Skip to main content

How do you test for multiple sclerosis?

Medically reviewed by Carmen Fookes, BPharm. Last updated on Oct 29, 2021.

Official answer


There is no specific test for multiple sclerosis (MS), instead, a doctor will determine if you meet the long-established criteria for a diagnosis of MS by considering your symptoms, looking at your medical and family history, conducting a neurological exam, and performing various tests, such as magnetic resonance imaging (MRI), evoked potentials (EP) and spinal fluid analysis. Diagnosing MS is all about looking for features and findings typical of MS but ruling out all other possible causes. To make a diagnosis of MS, a doctor must:

  • Find evidence of damage in at least two separate areas of your central nervous system (CNS), which includes your brain, spinal cord, and optic nerves
  • Determine that these areas of damage occurred at least one month apart or at separate points in time
  • Rule out all other possible diagnoses

What are the most common symptoms of MS?

The most common symptoms of MS include:

  • Weakness or numbness in one or more limbs
  • The painful loss of vision in one eye (optic neuritis)
  • Tremor and abnormal, uncoordinated movements while walking
  • Double vision, slurred speech, or dizziness
  • Fatigue.

Most symptoms develop abruptly, within hours or days, reach their peak within a few days, and resolve slowly lasting for about 8 weeks from onset to recovery. However, symptoms of MS and how they develop or last vary greatly from person to person. When people first develop MS, attacks tend to strike approximately every 12 to 18 months. This is referred to as relapsing-remitting MS. But with time, the attacks begin more slowly, persist for longer, and are less likely to resolve completely, gradually transforming into a pattern of steady deterioration rather than episodic flares. This pattern is referred to as secondary progressive MS.

Who is more likely to get MS? Medical and family history.

Almost twice as many women as men develop MS and it most often strikes between the ages of 20 and 40. Caucasians are especially vulnerable, particularly those from northern Europe or living in northern latitudes. There is a 1 to 5% risk of developing MS if a parent or sibling has the disease, and at least a 25% likelihood among identical twins.

Your doctor will also perform a variety of tests including evaluating your mental, emotional, and language functions, movement and coordination, balance, and vision.

What do doctors look for in an MRI for MS?

MRI is the best imaging technology for detecting the presence of MS plaques or scarring (also called lesions) in different parts of the CNS. It can also tell the difference between old and new lesions although a diagnosis of MS cannot be made solely based on an MRI as many elderly people have lesions that look similar to those caused by MS and about 5% of people who are confirmed to have MS do not initially have brain lesions on MRI.

What are evoked potentials?

In an evoked potential test, your doctor analyzes how your brain reacts to an alternating checkerboard pattern. These tests can sometimes provide evidence of scarring along nerve pathways that do not show up during a neurologic exam.

What is a spinal fluid analysis?

Spinal fluid is examined for proteins and inflammatory cells called oligoclonal bands that are found in the spinal fluid of 90-95% of people with MS (although they may be found in other conditions as well). It can also help rule out other conditions or infections.

What conditions can resemble MS?

Other conditions that can resemble MS symptoms or affect myelin include:

  • Viral infections
  • Collagen vascular disease
  • Exposure to toxic materials
  • Guillain-Barré syndrome
  • Severe vitamin B-12 deficiency
  • Rare heredity disorders
  • Other autoimmune disorders.

Are there any blood tests that will diagnose MS?

Although there is no definitive blood test for MS, blood tests can rule out other conditions with symptoms similar to those of MS, including Lyme disease, collagen-vascular diseases, certain rare hereditary disorders, and AIDS.

  • Rolak LA. Multiple sclerosis: it's not the disease you thought it was. Clin Med Res. 2003;1(1):57-60. doi:10.3121/cmr.1.1.57
  • Multiple sclerosis Mayo Clinic.

Related medical questions

Related support groups