Reviewed by: HU Medical Review Board | Last reviewed: May 2021

Diagnosing MS can be challenging for many reasons. The road to receiving a diagnosis often involves many of these experiences:

Receiving a correct diagnosis

It is common for a diagnosis of MS to be slow. There are many other conditions that have similar symptoms and imaging findings to those of MS. These include other autoimmune conditions like lupus. Infections like Lyme disease and HIV can also cause MS-like symptoms. Trauma to the spine or slipped discs in the back look like MS, too.1

How is MS diagnosed?

MS is a clinical diagnosis. This means there is no 1 test that confirms it. Instead, a healthcare provider can use many different signs and test results to make the final call. Data can be collected from a person’s history, physical exam, lab tests, and imaging. Most of the steps toward diagnosis will be completed with a neurologist. A neurologist is a doctor who specializes in conditions of the nervous system.1-3

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History and physical exam

The first step in diagnosing MS is taking a history. You will be asked questions about your symptoms, how often they occur, and where they are in the body. You will also be asked about personal and family history of other medical issues. Other symptoms, like bowel or bladder problems, fatigue, and fevers, will also be discussed.

After this is the physical exam. While a full exam is completed, the most important part is the neurological exam. Your doctor can look for signs of neurological issues and find parts of the body affected. They will test many aspects of the nervous system, including facial movements, eyesight, muscle function, and reflexes.1,2

Testing: labs, evoked potentials, and CSF analysis

It is possible to make an MS diagnosis from the history and physical exam alone. However, most doctors order other tests for more information. Blood tests may rule out other conditions with similar symptoms. These include tests for infections or autoimmune antibodies.

Further testing may include evoked potential tests and cerebrospinal fluid (CSF) analysis.1-3

Evoked potential tests record and measure electrical signals as they travel through the nervous system. These can detect minor changes in nerve communication due to damage.1-3

CSF is the fluid that surrounds the brain and spinal cord. A small sample of CSF can be collected during a lumbar puncture. This involves sticking a needle into the lower spine. The collected fluid can be studied for signs of infection, inflammation, and proteins. One protein, called oligoclonal bands (O-bands), may indicate a person has MS.1-3

Magnetic resonance imaging (MRI)

The most helpful test in diagnosing MS is a magnetic resonance imaging (MRI) scan. An MRI scan can look at the brain and spinal cord in great detail. It can detect small abnormalities called lesions. These lesions are a sign of inflammation. When looking for MS on an MRI scan, most doctors use IV contrast. Contrast helps doctors see different structures in the body better. When a lesion takes up the contrast and becomes bright, the lesion is new or active.1-4

People with MS often have lesions in several areas of the brain. Some of the lesions may become bright from the IV contrast, while other lesions do not. This means that some of the lesions are new, while others are older. The presence of lesions that are separated by space (in different areas of the brain) and by time (some new and some old) can help make the diagnosis of MS.1-4

McDonald criteria for MS diagnosis

The McDonald criteria is a set of guidelines developed in 2010 by the International Panel on the Diagnosis of Multiple Sclerosis. They are used to aid in diagnosing MS. The criteria were most recently updated in 2017. The McDonald criteria take into account the number of clinical attacks (symptom episodes) a person has had as well as any lesions present on imaging. In some cases, the presence of O-bands or CSF analysis can also be considered.1-4

The overall goal is to determine if a person has multiple different sites of MS-related damage that occurred at different times.1-4

Clinically isolated syndrome (CIS)

A person’s first episode of MS-like symptoms may be considered clinically isolated syndrome (CIS). In CIS there is also inflammation or loss of myelin on nerve cells. CIS falls on the spectrum of MS conditions but does not necessarily meet the diagnostic criteria for MS. Some will develop symptoms again later on and progress to MS. Others may never experience issues again.

A person with CIS can have 1 symptom or a variety of symptoms throughout the body. Those at the highest risk of developing MS have symptoms with evidence of one or more MS-like brain lesions on MRI.1,4,5

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