Secondary progressive multiple sclerosis (SPMS) is a form of MS that typically follows relapsing-remitting MS (RRMS). It is characterized by steady accumulation of disability without relapses.
About 65% of patients with RRMS will develop SPMS within 15 to 20 years of diagnosis, and 90% of RRMS patients transition to SPMS within 25 years of diagnosis. The exact role of disease-modifying treatments (DMTs) in delaying this transition remains unclear.
In SPMS, there is steady buildup of disability and relapses are considered rare. When attack does occur, recovery is usually slow and, in many cases, incomplete. Existing symptoms can get worse and physical mobility becomes increasingly difficult.
Not every patient with SPMS experiences the same symptoms at the same stages of disease progression. Some people with SPMS experience relapses, and this makes it difficult to distinguish between RRMS and SPMS.
Diagnosis of SPMS
The inflammatory phase that occurs in RRMS tends to fade with time, and the number of relapses decreases gradually while disease progression and disability continues to accumulate. This phase of MS is SPMS.
The transition from RRMS to SPMS occurs slowly, so many physicians usually have a hard time distinguishing between the two phases.
Incomplete recovery from a relapse that led to permanent but stable damage is one reason symptoms can worsen over time. This incomplete recovery usually indicates RRMS or disease progression in the absence of inflammatory relapses and typically signifies transition to SPMS.
Since SPMS is difficult to diagnose, neurologists will only confirm SPMS after a minimum of 6 months of clear disease progression. Diagnosing a transition from RRMS to SPMS includes careful study of the changes in symptoms, a neurologic examination, and magnetic resonance imaging (MRI) scans.
While it’s possible, it’s often rare for patients to be diagnosed with SPMS during initial diagnosis of MS without RRMS being identified.
Management of SPMS
SPMS treatment includes the managing of symptoms and relapses. Medications, diet, exercise, and physiotherapy are the most common tools utilized during SPMS treatment.
SPMS with relapses can be managed using steroids or beta interferon-based DMTs. Some of the FDA-approved interferon beta medications used to modify the disease course of relapsing forms of MS, including SPMS, are:
If these medications fail to control disease activity, the chemotherapeutic agent Novantrone® (mitoxantrone) can be used. It is the only FDA-approved drug specifically used to treat SPMS with or without relapses.
Modifiers in SPMS
With the help of neurologic examination and MRI, activity and progression of disease is evaluated at least once per year so as to track the disease course continuously and adjust treatment options accordingly.
- If SPMS is active, a DMT will need to be started to mitigate the risk of an attack.
- If SPMS progression does not respond to medication, it’s time to switch to a more aggressive treatment method.
- If SPMS is inactive but still progressing with buildup of disability, rehabilitation strategies should be in place to enhance mobility and function while promoting independence.
- If SPMS is stable without progression, treatment should focus on symptom management and improving quality of life.
SPMS and other forms of MS
SPMS is characterized by steady progression of disease as well as nerve damage with less relapses. Contrary, RRMS patients experience frequent relapses caused by inflammation. SPMS usually occurs as the second phase of disease in many patients who were first diagnosed with RRMS, while primary-progressive MS (PPMS) is the first and only phase of the disease in about 15% of individuals with MS.