Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease (MOGAD) Initially Presenting as Septic Meningoencephalitis in a 16-Year-Old Male.

Background: We describe a case of myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) in a 16-year-old patient who initially presented with clinical features of septic meningoencephalitis. This case outlines the importance of considering a diagnosis of MOGAD in patients who fail to improve with appropriate antimicrobial therapy or show a positive clinical response to glucocorticoids (often used in treatment of meningococcal meningitis). We emphasise the importance of recognising that an infectious prodrome can precede MOGAD.

Case description: A 16-year-old male was admitted with vomiting, fever, headache, photophobia and altered mental state. He was treated for meningoencephalitis with initial clinical improvement. Lumbar puncture findings were suggestive of viral meningoencephalitis. During admission the patient went through several periods of transient clinical and biochemical improvement, alternating with periods of symptomatic relapse. On day 17 of admission, he was transferred to a tertiary centre for suspected autoimmune disseminated meningoencephalitis (ADEM) and two days later, he suffered a catastrophic neurological decline with new dysarthria, dysphagia, aphasia, horizontal nystagmus and facial paralysis. He made a remarkable neurological recovery after commencing treatment with IV immunoglobulin, IV methylprednisolone and plasma exchange, with complete resolution of symptoms.

Conclusion: MOGAD can run a variable course and present soon after a central nervous system infection, making the diagnosis more challenging. Nonetheless, patients can achieve a full neurological recovery with early recognition, diagnosis and treatment of this rare entity.

Learning points: Autoimmune encephalitis can be preceded by an infectious prodrome which makes the diagnosis more challenging.Autoimmune encephalitis can run a subacute and fluctuating course with transient periods of symptomatic improvement preceding a rapid neurological decline.Glucocorticoids often used in treatment of patients with meningococcal meningitis may lead to transient symptomatic improvement in patients with autoimmune encephalitis, masking the diagnosis.MRI findings of demyelination in autoimmune encephalitis may lag behind clinical symptoms by days to weeks.