multiple sclerosis n a demyelinating disease marked by patches of hardened tissue in the brain or the spinal cord and associated esp. with partial or complete paralysis and jerking muscle tremor
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a chronic disease of the nervous system affecting young and middle-aged adults. The myelin sheaths surrounding nerves in the brain and spinal cord are damaged, which affects the function of the nerves involved. The course of the illness is usually characterized by recurrent relapses followed by remissions, but a small proportion of patients run a chronic progressive course. The disease affects different parts of the brain and spinal cord, resulting in typically scattered symptoms. These include unsteady gait and shaky movements of the limbs (ataxia), abnormal eye movements (e.g. nystagmus and internuclear ophthalmoplegia), defects in speech pronunciation (dysarthria), spastic weakness, and retrobulbar neuritis. The underlying cause of the nerve damage remains unknown. Steroid treatment may be used in an acute relapse, and beta-interferon therapy reduces the relapse rate in some patients.
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(MS) a disease in which there are foci of demyelination throughout the white matter of the central nervous system, sometimes extending into the gray matter; symptoms usually include weakness, incoordination, paresthesias, speech disturbances, and visual complaints. The course of the disease is usually prolonged, so that the term multiple also refers to remissions and relapses that occur over a period of many years. Four types are recognized, based on the course of the disease: relapsing remitting, secondary progressive, primary progressive, and progressive relapsing. The etiology is unknown.Medical dictionary. 2011.