Chapter 28: The CNS - Intro Flashcards
1
Q
Which cell type is evident 12-24 hrs after acute CNS hypoxic/ischemic insult?
A
Red neurons (“red dead guys”)
2
Q
Morphology of red neurons
A
- Shrinkage of cell body
- Pyknosis of nucleus
- Dissapearance of nucleolus
- Loss of nissl substance
- Intense eosinophilia of the cytoplasm
3
Q
What are the hallmarks of subacute and chronic neuronal injury (i.e., degeneration)?
A
- Cell loss —> Apoptosis
- Reactive gliosis
4
Q
What is gliosis?
A
Proliferation of astrocytes in response to brain injury
5
Q
What is the axonal reaction?
Best seen where?
A
- Change observed in cell body during regeneration of the axon
- Best seen in anterior horn cells of SC when motor axons cut
6
Q
Most important histopathologic indicator of CNS injury regardless of etiology?
Characterized by what 2 things; what cell?
A
- Gliosis
- BOTH hypertrophy and hyperplasia of astrocytes
7
Q
Morphology of the axonal reaction?
A
- Enlargement and rounding up of cell body
- Peripheral displacement of nucleus
- Enlargement of nucleolus
- Dispersion of Nissl substance from the center to the periphery of the cell (central chromatolysis)
8
Q
Which cells of the CNS are most sensitive to insult?
A
- Pyramidal neurons (hippocampus)
- Neocortical Betz cells
- Cerebella purkinje cells
9
Q
Intracellular inclusions seen in herpes, rabies and cytomegalovirus?
Where specifically in the cell is each seen?
A
- Cowdry body (intranuclear): herpes
- Negri body (intracytoplasmic): rabies
- Both nucleus and cytoplasm: CMV
10
Q
Intracytoplasmic inclusions seen in Alzheimer’s and Parkinson disease?
A
- Neurofibrillary tangles: Alzheimer’s disease
- Lewy bodies: Parkinson’s disease
11
Q
Abnormal vacuolization of the perikaryon and neuronal cell processes in the neuropil are seen in what disease?
A
Creutzfeldt-Jakob
12
Q
__________ act as the metabolic buffers and detoxify the brain; also contributing to the BBB (foot processes)
A
Astrocytes
13
Q
What is the intermediate filament found in Astrocytes and can be stained for?
A
GFAP
14
Q
Gliomas are positive for which stain?
A
GFAP
15
Q
What are characteristics of a gemistocytic astrocyte?
A
- Nucleus enlarges, become vesicular, and develop prominent nucleoli
- Bright pink cytoplasm, forms swaths around the eccentric nucleus that forms numerous stout ramifying processes
16
Q
Characteristics of Alzherimer Type 2 Astrocyte?
A
- Gray matter cell
- Large nucleus (2-3x)
- Pale-staining central chromatin
- Intranuclear glycogen droplet
17
Q
What type of astrocyte is seen in pt’s with long-standing hyperammonemia due to chronic liver disease (will have flapping tremor of hands with extension of the wrist, asterixis), Wilson disease, or hereditary metabolic disorders of the urea cycle?
A
Alzheimer Type II Astrocyte
18
Q
What type of cytoplasmic inclusion bodies are characteristic of Pilocytic Astrocytoma and also found in regions of long standing gliosis?
A
Rosenthal fibers
19
Q
Which heat-shock proteins are found in Rosenthal Fibers?
A
- αB-crystallin
- hsp-27
*Also ubiquitin
20
Q
What is Alexander disease and what cellular changes are seen in this disease?
A
- Leukodystrophy due to mutation in GFAP
- Rosenthal fibers, but more commonly seen are corpora amylacea (aka polyglucosan bodies)
21
Q
Corpora amylacea (aka polyglucosan bodies) are positive for which stain?
A
PAS positive
22
Q
______ are mesoderm derived phagocytic cells that serve as resident macrophages of the CNS
A
Microglia
23
Q
Which round, faintly basophilic, concentrically lamellated structures increase with age and are though to represent degenerative changes in the astrocyte?
A
Corpora amylacea (aka polyglucosan bodies)
24
Q
What are the cell surface markers of Microglia?
A
CR3 and CD68
25
What are 4 ways microglia respond to injury?
1) Proliferation
2) Dev. elongated nuclei (rod cell), as in **neurosyphillis**
3) **Microglial nodules:** microglia aggregate around small foci of necrosis
4) **Neuronophagia**: microglia congregate around cell bodies of dying neurons
26
How does the myelination ability of oligodendrocytes differ from schwann cells?
- Oligodendrocytes myelinate **numerous** internodes on **multiple** axons
- Schwann cells in peripheral nerve, has a one-to-one correspondance between cells and internodes
27
Injury or apoptosis of __________ cells is a feature of acquired demyelinating diseases and leukodystrophies?
Oligodendroglial cells
28
Glial cytoplasmic inclusions, primarily composed of ______ are found in oligodendrocytes in multiple system atrophy (MSA).
α-synuclein
29
What are Ependymal cells and where are they found in the CNS?
Ciliated columnar epithelial cells lining the ventricles
30
Disruption of the ependymal lining and prolferation of subependymal astrocytes produces what on ventricular surfaces?
Ependymal granulation
31
Which agent may produce extensive ependymal injury, with viral inclusions in ependymal cells?
CMV
32
Do oligodendrocytes or ependymal cells mediate significant responses to most forms of injury in the CNS?
NO
33
What is the response of astrocytes to neuronal injury?
- **Hypertrophy** of the cytoplasm, accumulation of GFAP, and **hyperplasia**
34
What is the response of microglia to neuronal injury?
Proliferate and accumulate during CNS injury
35
What is Vasogenic edema and is often seen following what?
- Increased **EXTRAcellular** fluid due to **BBB disruption** and **increased vascular permeability**
- Fluid shifts from INTRAvascular compartments to INTERcellular spaces
- Can be either **localized** (i.e., adjacent to neoplasms or inflammation) or **generalied** often follows **ischemic injury**
36
What is Cytotoxic edema and when is it seen?
- Increase in **INTRAcellular** fluid secondary to neuronal, glial, or endothelial cell membrane injury
- Generalized hypoxic/ischemic insult or w/ metabolic derangment
37
In practice, will oftens see elements of which type of edema(s)?
What morphological characteristics of the brain will be seen and this can lead to?
- Both vasogenic and cytotoxic edema
- Gyri flattened, sulci narrowed, and ventricles compressed ---\> Herniation!
38
What type of injury is associated with localized vs. generalized vasogenic edema?
- **Localized:** adjacent to inflammation or neoplasms
- **Generazlied:** follow ischemic injury
39
What is the most common cause of noncommunicating (obstructive) hydrocephalus in the neonate/infant?
Aqueductal stenosis
40
Enlargement of the **entire** ventricular system ("**symmetric dilation"**) due to accumulation of CSF not being properly absorbed at the dural sinus level is known as?
Communicating ("non-obstructive") hydrocephalus
41
What 2 congenital conditions cause ventricular system obstruction?
1) Acqueductal stenosis
2) Dandy-Walker malformation
42
What is Hydrocephalus Ex-Vacuo?
Whom is it seen in?
What is the CSF pressure?
- Compensatory increase in ventricular volume secondary to loss of brain parenchyma
- **Atrophy** with increasing age, **stroke** or other injury, **chronic neurodegenerative** disease
- **CSF pressure is NORMAL!!!**
43
Herniation is displacement of brain tissue due to _____ or \_\_\_\_\_\_
Mass effect or Increased intracranial pressure
44
What is diffuse vs. focal mass effect that is associated with herniation?
- **Diffuse:** generalzied brain edema
- **Focal:** tumors, abscesses, or hemorrhages
45
Subfalcine herniation involves displacement of the _______ under the \_\_\_\_\_\_\_
**Cingulate gyrus** under the **falx cerebri**
46
A subfalcine herniation may lead to compression of the ________ artery leading to infarction
Anterior Cerebral artery (ACA)
47
What symptoms would result from Subfalcine herniation with compression of the ACA?
Contralateral lower extremity weakness
48
Transtentorial (uncinate, mesial temporal) herniation occurs when?
Which **specific** part and of which lobe?
**MEDIAL aspect** of the **TEMPORAL** **lobe** is compressed against the free margin of the tentorium
49
What are 3 possible consequences of progression of transtentorial herniations?
1) Compression of CN III ---\> pupillary dilation; eye is "down and out" (ipsilateral to lesion)
2) Compression of PCA ---\> ischemia of primary visual cortex
3) Large herniation may compress contralateral cerebral peduncle ---\> hemiparesis ipsilateral to side of herniation = *Kernohan notch* = "false localizing sign"
50
What are Duret hemorrhages and are a result of what?
- Progression of **transtentorial herniation** producing secondary hemorrhagic lesions in the **midbrain** and **pon**
## Footnote
**- "Flame-shaped" lesions**
51
Why is it crucial to exam the eyes of a patient you expect to be suffering from increased intracranial pressure?
Look for **papilledema**
52
What are congenital causes of hydrocephalus?
- Intrauterine infections (TORCH)
- Agenesis/atresia/stenosis
- Arnold chiari malformations
- Dandy walker syndrome
- Cranial defects: Achondroplasia and Craniostenosis
53
Which rare type of brain tumor leads to increased CSF production, thus causing increased ICP and hydrocephalus?
Choroid Plexus Papilloma/Carcinoma
54
What is the most common parasitic nervous system disease in the world and can lead to hydrocephalus?
- Cysticercosis
- *Taenia Solium* (pork tapeworm)
55
What are the characteristic of normal pressure hydrocephalus and who is it seen in?
- Symmetric type usually occuring in adults \>60
- Develops slowly over time; drainage of CSF is blocked gradually
- Enlarged ventricles still exert pressure on brain and can become symptomatic w/ pt's exhibiting **dementia-like** manifestatons
- Dementia may be similar to Alzheimers and gait abnormalities may suggest Parkinson disease
- NPH is often misdiagnoses as one of these diseases
56
What is the classic triad of clinical findings exhibited by patients with normal pressure hydrocephalus?
- "Wet, wacky, and wobbly"
- Often exhibit a **magnetic gait**
- **Dementia-like** sx's; impaired recognition (often not severe)
- **Urinary incontinence**; appears late in illness and is generally of the spastic hyperreflexic, increased-urgency type
57
A right hemisphere trans-tentorial herniation, causes a Kernohan's notch in the _____ cerebellar peduncle, which results in ________ motor impairment.
A **right** hemisphere trans-tentorial herniation, causes a Kernohan's notch in the **left** cerebellar peduncle, which results in **right-sided** motor impairment.
58
What is a tonsillar herniation and why is it life threatening?
- Displacement of the cerebellar tonsils through the foramen magnum
- Can can brainstem compression and compromises vital respiratory and cardiac centers in the medulla
59
\_\_\_\_\_\_\_ refers to a diverticulum of disorganized **brain tissue** extending through a defect in cranium; most often occurring in the **posterior fossa**
Encephalocele (sometimes misleadingly referred to as a "nasal glioma")
60
Malformation of the **anterior end** of the neural tube leading to a "frog-like" apperance of a fetus is known as?
Anencephaly
61
The migration of neurons from the germinal matrix zone to the cerebral cortex follows what 2 paths?
1) **Radial migration** for excitatory neurons; due to **reelin** protein signaling
2) **Tangential migration** for inhibitory neurons
62
The cause of Microcephaly is linked to?
- Chromosomal abnormalities
- Fetal alcohol syndrome
- HIV-1 acquired in utero
63
What is Lissencephaly and the 2 general patterns observed?
- Reduction in the # of gyri; sometimes **agyria** = NO gyri
- **Type 1:** smooth surfaced; mutations disrupting signaling for migration and the cytoskeletal "motor" proteins that drive migration of neuroblasts
- **Type 2:** rough or cobblestoned; disruption of the "stop signal" for migration of neuroblasts
64
Periventricular heterotopias can be caused by mutations in the gene encoding?
**Filamin A**, an **actin-binding** protein
65
Which forebrain anomaly is characterized by small, unusually numerous, irregularly formed cerebral convolutions?
Polymicrogyria
66
What are Neural heterotopias; commonly associated with?
- Group of migrational diseases that are **commonly** associated with **epilepsy**
- Defined by **presence of neurons in inappropriate** **locations** along pathway of migration
67
The microtubule-associated protein DCX is encoded by a gene on the X chromosome and mutations in this gene lead to what in males vs. females?
- **Males**: lissencephaly
- **Females**: subcortical band heterotopias
68
What is Holoprosencephaly? Severe forms produce which abnormalities?
- Incomplete separation of the cerebral hemispheres across the midline
- Cyclopia; less severe variants (arrhinencephaly) show absence of olfactory CNs
69
Holoprosencephaly is associated with what disease and signaling mutation?
- Trisomy 13
- Sonic hedgehog signaling pathway
70
Radiologic imaging showing a "bat wing" deformity is associated with that condition?
Agenesis of the corpus callosum
71
What is an Arnold-Chiari Type II malformation and what other abnormalities is it associated with?
- **Small posterior fossa**, misshapen midline cerebellum w/ **downward extension of vermis through foramen magnum**
- May also see caudal displacement of the medulla, malformation of tectum, acqueductal stenosis, hydromelia, and cerebreal heterotopias
- More severe than type I
- Associated with **hydrocephalus** and **lumbar myelomeningocele**
72
What is an Arnold-Chiari Type I malformation?
- Low-flying cerebellar tonsils extend down vertebral canal
- May be **silent** or become symptomatic due to impaired CSF flow and medullary compression
73
Which condition is associated with an **enlarged** posterior fossa, absence of cerebellar vermis w/ replacement by a large midline cyst representing an **expanded roofless 4th ventricle**?
Dandy-Walker Malformation
74
Which condition has hypoplasia of the cerebellar vermis, elongation of the cerebellar peduncle and an altered shape of brainstem; together giving a 'molar tooth sign' on imaging?
Joubert syndrome
75
Syringomyelia is associated with what other condition; how does it present?
What part of the spinal cord is involved?
- Associated w/ Arnold-Chiari Malformations
- Sensory loss of pain and temperature w/ sparing of fine touch and position in the UE's ("cape-like" distribution) due to involvemet of the **anterior white commissure** of the **spinothalamic tract**
76
Expansion of the ependyma-lined central canal of the spinal cord is known as \_\_\_\_\_\_\_\_.
Hydromyelia
77
Dandy-Walker malformations have a large midline cyst that is lined by ______ and is continguos with _________ on its outer surface
Lined by **ependyma** and is contingous with **leptomeninges** on its outer surface
78
What is Cerebral Palsy and what are the clinical manifestations of this disease?
Occurs due to insults during which period?
- **Non-progressive** neurologic motor deficits characterized by combination of spasticity, dystonia, ataxia/athetosis, and paresis
- Pre-natal and perinatal periods (are present from birth)
79
What type of hemorrhage is seen in the germinal matrix of premature infants?
Often found near which junction; may extend where and cause?
- Intraparenchymal hemorrhage
- Junction between **thalamus** and **caudate nucleus**
- May extend into ventricles ---\> subarachnoid space ---\> hydrocephalus (obstructive)
80
Infarcts may occur in the supratentorial white matter of premature infants and are known as?
Characteristic finding?
- Periventricular leukomalacia
- Chalky yellow plaques = white matter necrosis and calcification
81
Extensive ischemic damage of both white and gray matter leading to large cystic lesions during the perinatal period is known as?
Risk factor for developing?
- Multicystic encephalopathy
- Cerebral Palsy
82
Perinatal ischemic lesions of the cerebral cortex leading to thinned-out, gliotic gyri is known as?
Ulegyria
83
Diastatic fracture
Fracture that **crosses a suture**
84
If the head is immobile at the time of trauma, what time of injury will be found?
Only a coup injury
85
Clinical term for altered consciousness secondry to a head injury typically brough about by a change in momentum of the head
Concussion
86
Which intracranial location is most susceptible to a direct parenchymal injury which results from trauma to the head?
Crests of the gyri = greatest amt. of force
87
What is the morphology of a brain contusion?
What is seen early on and within 24 hours?
- **Wedge shaped** w/ a broad base lying along the surface at the point of impact
- Early stages: pericapillary edema and hemorrhage
- 24 hours: pyknosis of the nucleus, eosinophilia of cytoplasm and disintegration of the cell
88
What is the characteristic appearance of old traumatic lesions on the surface of the brain?
Where is the morphology most commonly seen?
- Depressed, retracted, yellowish-brown patches involving the crest of the gyri (**plaque jaune**)
- Most commonly located at the sites of **countercoup** injuries
89
Diffuse axonal injury is best demonstrated using what lab techniques/stains?
- **Silver impregnantion (silver stain)**
- Immunoperoxidase stains for **amyloid precursor protein** and **α-synuclein**
90
As many as 50% of individuals who develop coma shortly after trauma, even **without cerebral contusions**, are believed to have?
Diffuse axonal injury
91
Sudden onset of severe headache ("worst headache of my life"), often with rapid neurologic deterioration is consistent with a _________ hemorrhage
Subarachnoid
92
Secondary injury associated seen in subarachnoid hemorrhage is often associated with what?
Vasospasm
93
A patient presents after a direct blow to the head which initially knocked him unconscious, after a couple hour lucid interval he begins to exhibit neurological deterioration, what do you suspect?
Epidural hematoma
94
What type of hematoma is associated with rupture of the bridging veins?
Subdural hematoma
95
Which patient populations are at higher risk for subdural hematomas?
- Elderly w/ brain atrophy due to increased stretching of the bridging vein
- Infants due to thin-walled bridging veins
96
What is the sequence/timeline for breakdown and organization of a subdural hematoma?
- Lysis of the clot (about **1 week**)
- Growth of fibroblasts from dural surface into the hematoma (about **2 weeks**)
- Early development of hyalinized CT (**1-3 months**)
\*Typically retracts to a thin layer of CT called **subdural membranes**
97
What is seen in the brains of individuals with CTE (dementia pugilistica) during a post-mortem autopsy?
- Atrophic w/ enlarged ventricles
- Accumulation of tau-containing neurofibrillary tangles
- Characteristic pattern involving superficial frontal and temporal lobe cortex
98
After some time following an injury to the spinal cord what is seen in cord sections above and below the injury?
Secondary ascending and descending **wallerian degeneration**, involving the **long white-matter tracts**
99
What is Penumbra?
Animal models have shown that this area may be rescued how?
- Area of "at-risk" tissue at the region of transition between necrotic tissue and the normal brain
- May be rescued by anti-apoptotic meaures, implying that cells in areas of ischemia may die by apoptosis
100
Which neurons are the most sensitive to global cerebral ischemia?
- Pyramidal cell layer of hippocampus (especially area CA1, *Sommer sector*)
- Cerebellar purkinje cells
- Pyramidal neurons in cerebral cortex
101
The border zone between which arteries in the cerebral hemispheres are most at risk for an infarct following global ischemia?
Between **ACA** and the **MCA**
102
Border zone ("watershed") infarcts are usually seen after ________ episodes
Hypotensive
103
Which pattern of injury is seen in the cerebral neocortex following global ischemia?
Pseudolaminar necrosis
104
What are the subacute changes seen 24 hours to 2 weeks after global ischemia?
- Tissue necrosis
- Influx of **M****acrophages and Reactive gliosis (10 days)**
- **Vascular proliferation**
105
Following global ischemia you see ______ of the gyri and _____ of the sulci
- Widening of the gyri
- Narrowing of the sulci
\*Edema
106
Global cerebral ischemia occurs after which events?
Cardiac arrest, shock, or severe hypotension
107
What is the most common cause of Embolism to the brain?
Important predisposing factors?
- **Cardiac mural thrombi** (often form post-MI) \> atheromatous plaques (carotid arteries)
- MI, valvular disease, and atrial fibrillation (pre-disposing factors)
108
Which artery is most frequently affected by embolic infarction?
MCA --- direct extension of the internal carotid artery
109
Widespread hemorrhagic lesions involving the white matter are characteristic of embolization of _______ after trauma
Bone marrow
110
Most common sites for thrombotic occlusions in the brain
- Carotid bifurcation
- Origin of MCA
- Either end of Basilar artery
111
Infectious vasculitis of small and large vessels occurs w/ syphilis and tuberculosis, but is now more common in the setting of?
- Immunosuppression
- Opportunistic infection (i.e., aspergillosis or CMV encephalitis)
112
Primary angiitis (aka granulomatous angiitis) of the CNS is characterized by?
Chronic inflammation, multinucleated giant cells, and destruction of the vessel wall
113
Thrombolytic therapy following an infarct is contraindicated in?
Hemorrhagic infarcts --\> may cause extensive intracerebral hematomas
114
Infarcts are often initially nonhemorrhagic, but secondary hemorrhage can occur from ______ injury
Ischemia-reperfusion
115
What are the most common locations for lacunar infarcts?
- Lenticular nucleus
- Thalamus
- Internal capsule
- Deep white matter
116
What are the cytoplasmic bodies seen in myoclonic epilepsy?
Lafora Bodies
117
How can HTN lead to the development of lacunar infarcts?
Cerebral vessesl develop **arteriolar sclerosis** and may become **occluded** ---\> Lacunes
118
Small slit like cavity that is surrounded by a brownish discoloration after reabsorption of a hemorrhage is known as what?
Slit hemorrhage
119
What is Binswanger disease?
Pattern of injury from multifocal vascular diseases involving **large areas of subcortical white matter** w/ myelin and axon loss
120
Hypertensive encephalopathy is a consequence of?
Malignant hypertension
121
Patients who have bilateral gray and white matter infarcts over many months and years may develop what distinct clinical syndrome characterized by dementia, gait abnormalities, pseudobulbar signs and other focal neuro deficits?
Vascular (multi-infarct) dementia
122
What is the risk factor most commonly associated with deep brain parenchymal hemorrhages?
HTN
123
What causes Charcot-Bouchard microaneurysms?
Chronic HTN
124
What is a Charcot-Bouchard microaneurysm vs. Saccular (berry) aneurysm?
Where is each most commonly seen?
- Charcot-Bouchard occur in vessels less than 300 um in diameter; most often within **basal ganglia**
- Saccular (berry) aneurysms occur in larger intracranial vessesl in the **subarachnoid space**
125
What is the risk factor most commonly associated with lobar hemorrhages?
Cerebral amyloid angiopathy (CAA)
126
The presence of which alleles may increase the risk of repeat bleeding from sporadic CAA?
ε2 or ε4
127
Where are the vascular abnormalities of CAA most often seen and how does CAA differ from arteriolar sclerosis?
- Leptomeningeal and cerebal cortical arterioles
- In CAA, there is **no fibrosis**
128
What is the mutation associated with Cerebral Autosomal Dominant Arteriopathy w/ Subcortical Infarcts and Leukoencephalopathy (CADASIL)?
NOTCH3
129
Cerebral Autosomal Dominant Arteriopathy w/ Subcortical Infarcts and Leukoencephalopathy (CADASIL) is characterized clinically how?
Recurrent strokes (usually infarcts, less often hemorrhages) and dementia
130
Most frequent cause of clinically significant subarachnoid hemorrhage is rupture of?
Saccular (berry) aneurysm
131
What is the structural abnormality of vessels that lead to saccular (berry) aneursyms?
Absence of **smooth muscle** and **intimal elastic lamina =** developmental disorder
132
There is an increased incidence of saccular (berry) aneursyms in people with what disorders?
- AD polycystic kidney disease
- Ehlers-Danlos type IV
- NF1
\*Smoking and HTN are risk factors
133
What is the most common site for Arteriovenous Malformations?
MCA; particularly its posterior branches
134
Who is most at risk for Arteriovenous Malformations?
How does it present?
- **Males** twice as frequently; between **ages 10-30**
- Presents as seizure disorder, intracerebral hemorrhage, or subarachnoid hemorrhage
135
Morphology of Arteriorvenous Malformations
**Tangled vessels ("worm-like")** that show prominent, pulsatile arteriovenous shunting with high blood flow -- **bypass a capillary bed**
136
Waterhouse-Friderichsen syndrome results from?
Occurs most commonly due to meningitis caused by?
- Meningitis-associated septicemia w/ hemorrhagic infarction of the **adrenal glands** and **cutaneous petechiae**
- Meningococcal and pneumococcal meningitis
137
What is chemical meningitis?
Nonbacterial irritant introduced into the subarachnoid space
138
How can hydrocephalus result from pyogenic meningitis?
Particularly with what organism?
- Capsular polysaccharide of **pneumococcal meningits** produces a gelatinous exudate that promotes arachnoid **fibrosis**
- Referred to as **chronic adhesive arachnoiditis**
139
What are predisposing conditions for the development of a brain abscess?
- Acute bacterial endocarditis
- Congenital heart disease (w/ right to left shunting)
- Loss of pulmonary filtration of organisms
140
Discrete lesions in the brain with central liquefactive necrosis surrounded by brain swelling, exuberant granulation tissue w/ neovascularization surrounding the necrosis is characteristic of?
Brain Abscess
141
Most common bacteria in brain abscesses of non-immunosuppressed patients?
- Streptococci
- Staphylococci
142
What type of edema is associated with brain abscesses?
- Vasogenic edema
- Newly formed vessels that are very leaky
143
Extradural abscess are commonly associated with?
Osteomyelitis
144
What are the common causes of chronic bacterial meningoencephalitis?
- *Mycobacterium tuberculosis*
- *Treponema pallidium*
- *Borrelia* species
145
What are the CSF findings with tuberculosis meningitis?
- Pleocytosis of mononuclear cells (sometimes mixed with neutrophils)
- Elevated protein
- Normal to moderately reduced glucose
146
The most serious complications of chronic tuberculosis meningitis are ________ producing hydrocephalus, and ________ producing arterial occlusion and infarction of underlying brain
The most serious complications of chronic tuberculosis meningitis are **arachnoid fibrosis** producing **hydrocephalus**, and **obliterative endarteritis** producing arterial occlusion and infarction of underlying brain
147
What stain is used to look for TB infection?
Acid-fast
148
Which form of neurosyphilis involves the base of the brain and may contain cerebral gummas (plasma cell-rich mass lesions) in the meninges and extending into the parenchyma?
Meningovascular neurosyphilis
149
Which organism causes Paretic neurosyphilis and how does it clinically manifest?
- *T. pallidum* (spirochete)
- Progressive cognitive impairment associated with **mood alterations** (including delusions and grandeur)
- Terminates in severe dementia (**general paresis of the insane**)
150
Iron deposits seen in Paretic neurosyphilis are demonstratable using what stain and where?
Prussian blue stain perivascularly and in the neuropil
151
Tabes dorsalis results from damage to?
**Dorsal column** medial lemniscus system (posterolateral columns, fasciculus cuneatus and gracilis)
152
Which condition presents with widened gait, impaired joint position sense and ataxia, loss of pain sensation leading to skin and joint damage (Charcot joints), characteristic "lightning pains," and absence of DTRs w/ corresponding atrophy and pallor in the dorsal columns of the SC?
Tabes dorsalis
153
What are the neurologic symptoms associated w/ Neuroborreliosis (Lyme Disease)
- Aseptic meningitis
- Facial nerve palsies
- Encephalopathy
154
Which virus is an important cause of epidemic encephalitis, especially in tropical regions of the world?
Arbovirus
155
Which CNS pathology shows multiple foci of necrosis of gray and white matter; with evidence of **single-cell neuronal necrosis** w/ phagocytosis of the debris (**neuronopahgia**)?
Encephalitides caused by various **arboviruses**
156
Involvement of the spinal cord in West Nile encephalitis can lead to ________ syndrome w/ paralysis
Polio-like syndrome w/ paralysis
157
Increased incidences of HSV encephalitis have been observed in patients with rare inherited loss-of-funtion mutations in the ________ pathway
TLR3 signaling
158
HSV-1 has a tropism for which lobes of the brain; what type of injury is seen when infected?
- Temporal lobes and orbital gyri of the frontal lobe
- Hemorrhagic lesions w/ Cowdry type A intranuclear viral inclusion bodies within neuron and glia
159
What does HSV-2 cause particularly in neonates born by vaginal delivery to a woman with active primary HSV genital infections?
Severe encephalitis
160
In immnosuppressed individuals, CMV most commonly causes?
Subacute encephalitis
161
Periventricular leukomalacia is characteristc of infection by which virus?
CMV
162
Poliovirus has a tropism for which neurons of the spinal cord?
Anterior horn motor neurons
163
CMV infection is confirmed by?
Immunohistochemistry
164
How does CNS infection by poliovirus present initially and what are the CSF findings?
- Meningeal irritation
- CSF consistent w/ aseptic meningitis (pleocytosis of lymphocytes, moderately elevated protein, nearly normal glucose)
165
What is post-polio syndrome?
- Happens to pt's 25-35 years after the resolultion of initial illness
- Characterized by progressive weakness and decreased muscle mass and pain in the affected area
166
Negri bodies associated with rabies infection are found where in the brain?
- Pyramidal neurons of the hippocampus
- Purkinje cells of the cerebellum
\*Sites usually devoid of inflammation
167
Which symptoms/findings are virtually diagnostic for rabies infection?
Malaise, headache and fever in conjunction w/ **local paresthesias around the wound**
168
What is seen during the acute phase of HIV infection of the CNS?
Mild lymphocytic meningitis, perivascular inflammation, and some myelin loss
169
What are the only CNS cell type to express both the CD4 coreceptor and the chemokine receptors (CCR5 or CXCR4) that are required in combination for efficient infection by HIV?
Microglia
170
What is immune reconstitution inflammation syndrome (IRIS)?
- Seen in AIDS patients
- Paradoxical deterioration after starting therapy and consists of an exuberant "reconstituted" inflammatory response while on antiretroviral therapy
- Intense inflammation w/ influx of CD8+ lymphocytes
171
What type of encephalitis is associated with **widely distributed microglial nodules**, often containing macrophage-derived multinuclated giant cells?
HIV encephalitis
172
Which virus causes Progressive Multifocal Leukoencephalopathy (PML)?
This virus has tropism for which cell, and what is its principle pathologic effect?
- JC polyomavirus
- Tropism for oligodendrocytes ---\> **demyelination** is its principal pathologic effect
173
Progressive Multifocal Leukoencephalopathy (PML) occurs almost exclusively in who?
Immunosuppressed individuals
174
Which encephalitis is characterized by patches of irregular, ill-defined white matter injury w/ **enlarged oligodendrocyte nuclei containing glassy amphopilic viral inclusions**?
Progressive Multifocal Leukoencephalopathy (PML)
175
Which encephalitis is characterized by **widespread gliosis and myelin degeneration**; **viral inclusions**, largely within the nuclei of oligodendrocytes and neurons; variable inflammation of white and gray matter; and neurofibrillary tangles?
Subacute Sclerosing Panencephalitis (SSPE)
176
How do most fungi reach the brain; what is another way they may invade?
- Most by hematogenous dissemination
- Direct extension may also occur, particularly **mucormycosis** in the setting of **diabetes mellitus**
177
What are the 3 main forms of injury to the CNS caused by fungal infections?
1) Chronic meningitis
2) Vasculitis
3) Parenchymal invasion
178
Vasculitis associated with fungal infections is most frequently seen with what organisms?
*Mucormycosis* and *Aspergillosis*
179
What are the most commonly encountered fungi that invade the brain?
*Candida* and *Cryptococcus*
180
Gelatinous material within the subarachnoid space and small cysts within the parenchyma (**"soap bubbles"**), especilly within the basal ganglia are characteristic of what type of infection?
Chronic meningitis associated w/ **cryptococcal infection**
181
What may be seen on CT with cerebral toxoplasmosis infection?
Ring enhancing lesions
182
What is the morphology of cerebral toxoplasmosis abscesses; most often seen where?
- Mostly affect the cerebral cortex (near the gray-white junction) and deep gray nuclei
- Central necrosis, petechial hemorrhage surrounded by acute and chronic inflammation, macrophage infiltration, and vascular proliferation
183
Which stain is used for *Naegleria* species to confirm a diagnosis of cerebral amebiasis?
PAS or Methenamine silver
184
Cerebral malaria is a rapidly progressing encephalitis caused by what organism?
*Plasmodium falciparum*
185
What are the clinical implications of infection with *Taenia Solium* causing cysticercosis?
- Form cysts within the subarachnoid space
- May obstruct CSF flow, leading to life threatening hydrocephalus
- Hemiplegia, severe headaches, and papilledema
186
Heterozygosity at which codon is protective against the development of diseases associated with prion protein (PrP)?
129
187
What are the clinical manifestations of Creutzfeldt-Jakob Disease (CJD)?
Subtle changes in memory/behavior followed by a **rapidly progessing dementia**, often associated with **pronounced involuntary jerking muscle contractions** on sudden stimulation (**startle myoclonus**)
188
Creutzfeldt-Jakob Disease (CJD) has a peak incidence during what decade?
How is it transmitted?
Average survival time?
- During the **seventh decade**
- **Iatrogenic transmission**, notably by corneal transplantation, deep implantation of electrodes in the brain, and administration of contaminated preparations of naturally derived GH
- Average survival = 7 months
189
Onset of the variant form of CJD is linked to consumption of?
Bovine spongiform encephalopathy agent in contaminated foods or blood transfusion
190
How does vCJD differ clinically from CJD?
- Behavioral changes early in the disease
- **Slower progression** of neurologic symptoms
191
What is seen on electron microscopy with CJD and vCJD?
How are they stained?
- **Kuru plaques:** extracellular deposits of aggregated abnormal protein (will have **halo** of spongiform in vCJD); usually seen in the **cerebellum**, but are abundant in the **cerebral cortex in cases of vCJD**
**- Congo red** and **PAS-positive**
192
Fatal Familial Insomnia (FFI) is caused by what specific mutation in the *PRNP* gene?
**Aspartate** substitution at residue **178** or PrPc
193
What is the characteristic morphology of Fatal Familial Insomnia (FFI)?
- Neuronal loss and reactive gliosis in the **anterior ventral** and **dorsomedial nuclei** of the **thalamus**
- Neuronal loss is also prominent in the **inferior olivary nuclei**
194
What are the clinical manifestations of Fatal Familial Insomnia (FFI)?
- Sleep disturbances in the initial stages
- Ataxia, autonomic disturbances, stupor, and finally coma
195
Polymorphisms at which codon influence the development of prion diseases?
Codon 129 encoding either Met or Val
196
How does FFI differ from the other prion diseases, morphologically?
Does **not** show spongiform pathology
197
Where are the densest amounts of exudate found with acute meningitis caused by *P**neumococcal meningitis* and *H. influenzae?*
- ***P. meningitis***: often densest over convexities near sagittal sinus
- ***H. influenzae:*** usually basal location
