Meningitis without meningeal irritation signs: What are the alerting clinical markers?

Objective: To identify parameters that may increase the likelihood of meningitis, and suggest a need for lumbar puncture (LP), in patients without meningeal irritation signs (MIS). Methods: We included consecutive adult patients who underwent LP in the emergency department (ED) of Rabin Medical Center between October 2015 and May 2017. Those hospitalized during this period, who did not undergo LP in the ED, but subsequently underwent LP during their hospitalization to rule out central nervous system infection, were also included. Each patient was evaluated prior to LP by a neurologist according to predefined parameters concerning the current disease history and the neurological examination. Patients' medical records were reviewed to obtain additional data. Patients evaluated while in coma or under sedation were excluded. Results: Three hundred and thirty eight patients were included in the final analysis: 96 (28.4%) with meningitis without MIS, 149 (44.1%) without MIS or meningitis, 57 (16.9%) with meningitis and MIS, and 36 (10.6%) with MIS without meningitis. In the absence of MIS, younger age (p = .005), headache (p < .001), nausea (p < .001), vomiting (p = .001), painful eye movements (p < .001) and phonophobia (p = .04) increased the likelihood of meningitis, while fever, laboratory results (leukocytosis; lymphopenia; CRP) and immunosuppression were of no value in this prediction. Photophobia and lymphopenia were more common in meningitis with MIS. Headache was suggestive of meningitis when MIS were present. Conclusion: Our study identified several parameters that increase the likelihood of meningitis in patients without MIS. These should be taken into evaluation when LP is considered.