Neuropathology 2

Question 1

What is demyelination?

Answer 1

Destruction of myelin sheath surrounding axon, with relative preservation of axons themselves

Question 2

What is the purpose of myelin?

Answer 2

Insulation- allows rapid conduction of electrical impulses along cell membranes

Question 3

How is demyelination classified?

Answer 3

Primary
Secondary
Metabolic
Toxic

Question 4

The aetiology and pathogenesis of MS are not fully understood, what factors have been implicated however?

Answer 4

Environmental

Genetic

Immune

Question 5

What appearance does the brain and spinal cord have in MS

Answer 5

External appearance is usually normal, when surface is cut reveals multiple areas of demyelination called plaques

Question 6

What is the distribution of plaques?

Answer 6

Any site in CNS, commonly seen in CN II, Periventricular white matter, corpus callosum, brainstem and spinal cord

Question 7

What are the 4 types of MS plaques?

Answer 7

Acute active
Chronic (Inactive)
Chronic active
Shadow

Question 8

What is an active plaque?

Answer 8

Evidence of ongoing myelin breakdown with abundant macrophages

Question 9

What is an inactive plaque

Answer 9

Centre contains little or no myelin, astrocytic proliferation and gliosis are prominent

Question 10

What are shadow plaques?

Answer 10

Border between normal and affected white matter not clear, some abnormally thinned out myelin sheaths can be identified especially at outer edges.

Question 11

How do acute plaques appear?

Answer 11

Demyelinated plaques are yellow/brown, with an ill defined edge which blends into surrounding white matter

Question 12

How do chronic plaques appear?

Answer 12

Well demarcated grey/brown lesions in white matter, classically situated around lateral ventricles.

Question 13

What are the 3 main features of MS histologically?

Answer 13

Demyelination

Inflammation - Perivascular with oedema

Gliosis- Astrocytic gliosis prominent feature in MS

Question 14

What is dementia?

Answer 14

Impairment of occupational or social functioning due to development of memory impairment, associated with impairment of intellectual function

Question 15

What are the primary dementias?

Answer 15

Alzheimers
Lewy body
Huntingtons disease
Pick’s disease

Question 16

What are the secondary dementias?

Answer 16

Disorders resulting in secondary changes in CNS resulting in dementia eg vascular, metabolic, infection and trauma

Question 17

What is the macroscopic features of Alzheimers?

Answer 17

Cortical atrophy
Widening sulci
Narrowed Gyri
Compensatory dilation of ventricles
Frontal temporal and parietal lobes affected
Brainstem and cerebellum normal

Question 18

Microscopic features of Alzheimer’s

Answer 18

Intracytoplasmic neurofibrillary tnagles

Amyloid angiopathy

Amyloid plaques

Extensive neuronal loss with astrocytosis

Question 19

What are the hallmarks of lewy body dementia?

Answer 19

Hallucinations and fluctuating level of attention

Fluctuation in severity on day to day basis

Question 20

What are the pathological features of LBD?

Answer 20

Degeneration of substantia nigra

Remaining nerve cells contain lewy bodies

Degeneration of cortical areas

Lewy bodies can be detected by immunochemical staining for Ubiquitin protein

Question 21

What are the symptoms of Huntington’s disease

Answer 21

Chorea, myoclonus, clumsiness, slurred speech, depression, irritability and apathy

Question 22

Which gene is affected in huntingtons

Answer 22

Huntingtin gene of chromosome 4p

Question 23

Histological appearance in Huntington’s?

Answer 23

Loss of neurones in caudate nucleus and cerebral cortex, accompanied by reactive fibrillary gliosis

Question 24

What is Pick’s disease?

Answer 24

Progressive dementia commencing in middle life (50 to 60), slowly progressing changes in character and social deterioration leading to impairment of intellect, memory and language

Question 25

How is the brain affected morphologically in Picks?

Answer 25

Extreme atrophy of frontal and temporal lobes, neurone loss and astrocytosis

Question 26

What are the histological hallmarks of Picks

Answer 26

Picks cells (Swollen neurones)

Intracytoplasic filamentous inclusions know as pick’s bodies

Question 27

Symptoms of Picks

Answer 27

Personality and behavioural change
Speech and communication problems
Change in eating habits
Reduced attention span

Rapidly progressive illness, may last between 2-10 years

Question 28

What is multi infarct dementia

Answer 28

Deterioration in mental functioning due to changes or damage to brain tissue from hypoxia or anoxia as a result of multiple blood clots within the blood vessels supplying the brain