Experts in the field of AE came together in 2016 to establish a set of clinical diagnostic criteria to be used early in the course of disease (Graus et al). This was developed so that patients might be diagnosed with suspected AE and treated promptly, while still awaiting test results or in areas where antibody testing is not available. These criteria may also be applied in suspected antibody-negative cases. Recently clinicians undertook a study comparing 29 children with AE as compared to 74 with other challenging differential diagnoses, and concluded that the established criteria are both highly sensitive and specific. They also noted, however that failure to fulfill the criteria did not exclude the diagnosis of anti-NMDA receptor AE as a small number of children did not initially meet them. They also stated that they do not recommend clinicians wait until 4 criteria are met, but stated “we would recommend starting immune therapy as soon as autoimmune encephalitis is considered possible.” Early recognition of anti-NMDA receptor encephalitis is necessary for better patient outcomes.
Importantly, they noted the original paper concluded that diagnosis of probable AE can be made if all three of the criteria are met. The first criterion is rapid onset (<3 mos) of at least 4 of 6 clinical symptoms: 1) abnormal (psychiatric) behavior or cognitive dysfunction, 2) speech dysfunction, 3) seizures, 4) movement disorders, 5) decreased consciousness, 6) autonomic dysfunction or central hypoventilation. The second criterion is either abnormal EEG or CSF. Lastly, reasonable exclusion of other types of illness is necessary. Clinicians in Australia, the United Kingdom and New Zealand collaborated in this study to determine whether the criteria accurately identified cases of anti-NMDA receptor encephalitis as compared to other types of infectious and immune-mediated encephalitis in children. This validating study is newly released, so only the abstract is currently available (at no cost) here.
Post by Lynn Chapman