Department of Diagnostic
and Interventional Imaging
Department of Pediatrics
Control #: 326
Cerebellar Infections in Children. Clinical and
Imaging Vignettes
eEdE#: eEdE-165
Eliana Bonfante M.D.
Rajan Patel M.D.
Gloria Heresi M.D.
Roy Riascos M.D.
No Disclosure
Purpose
• To describe the clinical presentation and
diagnostic algorithm for infections of the
posterior fossa in children.
• To illustrate the imaging findings of frequent
and infrequent infectious diseases that affect
preferentially the posterior fossa structures.
Approach
Using a case based format we review the clinical
presentation, diagnostic workup and imaging
findings of multiple infectious processes that
present predominantly in the posterior fossa in
children.
Discussion
Cerebellar Infections in Children.
Clinical and Imaging Vignettes
Introduction
• Different infectious agents result in a preferential
involvement of the cerebellum in pediatric patients.
• The clinical presentation, workup, and imaging
findings of posterior fossa infections in children will
be discussed in a case based format.
Infections of the posterior fossa in
children
Clinical
presentation
• Ataxia
• Fever
• Nausea and
vomiting
Workup
• CBC
• CSF analysis
• Urine and
serum drug
screen
Imaging
findings
• CT
• MRI
Clinical presentation
• Ataxia (Greek: ataktos, lacking order) refers to a pathologic
abnormality of organization or modulation of movement.
• Causes of cerebellar ataxia in children:
– Infectious/immune-mediated cerebellar disorders (acute
cerebellar ataxia, acute demyelinating encephalomyelitis, systemic
infections)
– Toxic: alcohol and drug related
– Mass lesions : tumor, vascular lesions, abscesses ,
– Hydrocephalus
– Trauma
– Stroke
– Paraneoplastic disorders (Opsoclonus-myoclonus syndrome)
– Sensory ataxia (Guillain-Barré syndrome Miller Fisher syndrome)
– Paretic ataxia
– Inborn errors of metabolism
Clinical presentation
Acute Cerebellar Ataxia
AKA Acute cerebellitis
• The most common cause of childhood ataxia (40% of
all cases)
• Postinfectious cerebellar demyelination > direct
infection of the cerebellum.
• Postinfectious cerebellar demyelination is thought to
be an autoimmune phenomenon incited by infection
or immunization, with subsequent cross-reaction of
antibodies against cerebellar epitopes, although
specific autoantibodies have only rarely been
identified.
Workup
Reported Causes of Infectious/Postinfectious
Cerebellitis in Childhood
Systemic
infection
Direct Infection
•
•
•
•
•
•
•
Echovirus type 9
Varicella zoster
Coxsackie B
Bacterial
meningitis
(pneumococcal,
meningococcal)
Coccidiomycosis
Histoplasmosis
Toxoplasmosis
Post- or Parainfectious
Cerebellitis
•
•
•
•
•
•
•
•
•
Varicella zoster
Epstein-Barr
virus
Mumps
Legionella
pneumophilia
Hepatitis A
Influenza A and
B
Herpes simplex
virus I
Coxsackie A
•
•
•
•
•
•
•
•
Echovirus type
6
Enterovirus
type 71
Malaria
Poliovirus type
1
Japanese B
encephalitis
Parvovirus B19
Measles
Mycoplasma
pneumoniae
•
•
•
•
Typhoid
fever
Scarlet fever
Mycoplasma
pneumoniae
Diphtheria
Leptospirosis
Workup
• Routine CSF analysis includes
–
–
–
–
–
Cellularity (total WBC and red blood cell [RBC] counts)
Absolute neutrophil count
Chemistry (glucose and total protein concentrations
Gram-stained smear of the sediment
Bacterial culture.
• Ancillary CSF microbiologic testing:
– Culture for viruses, mycobacteria, fungi
– Polymerase chain reaction (PCR): ideally suited for identifying fastidious
organisms that may be difficult or nearly impossible to culture such as
enteroviruses, herpes simplex virus (HSV), Epstein-Barr virus, Borrelia
burgdorferi, and has been especially useful in the diagnosis of DNA and
RNA viral meningitis.
Workup
CSF feature
Significance
Lymphocytosis
Supports presence of inflammatory
process
Pleocytosis, elevation of CSF protein
Suggest meningitis or encephalitis
Glucose
Decreased in bacterial meningitis
Protein
Elevated in meningitis and in 26-50 % of
postinfectious cerebellar ataxia
Cytoalbuminologic dissociation
Guillain Barre, Miller Fisher
Oligoclonal bands, elevation of serum to
CSF immunoglobulin index and myelin
basic protein
Acute cerebellar ataxia, acute
postinfectious demyelinating
encephalopathy, and multiple sclerosis
Imaging workup
• Neuroimaging is often obtained in the
emergency room to exclude a mass lesion. In
the absence of altered consciousness, focal
neurologic signs, or marked asymmetry of
ataxia, the yield of such scans is low.
• Computed tomography (CT) and magnetic
resonance imaging (MRI) of the brain are
normal in most children with postinfectious
ataxia.
Case 1
Clinical
presentation
2 year old
female
presented with
acute
respiratory
failure that
required CPR
and intubation.
Workup
• CBC leukocytosis
• Negative blood and
urine viral cultures
• CSF not suggestive
of meningitis
(Glucose 67, Protein 94,
RBC 6950, WBC 22, 77%
Segs, 14% Lymphs.)
• Tracheal aspirate
positive for Group
A Streptococcus
and adenovirus.
Imaging
findings
• Chest x-ray
showed
bibasilar
atelectasis
• Brain CT
showed
edema in the
cerebellar
hemispheres
Case 1 - Imaging findings
Brain CT shows edema in both cerebellar hemispheres. MRI demonstrates
cytotoxic edema and hemorrhage in both cerebellar hemispheres. There is also
gyriform contrast enhancement.
Case 1- Analysis
• The patient developed acute hydrocephalus that required
occipital decompressive craniectomy and shunt placement.
• Empiric broad spectrum antibiotics were started.
• Workup yielded positive tracheal cultures for adenovirus
and Group A Streptococcus.
• Group A Streptococcus was deemed to be the most likely
causative agent.
Case 2
Clinical
presentation
• 8 year old
female with
history of
absence
seizures who
presented with
fever, nausea
and vomiting
followed by
rapid mental
status decline
Workup
• CSF and blood
cultures were
unrevealing.
• Stool culture
for Shigella
Sonnei was
positive
Imaging
findings
• Brain CT and
MRI showed
edematous
changes in the
right cerebral
hemisphere and
left cerebellum.
Case 2 – Imaging findings
Brain MRI shows cytotoxic edema in the right cerebral and left cerebellar
hemisphere. A decompressive hemicraniectomy on the right was performed.
Case 2 - Analysis
• The patient required decompressive hemicraniectomy due to severe
right hemispheric swelling.
• A positive stool culture for Shigella sonnei made Ekiri syndrome the
most likely diagnosis.
• Shigella infection is known to be associated with seizures,
encephalopathy with lethargy, confusion, and headache.
• Ekiri Syndrome is a particularly lethal and rare syndrome associated
with Shigella characterized by the rapid development of seizures,
cerebral edema and coma in patients with high fever and few
dysenteric symptoms.
Case 3
Clinical
presentation
• 9 year old African
American male
presenting with
jaundice,
abdominal pain,
and lethargy.
• The patient had a
history of travel
to Tanzania in
Eastern Africa
two months prior
to admission.
Workup
• Blood smear
positive for
Malaria
Imaging
findings
• Brain CT
demonstrated
bilateral
cerebellar edema.
• Brain MRI showed
edema and
hemorrhage in
both cerebellar
hemispheres.
Case 3 - Imaging findings
Brain MRI shows cytotoxic edema in both cerebellar hemispheres, with small
foci of hemorrhage.
Case 3 - Analysis
• CNS malaria is a life-threatening complication seen in 2%
of malaria cases, particularly in Plasmodium falciparum
infection.
• Cerebral damage in malaria is due to vascular
sequestration of parasitised erythrocytes and the potential
cerebral toxicity by cytokines.
• Reported MRI findings include focal or diffuse signal
changes in centrum semiovale, corpus-callosum, thalamus,
and insular cortex. Central pontine myelinolysis,
myelinolysis in the upper medulla, cerebellar syndrome
with demyelination, and micro infarcts of the cerebellar
hemispheres have also been reported.
Case 4
Clinical
presentation
Workup
• 13 year old female
presents with 1 day
history of severe
frontal headache.
• CSF with
elevated
protein,
leukocytosis,
and
lymphocytic
predominance,
but high
eosinophil
count.
• She also has
photophobia.
• 2 weeks ago,
patient had watery,
non-bloody
diarrhea for 3 days,
and bloody emesis.
Imaging
findings
• MRI
demonstrated
cerebellar
swelling and
enhancement
Case 4 – Imaging findings
Brain MRI shows cytotoxic edema in the superior cerebellum bilaterally, with
patchy linear contrast enhancement.
Case 4 - Analysis
• CSF with elevated protein, leukocytosis, and lymphocytic
predominance, but high eosinophil count.
• The workup for infections including HIV, HSV, West Nile virus,
adenovirus, parainfluenza, and influenza was negative.
• Mycoplasma EBV and CMV serologies showed old infections.
• Patient had a full recovery.
• Final diagnosis: Acute cerebellitis with unknown etiology.
Case 5
Clinical
presentation
Workup
•
• 10 yo male
presenting
with
headaches,
neck pain,
photophobia,
and right
sided
weakness.
CSF analysis
demonstrated
xanthrochromia,
elevated WBC and
RBC, as well as
eosinophilia on the
cell differential.
•
CSF and serum were
negative for
Histoplasma antigen
and Coccidioides.
•
Serum Mycoplasma
IgG and IgM were
positive.
Imaging
findings
• Brain CT shows
edema in the
right cerebellar
cortex.
• Brain MRI shows
severe edema in
the right
cerebellum, with
gyriform contrast
enhancement.
Case 5 – Imaging findings
Brain CT shows edema in the right cerebellar cortex. Brain MRI shows severe
edema in the right cerebellum, with gyriform contrast enhancement.
Case 5 - Analysis
• In the acute phase the patient required ventriculostomy to
manage acute hydrocephalus.
• The discharge diagnosis was culture negative eosinophilic
meningitis.
• Empiric antimicrobial treatment for bacteria, fungi, and
parasites was given.
• There was clinical improvement with residual right sided
weakness.
Case 6
Clinical
Presentation
• 16 year old
female
presented
with 3 days
history of
fever and
progressive
headache
Imaging
findings
Workup
• Seropositive for
HIV
• Serum
antitoxoplasma
IgG antibody
level 160 mg/dl
• CD4+ count 78
cells/mm
•
CT Head: Hypodensity in
the both cerebellar
hemispheres
(Right>Left)
•
MRI Brain: Multiple
target appearing
enhancing lesions in
both cerebellar
hemispheres with T2
hypointense rim,
characteristic for
Toxoplasmosis
Case 6 –Imaging findings
CT Head: Hypodensity in the both cerebellar hemispheres (Right>Left) with minimal mass effect over
the 4th ventricle.
MRI Brain: Multiple target appearing enhancing lesions with T2 hypointense rim in both cerebellar
hemispheres, findings are characteristic for Toxoplasmosis
Case 6 - Analysis
• With characteristic imaging findings and laboratory analysis, diagnosis
of Toxoplasmosis was confirmed.
• The patient received a 200-mg loading dose of pyrimethamine and
was placed on a regimen containing pyrimethamine (75 mg/day),
sulfadiazine (1500 mg 4 times daily), and leucovorin (10 mg/day).
• On day 3 of treatment, the patient’s symptoms began to improve.
• After 6 days, she was completely asymptomatic and was discharged.
• Treatment was continued for 6 weeks, and the patient was
subsequently prescribed pyrimethamine 50 mg/day, sulfadiazine 2
g/day, and leucovorin 10 mg/day orally for secondary prophylaxis
against Toxoplasma.
• Repeat MRI of the brain with contrast 1 month after
the diagnosis showed complete resolution of the lesions in both
cerebellar hemispheres.
Case 6 - Analysis
• In immunocompromised individuals (e.g. AIDS patients),
toxoplasmosis is the most common cause of a brain
abscess.
• Pathologically, parenchymal toxoplasma lesions have three
distinct zones:
– a central avascular zone of coagulative necrosis
– an intermediate vascular zone containing numerous
organisms
– an outermost zone of encysted organisms: Toxoplasma
lesions do not have capsule
• On post-contrast imaging, Toxoplasmosis demonstrates
“ring” enhancement. With delayed or double dose
contrast study, it shows central filling of contrast which will
give rise to “target” appearance as seen in our case.
Conclusions
• Numerous viral, bacterial, fungal, and parasitic infectious agents can
present with preferential or exclusive involvement of the
cerebellum in pediatric patients.
• CSF analysis, cultures and other ancillary test are useful to identify
specific causative agents.
• Imaging findings tend to be similar amongst different pathogens
but are helpful for the management of the acute neurologic
conditions.
• An infectious agent is not always isolated.
• Wide spectrum antimicrobial coverage, supportive treatment, and if
needed management of hydrocephalus are pivotal in the acute
phase.
References
•
•
•
•
•
•
•
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The University of Texas Health Science Center at Houston
Department of Diagnostic and Interventional Imaging
Department of Pediatrics
CONTACT US
Eliana.E.Bonfante.Mejia@uth.tmc.edu
Rajan.P.Patel@uth.tmc.edu
Gloria.P.Heresi@uth.tmc.edu
Roy.F.Riascos@uth.tmc.edu