In this article, we take a look at diseases that cause demyelination, the symptoms that may develop, and what can be done about them.
What are demyelinating diseases?
Demyelinating diseases damage the coatings of nerve cells.
Many of the nerve fibers in the nervous system are coated with a fatty white substance called myelin. These myelin sheaths allow electrical impulses to be transmitted along the nerve cells quickly and efficiently.
How well these impulses are conducted determines how smoothly and quickly a person can perform everyday movements with little conscious effort.
Some diseases cause damage to these protective myelin sheaths, which may cause problems in the brain, eyes, and spinal cord. These conditions are known as "demyelinating diseases."
Symptoms of demyelinating diseases
Typically, demyelinating diseases can affect:
- reflexes and movement
- the senses
- how often someone needs to use the bathroom
People who experience any of these symptoms may also experience persistent exhaustion that does not appear to have a particular cause.
People with a demyelinating disease may experience blurred vision, a loss of vision, "double vision," or they may feel like their vision is swinging back and forth.
Some people may also experience weakness in their limbs and the trunk of their body, or have problems balancing. In addition, the muscles might contract, causing stiffness or tightness and interfering with movement and speech.
People may also experience spikes in blood pressure and a rapid heartbeat due to an overreacting nervous system.
Some people may experience numbness, burning, or prickling sensations in their arms, legs, or feet. They may also feel pain when touched lightly.
Some people with a demyelinating disease, such as multiple sclerosis (MS), get a symptom called Lhermitte's sign. This feels like an electric shock that passes down the back of the neck into the spine and then out through the arms and legs.
Symptoms related to the brain
Demyelinating diseases can lead to memory problems, difficulty concentrating, and cognition issues.
People with a demyelinating disease can also experience tremor or incoordination. At times, actions such as swallowing, writing, eating, and walking can become difficult.
Memory, concentration, attention, and processing speed can all be affected by demyelinating diseases.
Symptoms affecting the genitourinary system
Demyelinating diseases can affect how often someone needs to use the bathroom. These conditions can make people either incontinent (where they cannot control their bladder or bowels) or constipated (where they cannot empty their bowels regularly and thoroughly).
Infections of the urinary tract can also be more common in people with demyelinating diseases.
The sexual health of individuals with demyelinating diseases may be affected. Men may be unable to get an erection, and both women and men may be unable to orgasm. People with demyelinating diseases may also experience pain during sex.
Types of demyelinating diseases
There are many different types of demyelinating disease. Diagnosis varies from disorder to disorder.
Below is a list of some of these conditions, along with information on possible treatment options.
Multiple sclerosis is the most common demyelinating disease.
The most common type of demyelinating disease is MS.
The term multiple sclerosis means "many scars." It refers to areas in the brain and spinal cord where myelin has been lost, leaving hardened scars that can appear at different times and in different places.
Unfortunately, there is no cure for MS at present, but many of the symptoms can be managed and treated.
Medications are available to treat relapses of MS and manage symptoms, which are usually taken orally or by injection.
MS is more common among women than men. In fact, about three women to two men have this particular demyelinating disease.
Although MS is not hereditary, some doctors believe that genes can make some people more susceptible to the condition than others.
Optic neuritis is another type of demyelinating disease that can arise from MS.
This condition is most common among people aged between 20 and 40. Its most common symptoms are pain with eye movement, vision loss, or loss of color vision.
Optic neuritis is often treated with corticosteroids, although if doctors suspect that MS is causing the problem, they may prescribe MS medications.
Neuromyelitis optica, or Devic's disease, occurs when the immune system attacks and destroys myelin, resulting in pain in the spine and limbs and causing bladder and bowel problems.
Neuromyelitis optica can sometimes result in death if a person's breathing becomes affected.
The initial attack of neuromyelitis optica is likely to be treated with corticosteroids.
Drugs that subdue the immune system, called immunosuppressives, may be used to prevent additional attacks.
Transverse myelitis is an inflammation of the spinal cord. This type of demyelinating disease affects sensation and can cause pain and weakness in the arms and legs, as well as causing bladder and bowel problems.
About 1,400 new cases of transverse myelitis are diagnosed each year in the United States.
Similarly to other demyelination diseases, corticosteroids may be prescribed to reduce the inflammation of the spine.
For those people who do not respond to corticosteroids, doctors may recommend plasma exchange therapy. This procedure involves replacing plasma (the fluid in which blood cells and antibodies travel) with special fluids.
Pain medicines such as acetaminophen, ibuprofen, and naproxen can also help with muscle pain.
Acute disseminated encephalomyelitis
Acute disseminated encephalomyelitis (ADEM) is a widespread attack of inflammation in the brain and spinal cord. The inflammation damages myelin and can lead to fever, exhaustion, headache, nausea, and vomiting.
Like transverse myelitis, corticosteroids or plasma exchange therapy may be considered to reduce the inflammation that causes ADEM.
Adrenoleukodystrophy and adrenomyeloneuropathy
Adrenoleukodystrophy and adrenomyeloneuropathy are rare, inherited demyelinating diseases that are caused by a gene mutation that usually only affects men. Some women can carry the gene, however, and in some cases, women may develop symptoms.
Symptoms of these conditions vary and span the full range of demyelinating disease symptoms described above.
If people with adrenoleukodystrophy or adrenomyeloneuropathy have low levels of adrenaline and cortisol, then a doctor can prescribe steroids, which can replace the hormones and improve a person's quality of life.
Other treatments for these conditions are currently in clinical trials.
There are currently no cures available for demyelinating diseases. As a result, treatment tends to focus on reducing and managing symptoms, as well as slowing the progress of the disease.
When demyelination occurs, new myelin can grow. However, the new myelin is not as strong and protective as the old myelin, which means that the transmission of electrical impulses is not as efficient as before.
Researchers are currently looking at what can be done to improve how the body produces new myelin.
For now, people with demyelinating diseases should be sure to speak with their doctor about their treatment options.