LAUSR

Dr. Chen et al. reported the case of a 62-year-old man presenting with confusion, agitation, and pressured tangential speech after a car accident, whose brain MRI showed left-hemispheric cortical ribboning. EEG showed left-hemispheric slowing but no epileptiform activity. The patient's cerebrospinal fluid (CSF) was positive for anti-NMDA receptor antibodies. The authors diagnosed this as an atypical presentation of anti-NMDA receptor encephalitis. In response, Dr. Budhram and colleagues inquire whether testing was performed for antibodies against myelin oligodendrocyte glycoprotein (anti-MOG), noting that unilateral cortical abnormalities are seen in patients with anti-MOG–associated encephalitis with seizures (FLAMES), a minority of whom also harbor coexistent anti-NMDA receptor antibodies. They also inquire about the availability of susceptibility-weighted imaging (SWI) sequences, to look for underlying calcification or contusion, and whether the neuroimaging abnormalities resolved after immunotherapy. The readers also seek further clarification about the presence of other typical features of anti-NMDA receptor encephalitis and details about the antibody test methodology to allay concerns about false positivity. In another reader response, Dr. Scheel and colleagues note that most of the patients with anti-NMDA receptor encephalitis have normal MRI findings or just subtle white matter lesions, in contrast to the high frequency of cortical ribboning in patients with Creutzfeldt-Jakob disease (CJD), a subset of whom can have anti-NMDA receptor antibodies in their serum (i.e., the diagnosis of anti-NMDA receptor encephalitis should be confirmed by CSF testing, but even rare false-positive studies have been noted here as well). Therefore, they inquire whether CJD workup was performed in the patient and seek similar clarification about the details of antibody testing and about any subsequent immunotherapy given the patient's reported incomplete recovery. Unfortunately, despite our efforts to contact the authors, we received no response regarding these important reader comments. This exchange highlights important considerations regarding the differential diagnosis of cortical ribboning in the setting of subacute changes in mental status.