Demyelinating Disease (Bruch & Kamholz) Flashcards
_____ diseases such as multiple sclerosis are acquired, and presume normal myelin formation that is subsequently lost, while axons are relatively preserved.
demyelinating
_____ diseases such as leukodystrophy are genetic, and presume abnormal myelin formation with axons that undergo degradation.
dysmyelinating
most common demyelinating disease; causes through a variety of predisposing factors an inflammatory attack on myelin via CD4+ and CD8+ T cells, as well as macrophages and B cells.
multiple sclerosis
histological hallmark of MS are sharply bordered demyelinating plaques, frequently found where?
periventricular locations
True or False: MS causes marked dilatation of the ventricles, leading to increased ICP.
False. The chronic injury of MS causes brain atrophy and compensatory dilatation of the ventricles but NO ICP (ex vacuo hydrocephalus)
What microscopic finding is associated with active plaque formation?
ongoing myelin breakdown with abundant macrophages containing myelin debris, a well as lymphocytes; there will be relative preservation of axons though their number may be reduced
inflammatory demyelinating disease of the optic nerves and spinal cord, similar to MS but it does not involve the brain and rather than being a T-cell mediated disease, its pathophysiology is due to production of anti-aquaporin-4 antibodies.
neuromyelitis optica (NMO)
this is a postinfectious autoimmune reaction to myelin with acute onset, monophasic, nonspecific illness (headache, lethargy coma) that progresses rapidly and is fatal in 20% of cases
acute disseminated encephalomyelitis (ADEM)
gross and microscopic findings in this disease include discoloration around vessels, due to perivenous inflammation and demyelination
ADEM
metabolic demyelination of the pons, which is a complication of rapidly corrected hyponatremia and low magnesium
central pontine myelinolysis
this disease presents with rapid onset of confusion, limb weakness, conjugate gaze palsies, dysarthria, dysphagia and hypotension; usually fatal
central pontine myelinolysis
this disease has a fluffy appearance on gross findings, and is caused by polyoma virus, resulting in focal neurological deficits in immuncompromised patients often leading to death
progressive multifocal leukoencephalopathy (PML)
pathologic findings of this disease include viral inclusions in oligodendroglia nuclei and atypical, bizarre astrocytes
PML
this disease presents:
- in infancy with motor disability, seizures or spasticity, developmental failure
- in childhood with ataxia, vision changes, behavioral issues
- in adulthood with behavioral changes, psychosis and spasticity
leukodystrophy
this specific gross finding is often seen in leukodystophy that is not seen in other myelin diseases
sparing of U fibers
this disease is marked by acute hemorrhage and necrosis of the mamillary bodies and over time may lead to atrophy and irreversible tissue injury
wernicke’s encephalopathy
*treat with thiamine to reverse symptoms: gaze palsies, ataxia, confusion
this deficiency is associated with pernicious anemia and causes demyelination of the posterior columns and corticospinal tracts; symptoms include numbness/tingling, ataxia, weakness of legs
vitamin B12 deficiency
where is the highest concentration of CO found after poisoning, characterized by necrosis and hemorrhage?
globus pallidus; this is because the globus pallidus has the highest concentration of hemoglobin in the brain, to which CO bidns tightly
name two differences between oligodendrocytes and schwann cells
- oligodendrocytes:
- live in the CNS
- each cell can myelinate up to 70 axons
- schwann cells
- live in the PNS
- each cell myelinates only 1 axon
this term refers to the propagation of action potentials along myelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of action potentials
saltatory conduction
where are plaques usually found in multiple sclerosis?
in the periventricular and juxtacortical regions
the acute signs and symptoms of MS (relapse) are probably caused by what?
conduction block due to demyelination, paranodal retraction and/or inflammatory mediators
25 year old woman was previously health until 3 days prior to her visit to the ER when she noted the onset of pain with movement of her left eye. Over the next several days she developed decreased visual acuity in the left eye, particuarly in the central visual field. Her neuro and opthalmological exams were otherwise normal. Is it MS relapse or something else?
something else; time course of visual disturbance is not consistent with MS
The same patient was admitted to neurology where blood work indicated increased WBCs. An MRI showed enhancing periventricular and juxtacortical distribution of lesions. Is it MS or something else?
MS
65 year old man with known MS complained of decresed vision in his right eye, that began suddenly when he was watching tv. There was no pain or other associated symptoms. By the time he got to the ER his vision was normal. Blood work was normal. MRI showed periventricular and juxtcortical signal abnormalities on T2 and FLAIR. In addition, there was a large area of increased signal on diffusion weighted imaging in the posterior left occipital lobe. Is this MS or something else?
something else (namely, a stroke). MS relapse does not present with this sort of sudden onset.
True or False: MS is primarily a disease of demyelination, though axonal damage is common even in normal tissue in patients with MS versus controls
True. There are 17 times more transected axons in non-lesion white matter in patients with MS versus control.
True or False: Recovery of clinical function in MS is mostly due to remyelination that occurs in the CNS over time.
False! Mostly this is due to the redistribution of Na+ channels, whether or not remyelination has occurred.
The chronic signs of MS are probably caused by what?
axon degeneration
All of the following are pieces of evidence for the genetic basis of MS except:
A. There is an increased risk to first degree relatives of people with MS
B. There is an association of MS with specific HLA haplotypes
C. The risk of developing MS for first degree relatives of an adopted person with MS is not increased compared to the general population
D. MS can be treated by modulating the immune system
D is true, but it is not evidence for the genetic basis of MS; rather it is evidence for the immune basis.
Which of the following statements about MS is FALSE?
A. It is most prevalent among Caucasians
B. There are no drugs for the treatment of progressive MS.
C. Current available treatments are all directed toward modulating the immune system (DMARDs) during relapse
D. There is no single diagnostic test; rather it is made clinically after exclusion of other causes
E. It is prevalent in American Indian and black African populations.
E.
MS is very low in african Blacks and virtually unseen in American Indians.
