Unilateral cortical FLAIR-hyperintense Lesion in Anti-MOG-associated Encephalitis with Seizures (FLAMES) on TNF inhibitor therapy

A 34-year-old man presented with new-onset right-sided headache, episodic visuospatial disorientation and episodic photopsia in his left visual field. His medical history was significant for ulcerative colitis, well-controlled on infliximab 450 mg intravenous every 8 weeks which he had been receiving for the past 10 years. On brain MRI, T1-weighted post-gadolinium imaging revealed right inferior parietal and occipital leptomeningeal enhancement (figure 1A, white circle), with corresponding gyral and sulcal hyperintensity on T2-fluid attenuated inversion recovery (FLAIR) imaging (figure 1B, white circle). No abnormality was seen on T2-weighted or diffusion-weighted imaging (not shown). We suspected focal meningo-encephalitis. Given the concern for an inflammatory central nervous system (CNS) event, infliximab was discontinued. He was trialled on levetiracetam 250 mg PO two times per day for possible focal-onset seizures, but had ongoing episodic photopsia followed by left-sided visual loss 2 weeks later. Neurological examination showed left-sided homonymous hemianopsia. Repeat brain MRI revealed progression of T2-FLAIR hyperintensity involving the right parietal and occipital lobes, with extension to the splenium of the corpus callosum (figure 1C1,C2) and persistent leptomeningeal enhancement (not shown). Repeated cerebrospinal fluid (CSF) …