Prognostic value of cerebrospinal fluid lactate in meningitis in postoperative neurosurgical patients

Objective: To evaluate the prognostic usefulness of cerebrospinal fluid (CSF) lactate in postoperative bacterial meningitis (POBM) and to establish the optimal CSF lactate cut-off values in our population to identify POBM in neurosurgical patients. Patients and Methods: A prospective study of postoperative neurosurgical patients with presumed and established bacterial meningitis in the Department of Neurosurgery, NIMS, Hyderabad, India, from September 2012 to December 2014. The diagnostic and prognostic values of CSF lactate have been evaluated and compared with other well-established CSF markers. All the patients who have undergone intradural cranial surgery with features of meningism have been included. Results: The study included 37 patients. The CSF value of the first lumbar puncture (LP) was taken to evaluate the diagnostic value of CSF lactate. Twenty three corresponded to Group A, and 14 to Group B. The mean CSF lactate in Group A was 5.94 +/- 2.36, and in Group B 4.60 +/- 2.31. Subsequent LPs were performed and CSF analyzed to evaluate the prognostic value of CSF lactate. The CSF markers like neutrophil count (P = 0.003), CSF/blood glucose ratio (P = 0.012), CSF lactate (P = 0.024), lymphocyte count (P = 0.046), leukocyte count (P = 0.047) have shown their prognostic value in a descending order. CSF markers like the presence of red blood cells (P = 0.540) and proteins (P = 0.757) did not show prognostic significance. The decline in CSF lactate (content and concentration) after initiation of antibiotics correlated with subsidence of fever (P = 0.0001), decrease in neck rigidity (P = 0.022) and improvement in sensorium. They were also correlated improvement in CSF/blood glucose ratio and CSF white blood cell counts. Conclusions: In our study, CSF lactate was noted to have a dependable prognostic value in POBM. As routine CSF markers can be ambiguous in POBM, CSF lactate can be considered a better alternative for both establishing the diagnosis and prognostication.