Macular degeneration (MD) is a group of eye conditions in which the central retina (called the macula)…
What is multiple sclerosis?
Multiple sclerosis (MS) is a condition of the central nervous system that interferes with the transmission of nerve impulses in the brain and spinal cord. Multiple sclerosis takes its name from the Greek word, sclerosis, which means scars. Multiple sclerosis is associated with multiple scars, called plaques or lesions, which can appear across the brain and spinal cord. These plaques give rise to the symptoms of multiple sclerosis. The exact cause of MS is unclear.
Multiple sclerosis is:
- More common in women than men;
- The most common chronic condition of the central nervous system in young adults;
- Generally diagnosed in adults aged between 20-40 years of age, and;
- Less common in countries closer to the equator.
Multiple sclerosis involves damage to the myelin sheath, which is the fatty, protective coating around the outer part of nerves. The myelin sheath helps to speed up electrical signals within nerves. When this myelin sheath is damaged, as is the case in multiple sclerosis, nerve transmission is disrupted and this leads to impaired sensation, movement and cognition.
Current understanding of the cause of MS suggests it may be due to factors such as:
- An abnormal response of the immune system;
- Specific genetic risk factors, and;
- Specific environmental factors.
It is likely that MS is caused by changes in several genes, alongside specific environmental factors.
Having a close family member with MS or having a specific family of genes, called human leukocyte antigen (HLA) complex, may increase the risk of developing MS. HLAs are found on the surface of cells and play an important role in the process that allows the immune system to distinguish healthy cells from those needing removal. The strongest genetic risk factor for developing MS has been attributed to changes in the HLA-DRB1 gene. The vast majority of people with this genetic change will not go on to develop MS, but the effect of such a genetic change on the immune system is highly complex and yet to be clearly understood.
Women are more likely to develop MS than men. For every two men diagnosed with MS, there are three women diagnosed.
There is a higher incidence of MS in countries farther from the equator. This is thought to be linked to lower levels of sunshine and reduced production of vitamin D in the body. There is a suggested link between low levels of vitamin D production during childhood and the development of MS.
Exposure to smoking is associated with an increased risk of developing MS.
Underlying medical conditions
The risk of developing MS is potentially higher in people with a chronic autoimmune condition, such as type 1 diabetes.
There are four main types of MS:
Relapsing-remitting multiple sclerosis (RRMS)
People with RRMS have temporary episodes, called relapses, during which time their symptoms reappear. These relapses are followed by recovery periods (remissions). During remission, their symptoms partially or completely clear up. This is the most common form of MS.
Secondary-progressive multiple sclerosis (SPMS)
In SPMS, people start with RRMS and eventually transition to having symptoms that progressively worsen over time. There may or may not be relapses or remissions in this type of MS.
Primary-progressive multiple sclerosis (PPMS)
This is one of the less common forms of MS and is characterised by symptoms that progressively become worse from the onset of the condition. People with PPMS do not experience any remissions.
Progressive-relapsing multiple sclerosis (PRMS)
This is a rare form of MS that is characterised by symptoms that steadily become worse, but also acute periods of worsening symptoms (known as flares).
Signs and symptoms
There are a few different types of multiple sclerosis and people may experience a wide range of symptoms that can vary in intensity and frequency. Some people may have intermittent symptoms, while others may find their symptoms follow a progressive pattern. The changing nature of the symptoms of this condition may make life unpredictable.
Many people with MS experience a feeling of extreme mental and/or physical exhaustion. Fatigue may be experienced for hours, days or even months. Depending on its frequency and intensity, fatigue may interfere with the capacity to work, exercise and take part in social activities.
Cognition and emotion changes
For many people affected by MS, the emotional changes and impaired cognitive function can prove challenging. Half of all people with MS will not experience any cognitive changes, but for those who are affected, they may notice changes that may include:
- Memory loss;
- Decreased attention span;
- Difficulties with reasoning and problem-solving, and;
- Difficulties with some aspects of speech and language.
Some people with MS may find their mood has been affected and they may become depressed, or experience mood swings that may manifest as bipolar disorder. The types of changes that someone may experience will depend on which parts of the brain have been affected by the lesions associated with MS.
Bladder and/or bowel problems
Depending where damage has occurred, some people with multiple sclerosis may experience problems with their bladder and bowel function. Bladder problems may include urinary incontinence, incomplete voiding (emptying of the bladder) or increased urinary frequency and urgency. Constipation is the most common bowel problem for people with MS.
Because sexual response is controlled and interpreted by the central nervous system, some people with MS may experience sexual dysfunction such as impotence. There is a range of symptoms that may be experienced and these may vary, depending on where the lesions have occurred in the central nervous system.
Up to two thirds of people with MS experience pain that can affect their capacity to carry out work, exercise and social activities.
Musculoskeletal pain is the result of weakness, wasting and spasticity. This pain is often felt in the back, hips, legs and arms. Some people with MS may experience back pain when sitting down or standing, while leg spasms or cramps can often occur during sleep.
Neuropathic pain is the result of disruption to messages transmitted by nerves within the brain and spinal cord. Neuropathic pain can include altered sensation and typically occurs in the extremities. This type of pain is often described as:
- Pins and needles;
- Prickling, and;
A particular type of neuropathic pain can be experienced in the trigeminal nerve, which carries impulses between the brain and the face. This is called trigeminal neuralgia and is often an early symptom of MS. The pain associated with trigeminal neuralgia can range from a constant ache to intense stabbing in the jaw or face. This pain may last from a few seconds to several minutes.
Movement and coordination problems
Multiple sclerosis can cause some people to have problems with movement, balance and coordination including:
- Loss of balance;
- Unstable gait;
- Involuntary muscle spasms, and;
It is common for people with MS to experience problems with their vision and this is often the first symptom noticed. A condition commonly associated with MS is optic neuritis. Optic neuritis is the inflammation of the optic nerve. The optic nerve sends the visual information from the eye to the brain. The degree of impairment to vision depends on how much inflammation has occurred in the optic nerve. Vision generally returns partially or fully within a few weeks. Some people with MS experience recurrent episodes of optic neuritis.
The types of visual problems that may be associated with optic neuritis may include:
- Blurred vision;
- Dim vision, and;
- Pain in the back of the eye.
Other vision problems
Some people may develop visual problems that are not related to optic neuritis and these may include:
- Diplopia - double vision, and;
- Nystagmus - where the eye makes involuntary jumping movements either sideways or up and down.
Methods for diagnosis
Early MS may present as a vague set of symptoms that may occur sporadically over a long period of time. Although there is no single test for the diagnosis of MS, there are specific criteria used by healthcare professionals to help them make an accurate diagnosis.
For a diagnosis of MS to be made, there must be:
- Two different areas of the central nervous system affected, and;
- Symptoms experienced on at least two separate occasions of at least one month apart, supported by a magnetic resonance image (MRI) scan that shows plaques, or lesions.
Medical history and neurological examination
A doctor will take a person's detailed medical history and conduct a neurological examination.
Magnetic resonance imaging (MRI)
Imaging of the brain and spinal cord form an important part of the diagnosis. MRI scans help the doctors to see if there are any lesions in a person's brain and spinal cord that would explain their symptoms.
Blood tests may be ordered to exclude other possible causes of symptoms. These tests analyse:
Types of treatment
Treatment for MS may vary, depending on factors such as:
- The particular type of MS;
- The severity and frequency of symptoms;
- What other medication has been used previously, and;
- Whether there are any other underlying medical conditions, such as diabetes or hypertension.
Medication is used to either slow the progression of MS, or to manage accompanying symptoms. When medication is administered, the dosage may vary between individuals and it may be altered throughout the course of the disease. As with any medication, treatment of MS may be associated with side effects of varying severity.
MS patients who have a relapse and whose symptoms are affecting functions such as vision and walking can be treated with intravenous methylprednisolone, usually for three days. Patients with severe relapse are usually administered methylprednisolone for five days.
Intravenous immunoglobulin (IVIG)
For patients who show no improvement with methylprednisolone, or when its use is not advised (such as in patients with hypertension or poorly-controlled diabetes), treatment includes intravenous administration of immunoglobulin (IVIG). Although it is not yet clear how IVIG works, it is thought to ease the inflammatory response seen in MS patients and it may also play a role in the repair of the myelin sheath.
- Interferon beta-1a/Interferon beta-2a - these are synthetic versions of interferon proteins that are naturally produced in the human body. Interferons are thought to slow disease progression by reducing inflammation and preventing nerve damage;
- Glatiramer - this is a synthetic protein that appears to block the immune cells that destroy the myelin sheath in people with MS;
- Teriflunomide - this drug appears to slow disease progression by blocking the reproduction of overactive immune cells;
- Dimethyl fumarate - this drug reduces relapses and works by helping nerve cells to defend themselves against inflammation and reduce myelin sheath damage;
- Natalizumab - this is an antibody that appears to reduce relapses and ease symptoms by blocking inflammatory immune cells from reaching the brain, and;
- Fingolimod - this drug appears to reduce relapses by binding to a receptor on certain inflammatory immune cells and traps them in lymph nodes, thus reducing inflammation and myelin sheath damage in the central nervous system.
Treatment for MS symptoms
Fatigue is a common symptom experienced by people with MS. People experiencing fatigue may be advised to first try gentle exercise and weight training, and good sleep-hygiene practices. If such therapies fail to provide a benefit, certain medications may help, such as amantadine.
People with MS who are experiencing urination frequency, urgency and incomplete voiding may be advised to avoid caffeine, which can often worsen these symptoms. If symptoms are severe and disruptive, medications may prove beneficial, such as oxybutynin.
One of the more distressing and painful symptoms experienced by people with MS is abnormal sensation.
If the symptoms are severe and interfere with function, low-dose anticonvulsants may be prescribed. Examples of medication that may be used in such treatment include gabapentin, pregabalin and carbamazepine.
Pain and associated muscular problems
Exercise and physical therapy can help to decrease spasticity and soreness of muscles that is commonly experienced by people with MS.
Massage, hydrotherapy and relaxation techniques such as meditation and deep breathing may also help ease chronic pain.
When these therapies fail to improve symptoms, medications may be prescribed. The medication may vary depending on the exact symptoms, but some of the more common medications that may be used include carbamazepine, antidepressants and non-steroidal anti-inflammatory drugs (NSAIDs).
Double vision may be treated with steroids or eyeglasses with special prisms that minimise double vision.
For people who experience nystagmus, medication may prove beneficial, such as clonazepam.
Some factors contributing to MS complications may include:
- Inadequate diet;
- Poor hydration;
- Sedentary lifestyle, and;
- Poor personal hygiene.
Because MS is a chronic illness, it has the potential to affect people across their work, relationships, sleep, diet and ability to exercise. Some of the more common complications that may be associated with MS may include:
Although there is currently no cure for MS, people with MS can have a similar life expectancy as the general population.
There are no clear strategies to prevent the development of MS.