Multiple sclerosis

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Multiple sclerosis

Nervous system


Multiple sclerosis


0 / 13 complete

USMLE® Step 1 questions

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High Yield Notes

8 pages


Multiple sclerosis

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USMLE® Step 1 style questions USMLE

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A 27-year-old woman comes to the emergency department due to sudden loss of vision in the right eye that began several hours ago. The patient has intense pain with any movement of the eye. She has no significant past medical history, but she did have an episode of reduced sensation in her legs 6 months ago. This episode resolved spontaneously after several days. On neurologic examination, there is a relative afferent pupillary defect in the right eye. There is reduced adduction of the left eye with right lateral gaze. Convergence testing shows no abnormalities. Physical examination reveals decreased pain and light touch perception in both legs. Mild bilateral spasticity is observed. MRI of the brain and spine is inconclusive. Further testing is likely to demonstrate which of the following?  

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multiple sclerosis p. 541

β -interferon

multiple sclerosis p. 541

Cerebrospinal fluid (CSF)

multiple sclerosis p. 541

IgG antibodies p. 103

multiple sclerosis p. 541

Intention tremor p. 537

multiple sclerosis p. 541

Intention tremors

multiple sclerosis p. 719

Internuclear ophthalmoplegia p. 528, 563

multiple sclerosis p. 719

Marcus Gunn pupils p. 559

multiple sclerosis p. 541

Multiple sclerosis p. 541

Daclizumab p. NaN

heart murmur with p. 298

HLA-DR2 and p. 98

IFN- β for p. 201

internuclear ophthalmoplegia p. 563

natalizumab for p. 120

oligodendroglia in p. 509

presentation p. 719

recombinant cytokines for p. NaN

as type IV hypersensitivity p. 111

Muscarinic antagonists p. 242, 712

multiple sclerosis p. 541

Natalizumab p. 120

multiple sclerosis p. 541


multiple sclerosis p. 541, 719


multiple sclerosis p. 541

Urinary incontinence p. 624

multiple sclerosis p. 541

White matter

multiple sclerosis p. 541


Content Reviewers

Multiple sclerosis is a demyelinating disease of the central nervous system, which includes the brain and the spinal cord.

Myelin is the protective sheath that surrounds the axons of neurons, allowing them to quickly send electrical impulses.

This myelin is produced by oligodendrocytes, which are a group of cells that support neurons.

In multiple sclerosis, demyelination happens when the immune system inappropriately attacks and destroys the myelin, which makes communication between neurons break down, ultimately leading to all sorts of sensory, motor, and cognitive problems.

Now, the brain, including the neurons in the brain, is protected by things in the blood by the blood brain barrier, which only lets certain molecules and cells through from the blood.

For immune cells like T and B cells that means having the right ligand or surface molecule to get through the blood brain barrier, this is kind of like having the a VIP pass to get into an exclusive club.

Once a T cell makes its way in it can get activated by something it encounters - in the case of multiple sclerosis, it’s activated by myelin.

Once the T-cell gets activated, it changes the blood brain barrier cells to express more receptors, and this allows immune cells to more easily bind and get in, it’s kind of like bribing the bouncer to let in a lot of people.

Now, multiple sclerosis is a type IV hypersensitivity reaction, or cell-mediated hypersensitivity. And this means that those myelin specific T-cells release cytokines like IL-1, IL-6, TNF-alpha, and interferon-gamma, and together dilate the blood vessels which allows more immune cells to get in, as well as directly cause damage to the oligodendrocytes.


Multiple sclerosis is a progressive, demyelinating disease on the central nervous system, characterized by the destruction of myelin, the protective sheath surrounding nerve cells, as well as inflammation and scarring of nerve fibers.

Damage to these nerves disrupts the ability of parts of the nervous system to transmit impulses, resulting in a wide range of signs and symptoms, including physical, mental, and sometimes psychiatric problems. Symptoms vary widely, but they may include muscle weakness, fatigue, vision problems, balance and coordination problems, and problems with memory and thinking.


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  2. "Harrison's Principles of Internal Medicine" McGraw Hill Education/ Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw Hill Professional (2019)
  5. "Multiple sclerosis" The Lancet (2008)
  6. "Defining the clinical course of multiple sclerosis: Results of an international survey" Neurology (1996)

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