Adult Neurological Complications Associated With Seasonal Influenza Infection

Background. Neurological manifestations are an important complication of influenza infection. In this study, we aimed to describe the neurological manifestations and outcomes in the adult population.

Methods. A retrospective chart review of adult patients presenting to a large urban hospital in Detroit, Michigan between 1 July 2013 and 31 March 2014 with laboratory-confirmed influenza A or B infection was performed. Children under the age of 18 were excluded from the study. Cases with acute neurological complications associated with influenza virus infection were defined as having seizures, encephalopathy, or encephalitis within 1 week of laboratory-confirmed influenza infection. A descriptive analysis of the cases was performed.

Results. There were 325 cases with laboratory-confirmed influenza A or B. Of these, 16 (4.92%) displayed neurologic manifestations. The age range was 38-87. Ten were males and 6 were females. Two had pre-existing neurological disorder; 1 had Down syndrome and the other one had seizure disorder. Three had Encephalopathy/Encephalitis with movement disorder (choreoathetosis), 9 had Encephalopathy and 4 had Encephalitis. Four had no flu symptoms prior to development of neurological manifestations. Only 4 had already received the influenza vaccine. Fifteen were admitted to the hospital. Eight required intensive care. Median length of hospital stay was 13 days (3-34 days). Twelve underwent neuroimaging; 5 with brain MRI and 7 with CT of the head. All findings were non-specific. EEG was performed in 7 cases; 6 showed generalized diffuse slowing consistent with encephalopathy and 1 showed both generalized diffuse slowing and focal spikes consistent with seizure activity. Lumbar puncture was performed on 7 cases; 6 showed lymphocytic pleocytosi, all CSF studies (bacterial and viral) remained negative. Thirteen received treatment with Oseltamivir. Duration of therapy ranged from 4-10 days. All patients except 3 recovered completely without neurologic sequelae: 2 died and 1 continued to have neurologic sequelae despite therapy.

Conclusion. Encephalopathy was the most common neurological manifestation of influenza infection in adults. In a few cases, neurological manifestations were the only manifestation of influenza infection. Outcomes in adults are usually very good; with complete recovery in most of the cases.

Disclosures. All authors: No reported disclosures.

Author notes

Session: 138. CNS Infection

Friday, October 9, 2015: 12:30 PM