tetano
Editor, Senior Moderator
TORONTO -- The neurological symptoms of the H1N1 pandemic flu are mostly mild, with few long-term after-effects, researchers said here.
But in a small retrospective study, nearly 30% of patients with such symptoms had an underlying neurological condition, according to Asha Prerna, MD, of Singapore's National Neuroscience Institute and colleagues.
Overall, about 65% of patients had seizures, another 19% developed encephalopathy, and 7% had syncope that included loss of consciousness, Prerna said at the American Academy of Neurology meeting.
The study included all confirmed H1N1 flu patients with a neurological manifestation treated at three Singapore hospitals -- two general and one pediatric -- between July 2009 and January 2010, Prerna said.
All told, she said in an oral presentation, there were 59 patients, all but 10 of them younger than 18.
It's difficult to say how common neurological complications of the flu were, Prerna told MedPage Today in an interview later, because Singapore's routine testing to confirm H1N1 flu stopped in September 2009.
But she said Singapore confirmed 280,000 cases and 19 deaths from the start of the pandemic to the end of September.
Singapore, she noted, is in the tropics and has flu year-round, typically with two peaks a year.
In general, Prerna said, central nervous system symptoms from the seasonal flu are rare and more common in children than adults, a pattern similar to that seen during the pandemic.
The researchers identified all patients with neurological symptoms and pandemic flu confirmed by polymerase chain reaction (PCR) testing on nasal and throat swabs, she said. Those who had been treated already with oseltamivir (Tamiflu) were excluded to avoid confounding with possible side effects of the medication, Prerna said.
The researchers found:
* On average, the neurological symptoms started 2.6 days after the systemic symptoms, but the time ranged from one to 10 days.
* Of the 59 patients, 38 (64.4%) had seizures (including three in status epilepticus), 11 (18.6%) had acute encephalopathy, and four (6.8%) had syncope.
* There were 16 patients (27.1%) who had underlying neurological disorders -- eight with previous seizures and one each with cerebral palsy, tuberous sclerosis, congenital rubella, congenital hypothyroidism, myasthenia gravis, migraine, stroke, and chronic progressive external ophthalmoplegia.
Most of the patients had no after-effects, with the exception of one who presented with a stroke, Prerna said. A second patient was lost to follow-up, she added.
Physicians performed cerebrospinal fluid analyses on six patients and three were abnormal, including two with elevated protein levels, she said. H1N1 PCR testing on the cerebrospinal fluid, done in one patient, was negative.
Neuroimaging was performed only in a minority of patients, she said, including 14 who had a CT scan and 10 who had magnetic resonance imaging.
Of those, she said, five CT scans were abnormal (including two with multiple foci of dystrophic calcification) and two MRIs showed brain atrophy.
All of the five electroencephalograms performed were normal, Prerna said.
The findings are "a little bit surprising," said Michael Dobbs, MD, of the University of Kentucky in Lexington, who moderated the session at which the study was presented, but who was not part of the study.
The neurological impact of the flu "just seems much more rare than we thought it would be," he told MedPage Today.
http://www.medpagetoday.com/MeetingCoverage/AAN/19499
But in a small retrospective study, nearly 30% of patients with such symptoms had an underlying neurological condition, according to Asha Prerna, MD, of Singapore's National Neuroscience Institute and colleagues.
Overall, about 65% of patients had seizures, another 19% developed encephalopathy, and 7% had syncope that included loss of consciousness, Prerna said at the American Academy of Neurology meeting.
The study included all confirmed H1N1 flu patients with a neurological manifestation treated at three Singapore hospitals -- two general and one pediatric -- between July 2009 and January 2010, Prerna said.
All told, she said in an oral presentation, there were 59 patients, all but 10 of them younger than 18.
It's difficult to say how common neurological complications of the flu were, Prerna told MedPage Today in an interview later, because Singapore's routine testing to confirm H1N1 flu stopped in September 2009.
But she said Singapore confirmed 280,000 cases and 19 deaths from the start of the pandemic to the end of September.
Singapore, she noted, is in the tropics and has flu year-round, typically with two peaks a year.
In general, Prerna said, central nervous system symptoms from the seasonal flu are rare and more common in children than adults, a pattern similar to that seen during the pandemic.
The researchers identified all patients with neurological symptoms and pandemic flu confirmed by polymerase chain reaction (PCR) testing on nasal and throat swabs, she said. Those who had been treated already with oseltamivir (Tamiflu) were excluded to avoid confounding with possible side effects of the medication, Prerna said.
The researchers found:
* On average, the neurological symptoms started 2.6 days after the systemic symptoms, but the time ranged from one to 10 days.
* Of the 59 patients, 38 (64.4%) had seizures (including three in status epilepticus), 11 (18.6%) had acute encephalopathy, and four (6.8%) had syncope.
* There were 16 patients (27.1%) who had underlying neurological disorders -- eight with previous seizures and one each with cerebral palsy, tuberous sclerosis, congenital rubella, congenital hypothyroidism, myasthenia gravis, migraine, stroke, and chronic progressive external ophthalmoplegia.
Most of the patients had no after-effects, with the exception of one who presented with a stroke, Prerna said. A second patient was lost to follow-up, she added.
Physicians performed cerebrospinal fluid analyses on six patients and three were abnormal, including two with elevated protein levels, she said. H1N1 PCR testing on the cerebrospinal fluid, done in one patient, was negative.
Neuroimaging was performed only in a minority of patients, she said, including 14 who had a CT scan and 10 who had magnetic resonance imaging.
Of those, she said, five CT scans were abnormal (including two with multiple foci of dystrophic calcification) and two MRIs showed brain atrophy.
All of the five electroencephalograms performed were normal, Prerna said.
The findings are "a little bit surprising," said Michael Dobbs, MD, of the University of Kentucky in Lexington, who moderated the session at which the study was presented, but who was not part of the study.
The neurological impact of the flu "just seems much more rare than we thought it would be," he told MedPage Today.
http://www.medpagetoday.com/MeetingCoverage/AAN/19499