Primary lateral sclerosis is characterized by?

Primary lateral sclerosis is characterized by?

• A. A very rare motor neuron disease involving upper motor neurons only, leading to slow progression and upper motor neuron signs.
• B. Involves degeneration of lower motor neurons only.
• C. Causes acute demyelination of the peripheral nerves.
• D. Results in rapid, reversible weakness.

Answer: (A)

Primary lateral sclerosis is a neurodegenerative condition that affects the upper motor neurons, producing a slowly progressive picture of spastic weakness with signs like hyperreflexia and Babinski, while sparing the lower motor neurons. This upper motor neuron–only involvement and the slow course are what set it apart from other motor neuron disorders and acute neuropathies. The other descriptions don’t fit: degeneration limited to lower motor neurons points to different diseases; acute peripheral nerve demyelination describes a rapid, post-viral or autoimmune process like Guillain-Barré; and rapid, reversible weakness isn’t characteristic of a chronic, progressive upper motor neuron disease.

Primary lateral sclerosis is a neurodegenerative condition that affects the upper motor neurons, producing a slowly progressive picture of spastic weakness with signs like hyperreflexia and Babinski, while sparing the lower motor neurons. This upper motor neuron–only involvement and the slow course are what set it apart from other motor neuron disorders and acute neuropathies. The other descriptions don’t fit: degeneration limited to lower motor neurons points to different diseases; acute peripheral nerve demyelination describes a rapid, post-viral or autoimmune process like Guillain-Barré; and rapid, reversible weakness isn’t characteristic of a chronic, progressive upper motor neuron disease.