A clinical approach to diagnosis of autoimmune encephalitis.
Graus F, Titulaer MJ, Balu R, Benseler S, Bien CG, Cellucci T, Cortese I, Dale RC, Gelfand JM, Geschwind M, Glaser CA, Honnorat J, Höftberger R, Iizuka T, Irani SR, Lancaster E, Leypoldt F, Prüss H, Rae-Grant A, Reindl M, Rosenfeld MR, Rostásy K, Saiz A, Venkatesan A, Vincent A, Wandinger KP, Waters P, Dalmau J.
Lancet Neurol. 2016. Apr;15(4):391-404.
http://www.ncbi.nlm.nih.gov/pubmed/26906964
Overview:
The progress made over the past 15 years in the field of autoimmune encephalitis has transformed the diagnostic approach to these disorders and led to the identification of new syndromes and biomarkers. As these diseases are less rare than initially anticipated, most neurologists will consider autoimmune encephalitis in some of their patients, and as developments have progressed so quickly, many might feel uncomfortable when to consider, what to test for, and how to treat. This paper focuses on how to establish a prompt diagnosis of autoimmune encephalitis when the patient is presenting with subacute onset of memory deficits or altered mental status. The authors have important expertise in the field. They reviewed the literature and developed a practical, syndrome-based diagnostic approach to autoimmune encephalitis. This paper provides guidelines on how to navigate through the differential diagnosis to assess the levels of evidence for autoimmune encephalitis (possible, probable, or definite). Since autoantibody test results and response to therapy are not available at disease onset, the authors base the initial diagnostic approach on neurological assessment and conventional tests that are accessible to most clinicians. The paper has an important practical value and is a must read for those neurologists dealing with autoimmune and inflammatory brain disorders and those who need to acknowledge these conditions in primary care setting.
Key points:
1. The results of antibody testing and response to immunotherapy are not available at disease onset and this might delay the diagnosis. Diagnosis of autoimmune encephalitis can be reached through a step-by-step differential diagnosis taking into account the clinical, radiological and biological profiles at presentation.
2. The diagnosis of autoimmune encephalitis is made when all three of the following criteria have been met: 1 Subacute onset (rapid progression of less than 3 months) of working memory deficits, altered mental status or psychiatric symptoms. 2 At least one of the following: new focal CNS deficits; seizures not explained by a previously known seizure disorder; CSF pleocytosis; MRI features suggestive of encephalitis. 3. Reasonable exclusion of alternative causes. The paper lists many of the diagnoses to consider and to exclude.
3. Diagnostic criteria relying on a step-by step logical clinical approach are provided for autoimmune limbic encephalitis, Hashimoto encephalopathy, Bickerstaff brainstem encephalitis, acute-disseminated encephalomyelitis, anti-NMDA receptor encephalitis and antibody-negative but probable autoimmune encephalitis.