Their findings, published today in the Annals of Neurology, show that while such complications remained rare, H1N1 caused more serious neurological complications than seasonal flu did.
The flu complications included encephalopathy a general term meaning the brain isn't working, with symptoms ranging from confusion to a comatose state; aphasia, in which the child cannot talk; and "focal neurological findings," which means a specific part of the nervous system wasn't working, such as a child's eyes not being able to track.
As with seasonal flu, H1N1 was also associated with causing epilepsy.
"In the past, you treated the flu [as] not that big of a deal," Bonkowsky said. But having witnessed the range of problems, his advice is: "Don't mess around. Get the flu vaccination."
This year, only one dose of vaccine will be necessary to protect against seasonal and H1N1 flu strains. It is recommended for everyone over age 6 months.
Last year, 29 percent of Utahns older than 6 months were vaccinated against H1N1, compared with 24 percent nationally. Forty-one percent of Utah adults received the seasonal vaccine.
In their study, Bonkowsky and colleagues found 303 children were hospitalized at Primary Children's for H1N1 between April and November last year, with 18 children having a neurological complication.
By comparison, 234 children were hospitalized in Utah with seasonal flu from 2004 to 2008, 16 with neurological complications.
The study showed children with a pre-existing neurological condition like epilepsy were at a higher risk for developing neurological complications from H1N1, but 34 percent of the patients didn't have prior conditions.
The H1N1 patients were also more likely to have abnormal electroencephalographys (EEGs), a measure of the brain's electrical activity.
The study didn't address why H1N1 took a more severe toll. Bonkowsky speculates that because children had no immunity to the strain, their bodies put up a more severe immune response.
There are no proven treatments for flu-related neurological complications.
Of the 18 H1N1 patients, most improved during hospitalization; one died. Four continued to have neurological problems at discharge, with two of the children getting better after six months.
A third did not improve and is considered "neurologically devastated." It's unknown what happened to the fourth.
"Once the ball is in motion, you can't stop the chain of events as far as we can tell," Bonkowsky said. "The better thing is not to get the flu."
The study was funded by the Centers for Disease Control and Prevention, Primary Children's Medical Center Foundation and the U.
H1N1 toll in Utah
In Utah during the 2009 flu season, it hospitalized 500 children and killed four.
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