Secondary progressive MS (SPMS) is marked by a gradual, steady worsening of neurological function, most notably increasing difficulty with walking and movement. Unlike relapsing-remitting MS, where symptoms flare up and then partially or fully recover, SPMS involves a slow accumulation of disability that doesn’t bounce back. The shift is often subtle at first, making it hard to pinpoint exactly when it begins.
How SPMS Differs From Relapsing-Remitting MS
In relapsing-remitting MS (RRMS), you experience distinct attacks followed by periods of recovery. In SPMS, the pattern changes. Disability builds steadily over months and years, independent of relapses. You may still have occasional relapses on top of this gradual decline, but the defining feature is progression that continues even between flare-ups.
Most people with MS start with the relapsing-remitting form. About 10% transition to SPMS within 10 years, roughly 50% by 20 years, and up to 93% by 30 years. Modern disease-modifying treatments appear to slow this timeline compared to earlier decades, but the transition remains common over a lifetime with MS.
SPMS is further classified as “active” or “non-active.” Active SPMS means you’re still experiencing occasional relapses or new lesions visible on MRI, layered on top of the steady progression. Non-active SPMS means the gradual worsening continues without new inflammatory activity. Both types involve the same core symptoms.
Increasing Difficulty With Walking and Movement
The hallmark of SPMS is worsening motor function. Walking becomes harder over time, often progressing from slight unsteadiness to needing a cane, then eventually a walker or wheelchair. This isn’t because of a single bad relapse. Instead, each month or year brings a small, incremental decline in leg strength and coordination that accumulates.
Spasticity plays a major role. Damaged nerve pathways lose their ability to regulate muscle tone properly, leading to stiffness that ranges from a mild tightness in the legs to severe, painful rigidity. Spasticity can cause involuntary leg crossing, sudden muscle spasms (especially at night), and over time, permanent shortening of muscles and tendons called contractures. Many people also experience clonus, a series of rapid involuntary contractions that feel like a tremor, most often in the ankles.
Balance and coordination deteriorate as well. Tasks that require precise movement, like stepping over a curb or navigating uneven ground, become increasingly risky. Falls are a significant concern.
Loss of Hand Dexterity and Upper Body Function
While walking problems tend to get the most attention, upper limb impairment affects roughly two-thirds of people with MS and becomes especially significant in the later stages of the disease. Grip strength declines, fingers become less nimble, and tasks like buttoning a shirt, opening jars, or typing grow difficult.
In one study, 95% of people with MS rated upper limb function as more important to them than lower limb function. This makes sense: once someone relies on a walking aid or wheelchair, arm and hand strength become essential for daily independence. Hand dysfunction is also closely linked to unemployment, alongside fatigue and cognitive decline.
Cognitive Decline
Cognitive impairment affects an estimated 40 to 70% of people with MS across all stages, but it tends to deepen in SPMS. The changes are specific. Processing speed slows, meaning it takes longer to absorb and respond to information. Memory for recent events weakens. Executive functions like planning, organizing, and multitasking become harder. Verbal fluency and the ability to find the right word can also decline.
These cognitive shifts can appear before physical disability worsens, and unlike motor symptoms, they rarely improve with treatment. Many people describe a mental “fog” that makes work and social situations exhausting. The changes are often more distressing than physical symptoms because they affect how you think, communicate, and engage with the people around you.
Pain Patterns in SPMS
Pain affects anywhere from 28 to 87% of people with MS, depending on the type and how it’s measured. In SPMS, pain typically falls into a few recognizable categories.
The most common form of nerve pain is a constant burning, tingling, or throbbing sensation in the legs and feet. It’s generated by the damaged nerves themselves rather than by an injury, which is why it can persist even at rest. Some people also experience trigeminal neuralgia, a sudden, electric shock-like pain in the face triggered by the irritation of a specific facial nerve. It’s brief but intense.
Painful muscle spasms, particularly in the legs, tend to worsen at night and result from misfiring nerve signals along damaged pathways. There’s also musculoskeletal pain caused by altered posture, reduced mobility, and the strain that spasticity places on joints over time. These different pain types often overlap, making pain management in SPMS complex.
Fatigue That Goes Beyond Tiredness
Fatigue in SPMS is qualitatively different from ordinary tiredness. It’s an overwhelming, whole-body exhaustion that doesn’t fully resolve with rest or sleep. It can appear suddenly and without a clear trigger, and it worsens with heat. Many people describe it as feeling like they’re moving through water. This type of fatigue is driven by the disease itself, not just by poor sleep or physical effort, and it compounds every other symptom. Walking is harder when you’re exhausted. Thinking is slower. Pain tolerance drops.
Bladder, Bowel, and Autonomic Changes
As SPMS progresses, the autonomic nervous system, which controls functions you don’t consciously manage, becomes increasingly affected. Bladder problems are among the most common: urgency, frequency, incomplete emptying, or incontinence. Bowel dysfunction, including constipation or loss of bowel control, also develops in many people. Sexual dysfunction is frequently reported but often goes undiscussed.
These symptoms reflect the same underlying process driving the motor and cognitive decline: progressive nerve damage that disrupts the signals between the brain, spinal cord, and the rest of the body. They tend to worsen in parallel with walking difficulty, though the timeline varies from person to person.
How Symptoms Progress Over Time
SPMS doesn’t follow a single predictable path. Some people experience a slow, steady decline over decades. Others worsen more quickly for a period and then plateau for years before declining again. Phases of relative stability are common and don’t mean the disease has stopped.
The general pattern, though, is a broadening of symptoms. Early SPMS might look like gradually worsening leg weakness and occasional spasticity. Over time, the picture expands to include hand dysfunction, cognitive changes, worsening pain, bladder issues, and deepening fatigue. The combination of these symptoms, rather than any single one, is what progressively limits independence and quality of life.