Clinical Scenario:
A 4-year-old boy is brought with a 2-week history of low-grade fever, irritability, decreased playfulness, and intermittent vomiting. Four weeks earlier, he had a generalized febrile rash illness with cough and conjunctivitis from which he recovered. On examination, he is drowsy, has neck stiffness, and right lateral rectus palsy. CSF analysis reveals 180 cells/mm³ (90% lymphocytes), protein 210 mg/dL, and glucose 25 mg/dL (blood glucose 90 mg/dL).
What is the most likely diagnosis?
A. Acute bacterial meningitis
B. Herpes simplex encephalitis
C. Subacute sclerosing panencephalitis
D. Tuberculous meningitis
E. Viral meningitis
Correct answer & Explanation
D. Tuberculous meningitis
Discussion: Tuberculous Meningitis
The child has a subacute presentation with progressive neurological symptoms over 2 weeks, signs of meningeal irritation, and a cranial nerve palsy. The preceding measles infection is an important clue because measles causes transient suppression of cell-mediated immunity, increasing the risk of progression or reactivation of tuberculosis.
The CSF findings are classic for tuberculous meningitis (TBM):
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Lymphocytic pleocytosis
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Markedly elevated protein
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Low CSF glucose
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Subacute course
Cranial nerve palsies, particularly involvement of the sixth cranial nerve, are common in TBM due to basal meningeal inflammation.
Why the Other Options are Incorrect
A. Acute bacterial meningitis
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Usually presents acutely over hours to days.
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CSF typically shows neutrophilic predominance rather than lymphocytosis.
B. Herpes simplex encephalitis
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Characterized by encephalopathy, seizures, and focal neurological deficits.
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CSF glucose is usually normal.
C. Subacute sclerosing panencephalitis
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Occurs years, not weeks, after measles infection.
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Presents with cognitive decline, behavioral changes, and myoclonic jerks.
E. Viral meningitis
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Typically has normal CSF glucose and only mildly elevated protein.
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Cranial nerve palsies are uncommon.
Learning Point
In a child from a tuberculosis-endemic area, a history of recent measles followed by a subacute meningoencephalitic illness with lymphocytic CSF, high protein, low glucose, and cranial nerve palsy should strongly suggest tuberculous meningitis.
