Question

Select a disease that affects one of the organ systems studied this week..  Put the name of the disease in the subject line of your post. When choosing a disease, make sure that your selection is unique. Repetitive posts will earn minimal, if any credit. You can always comment on classmates’ post providing additional, in depth insight to fulfill weekly participation requirements.

In your post address following:

1. Name(s) of the disease and the system that is primarily affected by the chosen disease.

2. What category does the chosen disease belong to? (See Module 1)

3. Classify the disease based on its intensity and duration. (acute, chronic, latent).

4. Identify the homeostatic mechanism that has failed.

5. Select two signs (remember that sign is an objective characteristic of the disease) and describe what causes the presence of the selected signs.

6. Select two symptoms (symptom is the patient’s subjective perception of a change in normal body function) and describe what causes the presence of the selected symptoms.

7. What diagnostic tool (choose at least one) would help you in diagnosing this disease and how?

Answer 1

QUESTIONS AND ANSWERS

MULTIPLE SCLEROSIS

1. Name(s) of the disease & the system that is primarily affected by the chosen disease.

• Name of the disease     – Multiple sclerosis
• Organ system affected – Nervous system

2. Category of the chosen disease.

                              Multiple sclerosis is an autoimmune inflammatory disease.

3. Classify the disease based on its intensity & duration. (Acute, Chronic, Latent).

                               Multiple sclerosis belongs to the group of chronic diseases that affects the central nervous system.

4. Identify the homeostatic mechanism that has failed.

                               Homeostasis of the central nervous system (CNS) is failed.

5. Select two signs (remember that sign is an objective characteristic of the disease) & describe what causes the presence of the selected signs.

• Weakness – due to lack of use or stimulation due to nerve damage,
• Numbness, tingling or unsteadiness of the limbs - are the most common signs - In multiple sclerosis, the protective coating on nerve fibers (myelin) in the central nervous system is damaged. This creates lesions depending on the location in the central nervous system &causes symptoms such as numbness, pain or tingling in parts of the body.
• Urinary urgency or retention- Bladder dysfunction in MS happens when nerve signals to the bladder & urinary sphincter (the muscles surrounding the opening to the bladder) are blocked or delayed because of MS lesions in the brain &/or spinal cord.
• Blurry vision & double vision are all common initial manifestations of multiple sclerosis -Problems with vision can result from damage to the optic nerve or a lack of coordination in the eye muscles.

6. Select two symptoms (symptom is the patient’s subjective perception of a change in normal body function) & describe what causes the presence of the selected symptoms.

• Ataxia – due to the involvement of the tracts of the cerebellum can occur - Movements such as walking & speaking involve complex messages from the brain & feedback from the nerves. When multiple sclerosis causes nerve fibre damage that delays or interrupts the matching of these messages; results in ataxia. (Ataxia – is the loss of full control of bodily movements).
• Spastic paralysis - Spasticity is generally caused by damage or disruption to the area of the brain & spinal cord that are responsible for controlling muscle & stretch reflexes. These disruptions can be due to an imbalance in the inhibitory & excitatory signals sent to the muscles, causing them to lock in place.

7. What diagnostic tool (choose at least one) would help you in diagnosing this disease & how?

                      Magnetic resonance imaging – is the widely used diagnostic tool for Multiple sclerosis.

• MRI of the head & spine (more sensitive than CT): May show many plaques. MRI reveals multiple lesions with high T2 signal intensity & one large white matter lesion. These demyelinating lesions may sometimes mimic brain tumors because of the associated oedema & inflammation.
• MRI of the brain is considered as the most accurate test to diagnose MS, reaching a sensitivity of 88 to 95% in symptomatic persons. Increased T2 & decreased T1 intensity represent the increased water content of demyelinated plaques in the cerebrum & spine. Enhancement of lesions with gadolinium indicates active MS lesions that may enhance for up to 2 to 6 weeks after an exacerbation.

EXPLANATIONS

MS Or multiple sclerosis is an autoimmune inflammatory disease of the Central nervous system white matter characterized by a relapsing or progressive course.

• One of the most common CNS / central nervous system diseases.

• Characterized by the appearance of patches of demyelination in the white matter of the CNS, generally starting in the optic nerve, spinal cord / cerebellum.

• The myelin sheaths degenerate & the myelin is removed by the microglial cells. Astrocytes proliferate leading to the formation of the gliotic scar.

• As demyelination occurs the conduction of the nerve impulses in the axons is impeded.

• MS is confined to the CNS, causing demyelination of ascending & descending tracts.

• Blood-brain barrier breach results in the invasion of brain & spinal cord by some infection allowing leukocytes to enter normally immunologically protected CNS.

• The inflammation & demyelination with loss of myelin sheath results in the breakdown of the insulation around the axons & the velocity of AP are reduced & ultimately becomes blocked.

• Myelin is relatively rich in lipid (70-80%) & also contains proteins that play a role in its compaction.
• Many of the proteins found in CNS differ from those in the peripheral nervous system.
• It is possible that mutations in the structure of the myelin protein can occur & be responsible for some inherited forms of demyelination.
• It is also possible that auto antigens may develop in Multiple Sclerosis.
• The course of MS is chronic with exacerbations & remissions.
• Due to the widespread involvement of the different tracts at different levels of neuro - axis, the signs & symptoms are multiple.

• Remissions in MS is by the remodeling of the demyelinated axonal plasma membrane so that it acquires a higher than the normal number of sodium channels which permit AP conduction despite myelin loss.

• In progressive form of this disease without remissions patients may have substantial damage to the axons and myelin sheath suggesting the axonal pathology of Multiple Sclerosis .

It is a disease of young adults. Most cases occur between the age of 20 & 40 years.

• Females are affected more than males.

• The cause of the disease is exactly unknown; reasons may interplay between viral infections, host immune responses & hereditary alone or in combination of these can play a role.

• Breach in blood-brain barrier in the genetically predisposing individual would be responsible for MS.

• Weakness, numbness, tingling or unsteadiness of the limbs is the most common sign.

• Ataxia due to involvement of the tracts of the cerebellum may occur, spastic paralysis may also be present.

• Urinary urgency or retention, blurry vision & double vision are all common initial manifestations of the disease.

• Symptoms may persist for several weeks or may resolve spontaneously over a few days.

The most common early symptoms of MS are:

• Fatigue,Vision problems,Tingling & numbness,Vertigo & dizziness,Muscle weakness & spasms,Problems with balance & coordination .

Other less common, symptoms include:

• Speech & swallowing problems ,Cognitive dysfunction, Difficulty with walking ,Bladder & bowel dysfunction ,Sexual dysfunction ,Mood swings &depression.