Synonyms for Lethargic Encephalitis (same or very similar meaning)
WordNet sense 1 (an encephalitis that was epidemic between 1915 and 1926; symptoms include paralysis of the extrinsic eye muscle and extreme muscular weakness):
sleeping sickness, encephalitis lethargica, epidemic encephalitis, sleepy sicknessFrom the ODE community, based on WordNetadd/edit