Objectives: To describe the incidence and etiology of meningitis among patients presenting to the emergency department (ED) who undergo lumbar puncture (LP) and to describe clinical criteria to select which adult patients would not need an LP because the likelihood of meningitis is low.
Materials and Methods: This was a retrospective chart review of the results of LPs performed in a tertiary care ED from March to October 2003 on patients aged 16 to 50 years suspected of having meningitis. Using the electronic record, we recorded presenting symptoms, comorbidities, results of (cerebrospinal fluid) analysis, ED length of stay, and complications. The association between specific physical examination or laboratory findings and meningitis was determined through the calculation of sensitivity, specificity, and negative/positive predictive values.
Results: Data from the results of 164 LPs were analyzed. Eleven patients (6.7%) had meningitis confirmed by gram stain, culture, or DNA analysis. The causative agents included 55% viral (2 enterovirus, 2 herpes simplex virus, 1 varicella, and 1 coxsackie), 27% bacterial (1 coagulase-negative Staphylococcus aureus, 1 rickettsial, and 1 syphilis) and 18% parasitic/fungal (1 cysticercosis and 1 Cryptococcus neoformans). The most common presenting symptoms or comorbidities in patients receiving an LP were headache (75.6%), fever (47.6%), neck pain or stiffness (23.8%), HIV (11.6%), a history of migraine headaches (4.9%), or a history of cancer or chemotherapy (4.9%). No combination of clinical criteria-including the absence of the classic triad of headache, neck stiffness, and altered mental status-ruled out meningitis. Cerebrospinal fluid findings such as pleocytosis and lymphocytic predominance were strongly associated with meningitis (P = 0.0003 and 0.0004, respectively). Patients receiving an LP stayed in the ED 48.6% longer than other ED patients, and 10 patients (6.1%) returned to the ED within 1 week complaining of headache.
Conclusions: In this study, no clinical criteria were identified to select which adult patients would not need an LP because the likelihood of meningitis is low. The absence of fever, neck stiffness, and altered mental status did not rule out adult meningitis. More research may be needed to evaluate the need for adding antiviral agents to the standard regimen when treating presumptive meningitis on adults in the ED. More research is needed to risk stratify adult patients and improve the utilization of LPs in the ED.