Toledano, Michel

Background: Episodic hypothermia (EH) can occur in multiple sclerosis (MS). The putative mechanism is impairment of thermoregulation due to a presumed demyelinating hypothalamic lesion. Objective: To describe a cohort of patients with MS, who developed EH. Methods: Patients were identified through review of the Mayo Clinic electronic medical record (1996 to July 2015). Search terms were [multiple sclerosis] or [MS] within the diagnoses field and [hypothermia] within any field. We reviewed records for accuracy of diagnoses and abstracted relevant data. Magnetic resonance imaging (MRI) was reviewed for presence of hypothalamic lesions. Results: Of 156 patients, 34 had concurrent MS and hypothermia. Thirty-two (94%) had progressive disease at EH onset. Median MS duration was 19.9 years, and median expanded disability status scale (EDSS) was 8.0. Most patients presented with alterations in consciousness. Infection was suspected as the precipitating factor in 19 (56%), but clinically/laboratory supported in only 9 (28%). MRI lesions were evident within the hypothalamus in only 4 (14%). Conclusion: EH occurs predominantly in patients with advanced secondary progressive MS. The major manifestation is altered consciousness. Infection is often suspected as causal, but infrequently confirmed. Although commonly implicated, hypothalamic lesions were rarely evident on MRI and were absent in two post-mortem evaluations.

Purpose of review We describe clinical and diagnostic features of various autoimmune and viral encephalitis subtypes. Recent findings Population-based studies have demonstrated both autoimmune and viral causes have similar prevalence and incident rates. Repertoire of autoimmune biomarkers has considerably increased with discovery of many novel neural antibodies including glial fibrillary acidic proteinα-immunoglobulin G. Similarly, with use of next generation sequencing and DNA libraries, many viral causes are being detected which would have been categorized as encephalitis of unknown cause a decade ago. Summary Autoimmune and viral encephalitides can resemble one another and sometimes autoimmune encephalitis may be triggered by viral infections. Early diagnosis and treatment is the key to both causes, which emphasizes the importance of clinical diagnosis before laboratory confirmation.

Objective To evaluate the incidence and prevalence of autoimmune encephalitis and compare it to that of infectious encephalitis. Methods We performed a population‐based comparative study of the incidence and prevalence of autoimmune and infectious encephalitis in Olmsted County, Minnesota. Autoimmune encephalitis diagnosis and subgroups were defined by 2016 diagnostic criteria, and infectious encephalitis diagnosis required a confirmed infectious pathogen. Age‐ and sex‐adjusted prevalence and incidence rates were calculated. Patients with encephalitis of uncertain etiology were excluded. Results The prevalence of autoimmune encephalitis on January 1, 2014 of 13.7/100,000 was not significantly different from that of all infectious encephalitides (11.6/100,000; p = 0.63) or the viral subcategory (8.3/100,000; p = 0.17). The incidence rates (1995–2015) of autoimmune and infectious encephalitis were 0.8/100,000 and 1.0/100,000 person‐years, respectively ( p = 0.58). The number of relapses or recurrent hospitalizations was higher for autoimmune than infectious encephalitis ( p = 0.03). The incidence of autoimmune encephalitis increased over time from 0.4/100,000 person‐years (1995–2005) to 1.2/100,000 person‐years (2006–2015; p = 0.02), attributable to increased detection of autoantibody‐positive cases. The incidence (2.8 vs 0.7/100,000 person‐years, p = 0.01) and prevalence (38.3 vs 13.7/100,000, p = 0.04) of autoimmune encephalitis was higher among African Americans than Caucasians. The prevalence of specific neural autoantibodies was as follows: myelin oligodendrocyte glycoprotein, 1.9/100,000; glutamic acid decarboxylase 65, 1.9/100,000; unclassified neural autoantibody, 1.4/100,000; leucine‐rich glioma‐inactivated protein 1, 0.7/100,000; collapsin response‐mediator protein 5, 0.7/100,000; N‐methyl‐D‐aspartate receptor, 0.6/100,000; antineuronal nuclear antibody type 2, 0.6/100,000; and glial fibrillary acidic protein α, 0.6/100,000. Interpretation This study shows that the prevalence and incidence of autoimmune encephalitis are comparable to infectious encephalitis, and its detection is increasing over time. Ann Neurol 2018;83:166–177