ALS primarily involves which neurons?

ALS primarily involves which neurons?

• A. Upper and lower motor neurons
• B. Sensory neurons
• C. Autonomic neurons
• D. Interneurons

Answer: (A)

ALS is a motor system disease, with the primary targets being the neurons that control voluntary movement: the upper motor neurons in the cortex and the lower motor neurons in the brainstem and spinal cord. Degeneration of these neurons produces a mix of signs from both pathways—spasticity, hyperreflexia, and a Babinski sign from the upper motor neuron involvement, along with weakness, muscle atrophy, and fasciculations from the lower motor neuron loss. Sensory neurons are not the main players, so sensory deficits aren’t a hallmark feature. Autonomic neurons aren’t the primary site of degeneration in classic ALS, and interneurons are not the central pathology, making the combination of upper and lower motor neuron degeneration the defining characteristic.

ALS is a motor system disease, with the primary targets being the neurons that control voluntary movement: the upper motor neurons in the cortex and the lower motor neurons in the brainstem and spinal cord. Degeneration of these neurons produces a mix of signs from both pathways—spasticity, hyperreflexia, and a Babinski sign from the upper motor neuron involvement, along with weakness, muscle atrophy, and fasciculations from the lower motor neuron loss. Sensory neurons are not the main players, so sensory deficits aren’t a hallmark feature. Autonomic neurons aren’t the primary site of degeneration in classic ALS, and interneurons are not the central pathology, making the combination of upper and lower motor neuron degeneration the defining characteristic.