Amyotrophic Lateral Sclerosis


When some people hear of amyotrophic lateral sclerosis (ALS), they think of the unfortunate passing of theoretical physicist Stephen Hawking in 2018. Hawking’s death was symbolic of prevailing against the unfortunate statistics of significantly shortened longevity amongst those diagnosed with ALS. Hawking was diagnosed with ALS around age 21 and was expected to live no longer than his 25th birthday. However, Hawkings beat all odds and lived a long, inspiring, and successful life till the age of 76. Hawking’s accomplishments regarding his articulation of the black hole and his contributions to other ideas within theoretical physics, such as quantum gravity, are just some of the many elements that make him such an inspiration to the world. Battling and living with ALS for almost 55 years has definitely inspired and given hope to many others around the world, especially those of us living with ALS and those of us who know a loved one with ALS (Harmon, 2020).  

Many know that Hawking unfortunately died of ALS, but what exactly is ALS? Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disease that affects motor neurons in the brain and spinal cord, resulting in a loss of muscle control (Amyotrophic lateral sclerosis (ALS) – Symptoms and causes). Specifically, ALS affects both upper and lower motor neurons. This neurodegenerative disease is commonly classified to exist in either a sporadic or familial form. “More than 30 different genes have been linked to the familial form of ALS” (van Es et al., 2017). The familial form of ALS is due to genetic mutations, and approximately 10% of patients are diagnosed with familial ALS. A common mutation that accounts for 30-40% of familial ALS diagnosis is an increase in the G4C2 hexanucleotide repeats on gene C9orf72, beyond the normal repeat range of 30 to several hundred or thousands (Oskarsson, Gendron and Staff, 2018). 

The symptoms of ALS could differ depending on what neurons are specifically affected (Amyotrophic lateral sclerosis (ALS) – Symptoms and causes). If one were to experience the loss of lower motor neurons which extend from the spinal cord to the muscles, symptoms such as muscle weakness, cramps, and fasciculations or muscle twitches could occur. Loss of lower motor neuron features contribute to higher mortality rates compared to symptoms caused by the loss of upper motor neurons in the brain, which include spasticity, clumsiness, brisk reflexes, and functional limitations (Oskarsson, Gendron and Staff, 2018). Overall, the general symptoms someone with ALS may experience include difficulty walking, tripping and falling, leg or feet weakness, slurred speech, trouble swallowing, muscle twitching or cramps that occurs in the arms, tongue, or shoulders, cognitive and behavioral changes, and inappropriate laughing, crying, or yawning (Amyotrophic lateral sclerosis (ALS) – Symptoms and causes). 

There is a lot of variation amongst the various diagnoses of ALS. For instance, some individuals who are known to have “classical ALS” only experience the majority of ALS symptoms impacting motor involvement. However, around half of ALS patients demonstrate some degree of cognitive impairment and behavioral changes, which is also known as executive dysfunction. There are those patients who are diagnosed as having ALS-esi, which is when there is evidence of executive dysfunction, ALS-neci. when there is no executive dysfunction but there is some impairment in memory or other cognitive aspects, and ALS-bi, when only behavioral changes are present. A small fraction of ALS patients (around 5-10% of patients) may also have frontotemporal dementia (FTD) (van Es et al., 2017). Other variations in diagnosis include progressive muscular atrophy (PMA) and primary lateral sclerosis (PLS). PMA is a variation of ALS that is mostly isolated to the lower motor neurons that are impacted, whereas PLA is mostly isolated to the upper motor neurons (Harmon, 2020). This variation in diagnosis of ALS explains how individuals like Hawking can live so long despite the common statistical odds of a lifespan limited to 5 years after being diagnosed (Harmon, 2020). However, the unfortunate reality is that there are very few patients diagnosed with variations of ALS that progress as slowly as it did in Hawking. This means that this variation can be both good news for few and bad news for the majority. Nevertheless, it is better to look at this in a positive light and think of it this way: there is hope for slow progression due to all this variation in diagnosis, so there is hope for beating statistical odds as well.

 

References

Mayo Clinic. 2020. Amyotrophic Lateral Sclerosis (ALS) – Symptoms And Causes. [online] Available at: <https://www.mayoclinic.org/diseases-conditions/amyotrophic-lateral-sclerosis/symptoms-causes/syc-20354022> [Accessed 23 November 2020]. 

van Es, M., Hardiman, O., Chio, A., Al-Chalabi, A., Pasterkamp, R., Veldink, J. and van den Berg, L., 2017. Amyotrophic lateral sclerosis. The Lancet, 390(10107), pp.2084-2098. 

Oskarsson, B., Gendron, T. and Staff, N., 2018. Amyotrophic Lateral Sclerosis: An Update for 2018. Mayo Clinic Proceedings, 93(11), pp.1617-1628. 

Harmon, K., 2020. How Has Stephen Hawking Lived Past 70 With ALS?. [online] Scientific American. Available at: <https://www.scientificamerican.com/article/stephen-hawking-als/> [Accessed 23 November 2020]. 

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