Question

When Mary began experiencing paresis and spasticity in her lower extremities, she knew that something was seriously wrong. She was finally diagnosed as having a form of relapsing remitting multiple sclerosis. An MRI performed during one of her more severe “episodes” revealed lesions (lower left) that appeared to improve after three months (lower right). Her neurologist explained that all of her previous episodes could be explained by the underlying cause of this disease. Mary learned that the progression of this disease is highly variable and was told that while many of the symptoms she reported are common, the combination of symptoms in her experience is very rare.

1) In the MRI images you can see the lesions as bright “white spots” on the brain. Using what you know about the structure of a neuron, explain what is causing this spot to appear on the MRI. 2) The brain has specific cells that are responsible for the improvement that you can see in the MRI images. What are these cells and what function to they perform?

3) How does this form of MS differ from other forms?

Answer 1

Ans 1) The white spots or lesions which is present on the brain and this appears due to brain activity. The lesions appear as white spot within the brain and this appears due to the random firing caused by the neuron. This leads to the breakdown of the myelin sheath which creates white lesion. Majorly the white spots appear in the brain due to change in fluid movement as well as the water content that tends to cause inflammation of the brain cells. Due to this change, there is a change in the frequency of transmission of brain impulse caused by increase in the firing by the neuron. Due to the firing from the neuron at high intensity, the spots often observe decrease in the blood flow and hence appears white.

Ans 2) The special cells which are present in the brain and helps in providing a complete protection are called oligodendrocytes. These special cells are known to make a fatty substance which is called as myelin sheath and this is known to produce an insulation to the nerve axons. Due to the presence of the myelin it helps nerve impulse conduction. As the myelin insulate the nerve cell axons, it helps in passing of the electrical impulse along axon. The oligodendrocytes are basically glial cells and as they help in the production of myelin, it helps in imparting protection to the neurons and also support it.

Ans 3) MS or multiple sclerosis, it impacts the brain because it attacks the myelin sheath that protects and insulate the nerve fibers and hence hinders the nerve impulse transfer and communication between brain and all parts of the body. The white spots in the brain is different from rest of the type of MS because in this form of MS, it leads to generation of rapid firing by the neurons whereas in other forms the nerve impulse conduction is hindered and it breaks the communication.