Toxic Infant with a Full Fontanelle.
Radiology Cases in Pediatric Emergency Medicine
Volume 1, Case 1
Loren G. Yamamoto, MD, MPH
Kapiolani Medical Center For Women And Children
University of Hawaii John A. Burns School of Medicine
     This is a 5-month old male with fever, irritability, and 
vomiting.  His temperature at home was 38.0 rectally.  
He vomited five times since onset 8 hours ago.  He is 
feeding soy formula.  Past medical history is 
     Exam:  VS T38.0R, P150, R40 (crying), BP 
unobtainable, wt 50%ile.  Fussy, though consolable at 
times.  He doesn't focus or interact well and appears 
somewhat "toxic" to the examiner.  Anterior fontanelle is 
somewhat full, but he is crying so it is difficult to truly 
assess.  Eyes moist.  Pupils reactive.  TM's are shiny 
and slightly red.  Oral mucosa moist.  Neck is hard to 
assess due to crying.  Heart regular without murmur.  
Lungs clear.  Abdomen soft on inspiration.  No 
detectable tenderness evident.  No hernias.  Testes not 
swollen.  CVA tenderness is not apparent.  Color 
slightly pale.  Capillary refill time 2-3 seconds.  Muscle 
tone good.
     A lumbar puncture is done to rule out meningitis.  
The CSF is homogeneously bloody (blood mixed with 
CSF).  The blood does not clear.  All three tubes 
appear to be equally bloody.  A CBC, blood culture, and 
catheterized urine sample are sent to the lab.  An IV is 
started and the child is given 50mg/kg of cefotaxime IV.  
A CT scan is done to rule out subarachnoid 

View CT scan image.

     This CT scan was done without IV contrast.  It was  
read as a posterior inter-hemispheric subdural 
hematoma.  It shows blood in the subdural space and
an increased density (whiter than it should be) of the 
posterior falx secondary to a posterior inter-hemispheric 
subdural hematoma.  Other clinical findings and a social 
investigation confirmed the etiology as shaken baby 
Teaching Points:
     1.  Although the falx may enhance with IV contrast, 
an increased density of the posterior falx before IV 
contrast is administered should raise the suspicion of a 
posterior interhemispheric subdural hematoma.  This 
injury is highly indicative of a shaken baby.  Other 
findings such as retinal hemorrhages and a suspicious 
history add to the strength of this etiology.
     2.  An experienced physician who has done many 
lumbar punctures in infants usually knows when to 
expect bloody CSF due to the difficulty of the 
procedure.  If bloody CSF is unexpectedly encountered, 
and it does not clear, one should be highly suspicious of 
intracerebral hemorrhage with blood entering the 
subarachnoid space.
     3.  Although blood should not appear in the CSF if 
the hemorrhage is purely subdural, this injury is not 
purely subdural in nature.  Blood also enters the 
subarachnoid space.  Axonal shearing and 
generalized cerebral cellular injury take place as well.
     4.  A full fontanelle is not always indicative of
meningitis.  Intracerebral hemorrhage, cerebral edema, 
and acute hydrocephalus can all mimic the same 
clinical features.
     5.  Trauma specialists have often taught that 
intracranial hemorrhage alone cannot account for all 
the blood loss in a patient in hypovolemic shock.  In 
other words, if you have diagnosed an intracerebral 
hemorrhage in a trauma patient in hypovolemic shock, 
you must look elsewhere for additional hemorrhaging 
sites, such as in the abdomen.  Infants appear to violate 
this rule since many shaken babies present to the
emergency department in shock.  Although one must 
always be suspicious of other hemorrhaging sites from
injuries such as from fractures and internal injuries, 
subsequent work-ups on these patients may fail to 
identify significant hemorrhaging sites other than in the 
     6.  CT scans may fail to show a posterior
inter-hemispheric subdural hematoma if it is small.  MRI
scanning has been shown to be more sensitive at
identifying these hemorrhages and other brain injuries.

     1.  Ludwig S.  Child Abuse.  In:  Fleisher GR, Ludwig 
S, eds.  Textbook of Pediatric Emergency Medicine, 
third edition.  Baltimore, MD, Williams and Wilkins, 
1993, p. 1437.
     2.  Bogost GA, Crues JV, Moser FG.  MR Imaging
in the Evaluation of Trauma.  Emergency Radiology 
     3.  Sklar EM, Quencer RM, Bowen BC, Altman N,
Villanueva PA.  Magnetic resonance applications in 
cerebral injury.  Radiology Clinics of North America
     4.  Barkovich AJ.  Chapter 4 - Destructive Brain 
Disorders of Childhood.  In:  Pediatric Neuroimaging, 
second edition.  New York, Raven Press, 1995, pp. 

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Web Page Author:
Loren Yamamoto, MD, MPH
Associate Professor of Pediatrics
University of Hawaii John A. Burns School of Medicine