The Clinical Presentation, Diagnosis, Treatment, and Outcome of Encephalitis: Five Years of Experience at a Medical Center in Northern Taiwan

Background: To study the clinical presentation, diagnosis, treatment, and outcome of acute encephalitis. Methods: Records of 151 cases from January 1, 2004 to December 31, 2008 were reviewed retrospectively. Cases that met the definition of encephalitis were included and patients with bacterial meningoencephalitis or a post-operation infection were excluded. A total of 25 cases were enrolled after this screening; and age, sex, underlying diseases, brain computed tomography (CT) scan results, magnetic resonance imaging (MRI) results, and cerebrospinal fluid data were analyzed. Results: One patient positive for herpes simplex virus-I (HSV-I) by polymerase chain reaction (PCR) and one patient positive for HSV-II by PCR were detected among the 25 cases. Two positive Mycoplasma encephalitis cases by PCR were confirmed. One patient, who was human immunodeficiency virus positive, was diagnosed as having cerebral toxoplasmosis by brain MRI, serology results, and clinical response to treatment. All the patients’ brain CT scans showed no abnormalities. Among the 12 patients receiving brain MRI, six patients showed hyper-intense signs that were typical of HSV encephalitis. Acyclovir was given to four patients when the MRI results indicated a high suspicion of HSV encephalitis or when there was a clinical suspicion. Three of the 25 cases died. All of the patients who received acyclovir treatment survived. Conclusion: Brain MRI results have more clinical value than CT scans when diagnosing encephalitis. The administration of antibiotics should be discouraged when the clinical picture is consistent with HSV encephalitis. The timing of any administration of acyclovir should rely more on MRI than on the HSV PCR results because the sensitivity is low and the test is relatively unreliable. Early diagnosis and prompt management with acyclovir, especially when HSV is considered to be the cause of the encephalitis, are extremely crucial in order to obtain a better outcome