motor neuron disease

Motor neuron disease (MND) is a group of chronic progressive neurodegenerative disorders of unknown etiology that selectively affect the anterior horn cells of the spinal cord, brainstem motor neurons, cortical pyramidal cells, and pyramidal tracts. The clinical features are characterized by the coexistence of upper and lower motor neuron signs and symptoms, manifesting as various combinations of muscle weakness, muscle atrophy, and pyramidal tract signs, while sensory and sphincter functions are generally unaffected. The clinical presentation and progression of this disease exhibit considerable heterogeneity, with most patients dying within 3 to 5 years after symptom onset due to respiratory paralysis caused by respiratory muscle involvement or secondary pulmonary infection. Currently, the etiology and pathogenesis of this disease have not been fully elucidated.