Diagnosis

The CSF analysis is consistent with aseptic meningitis, but since this is usually a benign clinical entity, this child who is very sick, is not likely to have just aseptic meningitis. Bacterial meningitis is not likely (practically not possible) given this CSF analysis. Tuberculous meningitis is possible, but the clinical course is too acute for this. Viral encephalitis is the most likely since the CSF analysis suggests a viral picture and the patient's poor neurological status is consistent with an acute encephalitis. Additionally, the skin lesions on the patient's face may be herpes simplex lesions. Brain abscess is another possibility which needs to be ruled out by imaging. Cerebrovascular accident cannot be ruled out, but it is less likely. Shaken infant syndrome is usually associated with CSF which is grossly bloody. Brain imaging studies will help to obtain a more definitive diagnosis. A CT and a MRI are performed.

View her CT scan.


The CT scan without contrast demonstrates (upper two images) some hypodensity in the thalami and temporal lobes, indicative of bilateral cortical and subcortical edema. After the administration of IV contrast (lower two images), there is meningeal enhancement at the margins of the abnormal parenchyma, as well as mild central enhancement. This is consistent with a breach in the blood-brain barrier following vasculitis. There is no evidence of herniation.

View her MRI scan.

The areas of increased signal intensity in the MRI scan indicate the presence of abnormal water, consistent with the CT scan findings of cortico-medullary edema in the bilateral temporoparietal lobes. There is also meningeal enhancement over the affected areas of the brain. The above findings are compatible with bilateral temporoparietal lobe meningoencephalitis.

What additional tests would you request?
The CSF sample is positive for herpes simplex virus (HSV) DNA by polymerase chain reaction (PCR) although the viral culture of the CSF is negative. Her EEG is abnormal. It is diffusely slow for her age. These results are compatible with a diffuse encephalopathic process. In addition, there are some sharp waves emanating from the right frontotemporal and right frontal central regions, consistent with seizure foci in the affected areas shown on her brain CT and MRI.

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