How Secondary Progressive MS Is Diagnosed

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If you or a loved one has recently been diagnosed with secondary progressive MS (SPMS), you may wonder how your neurologist came to this conclusion.

Alternatively, maybe you have relapsing-remitting MS (RRMS) and wonder how your doctor will know when (or if) you will transition from RRMS to SPMS.

These are normal thoughts, and as a person living with MS, understanding the MS disease transition is important.

This way you are a bit more prepared for what your future holds and the challenges you may face.

Diagnosing Secondary Progressive Multiple Sclerosis

Multiple sclerosis (MS) is a complex neurological disease that can be challenging to diagnose. For one, the symptoms can mimic those of other health conditions. Secondly, there is no single test to confirm a diagnosis. Instead, diagnosing MS is like putting together a puzzle, and sometimes the pieces do not fit perfectly.

More specifically, the diagnosis of MS entails putting together a combination of objective evidence (for example, results from an MRI or a lumbar puncture), as well as subjective data, like a person's history of neurological events and physical examination.

That said, when it comes to diagnosing secondary progressive MS, your doctor must consider two essential steps:

Step One: Confirm a History RRMS

Confirming a history of relapsing-remitting MS (why it's called "secondary") can be difficult, as some people may experience the RRMS phase without even knowing it.

Perhaps they were misdiagnosed or their symptoms were so subtle, they did not even see a doctor.

Step Two: Confirm Your MS is Progressive

After confirming a history of RRMS, your doctor must then define your current disease course as one that is "progressive," or slowly getting worse over time.

To best understand what "progressive" means, it's easiest to consider both the biology of SPMS and the clinical picture, meaning what a person with SPMS experiences.

Biology of SPMS

In RRMS, we know that a person's immune system attacks the myelin sheath (the protective covering around nerve fibers), and this process is called demyelination. As the myelin sheath is damaged or destroyed, nerve signals are unable to be transmitted properly from the brain and spinal cord to the rest of the body.

This immune system attack on the myelin sheath is an inflammatory process, as evidenced by bright white spots (called gadolinium enhancing lesions) that appear on contrast MRIs during acute relapses.

However, in SPMS, there are less inflammatory changes in the central nervous system. Instead, hallmark features of SPMS are degeneration of gray matter and white matter and atrophy (loss of nerve cells), as seen on MRIs of the brain and spinal cord.

In fact, atrophy of the spinal cord is much more prominent in SPMS than RRMS and the degree of atrophy correlates with how physically disabled a person is. With spinal cord involvement, people with SPMS may develop more difficulties walking, as well as bladder and bowel problems.

It's important to understand there is still demyelination occurring in SPMS, but it's more widespread, as opposed to being focal, as in RRMS. Also, while there is still some ongoing inflammation occurring in SPMS, it's simply not as robust as that in RRMS.

Overall, the decline in inflammation in SPMS helps explain why people with SPMS do not get better with most disease-modifying treatments used to treat RRMS (which work by reducing inflammation).

Clinical Picture of SPMS

A person with RRMS (the most common type of MS) experiences episodes or flares (called relapses) of sudden neurological problems.

For instance, a common first relapse is optic neuritis, in which a person's optic nerve (a cranial nerve that connects the brain to the retina) becomes inflamed. A relapse of optic neuritis causes symptoms like eye pain upon movement and blurry vision.

With any relapse, a person's neurological symptoms may resolve completely or somewhat.

In other words, there could still be residual neurological problems after a relapse, but they are stable and do not get worse (unless another relapse in that same area of the nervous system occurs). 

On the other hand, in progressive MS, a person's MS follows a stepwise decline, getting worse over time. For instance, a person with SPMS may notice that his or her walking has worsened over the last six months, but cannot recall a specific day or point in time in which the walking suddenly got worse.

The Transition Period Between RRMS and SPMS

The tricky part about SPMS is that experts now realize there is often a transition period between when RRMS ends and SPMS begins. In other words, a person's clinical picture may overlap between the two types of MS—so a person's MS may be progressively worsening, while still getting a relapse here and there.

What to Keep in Mind After a Diagnosis of SPMS

If you or a loved one is diagnosed with SPMS, there are a few things to keep in mind.

First, it's important to know that moving into the SPMS phase from RRMS is not your fault. In fact, most people will transition to SPMS eventually, although the rate at which this transition occurs is still fuzzy. This is because the emergence of new disease-modifying therapies is causing some people's disease progress to slow down significantly.

Secondly, it's important to note that like RRMS, the symptoms of SPMS are variable, as is the rate of progression, meaning some people become more disabled than others (and at a faster speed than others).

Thirdly, if your MS is progressing, your neurologist will likely review rehabilitation interventions, in addition to your medications, to optimize your functioning and help maintain your muscle strength and walking.

A Word From Verywell

The bottom line here is that the diagnosis of SPMS requires a combination of diagnostic techniques, including a thorough neurological examination and repeat MRIs. As with RRMS, there are no slam-dunk tests. Instead, the diagnosis is clinical and based on a doctor's ability to put your MS puzzle together.


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National MS Society. (n.d.). Diagnosing secondary progressive MS (SPMS).

National MS Society. (n.d.). Frequently Asked Questions about SPMS.

Schlaeger R et al. Spinal cord gray matter atrophy correlates with multiple sclerosis disability. Ann Neurol. 2014 Oct;76(4):568-80.