Necrotic myelopathy (myelomalacia) in rats with allergic encephalomyelitis treated with tilorone.

Necrosis of the spinal cord was produced by administering tilorone to rats before or during the incubation period of experimental allergic encephalomyelitis (EAE). Under slected conditions of dose and timing, the drug delayed onset of clinical signs but did not prevent progression to paralysis. The lymphocytic component of the inflammatory lesions was reduced, but this was accompanied by a dramatic increase of monocytes in the spinal cord, followed by softening (myelomalacia). This new variant of EAE simulates necrotic myelopathy in man. The similarity provides support for an autoimmune etiology of the latter. Furthermore, the inverse relation between lymphocytic cuffs around vessels and massive monocytic infiltration of the cord adds to the growing evidence that lymphocytic cuffs protect the neural parenchyma by "vascular blockade."