neurologic disorders
Amyotrophic Lateral Sclerosis (ALS) and Other Motor Neuron Diseases (MNDs)
Introduction
Amyotrophic lateral sclerosis and other motor neuron diseases are characterized by steady, relentless, progressive degeneration of corticospinal tracts, anterior horn cells, bulbar motor nuclei, or a combination. Symptoms vary in severity and may include muscle weakness and atrophy, fasciculations, emotional lability, and respiratory muscle weakness. Diagnosis involves nerve conduction studies, electromyography, and exclusion of other disorders with MRI and laboratory testing. Treatment is supportive. (See also Overview of Peripheral Nervous System Disorders .) Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease (MND). MNDs may involve the central nervous system (CNS) as well as the peripheral nervous system. Usually, etiology is unknown. Nomenclature and symptoms vary according to the part of the motor system most affected. Congenital Myopathies have similar features but are disorders of the muscle membrane, contractile apparatus, or organelles. MNDs can be classified as upper and lower; some disorders (eg, ALS) have features of both. MNDs are more common among men, most often appearing during their 50s. 