CENTRAL NERVOUS SYSTEM
This is the body’s control system. Comprised of the brain and spinal cord, it sends and receives messages from the rest of the body through a network of neurons. Those neurons have a protective myelin sheath that helps with quick, efficient conductivity of signals.
IMMUNE SYSTEM
The immune system attacks foreign invaders to keep you healthy. But with MS, immune cells mistakenly invade the brain and spinal cord, damaging myelin and, to some degree, myelin-producing cells (oligodendrocytes) and the neuron itself. As the body tries to contain this damage from spreading, scar tissue — called a lesion, or plaque — forms.
WHAT THIS MEANS FOR YOU
Without myelin, nerve signals can become slow, weak, and disorganized. Your symptoms will reflect the nerves affected and what functions those nerves control. When a flare subsides, you may regain some or all previous function, called remission. This is likely due to remaining oligodendrocytes repairing myelin as well as healthy neurons making new connections. One theory for progressive MS is that not enough new connections can be made to compensate for the losses.
Relapsing-Remitting (RRMS)
Affecting about 85 percent of people diagnosed, according to the National MS Society, RRMS is experienced as acute episodes of symptoms (flares), followed by full or partial recovery (remission). After multiple relapses, you may have a new baseline of “normal” during remission.
Primary Progressive (PPMS)
People with PPMS typically don’t experience inflammatory episodes, but neurologic function slowly worsens from the onset of symptoms, without periods of recovery. About 15 percent of people with MS have PPMS, according to the National MS Society.
Secondary Progressive (SPMS)
In some people, RRMS becomes a progressive disease and is diagnosed as SPMS. Symptoms may steadily worsen with or without another relapse. While in the past most people with RRMS eventually developed SPMS, current medications greatly reduce this risk. “It looks a little cloudy, like you’re in a slightly foggy room,” says Dulci Hill, 48, from Bel Air, Maryland. In 1990, she temporarily lost sight in her right eye and since then has had some permanent vision changes. “When you live with it so long, you adapt and don’t even notice.”
OPTIC NEURITIS: HOW IT HAPPENS
Optic neuritis refers to inflammation and demyelination along the optic nerve, which transmits messages from the retina at the back of your eye to the visual cortex of the brain. If you looked closely at the eye, you might not see anything wrong — the cornea to the retina is intact and functioning as expected. But though the retina has a perfect image to show the brain, it can’t — inflammation and demyelination of the optic nerve interrupt it. When inflammation subsides, symptoms often go away, and most people can see as well as they did before the flare. However, some vision changes may persist due to eroded myelin or damage along the optic nerve.
WHY AM I SO TIRED ALL THE TIME?
Sleep disturbances, pain, and the emotional toll of managing MS all contribute to fatigue. What’s more, you may have a lower threshold for how much activity you can handle. One possible explanation: Your brain is working a lot harder. Because of damage from MS, some neurons can’t send or receive signals while others send them inefficiently. That means your healthy neurons have to work overtime to make up for those losses. In essence, they (and you!) get tired. Your metabolism may also contribute to fatigue. This chemical process provides energy to cells, and the brains of people with MS may not metabolize as efficiently.
WHAT ABOUT FLARES?
If you experience increased fatigue before or during a flare, that’s your immune response telling you to rest. There’s a cellular battle happening inside your body, and the best thing you can do is rest and let your body focus on recovery. If you’ve ever gotten confused in regular conversation, jumbled your words, or gotten lost in a familiar place, that’s cognitive fog. This insidious symptom can creep up without warning and make it hard to remember facts, process information, and solve problems. “I’m getting really good at making myself lists because I forget things,” Smith says. “Most days I look at my list, and I know what to do. But then there are days when I don’t know what any of it means.”
MAKING SENSE OF COG FOG
One explanation for cognitive problems in MS is cerebral atrophy, which refers to shrinking of the brain. As we age, everyone loses brain cells and eventually experiences some cognitive slowing. But people with MS may experience it at a faster rate. Why does this happen? When the connections between nerve cells are damaged or die, brain tissue shrinks, and the fluid that surrounds the brain and spinal cord expands to fill that space. What’s important to remember about cog fog is that you can figure out the answer or come up with the right word — it just might take you longer to get there. “It’s like my muscles are locked up,” says Gibson, who experiences spasticity after sitting or standing too long. “[My legs] feel like they are in a concrete case and I can’t move them.” While certain large muscles may tighten involuntarily, other muscles may weaken, causing symptoms like drop foot.
WHAT CAUSES LEG SPASTICITY?
Nerve signals constantly flow from your brain and spinal cord to your muscles, whether to keep them relaxed or to contract for movement. But a lesion can cause those nerve signals to slow or misfire. What happens next depends on the muscles affected. Extensor: The muscles that straighten your legs stiffen. When this happens, you can’t bend your legs, making them difficult to move. Flexor: When the hamstrings and hip flexors tighten, the legs bend and pull toward your chest. This can happen with a sudden jerk and either your legs get stuck in that position or spasm. MS can affect your senses in a number of ways, causing abnormal sensations often described as tingling, crawling, or pins and needles; painful sensations like shocks or burning; and numbness.
WHAT CAUSES NUMBNESS AND TINGLING
When your foot touches something, nerves in your foot send a message that travels up the spinal cord to your brain to process that sensation. An MS lesion anywhere along the sensory pathway can affect what you feel. However, the problem is not in your foot — or hand, face, or other body part. Nerve damage in your spinal cord or brain blocks or muddles the sensory message. As a result, you feel less (numbness) or feel extra (like tingling or pain). What about the MS hug? This tight sensation around the chest or waist is likely a combination of sensory changes and muscle contractions, both caused by lesions in the central nervous system. “It feels like you should have made your way to the bathroom five minutes ago,” says Hill. “The sensation is so strong that you are forced to make a decision between dignity and dry clothing.”
HOW THE BLADDER WORKS
Nerves in the bladder constantly tell the spinal cord and brain how full it is. For a small amount of fluid, the central nervous system suppresses the urge “to go.” Once full — approximately 4 to 8 ounces — a signal is sent to the bladder muscle (detrusor) to contract and to the sphincter to open, allowing urine to empty. Overactive: When any fluid enters the bladder, you have a strong urge to go because impulses are no longer suppressed. Nerve signals to the bladder are also slowed or blocked, and the detrusor and sphincter release without control. Underactive: Even though the bladder is full, demyelination in the brain and spinal cord prevents the nerve signal from reaching the bladder. The detrusor doesn’t contract and the sphincter doesn’t open. If the bladder continues to expand without being able to void, treatment may be needed to avoid complications.
