A 12-year-old boy comes to the physician because of headache, fever, nausea and vomiting. His mother reports that he has been unwell for a couple of days but seems to have become worse. In addition to his headache, he has a very stiff neck. He has no other past medical history except for well-controlled asthma His pulse 114/mm and he has a fever of 38.5°C (1O1.3F). His examination is notable for meningismus, as evidenced by discomfort elicited by movement of his neck. He also becomes visibly uncomfortable when you check his pupillary responses with a flashlight.
Which of the following patterns of cerebrospinal fluid would you expect to see if this boy turns out to have viral meningitis?
A 12-year-old boy comes to the physician because of headache, fever, nausea and vomiting. His mother reports that he has been unwell for a couple of days but seems to have become worse. In addition to his headache, he has a very stiff neck. He has no other past medical history except for well-controlled asthma His pulse 114/mm and he has a fever of 38.5°C (1O1.3F). His examination is notable for meningismus, as evidenced by discomfort elicited by movement of his neck. He also becomes visibly uncomfortable when you check his pupillary responses with a flashlight.
Which of the following patterns of cerebrospinal fluid would you expect to see if this boy turns out to have viral meningitis?
💡 Explanation
**Core Concept**
The patient's symptoms of headache, fever, stiff neck, and meningismus are suggestive of meningitis, an inflammation of the protective membranes covering the brain and spinal cord. Viral meningitis is the most common cause of meningitis in children and young adults.
**Why the Correct Answer is Right**
Viral meningitis typically presents with lymphocytic pleocytosis in the cerebrospinal fluid (CSF), which means an increased number of lymphocytes, a type of white blood cell, in the CSF. This is due to the body's immune response to the viral infection. The CSF in viral meningitis also typically shows a mild increase in protein levels and a decrease in glucose levels. The presence of a lymphocytic predominance in the CSF helps to distinguish viral meningitis from bacterial meningitis, which typically presents with a neutrophil predominance.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because bacterial meningitis typically presents with a neutrophil predominance in the CSF, not a lymphocytic predominance.
**Option B:** This option is incorrect because fungal meningitis typically presents with an increased number of eosinophils and neutrophils in the CSF, not a lymphocytic predominance.
**Option C:** This option is incorrect because tuberculous meningitis typically presents with a lymphocytic predominance, but also often shows an increased number of red blood cells and a high protein level in the CSF.
**Clinical Pearl / High-Yield Fact**
In patients with suspected meningitis, a lumbar puncture (LP) should be performed as soon as possible to obtain a CSF sample for analysis. However, in patients with signs of increased intracranial pressure or brain herniation, an LP should be delayed until imaging studies have been performed to rule out these complications.
**Correct Answer:** C.
✓ Correct Answer: C. Normal opening pressure; Elevated cell count; Elevated protein; Normal glucose
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