What is the underlying cause of paralysis in Guillain-Barré Syndrome?

In Guillain-Barré Syndrome (GBS), the primary underlying cause of paralysis is the demyelination of peripheral nerves. This condition occurs when the immune system mistakenly attacks the myelin sheath that surrounds and protects nerve fibers in the peripheral nervous system. The loss of myelin disrupts the normal transmission of electrical signals along the nerves, leading to symptoms such as muscle weakness, numbness, and paralysis.

Demyelination reduces the speed at which signals travel along the nerves, and in severe cases, it can lead to complete blockades of nerve transmission. This is why patients with GBS may experience rapid onset muscle weakness and, in some cases, life-threatening complications such as respiratory failure if the nerves controlling breathing are affected.

While viral infections and autoimmune responses can be associated with the onset of GBS, they are not the direct cause of paralysis. The autoimmune response in this context triggers the demyelination rather than being the primary mechanism of paralysis itself. Genetic predisposition may play a role in an individual's susceptibility to developing GBS but does not directly cause paralysis. Thus, the demyelination of peripheral nerves stands as the correct answer, as it is the most specific and direct explanation for the paralysis seen in this syndrome.