207 - Rehabilitation of Dipeptidyl-peptidase-like Protein 6 (DPPX) Encephalitis: A Case Report

A 50 year old man presented to the emergency department after a seizure. He had gastrointestinal upset, cognitive impairments, ataxia, and myoclonus. Workup was normal except for an inflammatory CSF profile. The patient was trialed on carbidopa-levodopa, intravenous methylprednisone, and intravenous immunoglobulins with minimal improvement. Myoclonus was resolved with clonazepam. The patient was discharged with a diagnosis of possible autoimmune encephalitis. 

One month later, serum and CSF analysis resulted positive for DPPX antibodies. He was readmitted to the hospital for plasma exchange with minimal neurologic improvement. Subsequent treatment with Rituxan resulted in mild improvement. He was then transferred to inpatient rehabilitation.

Upon admission, he was dependent for mobility, gait, and self-care. By discharge he progressed to touching-steadying assist for transfers and gait and maximum assist for bathing and toileting. He was discharged to a skilled nursing facility with rehabilitation services.

Discussions: DPPX encephalitis is caused by antibodies to the regulatory protein of the voltage-gated Kv4.2 potassium channels found in the brain and enteric nervous system. These locations are responsible for the classic triad presentation of GI upset, cognitive impairment, and CNS hyperexcitability. Only 100 cases have been reported in literature since its discovery in 2013. Treatment often includes steroids plus immunomodulators with initiation as soon as possible to prevent long term complications.

Conclusions: This patient had a classic disease presentation, but several factors delayed diagnosis. A GLP-1 medication concealed his 150 pound weight loss and pre-existing psychiatric conditions concealed his cognitive decline. Even after treatment he had persistent cognitive and functional impairments, but demonstrated some functional improvement during rehabilitation. Due to the rare nature of this disease, it is important to have clinical suspicion when presented with the classic triad of DPPX encephalopathy.