The effect of double filtration plasmapheresis and corticosteroids on patients with anti‐dipeptidyl‐peptidase‐like protein 6 encephalitis

Abstract Introduction Anti‐dipeptidyl‐peptidase‐like protein 6 (DPPX) encephalitis is a rare condition with varied symptoms including gastrointestinal issues, weight loss, cognitive and mental dysfunction, and hyperexcitability of the central nervous system. Methods We studied five patients with anti‐DPPX encephalitis who received immunotherapy, specifically DFPP, at our hospital. We analyzed their clinical symptoms, lab results, electrophysiological and imaging findings, and outcomes with immunotherapy. Results Patients presented with cognitive dysfunction, tremor, seizures, psychiatric disturbances, and cerebellar and brainstem dysfunction. Magnetic resonance imaging (MRI) showed brain abnormalities in one patient and elevated cerebrospinal fluid (CSF) protein levels in two patients. Antibodies against DPPX were detected in all patients and in CSF in two patients. One patient had antibodies against anti‐CV2/contactin response mediator protein 5 (CRMP5). All patients responded well to DFPP and corticosteroids. Conclusion DFPP may be an effective treatment for anti‐DPPX encephalitis. Further research is needed to understand disease progression and evaluate immunotherapy efficacy.