The case report of MOG and NMDAR IgG double positive encephalitis treated with subcutaneous ofatumumab

The phenotypic spectrum of myelin oligodendrocyte glycoprotein (MOG)- IgG-associated disorders (MOGAD) has broadened in the past few years, and atypical phenotypes are increasingly recognized. Isolated seizures and MRI-negative brainstem and cerebellar symptoms or encephalitis have rarely been reported as a feature of MOGAD and represent a diagnostic challenge. Meanwhile, the coexistence of MOG IgG and other CNS autoimmune antibodies is infrequent. We report a patient presented with isolated epileptic onset, relapsed with MRI-negative brainstem symptoms and MRI-negative encephalitis. He was positive for MOG IgG throughout the disease course while concomitant NMDAR IgG was not detected positive until second relapse. He showed decreasing response to conventional first-line therapy. The last relapse was during a COVID-19 epidemic with limited inpatient resources. Fortunately, he was ultimately controlled on subcutaneous ofatumumab, a novel fully humanized anti-CD20 mAb. This is the first report about subcutaneous ofatumumab treatment in MOG and NMDAR IgG double positive encephalitis with 12-month follow-up, depicting its potential as a therapeutic option.

Automated summary

The phenotypic spectrum of MOG-IgG-associated disorders has expanded, including atypical phenotypes such as isolated seizures and MRI-negative brainstem and cerebellar symptoms. Coexistence of MOG IgG and other CNS autoimmune antibodies is rare. This report describes a patient with epileptic onset followed by MRI-negative brainstem symptoms and encephalitis, positive for MOG IgG throughout the disease course with later detection of NMDAR IgG. The patient showed decreasing response to conventional therapy but ultimately responded to subcutaneous ofatumumab, highlighting its potential as a therapeutic option.