Progressive encephalomyelitis with rigidity and myoclonus: a syndrome with diverse clinical features and antibody responses.

Background/aims: To better characterize progressive encephalomyelitis with rigidity and myoclonus (PERM) syndrome and identify novel PERM phenotypes.
Methods: The clinical features and antibody status of PERM patients were investigated using immunoblots, cell-based assays, RIA, protein macroarray and ELISA.
Results: Two patients with supratentorial involvement showed abnormal PET or EEG findings. One patient was discovered to have renal cell carcinoma, and protein macroarray revealed Ma3-antibodies. Another patient with leucine-rich, glioma-inactivated 1 (LGI1) and glutamic acid decarboxylase (GAD) antibodies showed a good response to immunotherapy.
Conclusion: The heterogeneity of the immunological features suggests that PERM is caused by diverse pathogenic mechanisms. Seropositivity to well-characterized neuronal cell surface antigens might indicate a good treatment response.
(Copyright © 2013 S. Karger AG, Basel.)