Sem 2 - CNS

Question 1

What represents the main structural component of the blood-brain barrier?

Answer 1

tight junctions

Question 2

Which cell types is predominantly responsible for gliosis?

Answer 2

astrocyte

Question 3

Current evidence suggests that the cause of cognitive decline in Alzheimer’s disease results from which one of the following?

Answer 3

Interference in synaptic transmission by monomers of Abeta protein

Question 4

how would the meninges be expected to look during bacterial meningitis? why?

Answer 4

cloudy due to the purulent exudate(neutrophils) in the sub-arachnoid space

Question 5

What is hydrocephalus? Explain how it can develop in bacterial meningitis

Answer 5

Hydrocephalus is an increased volume of CSF. In meningitis it can be caused by the exudate itself, or, later, the scarred, organised exudate blocking arachnoid granulations, impairing CSF drainage.

Question 6

The presence of what histologic feature in grey matter distinguishes it from white matter?

Answer 6

neuron cell bodies

Question 7

he presence of what feature accounts for the pale macroscopic appearance of white matter?

Answer 7

myelin

Question 8

A 72-year-old man had a 6-month history of episodic loss of vision in his right eye. A bruit was heard on auscultation of his right carotid artery.
Explain how the patient’s visual symptoms are likely to be related to the disease process causing the carotid bruit

Answer 8

The cause of the carotid bruit is probably atherosclerosis. This has probably given rise to a thromboembolus or an atheroembolus that has travelled to the right retinal or opthalmic artery and temporarily occluded blood flow causing ischaemia of the retina and thus transient monocular blindness.

Question 9

Name 3 common pathologies in heart that cause emboli

Answer 9

MI (and subsequent LV aneurysm), infective endocarditis, atrial fibrillation

Question 10

will a CT show abnormalities 2 hours after a stroke? why or why not?

Answer 10

As with infarcts in other locations, the brain will not show abnormalities histologically or macroscopically for at least 6 hours after the onset of infarction

Question 11

what is one of the first histological changes seen in cerebral infarct? how long does it take?

Answer 11

red neurons (hours)

Question 12

describe the role of macrophages following cerebral infarct giving time frames

Answer 12

macrophages infiltrate the necrotic area to phagocytose dead tissue. Although they would start to migrate in after a few days, they will not predominate for several weeks.

Question 13

when would you see a reactive astrocyte and what does it look like histologically?

Answer 13

gliosis - more cytoplasm than normal

Question 14

how do haemosiderin-containing macrophages come about? in what pathology?

Answer 14

Macrophages phagocytose red blood cells following haemorrhage and the iron from haemoglobin is stored as haemosiderin. occurs in haemmorages

Question 15

how long does it take for a space and gliosis to appear

Answer 15

at least several months

Question 16

A 62-year-old ophthalmologist presented to his general practitioner complaining of a 6 week history of increasingly severe headaches which were not relieved by over the counter analgesics. He had also noted some loss of sensation of the right upper limb, a right visual field defect and he had begun to limp. He had no prior history of migraine or other relevant past medical history.

On examination he was noted to have some impairment of language comprehension, reduced sensation on the right arm and face, a partial right homonymous hemianopia, increased tendon jerk reflexes and abnormal plantar reflex on the right.

which region is the lesion likely to be? Most likely causes?

Answer 16

Tumour in left parieto-temporal.

Loss of sensation right upper limb, reduced sensation right arm and face: left somatosensory cortex or adjacent thalamocortical fibres (parietal white matter).

Limp, increased tendon jerk reflexes and abnormal plantar reflex on the right: left corticospinal tract (internal capsule).

Impairment of language comprehension - Wernickes area (left posterior temporal cortex) and/or related white matter.

Partial right homonymous hemianopia: left optic radiation in parietal and/or temporal white matter.

Question 17

in the only case with 62-year-old ophthalmologist (6 week history of increasingly severe headaches, some loss of sensation of the right upper limb, a right visual field defect and he had begun to limp) why is tumour most likely?

Answer 17

Intracerebral haemorrhages and infarctions will present with a short history of symptoms (minutes-hours), as will a subarachnoid haemorrhage (SAH). SAHs typically cause severe headache (from pressure or traction on the meninges) but they can also bleed into the brain causing focal cerebral symptoms and signs.Headache is not typically caused by stimulation or destruction (e.g. as in an intracerebral haemorrhage or infarct) of the brain tissue itself.

Question 18

What is a likely cause of the headache and blurred optic disc margins?

Answer 18

The likely cause is raised intracranial pressure.

Blurred optic disc margins are suggestive of papilloedema, one cause of which is raised intracranial pressure (ICP), which may also cause headaches. The raised ICP here is caused by the space occupying nature of the tumour. Headaches are not typically caused by stimulation or destruction of cerebral tissue itself. Pain results from traction, pressure or inflammation of pain sensitive structures in the cranial cavity e.g. meningeal arteries, dura at base of brain, venous sinuses.

Question 19

what is papilloedema and its cause?

Answer 19

optic disc swelling that is caused by increased intracranial pressure.

Question 20

what would be expected histologically in the only case

Answer 20

The lesion is very cellular. The cells show marked pleomorphism, including nuclear pleomorphism, and coarse nuclear chromatin. Occasional cells show prominent nucleoli. Multinucleate tumour cells are present and there is necrosis.

Question 21

likely diagnosis form only case

Answer 21

glioblastoma

Question 22

What material (general term, not the name of the specific protein) is staining pink in the Congo red stain?

Answer 22

amyloid

Question 23

Does amyloid deposit intracellularly or extracellularly?

Answer 23

extracellularly

Question 24

From what normal protein (full words please) in the brain does amyloid develop in Alzheimers?

Answer 24

In Alzheimer’s disease it is composed of A beta protein which is derived from the normal protein amyloid precursor protein (APP)