Multiple Sclerosis

^[1]

The answer first

Multiple sclerosis is a chronic autoimmune inflammatory demyelinating disease of the central nervous system in which autoreactive T cells and B cells attack CNS myelin, producing relapsing episodes of neurological disability (the relapsing-remitting phase) and, over time, a progressive neurodegenerative decline driven by axonal loss (the progressive phase). Approximately 85 per cent of patients present with relapsing-remitting MS (RRMS) — discrete attacks of neurological dysfunction separated by periods of remission — while 15 per cent present with primary progressive MS (PPMS), an insidious decline without relapses from onset ^[2]. Over decades, most RRMS patients transition to secondary progressive MS (SPMS), in which steady disability accumulation replaces discrete relapses.

The clinical presentation is determined by the location of demyelinating lesions: optic neuritis (painful unilateral visual loss with a relative afferent pupillary defect), transverse myelitis (sensory level, weakness, sphincter disturbance), brainstem syndromes (internuclear ophthalmoplegia, vertigo, diplopia), and cerebellar syndromes (ataxia, nystagmus, scanning dysarthria). Two eponymous signs are high-yield: the Lhermitte sign (an electric shock radiating down the spine on neck flexion, from cervical cord demyelination) and the Uhthoff phenomenon (transient worsening of pre-existing symptoms with heat or exercise, from conduction block in demyelinated axons at higher body temperature). ^[1]

Diagnosis rests on the McDonald 2017 criteria, which require dissemination in space and time demonstrated either clinically or by MRI, with CSF oligoclonal bands able to substitute for dissemination in time ^[1]. Treatment has two arms: acute relapse management (methylprednisolone 1 g IV for 3 to 5 days; plasma exchange for steroid-refractory severe relapses) and disease-modifying therapy (DMT) — a rapidly expanding armamentarium ranging from injectable first-line agents (interferon-beta, glatiramer) through oral agents (dimethyl fumarate, fingolimod, teriflunomide, cladribine, siponimod) to high-efficacy monoclonal antibody infusions (natalizumab, ocrelizumab, alemtuzumab) and, for aggressive disease, haematopoietic stem cell transplantation ^{[4] [5] [6]}.

DCE trap: The biggest pivot in the MS long case is recognising that management is no longer one-size-fits-all. The modern approach demands a risk-stratified DMT strategy — escalating from platform therapy to high-efficacy agents in active disease, while actively screening for the serious complications of each drug (PML with natalizumab, autoimmunity with alemtuzumab). The candidate who presents a coherent DMT strategy, names the monitoring requirements for each drug, and integrates symptom management and reproductive planning will pass the MS long case. ^[1]

---

References13ShowHide

1. [1]Thompson AJ, Banwell BL, Barkhof F, et al. Diagnosis of multiple sclerosis: 2017 revisions of the McDonald criteria Lancet Neurol, 2018.PMID 29275977
2. [2]Lublin FD, Reingold SC, Cohen JA, et al. Defining the clinical course of multiple sclerosis: the 2013 revisions Neurology, 2014.PMID 24871874
3. [3]Bjornevik K, Cortese M, Healy BC, Kuhle J, Mina MJ, Leng Y, Elledge SJ, Niebuhr DW, Scher AI, Munger KL, Ascherio A Longitudinal analysis reveals high prevalence of Epstein-Barr virus associated with multiple sclerosis Science, 2022.PMID 35025605
4. [4]Montalban X, Hauser SL, Kappos L, Arnold DL, Bar-Or A, Comi G, de Seze J, Giovannoni G, Hartung HP, Hemmer B, Lublin F, Rammohan KW, Selmaj K, Traboulsee A, Sauter A, Masterman D, Fontoura P, Belachew S, Garren H, Mairon N, Chin P, Wolinsky JS Ocrelizumab versus Placebo in Primary Progressive Multiple Sclerosis N Engl J Med, 2017.PMID 28002688
5. [5]Hauser SL, Bar-Or A, Comi G, et al. Ocrelizumab versus Interferon Beta-1a in Relapsing Multiple Sclerosis N Engl J Med, 2017.PMID 28002679
6. [6]Kappos L, Bar-Or A, Cree BAC, et al. Siponimod versus placebo in secondary progressive multiple sclerosis (EXPAND): a double-blind, randomised, phase 3 study Lancet, 2018.PMID 29576505
7. [7]Bloomgren G, Richman S, Hotermans C, et al. Risk of natalizumab-associated progressive multifocal leukoencephalopathy N Engl J Med, 2012.PMID 22591293
8. [8]Cohen JA, Coles AJ, Arnold DL, et al. Alemtuzumab versus interferon beta 1a as first-line treatment for patients with relapsing-remitting multiple sclerosis: a randomised controlled phase 3 trial Lancet, 2012.PMID 23122652
9. [9]Coles AJ, Twyman CL, Arnold DL, et al. Alemtuzumab for patients with relapsing multiple sclerosis after disease-modifying therapy: a randomised controlled phase 3 trial Lancet, 2012.PMID 23122650
10. [10]Giovannoni G, Comi G, Cook S, Rammohan K, Rieckmann P, Soelberg Sorensen P, Vermersch P, Chang P, Hamlett A, Musch B, Greenberg SJ A placebo-controlled trial of oral cladribine for relapsing multiple sclerosis N Engl J Med, 2010.PMID 20089960
11. [11]Gold R, Kappos L, Arnold DL, Bar-Or A, Giovannoni G, Selmaj K, Tornatore C, Sweetser MT, Yang M, Sheikh SI, Dawson KT Placebo-controlled phase 3 study of oral BG-12 for relapsing multiple sclerosis N Engl J Med, 2012.PMID 22992073
12. [12]PRISMS (Prevention of Relapses and Disability by Interferon beta-1a Subcutaneously in Multiple Sclerosis) Study Group Randomised double-blind placebo-controlled study of interferon beta-1a in relapsing/remitting multiple sclerosis. PRISMS (Prevention of Relapses and Disability by Interferon beta-1a Subcutaneously in Multiple Sclerosis) Study Group Lancet, 1998.PMID 9820297
13. [13]Confavreux C, Hutchinson M, Hours MM, et al. Rate of pregnancy-related relapse in multiple sclerosis. Pregnancy in Multiple Sclerosis Group N Engl J Med, 1998.PMID 9682040