NEUROMUSCULAR DISEASE | Upper Motor Neuron

Abstract

Upper motor neuron diseases are a heterogeneous group of disorders in which a degeneration of motor neurons of the cortex and tronchoencephalic motor nucleus occurs. Clinically, these disorders are characterized by weakness, motor clumsiness, spasticity, and hyperreflexia. The major cause of morbidity and mortality in these disorders is due to the involvement and dysfunction of respiratory muscles. Amyotrophic lateral sclerosis is the most characteristic example of motor neuron disease in which both the upper and lower motor neuron are involved; when only the upper motor neuron is affected, it is called primary lateral sclerosis. Other diseases with upper motor neuron dysfunction are spinal cord injury, multiple sclerosis, and stroke. In Parkinson's disease, the upper motor neuron is indirectly affected. Respiratory muscle involvement entails alveolar hypoventilation, decreased cough capacity, and the risk of aspiration due to bulbar dysfunction. The use of respiratory muscle aids, noninvasive mechanical ventilation, and manually and mechanically assisted cough can improve survival, quality of life, and avoid hospitalization when respiratory muscles are involved. Moreover, during acute respiratory episodes, the combined use of inspiratory and expiratory muscle aids can avoid endotracheal intubation; this means continuous noninvasive ventilation with adequate respiratory secretions management if different interfaces are correctly used.