Nondominant hemisphere encephalitis in patient with signs of viral meningitis, New York, USA

Herpesvirus encephalitis diagnosed by polymerase chain reaction at the National Institute of Neurology of Mexico

The frequency of central nervous system infections due to herpesvirus have been studied in various populations; however, studies in Mexican mestizo patients are scant. This paper documents the frequency of herpesvirus encephalitis in Mexican mestizo patients from the National Institute of Neurology and Neurosurgery (NINN) of Mexico. To study the frequency of herpetic viral encephalitis at the NINN in the period from 2004 to 2009. We reviewed clinical records from patients with clinically suspected encephalitis; polymerase chain reaction assays were done for detection of herpesviruses in cerebrospinal fluid (CSF) samples. The total number of patients studied was 502; in 59 (12%), the diagnosis of herpetic encephalitis was confirmed by PCR-based testing of CSF. Of them, 21 (36%) were positive for herpes simplex virus type 1, 15 (25%) for Epstein-Barr virus, 10 (17%) for varicella zoster virus, 8 (14%) for cytomegalovirus, 3 (5%) for human herpesvirus 6, and 2 (3%) for herpes simplex virus 2. Our results show a varied frequency of viral encephalitis in mestizo patients due to herpesviruses in a tertiary neurological center and point out the importance of modern molecular technology to reach the etiological diagnosis in cases of encephalitis.

Pitfalls associated with the diagnosis of herpes simplex encephalitis

Herpes simplex encephalitis (HSE) still remains a serious illness with high morbidity and mortality. The characteristic presentation of HSE usually consists of fever, headache, and altered mental function. We present three patients with atypical features of HSE. First, a 48-year-old man with symptomatic posttraumatic epilepsy, who developed a gastrointestinal infection, seizures, and fever. After significant clinical improvement, the patient had fever again and developed a status epilepticus, which led to the diagnosis of HSE. Second, an 84-year-old woman with hyperactive delirium after levofloxacin intake. Cranial computed tomography (CCT) revealed hypodense temporal changes, prompting lumbar puncture and diagnosis of HSE. Third, a 51-year-old diabetic woman presented with fever and acute confusion. As CCT and cell count of cerebrospinal fluid (CSF) were normal, infection and hyperglycemia as initial diagnoses were postulated. Due to aphasic symptoms, the differential diagnosis of a stroke was taken into account. Thus a second lumbar puncture led to the correct diagnosis of HSE. These atypical presentations need a high grade of suspicion and a high willingness to reconsider the initial working diagnosis, in order to prevent a diagnostic delay.