Neurology of the H1N1 pandemic in Singapore: a nationwide case series of children and adults.
Neurologic complications have long been associated with influenza. A novel strain of influenza A (H1N1) first described in humans to have outbreak potential in 2009 in Mexico went on to become the first influenza pandemic of this century. We evaluated the neurologic complications of the novel influenza A (H1N1) 2009 in children and adults admitted to all public hospitals in Singapore during the influenza A (H1N1) 2009 pandemic between May 2009 and March 2010. All patients were positive for novel H1N1 infection and presented with neurologic symptoms prior to oseltamivir treatment. Ninety-eight patients (median age 6.6 years, range 0.4-62.6) were identified; 90 % were younger than 18 years; 32 % suffered from preexisting neurological, respiratory, or cardiac disease; and 66 % presented with seizures. Of those presenting with seizures, new onset seizures were the most common manifestation (n = 40, 61.5 %), followed by breakthrough seizures (n = 18, 27.7 %) and status epilepticus (n = 7, 10.8 %). Influenza-associated encephalopathy occurred in 20 %. The majority of children (n = 88) presented with seizures (n = 63, 71.6 %), encephalopathy (n = 19, 21.6 %), and syncope (n = 4, 4.5 %). Among adults, a wider range of neurological conditions were seen, with half of them presenting with an exacerbation of their underlying neurological disease. The neurological symptoms developed at a median of 2 days after the onset of systemic symptoms. The median length of hospital stay was 3 days, and 79 % were monitored in general wards. Neurologic complications associated with the novel influenza A (H1N1) 2009 strain were generally mild and had a good outcome. They occurred more frequently in patients with underlying neurological disorders. Seizures and encephalopathy were the most common manifestations, similar to other influenza virus strains.
Department of Neurology, National Neuroscience Institute (Tan Tock Seng Hospital Campus), 11 Jalan Tan Tock Seng, Singapore, 308433, Republic of Singapore.
Asha
A
Prerna
Department of Paediatric Medicine, KK Women's and Children's Hospital, Singapore, Singapore.
Jocelyn Y X
JY
Lim
Department of Paediatric Medicine, KK Women's and Children's Hospital, Singapore, Singapore.|Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.|Duke-NUS Graduate Medical School, Singapore, Singapore.
Natalie W H
NW
Tan
Khoo Teck Puat-National University Children's Medical Institute, National University Health System, Singapore, Singapore.
Mas Suhaila
MS
Isa
Department of Medicine, Changi General Hospital, Singapore, Singapore.
Helen May-Lin
HM
Oh
Department of Neurology, National Neuroscience Institute (Singapore General Hospital Campus), Singapore, Singapore.
Norazieda
N
Yassin
Department of Infectious Disease, Singapore General Hospital, Singapore, Singapore.
Chian-Yong
CY
Low
Department of Paediatric Medicine, KK Women's and Children's Hospital, Singapore, Singapore.
Derrick W S
DW
Chan
Department of Paediatric Medicine, KK Women's and Children's Hospital, Singapore, Singapore.|Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.|Duke-NUS Graduate Medical School, Singapore, Singapore.
Chia-Yin
CY
Chong
Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.|Department of Infectious Disease, Tan Tock Seng Hospital, Singapore, Singapore.|Saw Swee Hock School of Public Health, Singapore, Singapore.|Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.
Yee-Sin
YS
Leo
Department of Clinical Epidemiology, Tan Tock Seng Hospital, Singapore, Singapore.|Saw Swee Hock School of Public Health, Singapore, Singapore.|Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.
Angela Li-Ping
AL
Chow
Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.|Department of Medicine, National University Hospital, Singapore, Singapore.
Paul Ananth
PA
Tambyah
Department of Neurology, National Neuroscience Institute (Tan Tock Seng Hospital Campus), 11 Jalan Tan Tock Seng, Singapore, 308433, Republic of Singapore. Kevin_Tan@nni.com.sg.|Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore. Kevin_Tan@nni.com.sg.|Duke-NUS Graduate Medical School, Singapore, Singapore. Kevin_Tan@nni.com.sg.
Kevin
K
Tan
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000150:complications* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009422:Nervous System Diseases / Q000453:epidemiology*; D058873:Pandemics; D012846:Singapore / Q000453:epidemiology; D055815:Young Adult
Influenza A (H1N1) 2009; Influenza-associated encephalopathy; Neurologic complications; Pandemic; Seizures