Numbness and tingling are often the result of minor nerve injuries or inflammation. But for people with Multiple Sclerosis (MS), these symptoms can become severe and interfere with walking or doing everyday tasks. Why does this happen?
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In patients with MS, we know what happens, but researchers are still puzzled about why it happens.
What causes MS symptoms
The problem is caused by what doctors call demyelination — the stripping of myelin, which surrounds our nerve fibers. When this occurs, the nerves can’t send clear signals to each other or back to the brain. This can causes symptoms like numbness and tingling at one end of the spectrum and difficulty walking or doing every-day tasks at the other end.
The nerve fibers are much like an electrical cord. When the cord loses its protective insulation, the wires underneath become exposed and frayed. And they may no longer conduct electrical signals properly.
Similarly, when the central nervous system loses this insulating protection, the neurons cannot go smoothly from one end of the “wire” to the other.
“You can’t get that signal across because the insulation isn’t there anymore,” says nurse practitioner Claire Hara-Cleaver, CNP. She often uses the analogy of a stripped wire with her patients. “You need that coating for the [electrical nerve] signals to jump across neurons,” she says.
People who have symptoms that may be caused by demyelination should take them seriously and get evaluated, Ms. Hara-Cleaver says. These symptoms include:
- Weakness in the limbs.
- Difficulty walking.
- Difficulty using your hands to do daily tasks.
Of course, many minor issues can also cause numbness and tingling, but it’s important not to ignore symptoms, especially if they get worse over time.
How MS is different
Doctors distinguish multiple sclerosis from other demyelinating conditions because the patient has had multiple attacks that cause lesions, separated by space and time. To confirm such a diagnosis, doctors perform spinal taps and neurological examinations. They also review the patient’s history to see if they have had relapses, Ms. Hara-Cleaver says. An MRI can show whether and where there have been lesions that injure the brain or spinal cord sheath, she says.
Other demyelinating conditions may result from just one such attack of lesions but can also leave lasting symptoms. And, as with MS, symptom severity can wax and wane over time for reasons that are difficult to pinpoint, Ms. Hara-Cleaver says.”They are similar in terms of, the person can have progressive physical disability over time,” she says. “Sometimes they will improve significantly, sometimes they won’t.”
Devic’s disease or neuromyelitis optica (NMO) is one such condition. A single attack of lesions that impact both the spinal cord and the optic nerve characterizes the condition. It can be tricky to distinguish, though, because MS also sometimes affects the optic nerve, Ms. Hara-Cleaver says. So specialists follow such NMO attacks with subsequent imaging because “additional lesions would turn this into multiple sclerosis, and not a one-time insult.”
Treatment can manage symptoms, but there isn’t much we can do yet to prevent demyelination from happening. Based on current research, specialists believe there is a genetic predisposition, and it’s thought that a virus or injury sets the lesions into motion. However, the exact cause is unknown, Ms. Hara-Cleaver says.
“I always say to people, ‘You didn’t do anything; it’s not your fault,’ ” Ms. Hara-Cleaver says. “It’s like saying, ‘Is there anything you can do to prevent cancer?’ It’s like the perfect storm. MS is a combination of things. We don’t exactly know what [the root cause] is.”
But researchers are hard at work trying to decode this mysterious condition, and currently, there are ten FDA-approved medications to slow progression of disease and prevent new lesions in relapsing forms of MS.