Multiple sclerosis (MS) is a chronic disease of the central nervous system (CNS). The most common forms of MS are relapsing-remitting MS (RRMS), secondary-progressive MS (SPMS), and primary-progressive MS (PPMS). 

In relapsing-remitting MS, which 80 to 85 percent of people are initially diagnosed with, symptom flares come and go. In time, RRMS progresses to secondary-progressive MS, where relapses occur less frequently or not at all, and symptoms steadily worsen over time. 

About 10 percent of people with MS are diagnosed with PPMS, which involves a steady worsening of symptoms from the onset, without periodic relapses and remissions.

What Are MS Spinal Cord Lesions?

Nearly everyone with MS has signs of lesions in the brain, as shown by magnetic resonance imaging (MRI) scans, according to Anthony Reder, MD, a multiple sclerosis specialist and professor of neurology at the University of Chicago Medicine.

Lesions, also called plaques, are damaged areas where the immune system has attacked the myelin sheath surrounding nerves. This leads to inflammation and scarring.

But the brain isn’t the only area where lesions can develop — MS can also attack the spinal cord. Because finding these lesions involves more elaborate imaging tests, spinal cord lesions in MS are studied less often. Many people with MS aren’t aware of the role these lesions may play in the disease process.

How MS Lesions Form on the Spinal Cord

Scientists don’t know exactly why certain people with MS have more lesions in their brain or spinal cord. What they do know, says Dr. Reder, is that spinal cord lesions “are more common in the more progressive forms of MS” than in other forms of MS. And in cases with spinal cord damage, there are sometimes actually fewer brain lesions, he adds.

Researchers, too, have knowledge gaps about this feature of the disease. Filling these gaps may lead to a better understanding of progressive forms of multiple sclerosis.

Spinal cord lesions in MS “probably” form through the same mechanisms as those in the brain, says Reder.

“For some unknown reason, white blood cells escape from the bloodstream, go through the blood-brain barrier, and get into the brain tissue,” he explains. These cells cause inflammation of the brain and spinal cord — mostly in the white matter, but also the gray matter.

According to Reder, toxic chemicals produced by these cells strip the myelin insulation off the connections between nerves. The resulting lesions tend to affect multiple nerves and tend to be 1 to 2 centimeters in length or diameter.

Symptoms of Spinal Cord Lesions

Lesions in the spinal cord often result in an increased risk of disability. Research has found that new spinal cord lesions are associated with an increased risk of both relapses and worsening disability, defined as an increase in the Expanded Disability Status Scale (EDSS) score.

The EDSS measures disability levels — such as walking impairment, bladder function, sensory or sight problems, and activity limitations — and progression of MS, on a scale of 0 to 10 (though most people with MS don’t experience the highest levels).

Types of disability commonly associated with spinal cord lesions include impairments in walking, coordination, and bladder and bowel function.

Another cause of disability in MS is spinal cord atrophy, or shrinkage, which can also be seen on MRI, and which causes disability independently of spinal cord lesions.

Diagnosing Spinal Cord Lesions in MS

An MRI (magnetic resonance imaging) can reveal spinal lesions. The spine has historically been challenging to image because of movement during the scan — breathing, cardiac movement, cerebrospinal fluid (CSF) pulsation, and blood flow can all interfere. But advances in technology have improved the process.

Not everyone with MS or suspected MS gets a spinal cord MRI. While a brain MRI is recommended for all patients in the process of being diagnosed with MS, a spinal cord MRI is only advised in certain circumstances: if your symptoms suggest a spinal cord lesion or PPMS; if your brain MRI is normal, but your doctor still suspects MS; or if the results of a brain MRI are inconclusive. 

To diagnose MS in patients, a conventional spinal cord MRI is commonly used. But advanced MRI techniques used to examine and assess the type and extent of spinal cord lesions are primarily limited to researchers.

Treatments for MS Spinal Cord Lesions

In 2017, the U.S. Food and Drug Administration (FDA) approved ocrelizumab (Ocrevus) to treat adults who have relapsing forms of multiple sclerosis and primary-progressive multiple sclerosis (PPMS).

 It was the first drug approved by the FDA for PPMS. 

“Ocrevus had the most effect in the first several months, but the modest benefit persisted over time,” says Reder.

In September 2024, the FDA approved an injectable version of ocrelizumab called Ocrevus Zunovo. Administered twice a year, it offers an alternative treatment delivery option. 

But Reder says it remains to be seen whether any therapy can help slow or halt the accumulating spinal cord lesions that affect some people with progressive MS and that are very difficult to treat.

“Any therapy that has prolonged effects on slowing of progression in MS,” he says, “would be a big breakthrough.”

The Takeaway

• Multiple sclerosis doesn’t just cause lesions in the brain, but also in the spinal cord, which can lead to an increased risk of disability and symptom progression. 
• Understanding and diagnosing these spinal lesions often involves sophisticated imaging techniques.
• Keeping your healthcare team up to date on any new symptoms can lead to more proactive and tailored management.

Source: Everydayhealth