Demyelinating Disease (Bruch & Kamholz)

Question 1

_____ diseases such as multiple sclerosis are acquired, and presume normal myelin formation that is subsequently lost, while axons are relatively preserved.

Answer 1

demyelinating

Question 2

_____ diseases such as leukodystrophy are genetic, and presume abnormal myelin formation with axons that undergo degradation.

Answer 2

dysmyelinating

Question 3

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.

Answer 3

multiple sclerosis

Question 4

histological hallmark of MS are sharply bordered demyelinating plaques, frequently found where?

Answer 4

periventricular locations

Question 5

True or False: MS causes marked dilatation of the ventricles, leading to increased ICP.

Answer 5

False. The chronic injury of MS causes brain atrophy and compensatory dilatation of the ventricles but NO ICP (ex vacuo hydrocephalus)

Question 6

What microscopic finding is associated with active plaque formation?

Answer 6

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

Question 7

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.

Answer 7

neuromyelitis optica (NMO)

Question 8

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

Answer 8

acute disseminated encephalomyelitis (ADEM)

Question 9

gross and microscopic findings in this disease include discoloration around vessels, due to perivenous inflammation and demyelination

Answer 9

ADEM

Question 10

metabolic demyelination of the pons, which is a complication of rapidly corrected hyponatremia and low magnesium

Answer 10

central pontine myelinolysis

Question 11

this disease presents with rapid onset of confusion, limb weakness, conjugate gaze palsies, dysarthria, dysphagia and hypotension; usually fatal

Answer 11

central pontine myelinolysis

Question 12

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

Answer 12

progressive multifocal leukoencephalopathy (PML)

Question 13

pathologic findings of this disease include viral inclusions in oligodendroglia nuclei and atypical, bizarre astrocytes

Answer 13

PML

Question 14

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

Answer 14

leukodystrophy

Question 15

this specific gross finding is often seen in leukodystophy that is not seen in other myelin diseases

Answer 15

sparing of U fibers

Question 16

this disease is marked by acute hemorrhage and necrosis of the mamillary bodies and over time may lead to atrophy and irreversible tissue injury

Answer 16

wernicke’s encephalopathy

*treat with thiamine to reverse symptoms: gaze palsies, ataxia, confusion

Question 17

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

Answer 17

vitamin B12 deficiency

Question 18

where is the highest concentration of CO found after poisoning, characterized by necrosis and hemorrhage?

Answer 18

globus pallidus; this is because the globus pallidus has the highest concentration of hemoglobin in the brain, to which CO bidns tightly

Question 19

name two differences between oligodendrocytes and schwann cells

Answer 19

• 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

Question 20

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

Answer 20

saltatory conduction

Question 21

where are plaques usually found in multiple sclerosis?

Answer 21

in the periventricular and juxtacortical regions

Question 22

the acute signs and symptoms of MS (relapse) are probably caused by what?

Answer 22

conduction block due to demyelination, paranodal retraction and/or inflammatory mediators

Question 23

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?

Answer 23

something else; time course of visual disturbance is not consistent with MS

Question 24

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?

Answer 24

MS

Question 25

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?

Answer 25

something else (namely, a stroke). MS relapse does not present with this sort of sudden onset.

Question 26

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

Answer 26

True. There are 17 times more transected axons in non-lesion white matter in patients with MS versus control.

Question 27

True or False: Recovery of clinical function in MS is mostly due to remyelination that occurs in the CNS over time.

Answer 27

False! Mostly this is due to the redistribution of Na+ channels, whether or not remyelination has occurred.

Question 28

The chronic signs of MS are probably caused by what?

Answer 28

axon degeneration

Question 29

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

Answer 29

D is true, but it is not evidence for the genetic basis of MS; rather it is evidence for the immune basis.

Question 30

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.

Answer 30

E.

MS is very low in african Blacks and virtually unseen in American Indians.