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Multiple sclerosis (MS)
Multiple sclerosis is an inflammatory demyelinating disease of the central nervous system, and the diagnosis rests on dissemination in space and time: lesions in several typical regions, appearing at different times, with no better explanation.
Why it matters in the exam
The classic scenario is a young woman with optic neuritis, ascending numbness or double vision, and on examination an internuclear ophthalmoplegia (INO) or Lhermitte's sign. Questions ask how the diagnosis is made (MRI, McDonald criteria, oligoclonal bands), what treats a relapse (high-dose steroids), which disease-modifying therapy fits, and which adverse effects are dangerous (PML with natalizumab). Common distractors include treating a relapse with low-dose oral steroids, confusing it with NMOSD, and forgetting that worsening with heat (Uhthoff's phenomenon) is not a new relapse. Relapses also fall in pregnancy and rise after delivery.
Key points
- Multiple sclerosis is a demyelinating disease, mainly in young women.
- McDonald diagnosis: dissemination in space and time on MRI, with oligoclonal bands as a substitute for time.
- A relapse is treated with methylprednisolone 1 g intravenously for 3 to 5 days.
- Early disease-modifying therapy; natalizumab needs JC antibody monitoring because of PML.
- Uhthoff is not a relapse; relapses fall in pregnancy and rise after delivery.
Summary table
| Topic | Core | Exam detail |
|---|---|---|
| Presentation | Optic neuritis, partial myelitis, brainstem syndrome (INO), numbness, fatigue | Lhermitte's sign (shock on neck flexion) and Uhthoff's phenomenon (worse with heat) |
| Dissemination in space | One or more T2 lesions in at least 2 of 4 regions: periventricular, cortical or juxtacortical, infratentorial, spinal cord | In the 2024 revision the optic nerve was added as a fifth region |
| Dissemination in time | Simultaneous gadolinium-enhancing and non-enhancing lesions, a new lesion on follow-up, or oligoclonal bands in the CSF | The bands can substitute for the time requirement |
| Relapse treatment | Methylprednisolone 1 g intravenously daily for 3 to 5 days; plasma exchange for a severe relapse that did not respond | Shortens the relapse, does not change the long-term course |
| Disease-modifying therapy | Moderate efficacy: interferon beta, glatiramer, teriflunomide, dimethyl fumarate; high efficacy: anti-CD20 (ocrelizumab, ofatumumab), natalizumab, cladribine, S1P modulators | Natalizumab — PML risk by JC antibodies; fingolimod — bradycardia and macular oedema; ocrelizumab is also approved for primary progressive disease |
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Sources
- Diagnosis of Multiple Sclerosis: 2017 Revisions of the McDonald Criteria (Lancet Neurology), 2018 — Dissemination in space and time
- ECTRIMS/EAN Guideline on the Pharmacological Treatment of People With Multiple Sclerosis, 2018 — Disease-modifying therapy
- McDonald Criteria Revision, 2024 — Optic nerve as an additional region
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.