Multiple sclerosis (MS) is a rare, intractable disease whose symptoms are caused by damage to the myelin sheath that surrounds the nerve fibers called axons that run throughout the body, including the brain, spinal cord, and optic nerves. When the myelin sheath is damaged, the axons are exposed to the outside, causing problems with the transmission of information through the nerve fibers. Depending on where and how much the myelin sheath is damaged, the symptoms of MS vary widely.

Some people will be in a frozen state, like those who have had a severe stroke; some will be paralyzed, and some will lose their vision. Because MS is a rare disease that usually affects people in their 20s and 40s, many different conditions need to be differentiated.

"Among the various diseases that need to be differentiated from MS, the most common is cerebral infarction," said Dr. Min Ju-hong, a professor of neurology at Samsung Medical Center. "Cerebral infarction is a neurological abnormality that usually occurs suddenly and can be recognized by diffusion-enhancing images and the shape and location of the lesion on a brain MRI."

It is also important to differentiate MS from neuromyelitis optica spectrum disorder (NMOSD), which is most similar to MS because they have different treatments. Fortunately, Professor Hong explained that there are clear differentiation points in NMOSD.

"There are several differentiation points for NMOSD, which occurs in the brain, spinal cord, and optic nerves like MS. Still, the most important is the presence of antibodies specific for NMOSD, such as aquaporin 4 antibodies and MOG antibodies, which can be identified through blood tests," Hong said.

Younger MS patients are also more likely to be diagnosed belatedly, as MS can be mistaken for spinal disorders, such as neck or herniated discs.

"As MS tends to occur in younger patients, localized symptoms, such as numbness in the arms, are often mistaken for a herniated disc, which can delay diagnosis," Professor Min said. "MRI of the brain and spinal cord can identify the lesion.

If imaging tests can confirm spinal disorders like neck and lumbar discs, multiple sclerosis can be ruled out, Min noted. However, people must take extra caution not to mistake MS spinal disorders common to many people because their imaging tests often confirm similar lesions, leading to misdiagnoses.

Also, MS is often mistaken for optic neuritis when the optic nerve is involved. "If you have decreased vision, optic nerve MRI, electroretinography, and optical coherence tomography can be used to confirm optic neuritis rather than other eye problems," Dr. Min said.

"It is important to perform MRI with contrast to identify brain, spinal cord, and optic nerve inflammation," Professor Min said. "We can also identify oligoclonal bands and increased production of immunoglobulin G in the cerebrospinal fluid, which suggests a breakdown of the blood-brain barrier, and rule out other conditions such as infection."