6/18- Demyelinating Diseases (MS) Flashcards
(42 cards)
What cells make myelin in the central nervous system?
Oligodendroglia
What cells make myelin in the peripheral nervous system?
Schwann cells
___ cells may invest multiple axons, while ___ invest a single axon
Oligodendroglia cells may invest multiple axons, while Schwann cells invest a single axon
Classification of Myelin Disorders:
- Central
- Peripheral
- Both
Central:
- Multiple sclerosis
- Post infectious encephalomyelitis
Peripheral:
- Guillain-Barre Syndrome
- Charcot-Marie-Tooth diseaes
Both:
- Leukodystrophies
What clinical advancement has greatly helped in the diagnosis and understanding of demyelinating diseases?
(Especially MS)
Diffusion Tensor Imaging (DTI)
- Revolutionizing our understanding of white matter tracts in health and disease
What may be seen in the gross neuropathology of MS?
- Plaques may occur anywhere there is myelin (typically periventricular, subpial, junctional [white/grey])
- Well-defined, clearly-demarcated gelatinous
- Grey due to loss of lipid in myelin
- May be symmetrical
- Acute plaque may be pink
Characteristics of lesions/plaques in MS (time)?
Lesions are disseminated in space and time (multifocal); this is required for diagnosis
- Onset typically in young adult life
What is this?
Periventricular demyelinating plaques in MS
Classic presentation of MS
- Normal white matter
- Grey area around ventricles (periventricular demyelinating plaques)
Stages of MS? Timeline?
Relapsing remitting phase
- Attacks and recovery
- All the drugs that treat MS work in this phase; this form can be favorably modified by immunomodulatory drugs
Secondary progressing phase
- Relentless, steady decline in function
- Typically occurs after a few years
Primary progressive MS
- Relentlessly progressive from the onset
- Not responsive to currently available immunomodulatory drugs
What is this?
- White matter sunken and more white than normal
- Large bilateral demyelinating plaques (MS)
If demyelination is occurring in frontal lobes, may get loss of executive function and other symptoms typically associated with dementia
What is this?
Demyelinating plaque in MS (dark spot in top right)
MRI is used for what in MS?
- Detection of asymptomatic plaques
- Aids in diagnosis
- Disease activity can be followed throughout time
- Aids in therapeutic trials and management
- Can demonstrate dissemination in space and time
Describe the criteria (for MS) of dissemination in space? In time?
Dissemination in space (DIS)
- Clinically asymptomatic lesions can be seen
- Multiple widely distributed plaques can be identified
Dissemination in time (DIT)
- Plaques show characteristics imaging feature depending on how old they are
- Lesion of differing age indicate dissemination in time
McDonald Criteria codefies diagnosis using MRI
T/F: Plaques are present when the patient with MS is asymptomatic
True
- Can have plaques that don’t result in many symptoms
- Plaques can be used to assess relative activity, though, with fewer plaques being less active
- … even at baseline, is active
What is this showing?
Left: Unstained pons
Right: Stained pons revealing MS
Normal myelin stains black or deep blue; plaques do not stain
- Not knocking out a specific system
- Not in a particular vascular territory
What is this?
Demyelination of the spinal cord: grey discoloration (right side) seen in MS
What is this?
Optic chiasm in MS
- Demyelination in chiasm (-> bitemporal binocular heminopsia field defect)
- Demyelination of optic n. (-> vision loss in one eye; optic neuritis)
Epidemiology of MS?
- Women > men
- Onset typically in early adulthood
- People who grew up far from the equator (e.g. Minneapolis native 3x greater risk than Houston)*
*Thought perhaps to be chronic VItamin D deficiency (role in bones, but also an immune regulator)
What is this? Symptoms?
Demyelination in nerve root entry zone leading to paroxysmal symptoms (abnormal synthesis of signals)
- Trigeminal neuralgia (severe episodic pain)
- Hemifacial spasm
- Radicular pain
For these symptoms in young, think MS; in mature, think vascular or mass
What is Redlich-Obersteiner’s zone?
Transition between CNS and PNS myelin
What is seen microscopically in MS?
- Perivascular lymphocytic infiltrate
- Loss of oligodendroglia
- Myelin sheath stripping
- Macrophage infiltration
- Astrogliosis
- Relative sparing of axons (especially in relapsing-remitting stage; immune system can shut down lymphocytes)
What do therapeutics target in MS?
Cellular immunity (tamp it down!)
- e.g. corticosteroids?
What is this?
Perivascular lymphocytes in MS
- Lymphocytic infiltrate around BV
What is this?
Spinal cord demyelination showing:
- Macrophages (cleaning up myelin debris or possibly stripping it off themselves)
- Denuded axons (axons relatively spared)
