Making a Diagnosis of MS

There is no avoiding it. Seeing a neurologist for evaluation of a diagnosis of MS can be very stressful. However, understanding what is needed to make a diagnosis may, at least in part, ease some of the anxiety.

Even with all the latest electronic and laboratory studies, an MS diagnosis is still one of exclusion. Unlike a positive biopsy for cancer, there is no single finding on history, exam, or diagnostic study that is unique, or only found, in persons with MS. Thus, making a diagnosis of MS remains one of excluding other diseases that can mimic MS. While this may seem easy, a recent paper from two MS centers reported that 1 out of 5 persons sent to the centers with a diagnosis of MS did not have this disease.1 More than 100 MS “look-alikes” have been described, but most are very rare, and only the most common ones are usually looked for. These include illnesses such as diabetes mellitus, lupus, Sjøgren’s disease, migraine with aura, high blood pressure, brain tumors, blood vessel inflammations and infections.

The overall goal in making a diagnosis of MS is to show that a person has inflammation in the central nervous system that changes over time (dissemination in time), involves more than one area of the central nervous system (dissemination in space) and cannot be explained by any other illness.
The first thing your neurologist should (must) do is obtain a careful history of both your general health and your neurologic difficulties. Having MS does not exclude the presence of other illnesses, and these may cause difficulties that overlap with those seen in MS. While some symptoms are very suggestive of MS, none are unique to MS, and symptoms alone are not sufficient to make a diagnosis.
Your neurologist should (must) then do a careful and complete neurologic exam, testing all aspects of nervous system function from cognition, to vision, to balance and coordination, to strength, and to reflexes. There are two nervous systems, the central nervous system and the peripheral nervous system, and symptoms and findings of the two can overlap. MS is a disease of the central nervous system, so your neurologist will be looking for evidence of central nervous system dysfunction. Indeed, if a person with MS is in remission, their neurologic exam may be entirely normal.
After a complete history and physical exam, blood work is needed to look for evidence of other diseases that can “look-like” MS. The bare minimum would be to measure liver, thyroid and kidney function, to have a complete blood count, to measure blood sugar levels, and to look for evidence of more generalized inflammation, infection and tumors. 

If blood test screening is normal or negative, with no suggestion of another disease mimicking MS, imaging of the central nervous system would be next. This is best done with an MRI of the brain, and in my practice also an MRI of the upper (cervical) spinal cord. I also usually administer contrast during the MRIs to look for signs of active inflammation. While a person with MS can have a normal MRI of normal central nervous system, it is most unusual, and should make one reconsider an MS diagnosis.

If there are changes on MRIs and they are compatible with a diagnosis of MS the next diagnostic procedure in my practice would be to perform a spinal tap (lumbar puncture) to look for evidence of inflammation in the spinal fluid. Not only would the presence of inflammation support a diagnosis of MS, but it also could suggest different clinical courses and treatment options. For example, a normal spinal fluid exam would not exclude a diagnosis of MS, but could suggest a milder clinical course.
In light of the difficulties involved in making a diagnosis of MS, I would advise seeing a neurologist specializing in this illness. The National MS Society can provide you with information on such centers, and you can reference this article listing the most recent diagnostic criteria for MS2.

1. Kaisey M, Solomon AJ, Luu M, Giesser BS and Sicotte NL. Incidence of multiple sclerosis misdiagnosis in referrals to two academic centers. Mult Scler Relat Disord. 2019; 30: 51-6.
2. Thompson AJ, Banwell BL, Barkhof F, et al. Diagnosis of multiple sclerosis: 2017 revisions of the McDonald criteria. Lancet Neurol. 2017.

The National Multiple Sclerosis Society is proud to be a source of information on multiple sclerosis related topics. Unless otherwise indicated, the information provided is based on professional advice, published experience, and expert opinion. However, the information does not constitute medical or legal advice. For specific medical advice, consult a qualified physician. For specific legal advice, consult a qualified attorney.
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Gary Birnbaum

Gary Birnbaum is a neurologist-immunologist. He has devoted his entire professional life to the care of persons with MS and to researching the immunological basis of this illness. Learn more about him and his work on his blog.