Which of the following is a characteristic of amyotrophic lateral sclerosis?

Amyotrophic lateral sclerosis (ALS) is primarily characterized by progressive weakness due to the degeneration of motor neurons in the brain and spinal cord. One major hallmark of this condition is that it leads to weakness without accompanying sensory deficits, meaning that patients typically do not experience changes in sensation while they experience muscle weakness.

This distinction is crucial in the diagnosis of ALS. As the disease progresses, patients often exhibit muscle stiffness, cramps, and significant motor impairment, but their sensory pathways remain intact. Sensory changes, such as paresthesia, are not characteristic of ALS, which helps differentiate it from other neurological conditions that may involve both motor and sensory pathways.

While it is possible to observe upper motor neuron signs in conjunction with lower motor neuron signs in ALS, the presence of signs from only one system does not accurately represent the full clinical picture of the disease. Thus, the understanding that ALS is primarily a motor neuron disease leading to progressive weakness without the involvement of sensory symptoms underscores why this particular characteristic is pivotal in identifying the disease.