Hyperacute experimental allergic encephalomyelitis in rhesus monkeys as a model of acute necrotizing hemorrhagic encephalomyelitis.

A comparative study of clinical and morphological findings in three fatal cases of acute necrotizing hemorrhagic encephalomyelitis (ANHE) and hyperacute experimental allergic encephalomyelitis (HEAE) in rhesus monkeys is reported. In all cases ANHE was characterized clinically by definite prodromal respiratory infection. The course was rapidly progressive with fatal termination. The salient histopathological changes were necrosis of blood vessels with plasma exudation and fibrin impregnation, hemorrhages and inflammatory reaction in the damaged cerebral tissue. Perivascular lymphoid histiocytic infiltration with glial proliferation was also noted in all cases. Numerous compound granular cells were found in one case. HEAE was detected in five rhesus monkeys immunized with homological spinal cord emulsion with complete Freund adjuvant. The illness was acute or subacute and the course was rapidly progressive with a fatal end. There was multiple necrosis of small blood vessels with plasma exudation, fibrin impregnation and massive neutrophila infiltration of the damaged brain tissue in all rhesus monkeys with HEAE. There was also widespread glial proliferation and numerous compound granular cells alongside with necrosis of blood vessels in the brain. These findings suggest that HEAE in rhesus monkeys can be viewed as an adequate model of ANHE.