Nerves send and receive messages from every part of your body and process them in your brain. Nerves allow you to talk, see, feel and think.
Many nerves are covered with myelin. Myelin is an insulating material. When worn or damaged, nerves can deteriorate, causing problems in the brain and throughout the body. The damage to the myelin around the nerves is called demyelination.
The nerves are formed by neurons. Neurons are composed of a cell body, dendrites and an axon. The axon sends messages from one neuron to the next. The axon also connects neurons with other cells, such as muscle cells.
Some axons are extremely short. Others are 3 feet long. Some axons are covered with myelin. Myelin protects axons and helps carry axon messages as quickly as possible.
Myelin is made of layers of membrane that cover an axon. This is similar to the idea of an electric cable with a coating to protect the metal below.
Myelin allows a nerve signal to travel faster. In unmyelinated neurons, a signal can travel along the nerves at approximately 1 meter per second. In a myelinated neuron, the signal can travel 100 meters per second.
Certain diseases can damage myelin. Demyelination slows down the messages sent along the axons and causes the axon to deteriorate. Depending on the location of the damage, loss of the axon can cause problems to feel, move, see, hear and think clearly.
Inflammation is the most common cause of damage to myelin. Other causes include:
- Certain viral infections.
- Metabolic problems
- Loss of oxygen
- Physical compression
Demyelination prevents nerves from transmitting messages to and from the brain. The effects of demyelination can occur quickly. In Guillain-Barre syndrome (GBS), myelin can only be under attack for a few hours before symptoms appear.
Symptoms can appear and disappear in chronic diseases such as multiple sclerosis (MS) and progress over the years. Nerves are a key part of your body’s functions. Therefore, a wide range of symptoms can occur when the nerves are affected by demyelination, which include:
- Loss of reflexes and uncoordinated movements.
- Badly controlled blood pressure.
- Blurry vision.
- Accelerated heartbeat or palpitations.
- Memory problems.
- Loss of control of the bladder and bowel.
The first symptoms of demyelination
Not everyone is affected by demyelinating diseases in the same way. However, some demyelinating symptoms are very common. The first symptoms include:
- Loss of vision
- Bladder or bowel problems
- Unusual nervous pain.
- General fatigue
These are among the first signs of a demyelinating disease.
Types of demyelination
There are different types of demyelination. These include inflammatory demyelination and viral demyelination.
Inflammatory demyelination occurs when the body’s immune system attacks myelin. Types of demyelination such as multiple sclerosis, optic neuritis, and acute disseminated encephalomyelitis are caused by inflammation in the brain and spinal cord.
It involves inflammatory demyelination of the peripheral nerves in other parts of the body.
Viral demyelination occurs with progressive multifocal leukoencephalopathy (PML). PML is caused by the JC virus. Damage to myelin can also occur with alcoholism, liver damage, and electrolyte imbalances. Hypoxic-ischemic demyelination occurs due to lack of oxygen or vascular disease in the brain.
Demyelination and multiple sclerosis
MS is the most common demyelinating disease. According to the National Society of MS, it affects 2.3 million people worldwide. In MS, demyelination occurs in the white matter of the brain and spinal cord.
Then lesions or “plaques” form in which the immune system attacks the myelin. Many of these plaques (or scar tissue) occur throughout the brain over the years.
The types of MS are:
- Clinically isolated syndrome.
- Recurrent-remitting MS.
- Primary progressive MS.
- Secondary progressive MS.
Treatment and diagnosis
There is no cure for demyelinating diseases. New myelin growth can occur in areas of damage. But new myelin is thinner and not as effective. Researchers are looking for ways to increase the body’s ability to produce new myelin.
Most treatments for demyelinating disease reduce the immune response. This is done with medications such as interferon beta-1a or glatiramer acetate.
In addition, people with low levels of vitamin D more easily develop MS or other demyelinating diseases. High levels of vitamin D can reduce the inflammatory immune response.
Demyelinating diseases, especially multiple sclerosis and optic neuritis (inflammation of the optic nerve), are detectable by magnetic resonance.
Magnetic resonance imaging can show demyelination plates in the brain and nerves, especially those caused by multiple sclerosis. Your doctor may locate plaques or lesions that affect your nervous system.
Then, the treatment can specifically address the source of demyelination in your body.
A note about statins
The central nervous system (CNS) is capable of producing its own cholesterol. Current studies show that if you take statins to lower cholesterol in your body, it is likely that they will not affect your CNS cholesterol.
Many studies have also found that statin treatment can protect against Alzheimer’s disease (AD) in patients who have not yet experienced cognitive decline and who are still relatively young.
Researchers have found that statins can decrease the rate of cognitive decline and delay the onset of AD.
The investigation continues and we still do not have a definitive answer. Some studies show that statins do not affect the central nervous system or remyelination, and still others say yes.
Currently, most evidence does not show that treatment with statins is detrimental to remyelination within the CNS. Even so, the effects of statins on cognitive function remain controversial at this time.
Vaccines and demyelination
The activation of the immune system with a vaccine can trigger an autoimmune reaction. This tends to occur only in a few people with hypersensitive immune systems.
Some children and adults experience “acute demyelinating syndromes” after exposure to certain vaccines, such as the flu or HPV. But there have only been 77 documented cases since 1979.