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Neurology > Neuropathology > Flashcards

Neuropathology Flashcards

1
Q

Neuroectodermal tissue is _________

A

CNS tissue consisting of neurons and glia

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2
Q

Mesodermal tissue is _______

A

blood vessels and meninges

microglia

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3
Q

What are the two main types of neuronal damage?

A

Rapid necrosis > associated with acute failure of function

Slow atrophic changes > associated with gradual loss of function

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4
Q

There is no regeneration of _________

A

destroyed neurons

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5
Q

Describe what happens in acute neuronal injury?

A

Occurs in the context of hypoxia / ischaemia
Typically visible 12-24 hours after an irreversible “insult” to the cell
Results in neuronal cell death

Pattern:
Shrinking and angulation of nuclei
Loss of the nucleolus
Intensely red cytoplasm

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6
Q

Describe what happens in axonal injury?

A

Increased protein synthesis -> cell body swelling, enlarged nucleolus
Chromatolysis – margination and loss of Nissl granules
Degeneration of axon and myelin sheath distal to injury

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7
Q

Describe what happens in simple neuronal atrophy?

A

Shrunken, angulated and lost neurons, small dark nuclei, lipofuscin pigment, reactive gliosis
occurs in groups of functionally related nerones

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8
Q

Describe what sub cellular alterations / inclusions are?

A

inclusions shown in some neurones in some disease
e.g. neurofibrillary tangles in Alzheimer’s disease
Inclusions appear to accumulate with ageing
Also get inclusion in viral infections affecting the brain

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9
Q

What type of injury are oligodendrocytes sensitive to?

A

oxidative injury

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10
Q

What are the main cells involved in repair and scar formation in the CNS?

A

astrocytes

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11
Q

What is gliosis?

A

the scarring process undertaken by astrocytes

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12
Q

What is the most important histopathological indicator of CNS injury regardless of the cause?

A

gliosis

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13
Q

Describe the process of gliosis?

A

There is hyperplasia and hypertrophy of the astrocytes
There is an increase in fibril production
Later the cells atrophy leaving a dense meshwork of fibres

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14
Q

Microglial cell response to injury?

A

Microglia proliferate
Recruited through inflammatory mediators
Form aggregates around areas of necrotic and damaged tissues

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15
Q

Describe cerebral autoregulation to blood flow?

A
  • If MABP rises, resistance vessels automatically constrict to limit blood flow
  • If MABP falls, resistance vessels automatically dilate to maintain blood flow

This auto regulation works between a MAPB of 60-160mmHg

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16
Q

Neurons are very susceptible to ______

A

hypoxia

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17
Q

Describe excitotoxicity in hypoxia?

A

Toxicity of hypoxia is exacerbated by excitotoxicity as energy failure results in neuronal depolarisation which causes glutamate release , at same time astrocytes cant uptake glutamate so then get glutamate storm and excitation

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18
Q

Explain what cytotoxic oedema is?

A

Intracellular swelling in acute cerebral ischaemia due to hypoxia causing failure of the ATP-dependent ion channels (mainly sodium) so influx of ions and therefore influx of water (water and sodium follow each other!)

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19
Q

Explain what vasogenic oedema is?

A

There is extravasation and extracellular accumulation of fluid in the cerebral parenchyma. This is due to the infarction causing damage to the endothelium and disruption of the blood brain barrier so fluid can leak out. At this point the endothelium aren’t damaged enough to let out red blood cells.

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20
Q

Explain what haemorrhagic conversion is?

A

This is a sequelae to vasogenic oedema. Endothelial integrity completely lost and blood can enter the extracellular space.

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21
Q

Why are middle cerebral artery events more common?

A

it is in line with the internal carotid artery

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22
Q

Describe what happens in global hypoxic ischaemic damage?

A

Generalised reduction in cerebral perfusion
E.g. in cardiac arrests, shock/ severe hypotension trauma
Autoregulatory mechanism cannot compensate when the MAP falls below 50mmHg

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23
Q

What is a stroke?

A

Sudden disturbance of cerebral function of vascular origin that causes death or lasts over 24 hours (results in irreversible tissues loss)

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24
Q

Most strokes are caused by?

A

Thromboembolic event
thrombosis from atherosclerotic segment in middle cerebral artery
embolism from vessels surrounding the heart

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25
Q

Describe pathological findings in a brain between 0-12 hours after cerebral infarction?

A

little visible macro or microscopically

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26
Q

Describe pathological findings in a brain between 12-24 hours after cerebral infarction?

A

Macro
Pale soft and swollen with ill defined margin between injured and normal brain

Micro
early neuronal damage e.g. red neurons

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27
Q

Describe pathological findings in a brain few days after cerebral infarction?

A

Macro
Brain becomes gelatinous and friable. A reduction in the surrounding tissue oedema demarcates the lesion.

Micro
Microglia become predominant cell type; myelin breakdown. Reactive gliosis begins from as early as 1 week

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28
Q

Describe pathological findings in a brain between several weeks to months after cerebral infarction?

A

Macro
Increasing liquification apparent. Eventual formation of cavity lined by dark grey tissue.

Micro
Ongoing phagocytosis brings increasing cavitation and surrounding gliotic scar formation

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29
Q

What are the two types of stroke?

A 
Ischaemic 
Haemorrhagic (spontaneous intracranial blaeding)
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30
Q

List 3 types of spontaneous intracranial bleeding that could cause stroke?

A

Intracerebral haemorrhage
Sub-arachnoid haemorrhage
Haemorrhagic Infarct

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31
Q

Describe some risk factors for intracerebral haemorrhage?

A 
Any causes of vascular injury ie:
Hypertension
Amyloid deposits (cerebral amyloid angiopathy)
Diabetes
Drugs: cocaine, alcoholism 
Vasculitis (infectious and inflammatory)
Aneurysms
Vascular malformations
Systemic coagulation disorders / iatrogenic anticoagulation
Open heart surgery
Neoplasms
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32
Q

Where does intracerebral haemorrhage most commonly occur?

A

most commonly in the basal ganglia

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33
Q

What type of vascular malformation is most commonly and most likely to result in a significant haemorrhage?

A

arteriovenous malformations

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34
Q

Describe what arteriovenous malformations are and how they predispose someone to intracerebral haemorrhage?

A

abnormal connection between arteries and veins, bypassing the capillary system resulting in torturous haphazardly arranged vessels containing arteries, veins and in between forms
Risk of bleeding is from shunting between arteries and veins which brings about hypertrophy of smooth muscle and loss of compliance and also formation of aneurysms in these areas which are also prone to rupture

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35
Q

Where do arteriovenous malformations most commonly occur?

A

In middle cerebral artery territory

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36
Q

What is the most common cause of a spontaneous subarachnoid haemorrhage?

A

rupture of a saccular aneurysm (Berry aneurysm)

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37
Q

CNS samples are normally ___________

A

acellular (occasionally with a small number of lymphocytes)

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38
Q

RBCs in a CSF sample would occur in ________

A

contamination of the sample

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39
Q

Increased lymphocytes in a CSF sample occurs in _______

A

autoimmune causes or underlying infection

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40
Q

Increased polymorphs/ neutrophils in a CSF sample will occur in ____________

A

bacterial infections e.g. bacterial meningitis

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41
Q

Increased protein levels in CSF sample will occur in ______________

A

bleeding, inflammation and tumour formation

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42
Q

Low glucose levels in a CSF sample will occur in _______________

A

bacterial, fungal or tuberculous meningitis

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43
Q

Define hydrocephalus

A

Increased volume of CSF within the cranial cavity

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44
Q

What is the most common cause of enlargement of the ventricles?

A

cerebral atrophy (loss of brain parenchyma as we get older so CSF fluid increases to accommodate)

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45
Q

Explain why hydrocephalus ex vacuo is?

A

Hydrocephalus ex-vacuo occurs when a stroke or injury damages the brain and brain matter actually shrinks. The brain may shrink in older patients or those with Alzheimer’s disease, and CSF volume increases to fill the extra space. In these instances, the ventricles are enlarged, but the pressure usually is normal

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46
Q

Acute hydrocephalus with increased ICP is most often due to ________

A

obstruction the free flow of CSF

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47
Q

Describe some things that could obstruct the flow of CSF and therefore cause hydrocephalus?

A

lesions adjacent to the inter ventricular foramen of Monro (inter ventricular foramina)
previous meningitis or subarachnoid haemorrhage resulting in partial obliteration of the CSF also blocks the flow
congenital malformations

48
Q

Cranial sutures typically close between ___1____

If hydrocephalus occurs before this you get ____2____

If hydrocephalus occurs after this you get _____3_____

A

1) 2-3 yrs age
2) cranial enlargement with increase in occipital frontal circumference inappropriate for gestational age
3) expansion of the ventricles and increased intracranial pressure

49
Q

What is normal range of intracranial pressure?

A

5-13 mmHg

50
Q

If the brain enlarges some ____1_____ must escape from the cranial vault to avoid a rise in pressure
Once this process is exhausted ___2______
Any further increase in brain volume ______3_____

A

1) blood and or CSF must escape from the cranial vault
2) venous sinuses are flattened and there is little remaining CSF
3) will result in a rapid increase in ICP

51
Q

Herniations occur through _______

The most common are ____________

A 
routes of weakest resistance
subfalcine 
tentorial 
tonsillar 
transcalvarial
52
Q

Describe subfalcine herniation ?

A

asymmetrical expansion of the cerebral hemispheres displaces the cingulate gyrus underneath the falx cerebri (can result in associated compression of anterior cerebral artery branches – weakness in contralateral leg)

53
Q

Describe tentorial herniation?

A

medial or inner most aspect of the temporal lobe herniates over the tentorium cerebelli (compression of ipsilateral 3rd cranial nerve and its parasympathetic fibres bringing about pupillary dilatation and a lack of responsiveness to light, also impairment of ipsilateral ocular movements)

54
Q

Describe tonsillar herniation?

A

displacement of cerebellar tonsils through the foramen magnum (life threatening as compresses the brainstem so comprises vital respiratory centres in the medulla oblongata)

55
Q

Describe transcalvarial herniation?

A

swollen brain herniates through any defect in the dura and skull

56
Q

When do headaches caused by tumours tend to be worse and why?

A

tend to be worse in the morning as in the morning you are slightly hypercapnia which increases blood flow to the brain which increases volume which even more increases the pressure caused by the tumour

57
Q

In children where do 70% of brain tumours arise? How does this differ from adults?

A

below the tentorium cerebelli

in adults the majority arise above the tentorium cerebelli

58
Q

Describe characteristics of metastatic tumours?

A

Tend to be multiple and tend to arise in the boundary between white and grey matter

59
Q

Explain why the terms benign and malignant do not readily apply to glial tumours?

A

No matter how differentiated or benign a glioma appears it almost invariably infiltrates into the adjacent brain, rendering complete surgical excision impossible and recurrence almost certain.
On the other hand no matter how rapidly growing and poorly differentiated the glioma appears, metastasis outside the CNS is very unlikely.

60
Q

Describe macroscopic and microscopic appearance of an astrocytoma?

A

Macroscopically the tumour may be difficult to distinguish from the surrounding brain
Histologically the tumour is composed of cells resembling astrocytes

61
Q

What type of variant of astrocytoma tends to occur in children and young adults?

A

pilocytic

62
Q

What is by far the most common glial tumour and who does it usually arise in?

A

glioblastoma

patients aged over 50

63
Q

Describe macroscopic and microscopic appearance of a glioblastoma?

A

Macroscopically it is firm white or yellow in colour with areas of haemorrhage and necrosis, it may appear well circumscribed but histologically there is infiltration of surrounding brain structures by tumour cells
mitoses, endothelial cell hyperplasia and tumour necrosis are present

64
Q

Describe macroscopic and microscopic appearance of a oligodendroglioma?

A

relatively circumscribed and commonly calcified tumours

cells resemble oligodendroglial cells

65
Q

Are oligodendrogliomas usually slow or fast growing?

A

slow

66
Q

What type of tumours is a medulloblastoma?

A

primitive neuroectodemeral tumour of the cerebellum

67
Q

Where does a medulloblastoma usually occur?

A

in the midline of the cerebellum

68
Q

Medulloblastomas tend to spread ________ leading to _______

A

subarachnoid space

obstruction of CSF flow and hydrocephalus

69
Q

Meningiomas are attached to the meninges and probably originate from ___________

A

arachnoid granulations

70
Q

Where do meningiomas tend to arise?

A

adjacent to the major venous sinuses, commonly parasagittal or from the base of the skull, often in the region of the olfactory groove or the sphenoidal ridge

71
Q

Single brain abscesses usually have a ________ e.g. ________

A

localised cause

chronic otitis media, sinusitis etc or direct implantation from skull fracture

72
Q

Multiple brain abscess suggest _______ and tend to occur _______________ in conditions such as _________

A

haematogenous spread
grey and white matter boundaries
pneumonia, bacterial endocarditis, congenital heart disease, IV drug abuse

73
Q

Symptoms of a brain abscess?

A

Symptoms of underlying infection PLUS symptoms of raided ICP

74
Q

What are the two principal types of head injury?

A

missile/ penetrating

non-missile/ blunt

75
Q

In blunt head injury what are the two main causes of damage to the brain?

A

acceleration/ deceleration

contact

76
Q

Describe primary damage vs secondary damage in trauma?

A

Primary: injury to neurones that occurs at the time of the injury, it is irreversible, current interventions are preventive measures e.g. seatbelts and helmets
Secondary: this accumulates after the primary injury, potentially reversible, this includes haemorrhage, oedema

77
Q

Describe some primary injuries after blunt trauma?

A 
· Scalp lesions
· Skull fractures
· Surface contusions 
· Surface lacerations
· Diffuse axonal injury
· Diffuse vascular injury
· Petechial haemorrhages
78
Q

What do skull fractures indicate?

A

high degree of energy involved in the injury

79
Q

Describe coup and contra coup injuries?

A

Coup injury occurs at site of impact

Contra coup occurs at site opposite impact

80
Q

What is diffuse axonal injury?

A

Form of traumatic brain injury, it happens when the brain rapidly shifts inside the skull as an injury is occurring. The axons are sheared as the brain rapidly accelerates and decelerates inside the hard bone of the skull.

81
Q

Where does diffuse axonal injury tend to occur?

A 
Affects the central areas:
brainstem
corpus callous
parasaggital areas 
inter ventricular septum
hippocampal formation
82
Q

Histologically what do you see with diffuse axonal injury?

A

axonal bulbing

83
Q

What things contribute to secondary brain injury after trauma?

A

Due to intracranial haematoma, reduced cerebral blood flow, hypoxia, excitotoxicity, odema, raised ICP, infection

84
Q

What do intracerebral haematomas tend to be associated with?

A

contusions and occur principally in the frontal or temporal lobe

85
Q

What does the term burst lobe refer to?

A

the combination of an intracerebral haematoma in continuity with a subdural haematoma through surface contusions

86
Q

What are extradural haematomas usually a complication of?

A

fracture in tempero-parietal region that involves middle meningeal artery

87
Q

Where do subdural haematomas usually occur?

A

over cerebral convexities

88
Q

Subdural haematomas have a high or low mortality?

A

high (so most people dot develop chronic ones)

89
Q

Describe chronic subdural haematomas?

A

presents weeks or moths after an apparently trivial head injury (common in elderly)
haematoma is organised and becomes encapsulated in a fibrous membrane, see blood tinged yellow membranous fluid
can become quite large before symptoms appear

90
Q

Define demyelination

A

Preferential damage to the myelin sheath

Relative preservation of the axons

91
Q

What is the most common demyelinating disease?

A

Multiple sclerosis

92
Q

Describe the macroscopic pathology of MS?

A

Principally a white matter disease so the exterior surface of the brain typically appears normal
The cut surface of the brain shows plaques
Plaques are Well circumscribed, well demarcated, irregular shaped areas, glassy and almost translucent appearance, vary from very small to large lesions
Can occur at any site in CNS
Tend to distributed in a non symmetrical manner

93
Q

What areas are MS plaques typically found?

A

periventricular areas, the corpus callosum, the optic nerves and chiasm, the brain stem, the ascending and descending fibre tracts, the cerebellum and the spinal cord

94
Q

Describe inactive and active plaques in MS?

A

In acute active lesions there is evidence of ongoing myelin break down with abundant microglia which contain phagocytosed lipid debris. Inflammatory cells are present.
As active plaques age astrocytes undergo reactive changes (gliosis) and inflammatory cells reduce in number.

95
Q

Define dementia

A

An acquired and persistent generalised disturbance of higher mental functions in an otherwise fully alert person

96
Q

Name 4 primary dementias?

A

Alzheimers
Lewy Body Dementia
Pick’s disease (fronto temporal dementia)
Huntingtons Disease

97
Q

What is the 1st, 2nd and 3rd most common dementias?

A

1st: Alzheimers
2nd: Vascular
3rd: Lewy body dementia

98
Q

Alzheimers disease is more common in _____

A

women

more common after 60 yo (earlier may suggest a familial cause)

99
Q

Describe macroscopic appearance of a brain with alzheimers disease?

A

Brain mass lost from cortical atrophy
location of atrophy is the frontal, temporal and parietal lobes (sparing of the occipital lobe)
there is widening of the sulk and narrowing of the gyri

100
Q

Name 4 histological hallmarks of Alzheimers disease?

A
  • extracellular senile plaques (amyloid a beta plaques)
  • intracellular neurofibrillary tangles
  • amyloid angiopathy
  • loss of neurons and synapses
101
Q

Almost all patients with Down’s syndrome who survive until they are 50 develop Alzheimers which suggests _______

A

chromosome 21 is important in the pathogenesis

102
Q

Theories of pathogenesis of Alzheimers?

A

Mutations in amyloid precursor protein which causes pathological a beta amyloid to be produced which accumulates and triggers neuronal degeneration

103
Q

Describe what sort of symptoms occur in Lewy body dementia?

A

Progressive dementia along with hallucinations and fluctuating levels of attention/ cognition
(some overlap with alzheimers but memory is affected later!)

104
Q

Describe the relationship between parkinsons and lewy body dementia?

A

Only some people with parkinsons get lewy body dementia but almost everyone with lewy body dementia shows features of parkinsons

105
Q

Macroscopic appearance of lewy body dementia?

A

similar to parkinsons, degeneration of substantia nigra, pallor in the substantia nigra where pigmented dopaminergic neurons run

106
Q

Microscopic appearance of lewy body dementia?

A

loss of pigmented neurons, reactive gliosis, remaining neurons may show lewy bodies

107
Q

Macroscopic appearance of brain in huntingtons disease?

A

Atrophy of the basal ganglia particularly the caudate nuculeus and to lesser extent the putamen, secondary atrophy of globus pallidus, compensatory expansion of the lateral and third ventricles. Later there is frontal, parietal and sometimes cortical atrophy.

108
Q

Microscopic appearance of the brain in huntingtons disease?

A

simple neronal atrophy of striatal neurons the basal ganglia, pronounced astrocytic gliosis

109
Q

Fronto temporal dementia is also known as ________

A

Picks Disease

110
Q

Describe what sort of symptoms occur in Picks Disease?

A

A progressive dementia commencing in middle life (usually 50 and 60) characterised by progressive changes in character and social deterioration leading on to impairment of intellect, memory and language.

111
Q

Describe macroscopic appearance of a brain with Picks disease?

A

Extreme atrophy of the cerebral cortex in the frontal and later in temporal lobes
Sparing the parietal and occipital lobes
Usually extent of atrophy is much more than alzheimers
Brain can be less than a kg

112
Q

Describe microscopic appearance of a brain with Picks disease?

A

picks cells (swollen neurons), intracytoplasmic filamentous inclusions known as Pick’s bodies

113
Q

Describe the pathogenesis of multi infarct dementia?

A

• Disorder involving a deterioration in mental functioning due to cumulative damage to the brain through hypoxia or anoxia (lack of oxygen) as a result of multiple blood clots within the blood vessels supplying the brain
• Successive multiple cerebral infarctions cause increasingly larger areas of cell death and damage
When a sufficient volume of the brain is damaged dementia results

114
Q

What feature characterises multi infarct (vascular dementia)?

A

Insight

Sufferers are aware of their mental deficits and are prone to depression and anxiety

115
Q

Describe pathological appearance of a brain with multi infarct (vascular) dementia?

A 
Macroscopically see evidence of large vessel infarcts,  larger infarcts are more common and scattered throughout the hemispheres, these are usually associated with atheroma of large cerebral arteries which provoke thromboembolism 
Small vessel (lacunar infarcts), rarer and occur in central subcortical distribution, particularly related to longstanding hypertension and atherosclerosis of small vessels

Neurology (22 decks)

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