Summary Encephalitis is a severe inflammatory disorder of the brain with many possible causes and a complex differential diagnosis. Advances in autoimmune encephalitis research in the past 10 years have led to the identification of new syndromes and biomarkers that have transformed the diagnostic approach to these disorders. However, existing criteria for autoimmune encephalitis are too reliant on antibody testing and response to immunotherapy, which might delay the diagnosis. We reviewed the literature and gathered the experience of a team of experts with the aims of developing a practical, syndrome-based diagnostic approach to autoimmune encephalitis and providing guidelines to navigate through the differential diagnosis. Because autoantibody test results and response to therapy are not available at disease onset, we based the initial diagnostic approach on neurological assessment and conventional tests that are accessible to most clinicians. Through logical differential diagnosis, levels of evidence for autoimmune encephalitis (possible, probable, or definite) are achieved, which can lead to prompt immunotherapy.

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A clinical approach to diagnosis of autoimmune encephalitis

https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(14)61060-6.pdf

Clinical efficacy and safety of a novel tetravalent dengue vaccine in healthy children in Asia: a phase 3, randomised, observer-masked, placebo-controlled trial

Background Encephalitis continues to result in substantial morbidity and mortality worldwide. Advances in diagnosis and management have been limited, in part, by a lack of consensus on case definitions, standardized diagnostic approaches, and priorities for research. Methods In March 2012, the International Encephalitis Consortium, a committee begun in 2010 with members worldwide, held a meeting in Atlanta to discuss recent advances in encephalitis and to set priorities for future study. Results We present a consensus document that proposes a standardized case definition and diagnostic guidelines for evaluation of adults and children with suspected encephalitis. In addition, areas of research priority, including host genetics and selected emerging infections, are discussed. Conclusions We anticipate that this document, representing a synthesis of our discussions and supported by literature, will serve as a practical aid to clinicians evaluating patients with suspected encephalitis and will identify key areas and approaches to advance our knowledge of encephalitis.

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Case Definitions, Diagnostic Algorithms, and Priorities in Encephalitis: Consensus Statement of the International Encephalitis Consortium

Background: The COVID-19 pandemic, caused by SARS-CoV-2, is of a scale not seen since the 1918 influenza pandemic. Although the predominant clinical presentation is with respiratory disease, neurological manifestations are being recognised increasingly. Based on knowledge of other coronaviruses, especially those that caused the SARS and MERS epidemics, we might expect to see rare cases of central nervous system (CNS) and peripheral nervous system (PNS) disease caused by SARS-CoV-2.

Recent developments: A growing number of case reports and series describe a wide array of neurological manifestations, but many lack detail, reflecting the challenge of studying such patients. Encephalopathy is relatively common, being reported for 93 patients in total, including 16 (7.5%) of 214 hospitalised COVID-19 patients in Wuhan, China, and 40 (69%) of 58 in intensive care with COVID-19 in France. Encephalitis has been described in 8 patients to date, and Guillain-Barre syndrome in 19 patients. SARS-CoV-2 is detected in the cerebrospinal fluid of some patients. Anosmia and ageusia are common and may occur in the absence of other clinical features. Unexpectedly, acute cerebrovascular disease is also emerging as an important complication, with cohort studies reporting stroke in 1.6-6% of hospitalised COVID-19 cases. So far, 88 patients have been described, mostly with ischaemic stroke, who frequently have vascular events in the context of a pro-inflammatory hypercoagulable state with elevated CRP, D-dimer, and ferritin.

Where next?: Careful clinical, diagnostic and epidemiological studies are needed to help define the manifestations and burden of neurological disease caused by SARS-CoV-2. Precise case definitions must be used to distinguish non-specific complications of severe disease, such as hypoxic encephalopathy and critical care neuropathy, from those caused directly or indirectly by the virus; these include infectious, para- and post-infectious encephalitis, hypercoagulable states leading to stroke, and acute neuropathies such as Guillain-Barre syndrome. Recognising SARS-CoV-2 neurological disease in patients whose respiratory infection is mild or asymptomatic may prove challenging, especially if the primary COVID-19 illness occurred weeks earlier. The proportion of infections leading to neurological disease will remain small. However, these patients may be left with severe neurological sequelae. With so much of the population infected, the overall number of neurological patients, and their associated health, social and economic costs, may be large. Healthcare planners and policymakers must prepare for this eventuality. The many ongoing studies investigating the neurological association will increase our knowledge base.

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Neurological Associations of COVID-19

Guillain-Barre syndrome (GBS) and its variant, Miller Fisher syndrome (MFS), exist as several clinical subtypes with different neurological features and presentations. Although the typical clinical features of GBS and MFS are well recognized, current classification systems do not comprehensively describe the full spectrum of either syndrome. In this Perspectives article, GBS and MFS are classified on the basis of current understanding of the common pathophysiological profiles of each disease phenotype. GBS is subclassified into classic and localized forms (for example, pharyngeal-cervical-brachial weakness and bifacial weakness with paraesthesias), and MFS is divided into incomplete (for example, acute ophthalmoparesis, acute ataxic neuropathy) and CNS subtypes (Bickerstaff brainstem encephalitis). Diagnostic criteria based on clinical characteristics are suggested for each condition. We believe this approach to be more inclusive than existing systems, and argue that it could facilitate early clinical diagnosis and initiation of appropriate immunotherapy.

Guillain–Barré and Miller Fisher syndromes—new diagnostic classification

Encephalitis, myelitis, and acute disseminated encephalomyelitis (ADEM): Case definitions and guidelines for collection, analysis, and presentation of immunization safety data

/pdf/kawasaki-like-syndrome-abacavir-hypersensitivity-lablg4b4sl.pdf

Therese Cvetkovich

Papers

Encephalitis, myelitis, and acute disseminated encephalomyelitis (ADEM): Case definitions and guidelines for collection, analysis, and presentation of immunization safety data

Kawasaki-like syndrome: abacavir hypersensitivity?