Multiple sclerosis

Last updated: September 20, 2022

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Multiple sclerosis (MS) is a chronic degenerative disease of the CNS characterized by demyelination and axonal degeneration in the brain and spinal cord, which are caused by an immune-mediated inflammatory process. The prevalence of MS is higher among women and people in temperate regions such as Europe and North America. Impaired vision (due to retrobulbar neuritis) is usually the first manifestation of MS; other neurological deficits appear as the disease progresses. The most common clinical course is characterized by exacerbations followed by periods of complete or incomplete remission. Diagnosis is made using clinical and MRI findings to identify the dissemination of CNS lesions in time and space. Characteristic MRI findings are demyelinated sclerotic plaques primarily located in white matter. Differential diagnoses of MS include other chronic demyelinating diseases and neurological infections (e.g., borreliosis, neurosyphilis). Acute exacerbations of MS are usually treated with high-dose glucocorticoids. Between exacerbations, patients may be treated with disease-modifying drugs (e.g., interferon beta, glatiramer acetate, natalizumab). There is currently no definitive treatment for MS.

  • Sex: : > (3:1) [1]
  • Age of onset: : 20–40 years of age [2]
  • Ethnicity: prevalence among the white population [2]
  • Prevalence: 50-300 per 100 000 people (greater among people who live further from the equator) [2]

Epidemiological data refers to the US, unless otherwise specified.

The etiology of multiple sclerosis is unclear; it is believed to develop in genetically predisposed people who have been exposed to certain environmental factors.

Definitions [6][7]

  • Exacerbation
    • New symptoms or significant worsening of symptoms caused by CNS demyelination that last at least 24 hours and are not accompanied by fever or infection
    • Also referred to as an attack, relapse, or flare
  • Remission: a period of recovery after an exacerbation during which clinical symptoms resolve completely or almost completely
  • Pseudorelapse: recurrence or significant worsening of existing symptoms due to stressors (e.g., infection, heat)
  • Radiologically isolated syndrome (RIS) [8]
    • The presence of demyelinating lesions characteristic of MS in an asymptomatic individual
    • Not considered an MS phenotype but may progress to MS
  • Clinically isolated syndrome (CIS)
    • A single episode of neurological symptoms resulting from CNS demyelination
    • A second episode of such symptoms increases the likelihood that the symptoms are not clinically isolated and that the patient meets the diagnostic criteria for MS.
  • Diffuse cerebral sclerosis (Schilder disease) [9][10]
    • A rare inflammatory demyelinating CNS condition that affects children and young adults
    • Large areas of demyelination lead to various neurological deficits and psychological changes.

Clinical course [6][11][12]

Clinical phenotypes of multiple sclerosis [6][11][12]
Phenotype Characteristics Frequency
Relapsing-remitting MS (RR-MS)
  • Exacerbations occur.
  • Symptoms remit almost completely between exacerbations.
  • ∼ 90% (most common clinical course)
Secondary progressive MS (SP-MS)
  • A progression of RR-MS characterized by continuous worsening of neurological function that occurs independently of exacerbation events
  • ∼ 50% of patients with RR-MS develop SP-MS.
Primary progressive MS (PP-MS)
  • Symptoms continuously worsen from the onset of the disease.
  • ∼ 10%

Fundoscopy is normal in 60% of cases of optic neuritis. Neither the patient nor the doctor are able to see anything.

Uhthoff phenomenon triggered by a viral infection may mimic an exacerbation of MS.

MS is a chronic condition that typically manifests in a relapsing-remitting form characterized by episodic CNS dysfunction (exacerbations) with at least partial recovery between episodes.

General principles [6][20]

  • Diagnosis of MS depends on a combination of clinical findings (e.g., optic neuritis, Lhermitte sign, sensory abnormalities, cerebellar signs), imaging, and laboratory results.
  • Consider early specialist (i.e., neurology) consultation for patients with history and clinical features suggestive of MS.
  • The McDonald Criteria for both DIT and DIS must both be met to confirm a diagnosis of MS: [6]
  • In some cases, electrophysiological, CSF, and laboratory studies may be necessary to support the diagnosis and exclude differential diagnoses. [21]

Clinical evidence or MRI findings consistent with the presence of CNS lesions that are disseminated in both time and space confirm the diagnosis of MS.

Imaging [6][12]

MRI is the imaging study of choice for the diagnosis and monitoring of MS.

Additional studies

Consider further testing for patients with nondiagnostic MRI and to rule out differential diagnoses.

The presence of multiple oligoclonal bands in CSF and their absence in the blood is highly suggestive of MS. [25][27]

Autoimmune diseases associated with inflammatory demyelination

Neuromyelitis optica spectrum disorders (NMOSD; previously known as Devic disease or neuromyelitis optica) [28][29]

Diagnostic criteria of NMOSD based on AQP4-IgG status
Serological criteria Clinical criteria Additional criteria
Positive AQP4-IgG
  • Exclusion of other causes (e.g., MS)
Negative AQP4-IgG or unknown status

Acute disseminated encephalomyelitis (ADEM, acute demyelinating encephalomyelitis) [30]

Other conditions

Transverse myelitis [31]

Overview of transverse myelitis types
Types of TM Manifestations MRI findings
Longitudinally limited TM (LLTM) Acute complete TM (ACTM)
Acute partial TM (APTM)1
Longitudinally extensive TM (LETM)


The differential diagnoses listed here are not exhaustive.

General principles [33]

Treatment should be initiated as early as possible; the goals of treatment are to manage the primary exacerbation, prevent further exacerbations, and slow disease progression.

Management of acute exacerbations [6][36]

If an acute exacerbation of MS is suspected, a specialist should be consulted immediately for management.

Mild exacerbations that do not impact physical functioning may not require medical treatment.

Disease-modifying MS therapy

  • There are multiple disease-modifying drugs available to treat MS.
  • The decision about agent requires careful consideration of:
    • Individual patient's characteristics (e.g., clinical phenotype, comorbidities)
    • Medication side effects
    • Other factors (e.g., medication availability, route of administration)
  • All patients receiving disease-modifying therapy for MS should use birth control.

Disease-modifying therapy for MS is generally not recommended for pregnant and breastfeeding patients. [42]

Commonly used disease-modifying MS drugs by clinical phenotype
Phenotype Drugs commonly used
Clinically isolated syndrome [43]
Relapsing-remitting MS [6]
Secondary progressive MS [44]
  • All disease-modifying therapies may be used for active SP-MS.
Primary progressive MS [45]

Monoclonal antibodies (e.g., natalizumab, ocrelizumab) have the highest efficacy for reducing exacerbations, but lower efficacy medications (e.g., interferon beta, glatiramer acetate) often have fewer side effects. [6]

Overview of disease-modifying drugs in MS therapy (DMDs) [6][12][43]
Medication Mechanism of action Adverse effects

Interferon beta

Glatiramer acetate (copolymer-1)

Dimethyl fumarate

  • An immunomodulator; protects nerve cells through its antiinflammatory effect [49]
  • Inhibits pyrimidine synthesis, which has an antiproliferative and antiinflammatory effect [50]
Cladribine [1][51]
Sphingosine 1-phosphate receptor modulators [52] Fingolimod


Monoclonal antibodies


Mitoxantrone [21][54]

Supportive care and symptom management [6][57][58]

Consider any of the following measures in a management plan tailored to the individual patient:

Physical therapy, occupational therapy, and psychotherapy are safe, nonpharmacological options that can improve multiple symptoms in patients with MS, including spasticity, fatigue, walking difficulties, and neuropathic pain.

Prognostic factors for disease progression [61][62]

  • Male sex
  • Age at MS onset > 40 years
  • Multiple symptoms with early motor and cerebellar involvement
  • Incomplete recovery after exacerbations
  • High relapse rate in the first 2 years after MS onset

Multiple sclerosis in pregnancy [6][42]



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