LITTLE FALLS, N.J. -- Clinicians encountering children with flu-like symptoms accompanied by neurologic symptoms should consider infection with the pandemic H1N1 (swine flu) virus, researchers said.
This study described four cases in which children with confirmed infection with the pandemic H1N1 virus had neurological complications without a known etiology.
Since April, the Dallas County health department has detected four cases of neurological complications in children with confirmed H1N1 infection, Dr. Jane Siegel, of the University of Texas Southwestern Medical Center in Dallas, and colleagues reported in the July 24 issue of Morbidity and Mortality Weekly Report.
When encountering children with flu-like symptoms and unexplained seizures or mental status changes, clinicians should begin antiviral treatment immediately -- especially in hospitalized patients -- and send specimens for viral testing, the researchers said.
Neurological complications, including seizures, encephalitis, encephalopathy, and Reye syndrome, had previously been associated with seasonal influenza viruses but had not yet been described in connection to the new pandemic strain.
The cases -- all boys -- were identified among 405 confirmed cases of infection and 44 hospitalizations in the Dallas area. The U.S. Centers for Disease Control was alerted on May 28.
All four boys, whose ages ranged from 7 to 17, recovered fully during hospitalization and were sent home without any remaining neurological symptoms.
All four had fever, three had encephalopathy, and two had seizures.
The onset of the neurological symptoms after the development of respiratory disease ranged from one to four days.
All received a five-day course of oseltamivir (Tamiflu); three also received rimantadine, which has proven to be ineffective against the pandemic H1N1 virus.
The researchers described the details of each patient's experience:
Patient A was a previously healthy black male, age 17, who was initially sent home with a prescription for oseltamivir after seeking treatment at a community hospital emergency room. He was admitted the next day because of increased weakness. He was disoriented and confused and gave slow and intermittent responses to questions. His mental status returned to normal on day three.
Boys with Seizures Found to Have Swine Flu
Patient B was a previously healthy Hispanic male, age 10, who presented with tonic-clonic seizure and a subsequent post-ictal mental state. He was transferred to the ICU after having a generalized seizure. During his hospitalization, he was confused and drowsy and had difficulty answering questions. Following another seizure on day four, his mental status returned slowly to normal by day seven.
Patient C was a white male, age 7, with a history of simple febrile seizure. He presented at the hospital with a seizure following two days of cough, nasal congestion, and fatigue. He was discharged on day three and completed a five-day course of antiviral treatment.
Patient D was a black male, age 11, with a history of asthma. A neurologic exam revealed ataxia and he had a seizure shortly after admission. He was disoriented and had visual hallucinations during the first two days of his hospitalization. He had difficulty responding to questions, slow speech, and decreased respiratory drive associated with encephalopathy. His mental status returned to normal on day four.
Because the pandemic H1N1 virus appears to affect children more frequently than adults, "additional neurologic complications in children are likely to be reported as the pandemic continues," according to an accompanying comment by the Morbidity and Mortality Weekly Report editors.
However, they said, "the severity of the neurologic disease in the four patients described in this report was less than the typical disease described in two studies of neurologic complications associated with seasonal influenza, which included reports of severe static encephalopathy and death."
They reiterated the recommendation that antiviral treatment should be started immediately for any hospitalized patient with neurologic symptoms accompanied by flu-like symptoms.
"However," they noted, "the effectiveness of antiviral treatment to prevent influenza-associated encephalopathy sequelae is unknown."