We present a case of a 65-year-old male who initially presented with cerebellar ataxia and myoclonus, and rapidly progressed to rigidity and progressive Encephalomyelopathy, with positive anti-glutamic acid decarboxylase (GAD) antibodies. Patient responded to Intravenous Immunoglobulin (IVIG) therapy. Patient ultimately recovered in terms of mentation, rigidity and myoclonus. 

A 65-year-old African American male with medical history of hypertension, atrial fibrillation, status post two kidney transplants (on Tacrolimus), and anoxic brain injury in 2017 with minimal neurology sequel, who presented with two weeks of poor balance and cerebellar ataxia. Within one week of admission patient developed rapidly progressive alteration in level of consciousness, multifocal myoclonic jerks, increased muscle tone and rigidity.  

We present a case of anti-GAD antibodies positive Progressive Encephalomyelitis with Rigidity and Myoclonus (PERM), who initially presented with cerebellar ataxia, and rapidly progressed to myoclonus and severe stiffness with encephalopathy. Unique features of this case include initial presentation of cerebellar ataxia, immunosuppressed status due to tacrolimus, consistent elevated anti-GAD antibody titers, non-neoplastic and return to baseline following IVIG administration.