What condition involves the degeneration of motor neurons in the spinal cord and brain?

• A. Spinal stenosis
• B. Amyotrophic lateral sclerosis (ALS)
• C. Multiple sclerosis
• D. Guillain-Barré syndrome

Answer: (B)

Amyotrophic lateral sclerosis (ALS) is characterized by the progressive degeneration of motor neurons located in the spinal cord and brain. This degeneration leads to muscle weakness and atrophy, as the motor neurons are responsible for controlling voluntary muscle movements. As these neurons deteriorate, the brain loses the ability to initiate and control muscle movement, resulting in significant physical impairment.

In contrast to other conditions listed, ALS specifically targets the motor pathways, affecting both the upper motor neurons in the brain and the lower motor neurons in the spinal cord. This dual impact distinguishes it from conditions like multiple sclerosis, which involves demyelination of neurons rather than direct degeneration of motor neurons. Spinal stenosis refers to narrowing of the spinal canal that can compress nerves, while Guillain-Barré syndrome is an autoimmune disorder that leads to peripheral nerve damage but does not directly affect the motor neurons in the spinal cord or brain in the same manner as ALS.