The Contrast Between the Brain Lesions Produced by Lead and Other Inorganic Poisons and Those Caused by Epidemic Encephalitis

Brain lesions caused by inorganic poisons, such as lead, are collectively designated encephalitis. The latter term is also used for cerebral lesions caused by infection, such as general paralysis, trypanosomiasis, epidemic encephalitis, Heine-Medin's disease and the so-called enzootic encephalomyelitis of horses (Borna disease1). Best studied are the cases belonging to the infectious group chiefly represented by paralytic dementia and epidemic encephalitis. These two morbid entities exhibit such typical interstitial and parenchymatous changes that they deserve to be dignified by the term encephalitis, that is to say, inflammation of the brain tissues. Being essentially alike in their histologic changes, they differ principally in the localization of the lesions which are mainly cortical in general paralysis and mesencephalic in epidemic encephalitis. The nonsuppurative cerebral lesions caused by organic or inorganic poisons are somewhat different from the foregoing group, the difference being, in some respects, striking enough to permit a differential diagnosis