Rosh Emergency Medicine Practice Test 2026 - Free Emergency Medicine Practice Questions and Study Guide

In the context of a patient presenting with a global headache and elevated opening pressure during a lumbar puncture, the suspicion often lies with conditions such as meningitis or other inflammatory processes affecting the central nervous system. Among the provided options, the presence of predominant polymorphonuclear leukocytes in the cerebrospinal fluid (CSF) is a key finding typically associated with bacterial meningitis.

When there's an infectious process in the CNS, particularly with bacterial pathogens, an acute inflammatory response occurs. This response leads to the recruitment of neutrophils, which are a type of polymorphonuclear leukocyte. Their predominance in the CSF is indicative of a robust immune response to infection. The elevated opening pressure observed in conjunction with this finding further supports a diagnosis of meningitis, as it can often be elevated due to increased intracranial pressure secondary to inflammation and infection.

In contrast, the other options correlate with different conditions: a decreased CSF protein level might suggest viral meningitis or a less severe inflammatory process; an elevated CSF to serum glucose ratio could signify a metabolic or non-infectious condition, rather than an acute infection; and the presence of hemoglobin degradation products would be more relevant in cases of hemorrhage rather than an infectious et