And luckily there’s a JAMA rational clinical exam to help with that question. Brad presented a case of a patient with fever and neck stiffness.
Attia et al (1999) showed a negative predictive value of near 100% for the absence of fever, encephalopathy, and neck stiffness, and at least 95% of patients with meningitis had at least two of those features. Threshold to LP should be low as missing bacterial meningitis results in increased mortality and morbidity.
Other meningitis pearls:
-Jeff Kohlwes reminded us the one setting where the lack of an increased white count is ominous: HIV patients w/ cryptococcal meningitis with low cell counts portends a poor prognosis
-CT before LP? Age>60, focal neuro deficits, new seizures, concern for elevated ICP, known mets
Define primary versus secondary, with primary being migraine or cluster, maybe tension as a third category though this is debatable. Migraines classically are debilitating unilateral headaches associated with nausea/vomiting and photophobia, though exceptions to every rule. Secondary causes come from infectious, vascular, mass effect from a tumor etc.