What is multiple sclerosis?

What is Multiple Sclerosis

Multiple sclerosis is a chronic, inflammatory, and autoimmune disease of the central nervous system that causes widespread focal degradation of the myelin sheath, variable axonal and neuronal injury, and progressive disability in young adults. 1

Disease Pathophysiology

• MS is characterized by inflammatory demyelination with axonal transection, where the body's immune system attacks its own central nervous system tissue 2, 3
• The disease leads to widespread focal degradation of the myelin sheath covering nerve fibers in the brain and spinal cord, with variable degrees of axonal and neuronal injury 1, 2
• The pathobiology includes both inflammatory and neurodegenerative mechanisms affecting white and gray matter 4
• The cause remains unknown, though research suggests genetic, immunological, and environmental factors (such as common viruses) are all involved in a complex etiology 1

Clinical Forms and Disease Course

Relapsing-Remitting MS (RRMS)

• Affects approximately 85% of clinical cases 1
• Nerve impulse conduction along axons may be affected during acute inflammatory phases (relapses), but tends to improve with healing during remission phases 1
• Over time, relapses cause extensive damage and scarring of the myelin sheath with progressive loss of neuronal function 1

Primary-Progressive MS (PPMS)

• Affects approximately 15% of clinical cases 1
• Characterized by progressive neurological damage rather than distinct relapses and remissions 1

Epidemiology and Demographics

• MS affects an estimated 900,000 people in the United States 2
• Worldwide prevalence ranges from 5 to 300 per 100,000 people, with higher rates at higher latitudes 2
• Typically presents in young adults with mean age of onset between 20-30 years 1, 2
• More commonly affects women, with a female-to-male ratio of nearly 3:1 2
• Overall life expectancy is reduced compared to the general population (75.9 vs 83.4 years) 2

Clinical Presentation

• MS presents with a wide range of neurological symptoms that vary significantly between patients 5
• Typical initial presentations include unilateral optic neuritis, partial myelitis, sensory disturbances, or brainstem syndromes such as internuclear ophthalmoplegia developing over several days 2
• Common symptoms include sensory disturbances, motor weakness, visual problems, and balance difficulties 5

Nutritional Complications

• Weight loss, malnutrition, and even cachexia are well-recognized features of MS patients 1
• Causes of malnutrition include reduced mobility and fatigue, inappropriate diet, physical difficulty eating or drinking, poor appetite, poor sight, reduced cognition, and dysphagia 1

Impact on Quality of Life

• MS is characterized by physical disability, cognitive impairment, and decreased quality of life 2
• The disease is the leading cause of nontraumatic neurological disability in young adults 6
• Patients require lifelong disease-modifying therapy and comprehensive symptom management 7, 6