Infections often trigger autoimmune diseases in children. Anti-NMDA receptor encephalitis（NMDARE）is an autoimmune encephalitis which is often associated with ovarian teratomas in young women, Immune cells target tumor-expressed NMDA receptors and produce anti-NMDA receptor antibodies. However, infection is another trigger for the development of NMDARE, and it is speculated that these infections may cause the infiltration of both autoantibodies and immune cells to the central nervous system. The most commonly studied prior infection is herpes simplex encephalitis（HSE）；27% of HSE cases are followed by autoimmune encephalitis, most frequently NMDARE；NMDARE usually develops within 3 months from the onset of HSE and presents with somewhat different symptoms than the initial HSE, including involuntary movements. Patients younger than 4 years tend to have a shorter interval between HSE and NMDARE and a poorer prognosis. Anti-NMDA receptor antibodies are usually negative at the onset of HSE and become positive thereafter, suggesting that infection triggers the production of autoantibodies. Japanese encephalitis is also known to induce NMDARE, and treatment of post-HSE NMDARE is similar to conventional NMDARE. Approximately half of all NMDARE cases are children and the clinical picture of NMDARE in children is different from that in adults. Probable diagnostic criteria for NMDARE have been proposed based on clinical symptoms and general laboratory findings without depending on the results of antineuronal antibodies. The probable NMDARE criteria are also applicable to children.

We investigated the usefulness of the FilmArray^Ⓡ meningitis/encephalitis panel for neonates and young infants with aseptic meningitis. One hundred fifty-two patients under three months of age who presented with fever underwent cerebrospinal fluid examination, where 27 exhibited pleocytosis and 125 had normal cell counts. Of the 27 cases with pleocytosis, 15 were diagnosed with aseptic meningitis；10 patients were positive for the panel（enterovirus［EV］in all cases）, and five patients were negative. The median duration of antibiotic administration in the EV-positive group was 2.4 days, which was significantly shorter than that in the respective negative group（4.8 days）（p＜0.04）. FE-M/A conducted in 15 of 125 patients without pleocytosis identified one patient with EV infection and two patients with human parechovirus infection. The panel may be helpful to reduce unnecessary antimicrobial administration.

We retrospectively reviewed 19 cases of Legionnaires1pneumonia admitted to our hospital during a 7-year period from January 2013 to December 2020, and here we report the neurological symptoms, clinical features and how they were investigated. The results showed that the neurological symptoms and imaging abnormalities of Legionella pneumonia were often reversible, and in many cases, neurologists did not examine the patients for neurological symptoms. In such cases, a certain number of cases may have been overlooked despite the presence of abnormal imaging findings. Therefore, appropriate cranial MRI and collaboration with other departments could lead to the elucidation of the pathogenesis of various Legionnaires' neurological symptoms.

We retrospectively examined the clinical course of 5 patients with acute encephalopathy with biphasic seizures and late reduced diffusion（AESD）who were hospitalized to our hospital from April 2014 to March 2019. We compared patients with and without intelligence quotient（IQ）decline after encephalopathy. Two patients showed a decline in developmental quotients. In 2 patients with IQ decline, the duration of the first seizure was ≥60 min, and additional anticonvulsant was required for the initial treatment of convulsions. Treatment after the first seizure, interval between the first seizure and second phase and subsequent treatment were not different between the 2 groups. If convulsions persist for ≥60 min or show resistance to the first anticonvulsants, multidisciplinary treatment with close observation of the patient's clinical course should be started at an early phase considering the high risk of sequelae.

We described three patients with central nervous system（CNS）disorders associated with the treatment　with immune checkpoint inhibitor（ICI）. A patient with myelitis showed mild improvement in neurological　features and reduction in abnormal intraspinal highintensities on MRI after both the discontinuation of ICI and　treatment with steroids. Second patient with encephalitis was underwent the treatment with steroids in　addition to withdrawal of ICI, and his consciousness became clear with disappearing cranial abnormal　highintensities on MRI. In third patient, asymptomatic hypertrophic pachymeningitis spontaneously　disappeared after stopping ICI only. When we encounter a patient with CNS disorders associated with ICI,　firstly ICI should be discontinued and additional immunological treatments such as steroids were recommend,　especially in patients whose CNS features were deteriorated or those with myelitis.

We report two cases of limb muscle weakness after coronavirus（COVID-19）infection, which could be saved with the diagnosis of Guillain-Barre syndrome（GBS）. We report two cases of Guillain-Barre syndrome （GBS）in70 and 50 year-old men, who developed distal limb weakness 15 and 17 days after the onset of cough and fever, respectively. The patients were intubated and placed on a ventilator in the ICU. Although both high-dose immunoglobulin therapy and simple plasma exchange therapy were performed, the extremities became almost completely paralyzed and the patient was placed on a long-term ventilator. Even though COVID-19 infection is widespread and there is a shortage of hospital beds to treat severe patients, GBS after COVID-19 infection is a serious disease, and it is necessary to secure hospital beds for its treatment.

A 76-year-old woman presented to our hospital with abnormal behavior and left hemiplegia ongoing for the last 4 days. On admission, she had fever, and magnetic resonance imaging（MRI）of the head showed a lesion along the nerve fiber tracts of the central nervous system with a partial contrast-effect. Blood tests revealed a mild inflammatory reaction, and whole-body computed tomography showed no other apparent cause of the fever；thus, empiric antibacterial therapy was started, with brain abscess and malignant lymphoma as differential diagnoses. Listeria monocytogenes was detected in the blood culture at admission；however, the cerebrospinal fluid culture was negative for L. monocytogenes. Brain biopsy was performed to confirm the diagnosis. As a result, neoplastic disease was excluded, and we diagnosed the presence of brain abscess caused by L. monocytogenes. After approximately 6 months of antibacterial treatment, the findings of cerebrospinal fluid and head MRI improved, and the patient was discharged with improved symptoms. L. monocytogenes is known to migrate along the nerve fiber tracts in the central nervous system and present a characteristic distribution pattern in the brain. Recognition of this feature may lead to early diagnosis of this disease and improve the outcome.