An 11-year-old boy is sent to the emergency department (ED) by his pediatrician based on the clinician’s suspicion of meningitis. The child has had nasal congestion, slight cough, headache, and fever on and off for about two to three weeks. His mom thought it was just a regular cold so gave it a few weeks to clear up but three days ago she finally decided it had been going on too long and took him to his doctor. He was diagnosed with the flu and the mother was reassured that, antibiotics were not required and that he should improve over the next few days. Since then, however, the boy’s headache worsened, the fever reached 102°F, and the child has developed weakness in his right leg with some trouble walking. They phoned the pediatrician who now directed them to the local emergency department to be evaluated for meningitis.
On physical examination the child’s vital signs are normal except for a temperature of 100.6°F. Eyes are clear without photophobia, but there is purulent nasal discharge on the left side. The neck is without mass but there is mild meningismus. Examinations of the heart, lungs, and abdomen are unremarkable. Skin is clear without rash. Neurologic exam shows notable right leg weakness with 15 beats of clonus and a positive Babinski sign on the right leg only. Examinations of the left leg and both arms are normal.
Results of a chest x-ray are normal as are those of a screening complete blood count and a metabolic panel. A CT scan of the head is performed and one cut is shown in Figure 1 (please click on image to enlarge).
The radiologist is uncertain of the significance of the midline left parafalcine fluid collection, but says since there is no mass effect, you may proceed with a spinal tap.
What is the differential diagnosis? What is your diagnosis?
What is the best course of action?
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