Extreme Delta Brush Electroencephalography Pattern in Anti-yo Encephalitis: A Case Report

Autoimmune encephalitis is complex and gradually being recognized. Anti-N-methyl-D-aspartate Receptor (Anti-NMDAR) encephalitis was the most well-known and its unique electroencephalography (EEG) pattern is extreme delta brush (EDB). Anti-Yo encephalitits is far less than common anti-NMDAR encephalitis (anti-NMDARE). A 78-year-old male presented with progressive apathy, hypotension, unsteady gait, and depressed consciousness. EEG revealed an EDB pattern while the serum test was positive for anti-Yo antibodies. The patient then received 10 rounds of plasma exchange, and his blood pressure stability improved. Consequently, urine cytology and abdominal computed tomography revealed atypical cells and linear enhancement in the bladder dome, respectively. However, instead of further pathological confirmation and treatment, the patient’s family requested hospice care. As a result, the patient died of desaturation 7 days later after the withdrawal of ventilatory support. First recognized in 2012, EDB is believed to be specific to NMDARE. However, to date, EDB has not been well described, and no description is available regarding its reactivity. To our knowledge, this is the first case of EDB with anti-Yo encephalitis. Similar to the cases of EDB with anti-NMDARE, our patient did not have satisfied prognosis despite no further investigation and treatment of the possible underlying malignancy. As the prevalence and underlying mechanism of this EEG pattern are unclear, further studies are warranted to identify the potentially similar mechanisms and correlation between anti-NMDAR and anti-Yo encephalitis.