Autoimmune Encephalitis Pattern on PET-MRI in a Patient with Amyotrophic Lateral Sclerosis.

Amyotrophic lateral sclerosis (ALS) is a progressive primary motor neuron disorder whose etiology is a subject of debate even today. Interplay between multiple genetic and environmental factors and co-existent/antecedent infection, inflammation, and malignancy have all been hypothesized as potentially causative for this disease. Owing to its hybrid diagnostic capability, fluorodeoxyglucose positron emission tomography-magnetic resonance imaging is highly valuable in detecting varied autoimmune encephalitis patterns, one of which we report in a patient with ALS providing insight into autoimmunity as a potential etiology in the pathogenesis of this disease.