Electroencephalography for diagnosis and prognosis of acute encephalitis.

Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology

PubMedID: 25476700

Sutter R, Kaplan PW, Cervenka MC, Thakur KT, Asemota AO, Venkatesan A, Geocadin RG. Electroencephalography for diagnosis and prognosis of acute encephalitis. Clin Neurophysiol. 2014;.
OBJECTIVES
To confirm the previously identified EEG characteristics for HSV encephalitis and to determine the diagnostic and predictive value of electroencephalography (EEG) features for etiology and outcome of acute encephalitis in adults. In addition, we sought to investigate their independence from possible clinical confounders.

METHODS
This study was performed in the Intensive Care Units of two academic tertiary care centers. From 1997 to 2011, all consecutive patients with acute encephalitis who received one or more EEGs were included. Examination of the diagnostic and predictive value of EEG patterns regarding etiology, clinical conditions, and survival was performed. The main outcome measure was in-hospital death.

RESULTS
Of 103 patients with encephalitis, EEGs were performed in 76 within a median of 1day (inter quartile range 0.5-3) after admission. Mortality was 19.7%. Higher proportions of periodic discharges (PDs) (p=0.029) and focal slowing (p=0.017) were detected in Herpes Simplex virus (HSV) encephalitis as compared to non-HSV encephalitis, while clinical characteristics did not differ. Normal EEG remained the strongest association with a low relative risk for death in multivariable analyses (RR<0.001, p<0.001) adjusting for confounders as coma, global cerebral edema and mechanical ventilation. None of the patients with a normal EEG had a GCS of 15.

CONCLUSIONS
Normal EEG predicted survival independently from possible confounders, highlighting the prognostic value of EEG in evaluating patients with encephalitis. EEG revealed higher proportions of PDs along with focal slowing in HSV encephalitis as compared to other etiologies.

SIGNIFICANCE
EEG significantly adds to clinical, diagnostic and prognostic information in patients with acute encephalitis.