Multiple sclerosis

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system in which the immune system attacks the myelin sheath that covers nerve fibers. This disrupts communication between the brain and the rest of the body and can cause permanent damage or deterioration of the nerves themselves.

MS is highly variable. Some people have mild symptoms and long periods of stability; others experience progressive disability. The most common course is relapsing-remitting MS, characterized by attacks (relapses) followed by periods of recovery (remissions). Over time, some people transition to secondary progressive MS. A minority have primary progressive MS from the outset.

There is no cure, but disease-modifying therapies can reduce relapses, slow progression, and limit new lesions on MRI. Early treatment and comprehensive symptom management improve long-term outcomes.

Symptoms depend on the location of lesions and may include:

• Numbness or weakness in one or more limbs, typically on one side of the body or the bottom half
• Electric-shock sensations that occur with certain neck movements (Lhermitte’s sign)
• Tremor, lack of coordination, or unsteady gait
• Partial or complete vision loss, usually in one eye at a time, often with pain during eye movement (optic neuritis)
• Prolonged double vision
• Blurry vision
• Slurred speech
• Fatigue
• Dizziness
• Tingling or pain in parts of the body
• Problems with sexual, bowel, and bladder function
• Cognitive changes (memory, attention, processing speed)
• Mood changes, including depression

Symptoms often worsen temporarily with heat (Uhthoff’s phenomenon).

The exact cause of MS is unknown. It is considered an immune-mediated disease occurring in genetically susceptible people after exposure to environmental factors. Leading contributors include:

• Genetic predisposition (many risk variants; strongest association with HLA-DRB1*15:01)
• Epstein–Barr virus infection
• Low vitamin D / limited sunlight exposure
• Smoking
• Obesity in early life
• Geographic latitude (higher rates farther from the equator)

The disease process involves inflammation, demyelination, axonal injury, and neurodegeneration.

Risk factors include:

• Age 20–40 at onset (though it can occur in children and older adults)
• Female sex (approximately 2–3 : 1 ratio in relapsing MS)
• Family history of MS
• Certain infections (EBV)
• Low vitamin D levels
• Smoking
• Obesity
• Northern European ancestry and living at higher latitudes

Possible complications include:

• Muscle stiffness and spasms
• Paralysis, typically in the legs
• Problems with bladder, bowel, or sexual function
• Mental changes (memory loss, trouble concentrating)
• Depression
• Epilepsy (somewhat more common than in the general population)
• Pressure sores, infections, and osteoporosis related to reduced mobility

There is no proven way to prevent MS. Not smoking, maintaining adequate vitamin D, and treating obesity may modestly reduce risk. Once MS is diagnosed, disease-modifying therapy and healthy lifestyle habits help prevent relapses and slow accumulation of disability.

Diagnosis is based on the McDonald criteria, which require evidence of lesions separated in time and space, and exclusion of alternative diagnoses. Evaluation typically includes:

• Detailed neurologic history and examination
• MRI of the brain and spinal cord with contrast
• Lumbar puncture (oligoclonal bands in CSF support the diagnosis)
• Evoked-potential studies in some cases
• Blood tests to exclude mimics (vitamin B12 deficiency, neuromyelitis optica spectrum disorder, infections, etc.)

Early and accurate diagnosis allows timely start of disease-modifying therapy.

See a doctor for persistent symptoms such as unexplained numbness, weakness, vision changes, or coordination problems lasting more than a day or two. Early evaluation by a neurologist experienced in MS improves diagnostic accuracy and access to treatment.

Seek urgent care for sudden severe neurologic deficits, which may represent a relapse or another neurologic emergency.

Treatment has several components:

Disease-modifying therapies (DMTs) reduce relapse rate and MRI activity and can slow disability progression. Options include injectables (interferons, glatiramer), oral agents (fingolimod, dimethyl fumarate, teriflunomide, siponimod, ozanimod, ponesimod, cladribine, and others), and infusion monoclonals (natalizumab, ocrelizumab, ofatumumab, ublituximab, alemtuzumab). Choice depends on disease activity, safety profile, comorbidities, and patient preference.

Relapse treatment — high-dose corticosteroids (and occasionally plasma exchange).

Symptom management — medicines and therapies for spasticity, pain, fatigue, bladder/bowel dysfunction, depression, and cognitive issues.

Rehabilitation — physical, occupational, and speech therapy; exercise; and lifestyle support.

A multidisciplinary MS team provides the best long-term care.

Helpful practices include:

• Adhering to the prescribed DMT and attending monitoring appointments
• Staying physically active within tolerance; cooling strategies for heat sensitivity
• Adequate vitamin D as advised by the clinician
• Not smoking
• Good sleep and stress management
• Prompt reporting of new or worsening neurologic symptoms
• Connecting with MS societies and support resources

Bring:

• Timeline of neurologic symptoms and any prior MRI or lumbar-puncture results
• Family history of MS or autoimmune disease
• Complete medication list
• Questions about diagnosis certainty, DMT options and side effects, monitoring, pregnancy planning, and symptom management
• A family member or friend if possible