A central area of necrosis
develops as the surrounding oedema
progresses. Peripheral accumulation of
fibroblasts preludes the development of
a capsule.
3. Early Capsule
Days 10-14: Establishment of a ring-enhancing capsule of wellvascularised tissue with further fibroblast migration and adjacent
reactive astrocytosis.
4. Late Capsule
Day 14 and beyond: Collagen fibre and granulation tissue deposition
leads to a thickening of the capsule effectively walling off the area of
focal suppurative infection.
Intracranial Infection I
THE DIAGNOSIS AND
MANAGEMENT OF
To establish intracranial infection, bacteria reach the brain via
three main routes:
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
1. Extension from a contiguous focus of infection, typically
the middle ear or paranasal sinuses
2. Haematogenous (metastatic) spread from a distant
extracranial source
3. Direct inoculation following neurosurgery or penetrating
trauma
However in up to 30% of cases of brain abscess, the route of
infection cannot be determined.
Suppurative intracranial infection can also manifest as subdural
empyema, in which pus collects between the dura and
arachnoid mater, and less frequently as extradural abscess, in
which pus accumulates in the potential space between the inner
skull table and dura mater. These conditions share a common
aetiological basis with brain abscess and may occur
concurrently.
Intracranial Infection II
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
Brain abscess is the most common pattern of intracranial
suppurative infection
Spectrum of Pathogens Implicated in the
Aetiology of Brain Abscess I
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
An understanding of the aetiology of brain abscess is important,
since the primary source of infection not only correlates with the
location of abscesses within the brain and hence their clinical
features, but also the potential spectrum of causative organisms
and thus informs the choice of antimicrobial treatment regimens.
The following pages will summarise the typical spectrum of
causative pathogens divided by source of infection. Initial
empirical antimicrobials treatment regimens are also suggested.
Scanning Electron Micrograph of
Staphylococcus epidermidis
Spectrum of Pathogens Implicated in the
Aetiology of Brain Abscess II
THE DIAGNOSIS AND
MANAGEMENT OF
Otogentic and Paranasal Sinus
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
Brain abscesses secondary to ear infections are diminishing in frequency
in developed countries as a result of the widespread use of early
antimicrobial treatment for suppurative otitis media. Otogenic infection
remains a frequent cause of brain abscess in the developing world.
Brain abscess complicating paranasal sinus infection is most commonly
seen in young men. Subdural empyema is particularly associated with
this route of infection.
Spectrum of Pathogens Implicated in the
Aetiology of Brain Abscess III
THE DIAGNOSIS AND
MANAGEMENT OF
Haematogenous
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
*Additional anti-staphylococcal cover with e.g. vancomycin is recommended for
presumed endocarditis-related brain abscess
**Bronchiectasis, lung abscess and empyema are important causes of infection
orginating in the respiratory tract
Haematogenous spread is now the most common route of infection.
Typically, multiple or multi-loculated abscesses are seen, occurring
predominantly within the territory of the middle cerebral artery, often at
the grey white matter interface where blood flow is most marginal.
Spectrum of Pathogens Implicated in the
Aetiology of Brain Abscess IV
THE DIAGNOSIS AND
MANAGEMENT OF
Haematogenous Other Sources
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
Peridontal infections often give to rise polymicrobial infections.
Congenital heart disease complicated by a right to left shunt was a well
recognised cause of brain abscess. Early diagnosis and operative repair
of such lesions has seen a marked reduction in brain abscess
attributable to this source.
Spectrum of Pathogens Implicated in the
Aetiology of Brain Abscess V
THE DIAGNOSIS AND
MANAGEMENT OF
Penetrating Head Trauma and Postoperative
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
Penetrating head trauma such as gun shot wounds, open
depressed skull fractures with foreign bodies in the brain
parenchyma and basal skull fractures with CSF fistula can give
rise to all forms of intracranial suppurative infection
Brain Abscesses in Immunosuppressed
Patients I
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
Whilst in immunocompetent individuals brain abscess are
usually caused by pyogenic bacteria, in the immunosuppressed,
a much broader array of organisms is implicated.
These include:
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Toxoplasma gondi (shown below)
Aspergillus species
Candida species
Nocardia
Mycobacterium tuberculosis
This is a high power view of brain
in treated cerebral
toxoplasmosis.
Immunocytochemical stain using
a specific antibody to
Toxoplasma gondii and the
immunoperoxidase method –
Wellcome Images.
Brain Abscesses in Immunosuppressed
Patients II
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
• Histological/Microbiological diagnosis
Moreover, in this patient group there is a high incidence of noninfective space occupying lesions such as lymphoma.
This highlights the particular importance of attempting to obtain
histological and microbiological confirmation of diagnosis in
these patients.
• HIV
There is an important caveat to this general principle for patients
with advanced HIV infection.
Here, toxoplasmosis is the likely cause of abscess-like lesions
and empirical therapy should be given for two weeks. If there is
no clinical or radiological improvement, diagnostic aspiration
should be performed.
Non-specific Nature of the Clinical Features
of Brain Abscess
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
The presentation of brain abscess is variable and relates to the location,
size and number of abscesses, the virulence of the infecting
microorganisms and the immunological status of the affected individual.
Males are affected approximately twice as commonly as females; the
median age is 30-45 years.
The clinical manifestations are nonspecific, meaning that diagnosis is
often delayed. They relate predominantly to a rapidly expanding
intracranial mass rather than an infective process.
Common presenting features are listed in the above table.
Investigation I
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
Neuroimaging
There is no single reliable confirmatory test for the diagnosis of brain
abscess.
• Blood samples
Laboratory tests on blood samples are often unremarkable.
• Neuroimaging
The diagnosis rests heavily on suggestive neuroimaging findings in the
individuals with a compatible clinical presentation.
The availability of neuroimaging techniques permitting detailed resolution
of the brain parenchyma has had a profound impact on the management
and outcome of brain abscess.
The appearance of brain abscesses varies significantly with their
pathological stage, hence precise clinical correlation regarding the timing
of scan with respect to the onset of symptoms is required.
Investigation II
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
A mature brain abscess appears as ring-enhancing lesions, for
which there is a broad differential diagnosis.
MRI I
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
The appearances of brain abscess on MRI are similarly dependent upon
their stage of evolution.
• T1-weighted Images
Early cerebral abscesses appear as a poorly-defined hypointense area
relative to the normal brain parenchyma.
As the abscess matures, the hypointense area becomes better
demarcated and the capsule becomes apparent as a slightly
hyperintense rim.
Ring-enhancement following
gadolinium is usually seen.
the
administration
of
intravenous
• T2-weighted Images
A mature abscess has a hyperintense central area, corresponding to the
pus-filled core, and a hypointense capsule and surrounding oedema.
CT is less sensitive than MRI for the detection of brain abscess, although
it has the advantages of being quick and readily performed in even the
most acutely unwell patients.
The changes produced by early brain abscess on CT are subtle and may
easily be overlooked on non-contrast scans.
MRI II
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
Early cerebritis appears as a focal area of low density that
enhances following the administration of intravenous contrast
medium.
As the abscess capsule matures, the classic appearance of a
ring-enhancing lesion becomes more evident
MRI (T1+contrast) showing a
small ring-enhancing lesion
Neuroimaging –
Further considerations
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
Neuroimaging alone cannot with certainty distinguish brain
abscess from other ring-enhancing lesions. Differentiating brain
abscess and metastatic tumour is an important diagnostic
challenge. Key features are listed below.
Interval scans have some utility in this setting; a rapidly
expanding lesion favours a diagnosis of cerebral abscess. Newly
developed techniques such as diffusion-weighted imaging and
MR spectroscopy also show some promise in differentiating
abscess from necrotic neoplasms and other cystic lesions.
Features suggestive of cerebral abscess:
• Thin walled capsule
• Thinning at the ventricular margin
• Peripheral contrast enhancement
Features suggestive of metastatic tumour:
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Thickened, irregular and nodular capsule
Diffuse contrast enhancement
Microbiological Investigations
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
Choosing appropriate antimicrobial therapy for brain abscess
relies on accurate identification of the causal pathogen.
In all but exceptional circumstances, brain abscess material
should be obtained for culture. With meticulous specimen
handling, culture yields approach 100% for samples obtained
prior to starting antimicrobials. Culture yields fall dramatically for
specimens obtained after treatment has started. The Gram stain
may, however, remain positive which alone may provide a useful
guide to management.
When obtained, specimens should be cultured for aerobic and
anaerobic bacteria, mycobacteria and fungi.
Other clues to the likely causative pathogen may be obtained by
culture of material from sites presumed to be the primary focus
of infection (e.g. paranasal sinus).
CSF analysis, however, rarely provides any useful information
and does not justify the substantial risk of brainstem herniation
that lumbar puncture entails.
Brain Abscess Management I
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
Overview
There are limited data from good quality clinical trials to guide the
management of brain abscess and historically clinical practices have
been diverse.
The main treatment strategies are:
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Antimicrobial agents
Needle aspiration - often using stereotactic guidance
Complete surgical excision
In addition, adjunctive therapies such
anticonvulsant agents are variably used.
as
corticosteroids
and
A combination of antimicrobial therapy and aspiration is now used for the
majority of cases, with medical therapy alone and complete surgical
excision reserved for particular circumstances.
Brain Abscess Management II
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
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Brain Abscess Management III
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
Antimicrobial therapy
Effective antimicrobial therapy for brain abscess relies on identification of
the causative microorganism allowing the selection of an appropriate
regimen. Ideally, it therefore follows an aspiration procedure.
There are several important factors to consider in choosing an
appropriate treatment regimen.
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Activity against implicated pathogens
Before culture information is available, the probable causative bacteria
are predicted on the basis of the putative source of infection and the
location of the abscess.
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Ability to penetrate abscess cavity
There is limited data available to guide practice.
Inferences are made from studies of CSF antimicrobial concentrations in
the treatment of bacteria meningitis, although the characteristics of the
blood-brain and blood-CSF barrier are known to differ.
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Brain Abscess Management IV
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
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Duration and route of treatment
 Lone medical management
Medical management alone is sometimes used in patients who are
regarded as poor candidates for surgery. It is preferable if the
causative pathogen can be inferred from results of positive cultures
from primary sites of infection, otherwise an empirical regimen is
selected.
It may also be considered for…
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Multiple small abscesses
Abscesses located in surgically unaccessible or eloquent areas
It is most likely to be successful if…
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Abscesses are small (i.e. <1.5cm)
In cerebritis stage
Located in a well vascularised cortical area
Frequent interval scans should be performed to assess therapeutic
response and to identify complications requiring definitive surgical
management.
Brain Abscess Management V
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
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Duration and route of treatment
 Corticosteroids
Adjuvant corticosteroids are often used to reduce vasogenic
oedema associated with brain abscesses.
There are important concerns regarding steroid use…
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Effectiveness in reducing oedema and mass effect not
established in human clinical trials
May retard abscess capsule development
May reduce antimicrobial penetration
Give false impression of a therapeutic response by reducing
ring-enhancement on follow-up scans
Most authors recommend that corticosteroids are reserved for
situations of raised intracranial pressure resulting in a clear risk of
brainstem herniation or other significant neurological deficit.
Brain Abscess Management VI
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
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Duration and route of treatment
 Anticonvulsants
Seizures are a frequent complication of brain abscess both in the
acute setting and for a prolonged period after the resolution of the
acute infection.
Some advocate the use of seizure prophylaxis for extended periods
in every case of brain abscess, although there are again few good
data.
If commenced, anticonvulsants should probably be continued for 612 months and then only withdrawn if the patient is seizure-free, the
EEG normal and no signs of on going inflammation on
neuroimaging.
Brain Abscess Management VII
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
Surgical
Surgical techniques for the management of brain abscess have evolved
significantly in recent years.
Whilst debate still continues as to the best approach in particular
situations, minimally-invasive aspiration and closed-drainage procedures
have largely replaced craniotomy and attempted excision as the first line
strategy.
Aspiration is not considered appropriate in all cases of brain abscess.
Circumstances when excision may be the preferred initial surgical option
are listed in the table on the next slide.
The most effective strategy for abscesses that do not improve or recur
following attempted aspiration is not established. Repeated aspiration
may be attempted, sometimes with the placement of a catheter to allow
on going drainage and instillation of intracavity antimicrobials.
Alternatively complete surgical excision is undertaken.
Brain Abscess Management VIII
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
Brain Abscess Management IX
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
Adjunctive therapies
As described in the introduction, advanced neurosurgical practices and
potent antimicrobial agents, supported by modern neuroimaging
technologies, have reduced mortality from brain abscess from being
nearly universal to current levels of around 10%.
However, significantly decreased level of consciousness at presentation
remains a poor prognostic indicator. In one series, 62% of patients with a
GCS of <9 either died or fell into a permanent vegetative state.
Major sequelae such as seizures, focal neurological deficit and cognitive
impairment are common in survivors.
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Seizures occur in up to 50% of patients and may have a latent period
as long as 5 years.
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Focal neurological deficit occur in 25-50%.
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Significant cognitive impairment occurs in 20% of survivors,
although is probably underreported.
Recurrence rates of between 10-50% have been reported. Surveillance
is recommended for at least 1 year
Key Points
THE DIAGNOSIS AND
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Brain abscesses are relatively uncommon and mortality is now
around 10%. However, significant attributable morbidity still occurs in
affected individuals.
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Focal multiplication of bacteria at sites of parenchymal damage (often
microscopic) lead to the formation of brain abscess.
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Bacteria reach the brain parenchyma via spread from a contiguous
skull-vault infection, haematogenous spread from a distant site or
direct inoculation following trauma or surgery.
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In immunocompetent individuals, abscesses are caused by a broad
but often predictable array of bacterial pathogens.
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The clinical features are nonspecific and relate mainly to an
expanding intracranial mass rather than an infective process.
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Modern neuroimaging techniques have dramatically improved our
ability to detect brain abscesses, but microbiological confirmation is
vital for directing treatment.
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Most brain abscesses can be managed with a combination of surgical
aspiration followed by appropriate antimicrobial therapy
MANAGEMENT OF
BRAIN ABSCESSES
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Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
Summary
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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•
•
•
•
•
•
•
•
•
•
•
•
•
•
Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
Having completed this session you will now be able to:
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Describe the stages of development and pathogenesis of brain
abscesses
Identify the typical spectrum of pathogens implicated in the aetiology
of brain abscess
Define the nonspecific nature of the clinical features of brain abscess
List the appropriate investigation of possible brain abscess and to
identify the important radiological features on CT and MR scanning
Develop a management plan for patients with brain abscess,
including antimicrobial treatment, surgical interventions and
adjunctive therapies
References
1. Mathisen GE, Johnson JP. Brain abscess. Clin Infect Dis 1997;25:763-81.
2. Solomon T. Intracranial space occupying infections and neurological HIV
disease. In: Donaghy M (Eds). Brain's Diseases of the Nervous System 12th Edition. Oxford University Press, USA; 2009.
3. Lu C-H, Chang W-N, Lui C-C. Strategies for the management of bacterial
abscess. J Clin Neurosci 2006;13:979-985.
4. Erdogan E, Cansever T. Pyogenic brain abscess. Neurosurg Focus
2008;24:1-10.
Self Assessment
THE DIAGNOSIS AND
MANAGEMENT OF
BRAIN ABSCESSES
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•
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•
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•
•
•
Learning Objectives
Introduction
Development and
Pathogenesis
Intracranial Infection
Pathogen Spectrum
Immunosuppressed
Patients
Clinical Features
Investigation
MRI
Further
Neuroimaging
Microbiological
Investigations
Management
Key Points
Summary
Self Assessment
Question 1
After how many days following initial bacterial ingress does
ring-enhancement typically first become evident on
neuroimaging studies?
A.
B.
C.
D.
E.
Less than 3 days
4-7 days
7-11 days
11-14 days
More than 14 days
To learn more about neurological infectious diseases…
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