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6# Demylenating Diseases
1. The most common demyelinating disease of the central nervous system is:
Neuromyelitis optica
Multiple sclerosis
Acute disseminated encephalomyelitis
Progressive multifocal leukoencephalopathy
Explanation:
Multiple sclerosis is the most common demyelinating disorder affecting the CNS.
2. A defining feature of multiple sclerosis lesions is that they are:
Confined to the spinal cord
Symmetric and continuous
Separated in time and space
Purely axonal
Explanation:
MS lesions characteristically show dissemination in time and in space.
3. The most frequent initial clinical manifestation of multiple sclerosis is:
Optic neuritis
Seizures
Dementia
Paraplegia
Explanation:
Optic neuritis with unilateral visual impairment is a frequent initial manifestation of MS.
4. The hallmark CSF finding in multiple sclerosis is:
Marked neutrophilia
Low glucose
High opening pressure
Oligoclonal IgG bands absent in serum
Explanation:
Oligoclonal IgG bands are present in CSF but absent in serum in MS.
5. Active MS plaques are histologically characterized by:
Complete myelin loss without inflammation
Myelin breakdown with perivascular lymphocytes
Pure axonal necrosis
Extensive hemorrhage
Explanation:
Active plaques show myelin phagocytosis, edema, and perivascular lymphocytic infiltration.
6. Chronic inactive plaques in multiple sclerosis show:
Ongoing inflammation
Preserved oligodendrocytes
Total myelin loss with gliosis
Vascular necrosis
Explanation:
Chronic plaques show complete myelin loss, loss of oligodendrocytes, and reactive gliosis.
7. The HLA type most strongly associated with multiple sclerosis is:
HLA-DR2
HLA-B27
HLA-DQ8
HLA-A2
Explanation:
HLA-DR2 increases susceptibility to multiple sclerosis.
8. Neuromyelitis optica is distinguished from MS by antibodies against:
Myelin basic protein
MOG
Oligodendrocytes
Aquaporin-4
Explanation:
Neuromyelitis optica is associated with pathogenic antibodies against aquaporin-4 water channels.
9. Central pontine myelinolysis is most commonly caused by:
Chronic hypertension
Rapid correction of hyponatremia
Vitamin B12 deficiency
Autoimmune demyelination
Explanation:
Rapid correction of hyponatremia causes osmotic demyelination in the central pons.
10. Acute disseminated encephalomyelitis typically occurs:
1–2 weeks after viral infection or vaccination
At birth
After chronic alcoholism
In elderly patients only
Explanation:
ADEM is an autoimmune demyelinating disorder occurring 1–2 weeks after infection or vaccination.
11. Which vitamin deficiency causes subacute combined degeneration of the spinal cord?
Vitamin B1
Vitamin B6
Vitamin B12
Vitamin E
Explanation:
Vitamin B12 deficiency causes demyelination of dorsal and lateral columns.
12. The histologic hallmark of hepatic encephalopathy is:
Lewy bodies
Negri bodies
Rosenthal fibers
Alzheimer type II astrocytes
Explanation:
Enlarged pale astrocytes with rimmed chromatin (Alzheimer type II) are typical.
13. The most common cause of peripheral neuropathy worldwide is:
Alcoholism
Diabetes mellitus
Guillain-Barré syndrome
Vitamin B12 deficiency
Explanation:
Diabetes mellitus is the most common cause of toxic/metabolic neuropathy.
14. Guillain-Barré syndrome is best described as:
Acute inflammatory demyelinating polyneuropathy
Chronic axonal neuropathy
Central demyelinating disease
Motor neuron disease
Explanation:
The most common form of GBS is acute inflammatory demyelinating polyneuropathy (AIDP).
15. The classic clinical pattern of Guillain-Barré syndrome is:
Descending paralysis
Pure sensory loss
Ascending paralysis
Hemiplegia
Explanation:
GBS classically presents with rapidly progressive ascending paralysis.
16. The typical CSF finding in Guillain-Barré syndrome is:
Low protein
Marked neutrophilia
Low glucose
High protein with minimal pleocytosis
Explanation:
Albuminocytologic dissociation (high protein, few cells) is typical of GBS.
17. Wallerian degeneration is defined as:
Degeneration of axon and myelin distal to injury
Primary demyelination with intact axon
Central neuron loss
Astrocytic swelling
Explanation:
Wallerian degeneration involves axonal and myelin degeneration distal to transection.
18. Segmental demyelination is characterized by:
Axonal transection
Intact axon with myelin loss
Neuronal necrosis
Vascular thrombosis
Explanation:
Segmental demyelination involves loss of myelin while the axon remains intact.
19. Onion bulb formation in peripheral nerves indicates:
Axonal regeneration
Wallerian degeneration
Repeated demyelination and remyelination
Primary neuronal loss
Explanation:
Onion bulb formations result from repeated cycles of demyelination and remyelination.
20. The regeneration rate of a transected peripheral nerve is approximately:
0.1 mm/day
5 mm/day
1 cm/day
1 mm/day
Explanation:
Peripheral nerves regenerate at approximately 1 mm per day.