Objective:

Background:

Encephalitis, an inflammation of the brain, is due to infectious or non-infectious etiologies (i.e. autoimmune) that can result in severe neurological complications and death. Hypoglycorrhachia [defined as a cerebrospinal fluid (CSF) glucose level <45mg/dl] occurs in adults with encephalitis but there is limited data on the etiologies.

Design/Methods:

We conducted a retrospective cohort study of patients from the Greater Houston and Baltimore regions between 2005-2022 diagnosed with encephalitis as per the International Encephalitis Consortium guidelines. Thirty-seven patients without a CSF glucose level were excluded from this study. A Cross-Tabulation analysis with Pearson Chi Square and Fisher Exact Test values were used for analysis.

Results:

Of the 610 patients enrolled, 287 had an infectious etiology (47%), 177 had autoimmune (29%), and 146 were unknown (23.9%). The leading infectious etiology was HSV (n=83) and the leading autoimmune etiology was seronegative limbic encephalitis (n=58). Overall, 114 (18.7%) patients had hypoglycorrhachia, with the majority having an infectious etiology (81/114, 71.1%, p<.0001). Within the infectious group, 58.1% of patients with bacterial and 84.2% of patients with fungal/parasitic etiologies had hypoglycorrhachia upon admission (p<.0001). Of the remaining patients with hypoglycorrhachia, 24 (21.1%) had an unknown etiology and only 9 (7.9%) had an autoimmune cause (antibody-mediated (n=5), seronegative limbic (n=3), and Hashimoto encephalopathy (n=1)). Thirty-three patients presented with severe hypoglycorrhachia, defined as a CSF glucose level <30mg/dl. Twenty-eight (84.8%) of them had an infectious cause, while the remaining had either unknown (n=4) or autoimmune (Hashimoto encephalopathy (n=1)) etiologies. 

Conclusions: