Abstracts

Rationale: Introduction:Encephalitis is a severe inflammatory disorder of the brain with many possible etiologies including autoimmune disorders. Autoimmune encephalitis presentation ranges from mild cognitive impairment to severe encephalopathy and refractory seizures. New biomarkers and syndromes have been identified over the last 10-15 years. Identifying limbic system radiological abnormalities suggestive of autoimmune encephalitis can help in identifying the diagnosis early. Electroencephalography (EEG) is a useful diagnostic tool and is often pathologic in anti NMDAR encephalitis. We reviewed the cases of autoimmune encephalitis at our institution over a 4-year period.  Methods: 175 patients were seen by the neurology service between May 2014 and April 2018 for whom autoantibody screening was requested. Antibody screening was positive in 61 patients. Twenty-seven of those patients presented with seizures or encephalopathy. The final diagnosis was autoimmune encephalopathy or autoimmune epilepsy in 13 patients. In the other 14 patients the etiology was considered nonimmune. Results: Patients’ age ranged between 25 and 72 years. Three of the patients were African American and 10 were Caucasian. Females were a majority (10) and males were 3. The specific antibodies found included GAD 65 (4), ANCA (1), anti-TPO (4), VGKC (1), NMDAR (3), LGI1 (1), p/q type Ca channel Ab (1). Two patients had more than one antibody: VGPC and TPO in one patient. GAD 65 and TPO in the other patient. The clinical presentation was encephalopathy in 4 patients, seizures in 2 patients and encephalopathy with seizures in 7 patients. EEG was abnormal in all patients. Generalized slowing was reported in 12 patients (92%). Seizures were seen on EEG in 5 patients (4 electrographic and one clinical/electrographic). Epileptiform discharges were reported in 9 patients. Six had focal epileptiform discharges and three had bihemispheric epileptiform discharges. Two patients had discharges with triphasic morphology. CSF was abnormal in 4 patients (30%). CSF Cell count in all patients ranged between 1 and 31. Protein ranged between 15 and 160. MRI was abnormal in 7 patients (53%). T2 hyperintensities reported in 6 patients (2 focal and 4 bilateral). Two patients had hippocampal sclerosis, one unilateral and the other was bilateral. Conclusions: Discussion:Females were more commonly affected by autoimmune encephalitis in this case series (76%). EEG was abnormal in all cases. Mild to severe generalized slowing was reported in all EEGs. 9 patients presented clinically with seizures and EEG showed ictal activity in 5 of them. Other EEG findings included triphasic morphology discharges in 2 patients. Focal epileptiform discharges were seen in all patients with anti NMDAR encephalitis. CSF cell count and protein were normal in most patients (9 out of 13) including 2 out of 3 anti NMDAR encephalitis patients. MRI was abnormal in just more than half of the patients (7 out of 13).Conclusion:In this case series, the clinical presentation, EEG, CSF and MRI findings in patients with autoimmune encephalitis is diverse and nonspecific. CSF cell count and protein; and MRI were normal in more than half of the patients in this case series.  Funding: No funding