Final answer:
Multiple sclerosis (MS) is an autoimmune disease that affects the central nervous system. It causes the breakdown of the myelin sheath, leading to a wide range of symptoms. There are four classifications of MS, each with different progression patterns.
Step-by-step explanation:
Multiple sclerosis (MS) is an autoimmune central nervous system disease that affects the brain and spinal cord. It is characterized by the breakdown of the myelin sheath, which insulates neurons and facilitates neuronal communication. This breakdown disrupts neuronal signaling and leads to a wide range of symptoms, including visual disturbances, muscle weakness, coordination difficulties, sensory abnormalities, and cognitive and memory problems.
There are four classifications of MS:
- Relapsing-remitting: This is the most common form of MS and is characterized by distinct episodes of new or worsening symptoms followed by periods of remission.
- Secondary-progressive: In this form, the disease initially follows a relapsing-remitting course, but over time, the symptoms worsen progressively without periods of remission.
- Primary-progressive: This form is characterized by a gradual progression of symptoms from the onset without distinct relapses or remissions.
- Progressive-relapsing: This is the least common form of MS and is characterized by a gradual progression of symptoms from the onset, with superimposed relapses.