MS Flashcards
What produces myelin that wraps around nerves?
Oligodendrocytes in the CNS and Schwann cells in the peripherary.
What is MS?
Multiple sclerosis( scarring)is a disease of the CNS.
Progressive disease, so symptoms usually worsen over time
Need to have two different symptoms, or occurring at different times.
No current cure, but treatments that can help manage symptoms.
Immunological disease.
Plaques of demyelination and scarring, and axonal loss in the White matter of brain and spinal cord..
Occur in different places in the CNS
Destroys the myelin which means the nerves are not able to conduct signals as well
How does demyelination in MS affect neuronal function?
Two main ways.
Loss of function - slows or completely prevents ability to conduct action potentials.
Hyper excitable - generate AP with minimal stimuli due to interference from nearby nerves.
What is a plaque in MS and where do they occur?
A plaque is an area of scarring due to demyelination, and is associated with inflammation, axonal loss and odema( accumulation of fluid).
They can occur at many places in the CNS, most commonly in the spinal cord, brain stem and optic tract and basal ganglia.
Because of this the symptoms are variable depending on where the plaques are located- if in a motor area, impaired movements etc.
What can be used to help support a diagnosis of MS?
MRI can show plaques by using a contrast.
What are the symptoms of MS?
Pretty much any symptom possible as so many different areas that plaques can occur.
Normal starts with general symptoms such as fatigue or tiredness. Optic tract is particularly prone so often visual disturbance.
Aproximatly 50% of MS sufferers suffer some cognitive impairment, such as memory problems, dementia, euphoria.
Other common symptoms are sensory disturbances, incontinence, weakness or spasticity in limbs, depression, moody swing, anxiety.
What are the risk factors of developing MS?
Most often the onset is in young adults 25-35.
Some genetic markers, changers in immune system.
Higher risk of MS in women, possibly linked to certain receptors, it is not x linked.
Quite prevalent in uk, common neurological disease.
What environmental factors are suggested to affect the probability of developing MS?
Latitude/light and vitamin D- both in development and in mother who are expecting.
Time of exposure to an unknown factor
Smoking increases likely hood of developing Ms.
No clear correlation, more like some insight into what is happening.
Ms is immunologically mediated, what does this mean?
Something happens in our immune response changes and causes demyelination.
In early life exposed to something( virus etc) that is similar to myelin, which has binding sites that out immune system recognises as foreign, and are then bound and destroyed by Activated T cells.This occurs in the periphery, and as there is low amounts of myelin in the peripherary, and it is fairly well protected this is not a problem.
However in MS, these cells adhere to and then penetrate the blood brain barrier. They are then reactivated in the CNS, causing a imflammatory cascade of macrophages, macrosites etc. As the body protector cells recognises the myelin in the CNS as being something alien, it starts to attack the myelin coating the neurons in the CNS.
In short what are the steps that take place in MS that lead to myelin degradation?
Peripheral activation - initial substance similar to myeling
Adhesion and penetration - T cells attach to BBB and pass through.
Central reactivation - Tcells reactivated in CNS causing cascade
Demyelination - attack of myelin by immune system
Neuron degeneration - neurons start to die, causing symptoms that are irreversible, as neurons are not replaced.
Why is it important to know that MS is an immunological disease?
It tells us that the drugs that are used to reduce MS symptoms are likely to target the immune system and to reduce inflammation.
How does MS first present?
Normally a patient has got to their 20/30’s with no problems, and suddenly experience a sudden episode, perhaps loss of muscle control, falling over, loss of vision, which lasts for a short period( 5/7 days) which then returns to normal.
The period of time when the symptoms occur is called a relapse.
What is a period of relapes and a period of remission in regards to MS?
Relapse is a period of disability where symptoms are present, caused by cytokines and cascades.
Remission is a period of recovery where symptoms either end or decrease in severity. Thee is limited ability of the CNS to repair damage, sometimes signals can be redirected through alternative routes.
What are the four types of Ms?
Relapsing/remitting
Secondary progressive
Primary progressive
Benign
What is relapsing/remitting MS?
This is experienced by 80% of MS sufferers.
They have periods of disability, followed by stable periods of recovery.
It is normal that the period of recovery does not quite return to normal, so there is a slow progression of the disease after each attack.
50% of sufferers will then develop into secondary progressive MS.
