History, Etiology, and Symptoms of Multiple Sclerosis

What is Multiple Sclerosis?

Multiple sclerosis is a chronic autoimmune disorder where an individual's immune system attacks and damages the protective covering of nerve cells (PubMed Health). This covering, called myelin, is crucial for proper nervous system function as it insulates the electric current that neurons use to communicate.

A neuron with a protective myelin sheath around its axon.
                                 

Currently, four different "types" of multiple sclerosis are recognized:

Clinically Isolated Syndrome (CIS): CIS is a 24-hour episode of MS-like symptoms caused by inflammation and demyelination of nerve cells. It can be a one time occurrence or can lead to progression of true multiple sclerosis(NMSS-Types of MS).

Relapsing-Remitting MS (RRMS): The most common form of MS, RRMS, follows a pattern of worsening symptoms (relapse) followed by periods of near complete recovery (remission)(NMSS-Types of MS). 

Secondary Progressive MS (SPMS): Many of the individuals diagnosed with RRMS will progress to SPMS. SPMS is a form of MS characterized by worsening of neurologic function(NMSS-Types of MS).

Primary Progressive MS (PPMS): PPMS is a form of MS where symptoms and neurologic function continue to worsen from onset of the disease without any periods of remission(NMSS-Types of MS). 

Multiple sclerosis is a relatively uncommon disease, affecting only around 400,000 people in the US (Loma, 2011) and 2.3-2.5 million people worldwide (NMSS-Who Gets MS). The disease has noticeable geographic and ethnic influence and is more likely to occur in Caucasians and/or in populations that are far from the equator. Geography and ethnicity seem linked as some non-Caucasian populations that are far removed from the equator, such as the Inuit, show low incidence rates of the disease (NMSS-Who Gets MS). Multiple sclerosis also affects certain genders and age groups differently, as women and young adults (20-40 yrs) are more susceptible to the disease (Loma, 2011). In the past decade, some research has indicated that the geographical influence in incidences is decreasing and the ratio of women to men is increasing (Alonso, 2008).

A Brief History

Evidence of multiple sclerosis has existed since the mid 1800's in the form of autopsy reports (Roth, 2005). In 1868, professor Jean-Martin Charcot associated neurological symptoms of living patients with the characteristics of the disease found in autopsies. He described and named the disease, but was unable to determine its cause or an effective treatment (Rolak, 2003). In the early 1900's, Dr. Thomas Rivers conducted research that proved that MS was not a viral disease. Some scientists thought that MS could be related to the immune system, but this theory wasn't studied further until the 1960's (Roth, 2005).
In the late 1900's, MRI and new drug treatments enabled doctors to better detect and treat MS (Roth, 2005).

The mystery of the cause of MS persists, but continuing research is uncovering more about the disease in the hope to find a cure. 

Etiology

Currently, there is no definitive cause of multiple sclerosis, however epidemiologists suspect a cocktail of genetic, environmental, and viral etiological agents are responsible for the disease. Individuals with first degree relatives who have contracted the disease are much more susceptible than those with no family history (Loma, 2011). This pattern of incidence would indicate a genetic component of the disease. Environmental factors also seem to play an important role due to trends of higher prevalence in regions further from the equator. Researchers have noted that individuals migrating from a region with high MS incidence rates to a region with low incidence rates are less likely to obtain the disease (Loma, 2011). Finally, some scientists have focused their attention on certain pathogens that could increase an individual’s risk to contract multiple sclerosis (Loma, 2011). These three etiological components will be discussed in further detail in the second blog post.

Symptoms

Because the nervous system is so crucial to so many body processes, multiple sclerosis can present in a wide variety of symptoms. Some symptoms affect the eyes, like blurred vision, red-green color distortion, and temporary blindness (PubMed Health). Other signs can be mental, like depression, dizziness and vertigo, mood swings, and cognitive problems (NMSS-MS Symptoms). Another set of symptoms can be physical, including bladder dysfunction, muscle weakness, numbness, fatigue, and difficulty with coordination and balance (NMSS-MS Symptoms). Symptoms of multiple sclerosis can range in severity from being a mild annoyance to a life-altering disability. 

Diagnosis

The symptoms of multiple sclerosis can be confounding at times due to the fact that they are not specific to this one disease. Other, differently treated illnesses, can present clinical signs that are similar to MS (PubMed Health). In order to diagnose the disease properly, doctors will utilize a patient's medical history with a range of neurological tests. These tests include MRI's to search for inflammation in the nervous system, evoked potential tests that measure nervous system response time, and spinal taps to eliminate other possible diseases (PubMed Health). 

References:

Alonso, A. & Hernán, M. A. (2008). Temporal trends in the incidence of multiple sclerosis: A systematic review. Neurology 71(2), 129-135. http://doi.org/10.1212/01.wnl.0000316802.35974.34

Loma, I. & Heyman, R. (2011). Multiple Sclerosis: Pathogenesis and Treatment. Current      
Neuropharmacology, 9(3), 409-416. http://doi.org/10.2174/157015911796557911

MS Symptoms. (n.d.). National Multiple Sclerosis Society. Retrieved from: http://www.nationalmssociety.org/Symptoms-Diagnosis/MS-Symptoms

Multiple Sclerosis. (n.d.). PubMed Health Glossary. Retrieved
from: https://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0024311/

Rolak, L. A. (2003). MS: The Basic Facts. Clinical Medicine and Research 1(1), 61-62.         Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1069024/

Roth, E. (2005). The History of Multiple Sclerosis: How Far Have We Come? Healthline
Media. Retrieved from: http://www.healthline.com/health/multiple-sclerosis/history#Overview1

Types of MS. (n.d.). National Multiple Sclerosis Society. Retrieved from: http://www.nationalmssociety.org/What-is-MS/Types-of-MS

Who Gets MS? (n.d.). National Multiple Sclerosis Society. Retrieved from: http://www.nationalmssociety.org/What-is-MS/Who-Gets-MS

Image Sources (in order of appearance):

https://i1.wp.com/selfhacked.com/wp-content/uploads/2016/10/myelin.jpg?resize=450%2C214&ssl=1

http://www.healthline.com/health/multiple-sclerosis/facts-statistics-infographic

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