What MS is, how symptoms and diagnosis vary, and how care differs from research into myelin repair.
Multiple sclerosis (MS) is a long-term condition of the central nervous system: the brain and spinal cord. The immune system can attack myelin, the protective covering around nerve fibres, and can also damage the fibres themselves. This can make messages between the brain and body less reliable, affecting functions such as vision, movement, sensation and thinking.
MS is not contagious. You cannot catch it from another person.
A simple comparison shows intact myelin, its loss and remyelination. The central line is the same nerve fibre in all three drawings.
Successive sheaths wrap the axon. The small gaps between them are normal.
The sheath is absent in the centre. The dashed outline shows where it was, not myelin that remains.
A new sheath can form. Here it is thinner and divided into shorter stretches than the original.
MS does not affect everyone in the same way. Symptoms, their intensity and the course of MS vary, and can change over time for the same person. Some people have fewer day-to-day difficulties, while others need more support. One person’s course does not predict another’s.
Fatigue, pain, difficulties with concentration or bladder problems can affect everyday life deeply even when someone looks well. The absence of visible symptoms does not mean the absence of disability — or a lesser need for understanding, support and adjustments.
These symptoms can have many causes and are not a way to diagnose MS.
Intense physical or mental exhaustion, beyond ordinary tiredness.
Blurred or double vision, eye pain, or other visual changes.
Weakness, stiffness, tremor, difficulty walking or problems with balance.
Numbness, tingling, altered sensation or pain.
Slower thinking, memory problems or difficulty concentrating.
Changes that can be difficult to discuss but are important to raise with a care team.
There is no single test that gives the answer on its own. A neurologist combines the person’s history, neurological examination and MRI scans. When needed, they use tests of cerebrospinal fluid collected by lumbar puncture and other specialist tests. Diagnosis uses international criteria and requires checking for other conditions that may explain the findings. Not everyone needs every test.
History and examination
MRI
Other tests when needed
Sources for this section: World Health Organization — Multiple sclerosis ↗ MS Trust — What is MS? ↗ MS Trust — Invisible symptoms ↗ MS Trust — McDonald criteria ↗ NHS — Multiple sclerosis ↗
How many people live with MS depends on the place, period and method used to count them. The full page shows each figure with its period, source and limitations.
Six milestones in chronological order — including the open question research is still trying to answer.
1868
Jean-Martin Charcot’s lectures brought clinical observation and pathology together under the name sclérose en plaques.
1981
An early study showed that nuclear magnetic resonance imaging detected lesions that CT had not shown. MRI later became central to assessment alongside clinical evidence.
1993
The US FDA record lists interferon beta-1b (Betaseron) for ambulatory people with relapsing-remitting MS. This was a US approval, not a worldwide approval.
2017
On 28 March, the US FDA approved ocrelizumab (Ocrevus) for relapsing and primary progressive forms of MS. This important US approval did not solve progression or mean the treatment is right for every person with progressive MS.
US FDA — Ocrevus (ocrelizumab) approval package, 28 March 2017 ↗
2024 criteria / published 2025
The 2024 revisions of the McDonald criteria were published in 2025. They incorporate newer diagnostic evidence, but diagnosis still needs neurological assessment and exclusion of a better explanation.
The Lancet Neurology — Diagnosis of multiple sclerosis: 2024 revisions of the McDonald criteria ↗
Today
Can treatments protect nerve cells and reliably repair myelin in a way that improves people’s daily function? This remains active research, not an established cure.
Limit new damage
Disease-modifying treatments (DMTs), when appropriate, can reduce relapses and new inflammatory activity and can help slow disability accumulation. Starting an appropriate treatment and regular monitoring can matter. There is no one treatment that fits everyone: choices are made with a neurologist, considering the MS pattern and activity, expected benefits, risks and the person’s needs. Symptom management, physiotherapy, occupational therapy, psychological support and practical adjustments are also part of care.
Sources for this section: MS Trust — Disease modifying therapies ↗ NHS — Multiple sclerosis ↗
Look for ways to repair
The body has natural ways to repair myelin, but in MS this repair is often not enough. Research is exploring how to strengthen these processes, restore the protective covering around surviving nerve fibres and protect them from further damage. At present, there is no established approved treatment in clinical practice that has been shown to reliably restore myelin in MS.
Sources for this section: MS Society — Myelin repair ↗ World Health Organization — Multiple sclerosis ↗
