title: Acute influenza virus-associated encephalitis and encephalopathy in adults: a challenging diagnosis.
abstract: Background: Acute influenza-associated encephalopathy/encephalitis (IAE) in adults is a rare but well-known complication of influenza virus infection. The diagnosis is difficult to make due to the absence of distinctive clinical symptoms and validated diagnostic criteria. We present an illustrative case and a case review on acute IAE in adults.Methods: We performed a Medline search of the English literature using the terms influenz*, encephal* and adult, and constructed a database of detailed descriptions of patients with influenza virus infection with influenza-like symptoms at the onset of neurological symptoms.Results: A total of 44 patients were included. Confusion and seizures were the most prevalent neurological symptoms, present in 12 (27 %) and 10 (23 %) patients, respectively. Magnetic resonance imaging (MRI) was performed in 21 patients and anomalies were found in 13 (62 %), with lesions located throughout the brain. Influenza virus RNA was detected in cerebrospinal fluid (CSF) in 5 (16 %) of 32 patients. Eight (18 %) of the forty-four patients died. The benefits of antiviral and immunomodulatory therapy have not been well studied.Discussion: Our results show that many different neurological symptoms can be present in patients with acute onset IAE. Therefore, the diagnosis should be considered in patients with fever and neurological symptoms, especially during the influenza season. Laboratory diagnosis consists of demonstration of influenza virus RNA in brain tissue, CSF or respiratory samples, and demonstration of intrathecal antibody production against influenza virus. The presence of brain lesions in MRI and influenza virus in CSF appear to be of prognostic value.
authors.affiliation: Perinatal Center, Wilhelmina Childs Hospital, University Medical Center Utrecht , KE 04.123.1, Lundlaan 6, PO Box 85090, Utrecht , The Netherlands.
authors.forename: Wouter J
authors.initials: WJ
authors.lastname: Meijer
authors.affiliation: Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Room G03-228 , Heidelberglaan 100, 3584 CX Utrecht , The Netherlands.
authors.forename: Francisca H H
authors.initials: FH
authors.lastname: Linn
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht , Heidelberglaan 100, 3584 CX Utrecht , The Netherlands.
authors.forename: Anne M J
authors.initials: AM
authors.lastname: Wensing
authors.affiliation: Department of Rheumatology and Clinical Immunology, University Medical Center Utrecht , Heidelberglaan 100, 3584 CX Utrecht , The Netherlands.
authors.forename: Helen L
authors.initials: HL
authors.lastname: Leavis
authors.affiliation: Department of Viroscience, Erasmus Medical Center , Wytemaweg 80, 3015 CN Rotterdam , The Netherlands.
authors.forename: Debby
authors.initials: D
authors.lastname: van Riel
authors.affiliation: Department of Viroscience, Erasmus Medical Center , Wytemaweg 80, 3015 CN Rotterdam , The Netherlands.
authors.forename: Corine H
authors.initials: CH
authors.lastname: GeurtsvanKessel
authors.affiliation: Department of Radiology and Nuclear Medicine, VU University Medical Center , De Boelelaan 1117, 1081 HV Amsterdam , The Netherlands.
authors.forename: Mike P
authors.initials: MP
authors.lastname: Wattjes
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht , Heidelberglaan 100, 3584 CX Utrecht , The Netherlands.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Murk
keywords: MRI; cerebrospinal fluid; corticosteroids.; oseltamivir