Demyelinating Disorders Flashcards
Who taught this lecture?
Laura Pulido (TA)
What is myelin?
Membrane extensions from oligodendrocytes (CNS) or Schwann cells (PNS)
What is the myelination process?
Myelin grows by the wrapping of the leading edge at the inner tongue around the axon together with the lateral extension of myelin membrane layers towards the nodal region
Advantages of myelination in the CNS?
- axon insulation and speeding up of axon potential propagation
- clustering of Na channels
- Metabolic support
What is the most common demyelinating disease of the CNS?
Multiple Sclerosis; It is an accumulation of demyelinating lesions that occur in the white matter and the gray matter of the brain and spinal cord
Who gets MS?
Individuals between 20-40 years old. Higher in women.
What is the MS pathogenesis?
- Leukocytes such as T and B lymphocytes infiltrate in the brian
- T cells target antigens in the brain, prompt the activation of microglia and macrophages, leading to local inflammation
- Inflammation produces NO, which can damage mitochondria (energy failure)
- Activation of proteolytic enzymes
Why are they unable to recruit oligodendrocyte progenitor cells (OPC) in chronic MS?
OPC numbers are reduced, and exhaustion of OPC due to repeated cycles of demyelination and remyelination
If they do manage to recruit OPC, why do they failure to differentiate?
Deficiency of factors needed for their recruitment
What is used to treat MS?
A) Steroids (short term recovery)
B) Interferons (reduce frequency and severity of relapses)
What component of the Schwann cell is essential for myelination
The polarized structure
What are the three compartments of the Schwann cells?
Abaxonal domain
Intermediate
Adaxonal domain
Symptoms of Guillain Barre Syndrome
a) Breathing difficulties
b) residual numbness or other sensations
c) heart and blood pressure problems
d) pain
How do they diagnose Guillain Barre syndrome
lumbar puncture or an electromyogram
What triggers Guillain Barre Syndrome?
Bacterial infection activates immune system, which targets gangliocytes in the brain that looks like bacterial surface
