Diagnosing Multiple Sclerosis

Jump to topic

Medical history and a neurological exam are fundamental to the diagnostic process of MS. Magnetic Resonance Imaging (MRI), evoked potentials and occasionally lumbar puncture, are tests that may be useful in confirming when a diagnosis of MS is suspected. A diagnosis of MS must include evidence of disease activity separated in time (lesions that formed at different points in time) and space (lesions in at least two separate areas of the CNS).

It is important to remember that there is no one test that can be used to diagnose MS. The diagnosis of MS is one made only once other potential causes for symptoms have been ruled out.

Magnetic Resonance Imaging (MRI)

MRI is a medical imaging technique commonly used in radiology to visualize the internal function and structure of the body. In MS, the MRI can provide pictures of the areas of damage (lesions) in the central nervous system, caused by MS, and can also reveal whether there is loss of brain volume.

Lumbar Puncture (LP)

Lumbar puncture or spinal tap involves inserting a small needle at the base of the spine, just above the tailbone, to draw a small amount of the cerebrospinal fluid (CSF) to test for the presence of particular proteins (antibodies), called oligoclonal bands, which are known to be present with inflammation in the CNS.

Evoked Potentials (EP)

Evoked potentials (EP) may be ordered by your neurologist to measure how quickly nerve impulses travel along the nerve fibres in various parts of the CNS.

MS Allied Diseases

MS Canada provides support and services to individuals with allied conditions including neuromyelitis optica spectrum disorder (NMOSD), transverse myelitis (TM) and acute disseminated encephalomyelitis (ADEM). Like MS, NMOSD, TM and ADEM are demyelinating conditions of the central nervous system. Although they share some of the same symptoms as MS, they are different conditions with distinct clinical features.

Neuromyelitis Optica Spectrum Disorder (NMOSD)

NMOSD is a rare autoimmune disorder of the central nervous system (CNS) where antibodies can damage the spinal cord and/or optic nerves during attacks. It is a demyelinating condition, meaning, it damages the protective myelin sheath around the nerve fibres. 

Learn more about NMOSD.

Transverse Myelitis (TM)

TM is a neurological disorder caused by inflammation of the spinal cord. It can occur in individuals of all ages and affects both genders. Symptoms of TM can include weakness of the legs and arms, pain, abnormal sensations (burning, prickling, tingling etc.) and bowel and bladder dysfunction. Most individuals will only have one TM attack although some may have a recurring attack. Transverse myelitis can also be the first symptom of MS or NMOSD*.

Acute Disseminated Encephalomyelitis (ADEM)

ADEM is a rare neurological condition characterized by a short-lived but widespread attack of inflammation in the central nervous system (brain, including optic nerve, and spinal cord) causing damage to the myelin. It is generally seen in children but can affect individuals of any age.

Learn more about ADEM.

Get Support

Have questions about diagnosing MS? Talk to an MS Navigator and get quality MS information and support tailored to your journey.

Conditions to Rule Out

When MS is suspected, it is important for doctors to rule out other potential causes for the symptoms an individual is experiencing. Many symptoms suggestive of MS are also seen in other conditions.

Lyme Disease

Lyme disease is an illness caused by the bacterium Borrelia burgdorferi, which can be spread through the bite of certain types of ticks. Lyme disease in humans can have serious symptoms, including neurological symptoms similar to those seen in MS, but can generally be treated with antibiotics. Lyme disease can cause rashes and joint symptoms unlike MS.

Neurological symptoms may include meningitis, encephalitis, Bell’s palsy, weakness, impaired language, fatigue and impaired memory. Brain MRI may or may not show lesions in the white matter. These lesions are usually non-specific, but sometimes may mimic MS lesions.

For more information about Lyme disease please visit the Public Health Agency of Canada.

Chronic Fatigue Syndrome

Chronic Fatigue Syndrome is a disorder characterized by extreme fatigue without an underlying medical condition. There is no one test to diagnose CFS. Some CFS symptoms are similar to MS symptoms however CFS symptoms also include sore throat and swollen lymph nodes in the neck or armpit, which are not seen in MS.


Lupus is a chronic inflammatory disease where an individual’s immune system attacks its own tissues and organs. Inflammation caused by lupus can affect different body systems, including the joints, skin, kidneys, blood cells, brain, heart and lungs. Lupus can be difficult to diagnose because signs and symptoms are similar to those seen in other conditions however there are distinct symptoms that are not seen in MS such as skin rash, shortness of breath and fever.

This is not an extensive list; your doctor may need to rule out other conditions. It is possible to have MS and another condition but this does not mean that they are related or that one has caused the other.

*With information from NINDS