Diagnosing MS Isn't Easy — Here's Why

Last updated: January 2023

This article is for undiagnosed people that go to online MS forums, list their symptoms, and ask if they have MS. It’s also for those who track their symptoms, google them, and convince themselves they have MS. Folks, it’s just not that simple. Here’s why.

How neurologists test for MS

Neurologists make the diagnosis partly based on a physical exam that checks all your cranial nerves, reflexes, coordination, balance, and vision. Some of the tests involve a tuning fork to check sensation; standing with our eyes closed to see if we sway, fall down, maintain our upright stance, or surprise them with something completely different. Our knees and elbows get hammered for reflex briskness or an absence of rebound. And there are many more weird little procedures that can expose a unilateral abnormality (just on one side), as well as limited vision, hearing, and touch. As thorough as it is, it’s just a snapshot in time.

MS is similar to other conditions

But MS poses some small problems. First, it tends to show itself in bits and pieces over time. Second, the symptoms—of which there are many—can indicate a bushel of other medical conditions. For example, one foot might have developed numbness. Maybe it started in one toe and then spread to the entire foot. It could be an early sign of MS. But it can also signal diabetes, or anything associated with damage to peripheral nerves (those located in the extremities and anything outside the central nervous system). That kind of cause is more common than conditions like MS that affect only the central nervous system (brain and spinal cord).

The need for blood work

This is why MS diagnostic tests start with blood work. The most common causes for neurological symptoms put markers in the blood, helping to rule out MS. Lyme, diabetes, thyroid disease, and vitamin deficiencies are major offenders that leave behind a smoking gun in the blood. (As of 2018, there is no blood test available for MS, although one has been developed and might soon become part of diagnostic testing.)

If blood work tests negative, the diagnostician turns to brain and spine MRIs. Lesions consistent with MS will appear in certain areas of the brain and cervical spine, and with a certain appearance and shape that only the trained eye can determine is being caused by MS and not a migraine, aging, or cancer. Radiologists and neurologists are not all equally gifted in this area, however. Doubt can linger, delaying a diagnosis and treatment. A misdiagnosis can delay proper treatment.

Other diagnostic tests

Evoked potentials testing involves sticking electrodes to your scalp. For vision, you stare at a checkerboard while a machine measures how long it takes electrical signals to travel from your eyes to your brain. For hearing, tones are sounded while the machine measures the speed at which signals travel from ear to brain. It’s just one more piece to add to the puzzle.

A lumbar puncture, or spinal tap, checks the cerebrospinal fluid for signs of inflammation within the closed system of the brain/spinal cord. If such inflammation exists, bands will appear that will be absent in the blood.

The tests could still be inconclusive

Now you’ve completed all diagnostic testing for MS. After all that grief, the diagnosis should float to the surface as easily as in a Magic 8-Ball, right? Not necessarily.

If you have MS and it’s early in the disease course, you might not have tested positive in all the MS tests. In fact, you might not have tested positive in any of the tests. Let’s say the blood tested negative for all differential diagnoses. But you also had negative lumbar puncture; one iffy spot in the brain MRI and none in the spine; iffy evoked potentials; and mostly normal physical exam with some iffy things such as numbness and one brisk reflex. Result? No diagnosis at this time. Not for MS and not for anything else.

Watching and waiting after the first signs

Now, you wait. You keep track of your symptoms. Whenever there is a change, you see your doctor.

This is the course many people with MS follow on their way to a diagnosis. Some people never get diagnosed. Others eventually get misdiagnosed or properly diagnosed with another disease. In any case, diagnosing MS is not a piece of cake and likely won’t be for some time to come.

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