Sections of the medulla and of the cervical region of the spinal cord from a case of disseminated sclerosis. They show plaques of degeneration (or patches of demyelinization) involving different parts and not confined to any definite tract, and also affecting the gray matter. All the long tracts of the cord become damaged to varying degrees, the motor systems being most affected. Thus the patient shows the effects of pyramidal tract interruption (spastic paralysis) as well as cerebellar ataxia. The combination of these two commonly leads to the development of an intention tremor − i.e. a coarse trembling of muscles which are taking part in a voluntary movement.

Disseminated sclerosis is characterized by attacks of severe paralysis affecting one or more limbs, followed by partial recovery. The attacks recur, and each time leave the patient in a worse condition. The progress of the disease is relatively slow, and even after 10-15 years the disability may still not be very severe. 

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