[Post-encephalitic syndrome in patients with tick-borne encephalitis].

BACKGROUND: It was 55 years ago when the first patients with tick-borne encephalitis (TBE) were diagnosed in the Koprivnica-Krizevci County. Since then, we have acquired some new knowledge about the disease. TBE is an endemic disease and the second most common tick-borne disease following Lyme borreliosis in our country, with an average morbidity rate of 12 patients per year and predominance of male individuals older than 50. There are no specific risk groups because such patients have been continuously vaccinated for the past 27 years. In 88.0% of patients, the infection is manifested as aseptic meningitis and meningoencephalitis with a biphasic course. As opposed to detailed descriptions of acute morbidity, there are few reports on the course of disease and its outcome.

OBJECTIVES: The aim of the study was to assess the presence of post-encephalitic syndrome (PES) in patients with TBE, to evaluate its incidence and demonstrate its characteristics.

PATIENTS AND METHODS: This prospective study was conducted from 1995 to 2008 and enrolled PES patients treated at Department of Infectious Diseases, Dr. Tomislav Bardek General Hospital in Koprivnica during the study period. The study included patients of both sexes older than 14 years with recent TBE virus infection, patients with clear temporal correlation between acute morbidity and PES onset, and patients where any other cause of PES was ruled out. The immunoenzyme linked assay (ELISA) was used for detection of serum IgM and IgG antibodies. Recent TBE virus infection was detected in 133 patients. Nine of these patients refused further cooperation, and the remaining 124 patients, 80 male (64.5%) and 44 female (35.4%), aged 16-76, were included in the study. We longitudinally examined the manifestation and characteristics of PES in each patient during a 3-year period (and longer if necessary). Study patients were divided into three groups of mild, moderate and severe PES based on data collected and entered into specially prepared questionnaire and by qualitative analysis of PES effect on their daily habits and activities.

RESULTS: Out of 124 patients included in the study, 60 (48.3%) had no symptoms/signs of PES, or these were mild and of short duration 15 (12.0%). The remaining 49 (39.5%) patients developed moderate (30/47.0%) or severe (19/30.0%) PES lasting for 3-18 months, with significant impact on their daily habits and activities requiring some adjustment. The main characteristics of PES were mental disorders, balance and movement coordination disorders, headache, general malaise, and reduced working ability. PES was recorded in 35 (28.2%) patients with meningoencephalitis and 14 (11.2%) patients with meningoencephalomyelitis. Permanent sequels were left over in 11 (17.1%) patients: spinal nerve paresis in five (4.0%), hearing impairment in six (5.6%), dysarthria in two (1.6%) patients, and severe mental disorder in one (0.8%) patient. In three patients we recorded simultaneous permanent spinal nerve paralysis and permanent deafness. During our longitudinal study three (2.5%) patients died.

CONCLUSION: The study undoubtedly confirmed the presence of PES in our patients with TBE. Moderate and severe PES has a significant impact on the patient quality of life, demands patient adjustment, and increases expenses of long-term sick-leave and rehabilitation.