Multiphasic Acute Disseminated Encephalomyelitis with a Temporal Gap of 26 Years: A Case Report with Novel Presentation.

Introduction: Acute disseminated encephalomyelitis (ADEM) is an acute autoimmune demyelinating disease of the central nervous system that typically follows an acute viral infection or post-vaccination. It is more common in children than in adults and is characterized by widespread demyelination of the white matter of the brain and spinal cord. ADEM typically presents as a monophasic illness. Multiphasic ADEM has been an emerging topic with case reports highlighting the importance of the need for further investigation and literature on this topic. Multiphasic ADEM in adults is a rare presentation with an atypical course that can cause a delay in diagnosis leading to disability in patients. Case Presentation: Multiple case reports have shown the presence of multiphasic ADEM without an established cause, emphasizing the importance of additional insight and data in this context. This is a unique case of multiphasic ADEM in a 59-year-old male with a temporal gap of 26 years with an idiopathic cause. He was suffering from many neurologic symptoms involving his upper and lower extremities and level of consciousness, and after he was diagnosed with ADEM, he was commenced on steroids and achieved a marked improvement in his clinical status. Conclusion: Rarely, ADEM can present with recurrence or multiple phases, which requires prompt diagnosis and treatment. These phases may or may not be preceded by an identifiable trigger. Most patients respond well to steroids. However, further studies are required to achieve a good understanding and guidelines when dealing with such cases.