So protean are the manifestations of chronic epidemic encephalitis, that one's diagnostic acumen is frequently taxed to the utmost in attempting to determine the exact nature of the syndrome that presents itself. This is especially true in the not uncommon cases in which the encephalitic onset is obscure or so transitory as to have been overlooked altogether. Then again, it is possible that the disease has become distorted since the severe pandemics of 1917 to 1920. Grinker1 expressed the belief that it may not have an acute or subacute onset, the virus being so attenuated or the host so resistant that the disease process may be chronic from the beginning and run a progressive, slow, malignant course.
The most frequent localization of the lesions of epidemic encephalitis is in the extrapyramidal motor system, and all are familiar with the striopallidal syndrome resembling paralysis agitans, which this produces. However, many
Dean SR. A FORM OF CHRONIC EPIDEMIC ENCEPHALITIS SIMULATING THE LANDOUZY-DEJERINE TYPE OF PROGRESSIVE MUSCULAR DYSTROPHYValue of Studies on Creatine in Conjunction with Ingestion of Amino-Acid as an Aid in Differential Diagnosis. Arch NeurPsych. 1937;38(5):1039-1046. doi:10.1001/archneurpsyc.1937.02260230137008