Histology of Nervous System

Question 1

In what pathology do you find Lewy bodies in neuron cytoplasm?

Answer 1

• Parkinson’s disease (Cytoplasmic inclusions of degenerating neurons in substantia nigra, pars compacta)
• certain forms of dementia (cortical and brain-stem neurons)

Question 2

What is the cause of the neurofibrillary tangles formation? in which diseases can you see them?

Answer 2

• tau protein excessively phosphorylated preventing crosslinking of microtubules
• prominent of degenerating neurons in alzheimer’s disease, amyotophic lateral sclerosis and down syndrome

Question 3

What proteins aid in anterograde and retrograde axonal transport with microtubules?

Answer 3

• anterograde: kinesin - precursors of peptide neurotransmitters to synaptic terminals (fast transport)
• slow anterograde transport - soluble cytoplasmic components, NO mediated by microtubules or ATPase motor molecules
• retrograde: dynein - lysosomes and recycled membrane (virus [polio, herpes, rabie virus], toxin [tetanus toxin])

Question 4

What is the initial segment and where is it?

Answer 4

• membrane with numerous voltage-sensitive sodium ion channels. “Trigger zone” of an action potential.
• adjacent axon hillock

Question 5

Why do the diabetes patients have axonal polyneuropathy?, what is the pattern of clinical presentation?

Answer 5

• hyperglycemia causes alteration of proteins that form microtubules - disrupt axonal transport
• “glove and stocking” - altered sensation and pain in the feet then in hands

Question 6

Deficiency enzyme in metachromatic leukodystrophy (MLD)?

Answer 6

Arylsulfatase A deficiency in lysosomes, myelin PNS and CNS

Question 7

What is the cause of the progressive multifocal leukoencephalopathy (PML)? Most common affected patients.

Answer 7

• CJD virus (Jacob-Creutzfeldt)

- immunocompromised (AIDS)

Question 8

How do you expect to find CSF in Guillain-Barré syndrome?

Answer 8

• albuminocytologic dissociation: ⬆️ CSF protein with normal cell count

Question 9

Where do you find demyelinated areas in multiple sclerosis?

Answer 9

• well-circumscribed demyelinated plaques often inperiventricular areas

Question 10

How do you expect to find in CSF of multiple sclerosis patient?

Answer 10

Increased IgG (oligoclonal bands)

Question 11

Why do you have internuclear Ophtalmoplegia in multiple sclerosis?

Answer 11

Involvement of medial longitudinal fasciculus (MLF)

Question 12

Focal demyelination of central area of basis pontis affecting corticospinal and clrticobulbar tracts. What patients commonly affected? Probably causes?

Answer 12

• central pontine myelinolysis
• malnourished, alcoholics, liver disease
• overly aggressive correction of hyponatremia

Question 13

How can a substance cross the blood-brain barrier?

Answer 13

• diffusion, selective transport, via ion channels

Question 14

Bilateral tumor that affects VIII cranial nerve fibers in neurofibrimatosis type 2 “pathognomonic”? Most frequent location, another signs?

Answer 14

• Schwannomas
• cerebellopontine angle
• hearing loss, tinnitus, CN V, VII signs

Question 15

Most common primary brain tumor? Main feature of this.

Answer 15

• Glioblastoma multiforme (grade IV Astrocytoma)
• highly malignant (usually lethal in 8-12 mo)
• butterfly glioma and pseudopalisading necrosis

Question 16

Benign tumor in posterior fosa in children and young adults, rosenthal fibers and immunostaining with GFAP?

Answer 16

Astrocytoma (pilocytic)

Question 17

Second most common primary brain tumor compressing brain without invasion and findings of psammoma bodies microscopic

Answer 17

Meningioma

Question 18

Familiar bilateral tumor associated with osteosarcoma

Answer 18

Retinoblastoma

*sporadic is unilateral

Question 19

Origin of craniopharyngioma and why produces its symptoms?

Answer 19

• oral epithelium (remnants of rathke pouch)

- encroach pituitary stalk or optic chiasm