What is of a nerve cell hardens in patients with multiple sclerosis?

In multiple sclerosis (MS), the myelin sheath that insulates nerve fibers in the central nervous system hardens due to an autoimmune attack. This process, known as demyelination, leads to the formation of scar tissue or plaques, which disrupts the transmission of electrical signals along the nerves. As a result, patients may experience a range of neurological symptoms, including weakness, coordination problems, and sensory disturbances.