Acute Infectious Encephalitis and Neurological Sequelae

Aim: To determine epidemiological, clinical, diagnostic features and neurological sequaelae of patients with infectious encephalitis treated in Kaunas Clinical Hospital from November 2017 to March 2020. Objectives: 1. To determine etiological causes of infectious encephalitis. 2. To assess clinical symptoms in acute phase of infectious encephalitis. 3. To determine neurological sequelae of infectious encephalitis 6 months after the onset of the disease. Methods: All patients underwent routine clinical and neurological examination during acute phase of the disease and at 6 months. To determine patients consciousness Glasgow coma scale was used. To determine degree of disability or dependence in the daily activities, Glasgow outcome, Rankin and modified Rankin scales were used. For cognitive functions after 6 months Montreal cognitive assessement was used. To evaluate patients life satisfaction, Satisfaction with life scale (SWLS) was used. „Excel 2013“ and statistical package „SPSS statistics subscription“ were used for data entry, editing, storage and graphical representation of research results. The distribution of quantitative traits in independent groups with sample less than 30 was compared using nonparametric Mann Whitney criterion. The homogeneity of the distribution of qualitative trait values was checked using the Fisher test. The Spearman correlation coefficient was used to determine the relationship between quantitative traits. A significance level of p < 0,05 was chosen to test the statistical hypotheses. Results: Infectious encephalitis etiological cause was identified for 32 (82%) patients. The most common etiology was tick-borne encephalitis virus, which caused 74% (29) of all cases. In addition, HSV, VZV and Listeria monocytogenes was identified for one patient each. The most common symptoms that presented before hospitalization were fever (79%), headache (62%) and confusion (49%). The most common symptoms during hospitalization were fever (100%), confusion (90%), consciousness disorder (85%) and behaviour disorder (67%). Lumbar puncture was performed for all patients, which showed lymphocytic pleocytosis with slightly elevated protein concentration and slightly decreased CSF : serum glucose ratio. 69% of patients had a favorable outcome, 25% moderate disability and 6% moderately severe disability. 88% of patients had neurologial sequelae, being memory disorder (63%), motor or sensitive disorder (56%), headaches (50%) and tremor (50%) the most common. 69% of patients had mild cognitive disorder. Conclusions: 1. The most common causative agent of infectious encephalitis, responsable for ¾ of all cases, was tick-borne encephalitis virus. Encephalitis caused by herpes group viruses (HSV, VZV) was rare and accounted for 6% of cases. The etiology of encephalitis remained unclear in almost one-fifth of patients. 2. The most common clinical manifestation during encephalitis was fever and it occurred in all patients. The most common neurological symptoms were confusion (90%), consciousness disorders (85%) and behavior disorders (67%). The absolute majority of patients with encephalitis required treatment in an intensive care unit, 1/3 – mechanical ventilation. EE symptoms did not differ from encephalitis of other etiologies, but resulted in longer treatment in an intensive care unit and worse outcomes. 3. In total, 2/3 of patients had a favorable outcome, 25% had moderate disability, 6% - moderately severe disability. 88% of patients had neurologial sequelae. The most common were memory disorders (63%), with slightly more than half of the patients reporting motor or sensitive disorders, headaches and tremor. 2/3 of patients had mild cognitive impairment