I have been tasked with writing a paper about amyotrophic lateral sclerosis (ALS). The ALS Association website has described ALS in a very clear and concise manner and I would like to share that with you know.
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord. Motor neurons reach from the brain to the spinal cord and from the spinal cord to the muscles throughout the body. The progressive degeneration of the motor neurons in ALS eventually leads to their death. When the motor neurons die, the ability of the brain to initiate and control muscle movement is lost. With voluntary muscle action progressively affected, patients in the later stages of the disease may become totally paralyzed. A-myo-trophic comes from the Greek language. "A" means no or negative. "Myo" refers to muscle, and "Trophic" means nourishment–"No muscle nourishment." When a muscle has no nourishment, it "atrophies" or wastes away. "Lateral" identifies the areas in a person's spinal cord where portions of the nerve cells that signal and control the muscles are located. As this area degenerates it leads to scarring or hardening ("sclerosis") in the region.
As motor neurons degenerate, they can no longer send impulses to the muscle fibers that normally result in muscle movement. Early symptoms of ALS often include increasing muscle weakness, especially involving the arms and legs, speech, swallowing or breathing. When muscles no longer receive the messages from the motor neurons that they require to function, the muscles begin to atrophy (become smaller). Limbs begin to look "thinner" as muscle tissue atrophies.

ALS is commonly referred to as Lou Gehrig’s disease. Lou Gehrig was the one of the greatest baseball players to ever play the game but he had his career cut short when he was diagnosed with ALS. Just imagine how many more consecutive games the “Iron Horse”, as Lou Gehrig was known in his Yankee heydays, could have played had he not suffered from ALS. But I digress we are here to talk about ALS not Yankee greats. In the pages that follow we will be taking a closer look at how ALS affects the motor neurons in our body, the different ways that it can be diagnosed, and the various methods to treat the disease.
To better understand the role of motor neurons in the nervous system it is important to understand how the nervous system works. The nervous system is broken down into two separate systems. The central nervous system (CNS) which consists of the brain and spinal cord and the peripheral nervous system (PNS) which consists of sensory neurons, motor neurons, and all the nerves that extend out from the brain and spinal cord. The sensory neurons or receptor neurons send messages to the brain. The brain is the processing center. It rapidly processes all of the information sent to it via the sensory neurons and sends messages back out to the body via motor neurons or effector neurons. Since motor neurons are a part of the PNS let’s take a closer look at how the PNS functions. The PNS is divided into two separate systems, the autonomic nervous system (ANS) and the somatic nervous system (SNS). The ANS is made up of sensory neurons that are located in the visceral organs of the body. The ANS also has motor neurons that conduct nerve impulses from the CNS to smooth muscle, cardiac muscle, and glands. These impulses happen without us consciously controlling their actions thus they are call involuntary. The SNS has receptors all throughout your body. The SNS sensory neurons send messages to the CNS when these receptors are stimulated. Some examples of receptor locations are in the skin, in the head, and in your arms and legs. The SNS has motor neurons that send nerve impulses from the CNS to skeletal muscles. These types of motor responses can be consciously controlled and are referred to as voluntary. These motor neurons are the only way for the CNS to send messages to the skeletal muscle. When motor neurons in the SNS become badly damaged or die our brain will lose the ability initiate and control muscle movement. It is precisely these motor neurons that ALS affects.
Now that we know which motor neurons are affected by ALS let’s examine how motor neurons send messages to muscle and what ways ALS inhibits those messages from being sent. A motor neuron has three main parts. It has a cell body, axon and dendrites. The following is Anatomy & Physiology: From Science to Life, Second Edition description of the parts of the neuron.
The cell body contains the nucleus surrounded by cytoplasm that contains typical organelles such as lysosomes, mitochondria, and a Golgi complex. Neural cell bodies contain prominent clusters of rough endoplasmic reticulum, termed Nissl bodies, where protein synthesis occurs. Newly synthesized proteins produced by Nissl bodies are used to replace cellular components, as material for growth of neurons, and to regenerate damaged axons of the PNS.
Two kinds of processes (extensions) emerge from the cell body of a neuron. Dendrites (= little trees) are the receiving or input portions of a neuron. They usually are short, tapering, and highly branched. In many neurons the dendrites form a tree-shaped array of processes extending from the cell body.
The single axon (= axis) of a neuron propagates nerve impulses towards another neuron, a muscle fiber, or a gland cell. An axon is a long, thin, cylindrical projection that often joins the cell body at a cone-shaped elevation called the axon hillock (= small hill). In most neurons, impulses arise at the junction of the axon hillock and the initial segment, called the trigger zone, from which impulses are conducted towards the distal end of the axon. The cytoplasm of the axon, called axolemma (lemma= sheath or husk). Along the length of the axon, side branches called axon collaterals may branch off, typically at a right angle to the axon. The axon and it collaterals end by dividing into many fine processes called axon terminals. The tips of some axon terminals swell into bulb-shaped structures called synaptic end bulbs, which are the sits of communication between the neuron and another neuron or an effector cell. There are also two other very important facts about motor neurons the book mentions. The first is that most neurons cannot divide (are amitotic) because they lack centrioles that are essential for mitosis to occur. The other is that damage to an axon can impede the flow of axoplasm, leading to altered transmission of chemical and electrical signals. The neuromuscular junction is where the message is passed from the motor neuron to the muscle. The neuromuscular junction includes the synaptic end bulb of the axon, the motor end plate of the muscle cell, and the synaptic cleft. The synaptic cleft is the space between the synaptic end bulb and the motor end plate. In order to get the message from the synaptic end bulb to the motor end plate neurotransmitters such as acetylcholine are released from the synaptic end bulb. When the message reaches the synaptic end bulb neurotransmitters substances such as acetylcholine are released. Acetylcholine diffuses across the synaptic cleft carrying the message the motor end plate. The motor end plate is the part of the sarcolemma of muscle cell, which is in closest proximity to the synaptic end bulb.
So what does all this scientific jargon mean anyways? A motor neuron has three parts a cell body, dendrites, and an axon. The cell body is the processing center of the neuron. This is where the neuron produces energy and processes the nutrients supplied by blood. The dendrites are the input centers. They receive messages from other neurons and send them down towards the axon. Transmission of the message is made possible by neurotransmitters that are present in the synaptic end bulb at the distal end of the axon. At the synaptic end bulb the electrical message is converted into a chemical message in order to cross the synaptic cleft. Once across the synaptic cleft the neurotransmitters complete their journey delivering the message to the muscle cell using the motor end plate. ALS causes a person’s motor neurons to shrink and disappear over time. A person suffering from ALS will eventually lose the ability to tell their muscles to move. “However, someone with ALS, even at an advanced stage, can still see, hear, smell, and feel touch. The nerves that carry feelings of hot, cold, pain, pressure, or even being tickled, are not affected by Lou Gehrig's disease.” (Steven Dowshen, 2009). By now you are probably asking yourself what are some of the early warning signs of this disease. ALS Association tells us that no two people with ALS experience the same symptoms or the same sequences or patterns of progression. But, progressive muscle weakness and paralysis are universally experienced. The hands and feet may be affected first, causing difficulty in lifting, walking or using the hands for the activities of daily living such as dressing, washing and buttoning clothes. Symptoms can begin in the muscles of speech, swallowing or in the hands, arms, legs or feet. Early symptoms vary with each individual, but usually include tripping, dropping things, abnormal fatigue of the arms and/or legs, slurred speech, muscle cramps and twitches and/or uncontrollable periods of laughing or crying.
Amyotrophic lateral sclerosis (ALS) does not lend itself to a quick definitive diagnosis early in its presentation. Often, neurologists need many months to exclude all other possible diagnoses in a patient presenting with upper and lower motor neuron signs…
The diagnosis of amyotrophic lateral sclerosis (ALS) is primarily clinical. ALS may be suspected whenever an individual develops insidious loss of function or gradual, slowly progressive, painless weakness in 1 or more regions in the body, without changes in the ability to feel, and no other cause immediately evident…
Nerve conduction studies and needle electromyography are useful for confirming the diagnosis of ALS and for excluding peripheral conditions that resemble ALS… (Armon Carmel, 2011) Once you have been diagnosed with ALS then what? How far has medicine come in the 140 years since ALS was discovered? What medical breakthroughs if any are on the horizon? While there is no cure for this terrible affliction medicine research is making incredible breakthroughs even as I type this paper.
Currently your doctor would prescribe drugs in an attempt to slow down the disease process. Maybe prescribe some physical therapy and occupational therapy for retaining muscle strength. This could change soon though. In August of 2011 Northwestern University scientists identified a common cause for all forms of ALS. “This opens up a whole new field for finding an effective treatment for ALS,” said senior author Teepu Siddique, M.D., the Les Turner ALS Foundation/Herbert C. Wenske Professor of the Davee Department of Neurology and Clinical Neurosciences at Northwestern’s Feinberg School and a neurologist at Northwestern Memorial Hospital. ”We can now test for drugs that would regulate this protein pathway or optimize it, so it functions as it should in a normal state.” (Northwestern.edu, 2011)
A cure for ALS is still a few years away. As previously stated scientists are just now identifying a common cause for all forms of ALS. They now have the first piece in of the puzzle for an effective treatment. Volunteer clinical trials are currently underway, experimenting with stem cells. “Those stem cells surround the sick nerve cells and form connections with the sick nerve cells and nurse it to health.” (Lego, 2011)
In previous decades a diagnosis of ALS was a death sentence waiting to be fulfilled. You would slowly lose the ability to move your own muscles and eventually die. Today the prognosis is a little brighter. While there is no cure medical advancements are being made that are promising. Hopefully within the next decade scientists will have discovered a safe and effective way to cure ALS. This is giving those that have been diagnosed with ALS hope for the future.

References
Northwestern.edu. (2011, August 22). Retrieved April 14, 2012, from http://www.northwestern.edu/newscenter/stories/2011/08/siddique-als-breakthrough.html
Amyotrophic Lateral Sclerosis Fact Sheet. (2012, January 30). Retrieved April 2, 2012, from National Institute of Neurological Disordaors and Stroke: http://www.ninds.nih.gov/disorders/amyotrophiclateralsclerosis/detail_ALS.htm
ALSA.org. (n.d.). Retrieved April 2, 2012, from http://www.alsa.org/about-als/
Armon Carmel, M. M. (2011, August 26). Amyotrophic Lateral Sclerosis (ALS) Clinical Presentation. (M. Lorenzo Nicholas, Editor) Retrieved April 14, 2012, from medscape.com: http://emedicine.medscape.com/article/1170097-clinical
Lego, V. (2011, August 25). wzzm13.com. Retrieved April 16, 2012, from http://www.wzzm13.com/news/article/176690/9/ALS-cure-could-be-just-ten-years-away
Steven Dowshen, M. (Ed.). (2009, August). Retrieved April 14, 2012, from kidshealth.org: http://kidshealth.org/kid/grownup/conditions/als.html

Amyotrophic Lateral Sclerosis
Anatomy & Physiology II
Professor Charles Whitney
April 16, 2012