インフルエンザ脳症
・10万人年あたり４人の罹患率
・神経合併症のあった72人中　
　　77%けいれん　11%インフルエンザ関連脳症　3%インフルエンザ後脳症
・日本のCross-ｓｅｃｔｉｏｎａｌ　Ｓｕｒｖｅｙ
　　年齢によって症状が違う
　　５歳以下に多い
　　年齢が高いほど、Ｂ型罹患が多く、意識障害などが神経初発症状として多く、
　　　　　　　　　　　　　けいれん、後遺症が少ない

・頻度　10/842＝1，25%

Of 842 patients with LCI, 72 patients had an INC: influenza-related encephalopathy (8), post-infectious influenza encephalopathy (2),
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49


TI Neurologic complications in children hospitalized with influenza: characteristics, incidence, and risk factors.

AU Newland JG; Laurich VM; Rosenquist AW; Heydon K; Licht DJ; Keren R; Zaoutis TE; Watson B; Hodinka RL; Coffin SE

SO J Pediatr. 2007 Mar;150(3):306-10.



OBJECTIVE: To determine the characteristics, incidence, and risk factors for influenza-related neurologic complications (INC). STUDY DESIGN: A retrospective cohort study of INC in children hospitalized with laboratory-confirmed influenza infection (LCI) from June 2000 to May 2004 was conducted. Systematic chart review was performed to identify clinical characteristics and outcomes. A neighborhood cohort was constructed to estimate the incidence of INC. Logistic regression was used to identify independent risk factors for INC. RESULTS: Of 842 patients with LCI, 72 patients had an INC: influenza-related encephalopathy (8), post-infectious influenza encephalopathy (2), seizures (56), and other (6). Febrile seizures were the most common type of seizures (27). No patient died from an INC. In our neighborhood cohort, the incidence of INC was 4 cases per 100,000 person-years. An age of 6 to 23 months (odds ratio [OR], 4.2; 95% CI, 1.4-12.5) or 2 to 4 years (OR, 6.3; 95% CI, 2.1-19.1) and an underlying neurologic or neuromuscular disease (OR, 5.6; 95% CI, 3.2-9.6) were independent risk factors for the development of INC. CONCLUSION: Seizures are the most common neurologic complication experienced by children hospitalized with influenza. In the United States, encephalopathy is uncommon. Young children and patients with neurologic or neuromuscular disease are at increased risk for INC.



AD Division of Infectious Diseases, Children's Hospital of Philadelphia and University of Pennsylvania School of Medicine, Philadelphia, PA, USA. jnewland1@cmh.edu

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Neurologic — CNS complications of influenza include aseptic meningitis, acute cerebellar ataxia, transverse myelitis, Guillain-Barré syndrome, acute necrotizing and postinfectious encephalitis (also known as acute disseminated encephalomyelitis), encephalopathy, febrile seizures, and acute mental status changes [49-54]. Reye syndrome is rare with the diminished use of aspirin in children. (See appropriate topic reviews).


Among a retrospective cohort of 842 children with laboratory-confirmed influenza, the incidence of neurologic complications was 4 per 100,000 person-years [49]. Neurologic complications were more frequent among children six months to four years of age and among those with underlying neurologic or neuromuscular disease. Among the 72 patients with neurologic complications, seizures occurred 77 percent, influenza-related encephalopathy in 11 percent, and postinfectious influenza encephalopathy in 3 percent. Data from the National Inpatient Register in Sweden indicate that the incidence of influenza-associated encephalitis is 0.21 per 1 million person-years and 1.5 per 1000 patients hospitalized with influenza [55].



The clinical manifestations of influenza-associated encephalitis in children were described in a cross-sectional survey in Japan [56]. Among 472 cases of influenza-associated encephalitis in children younger than 15 years, the peak incidence was at one to two years. The clinical manifestations varied according to age (0 to 5 years versus 6 to 15 years), with older patients having a greater incidence of influenza B infection, increased frequency of loss of consciousness or altered consciousness as the initial neurologic symptom, fewer seizures, and lower incidence of sequelae.