Multiple Sclerosis-Pathophysiology Flashcards
Multiple Sclerosis stands for
multiple areas of scarring (sclerotic tissue) or plaques
What is MS
An autoimmune disease characterized by a course of inflammatory attacks leading to demyelination and slowing down, and eventually halting, of saltatory conduction in the CNS (Brain and SC)
What is astrogliosis
Glial Scarring
MS disease characteristics
Episodes of CNS inflammation called attacks, relapses, or exacerbation, resulting in:
Astrogliosis – glial scarring
Destruction of myelin
Destruction of oligodendrocytes (build myelin)
Irreversible axonal damage
What to astrocytes do?
wide variety of essential functions
Roles in:
synaptic transmission
information processing by neural circuit functions
Astrogliosis
Hypertrophy of astrocytes
Astrocytes proliferation
Glial scar formation
Clear formation of dense, narrow, and compact glial scars
What is GFAP
glial fibrillary acid protein
Pathophysiology: “Reactive Astrogliosis”
The BBB is disrupted and triggers astrogliosis & ↑ production of a brain antigen called glial fibrillary acid protein (GFAP)
GFAP causes further disruption of BBB, which mobilizes “activated” lymphocytes & macrophages to the scene.
Macrophages initiate destruction of myelin sheaths & cell bodies of oligodendrocytes.
Fibrous astrocytes fill the demyelinated areas & form the glial scar or plaque.
Cytotoxic lymphocytes and macrophages are present in the plaques, leading to edema that can have a mass effect, simulating a tumor
How do steroids work to treat MS
The successful treatment of MS exacerbations with steroids is in part based on the drugs’ ability to control the edema resulting from the inflammatory response
Steroids decrease the inflammation that occurs during the inflammatory response
What is the main factor behind remyelination in early stages of MS attacks
The survival of oligodendrocytes is the factor behind remyelination in early attacks (early stages)
In the later stages of MS where does remyelination occur
In later stages of the disease, no oligodendrocytes are preserved, and remyelination occurs only at the borders of the plaques, if at all
What are plaques?
The demyelinating lesions of MS are termed “plaques”, and have sharply delineated lesions that can be viewed on MRI
Where are potential targets for MS lesions?
Myelin at all CNS sites are potential targets
Where are typical 1st lesions and what region typically has lesions
Typical lesions are in the periventricular region of the lateral ventricles and the optic nerves (often a 1st lesion)
What are one of the 1st symptoms that people with MS have
Visual disturbances because early on it typically affects the optic nerve
