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Pathology > Cns2 > Flashcards

Cns2 Flashcards

1
Q

Saccular (Berry) Aneurysms

• Occur at bifurcations

A

– Junction of carotid and posterior communicating a.

– Junction of anterior communicating a. connecting the two anterior cerebral a.

– Major division of the middle cerebral a. in the sylvian fissures

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2
Q

Saccular (Berry) Aneurysms

• Controversy: Two postulated mechanisms :

A

– Congenital, but aneurysm is not present at birth
• Inherited weakness in the blood vessel wall becomes an aneurysm later in life

– Acquired, degenerative lesion

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3
Q

Saccular (Berry) Aneurysms

• In 20 – 30% cases, multiple aneurysms

A
  • Present in ~ 1% of the general population
  • Found in 2% of postmortem examinations
  • Probability of rupture:
    – Increases with increasing size
    – >10 mm (1cm) have ~50% risk of bleeding per year
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4
Q

Saccular (Berry) Aneurysms
• Rupture is the most frequent complication

A
  • Rupture with clinically significant subarachnoid hemorrhage is most commonly occurs prior to the age of 50
  • Slightly more common in women
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5
Q

Saccular (Berry) Aneurysms: Clinical S&S

• Rupture can occur at any time
• Patients complain of sudden onset of excruciating headache
– “The worst headache I’ve ever had”

A

• Rapid loss of consciousness
• 25 – 50% of patients die with the first rupture
• Rebleeding is a problem in those who survive

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6
Q

Complications

Acute
Late

A
  • Acute
    Vasospasm causing ischemic injury in vessels other than those originally involved
  • Late sequelae
    – Meningeal fibrosis
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7
Q

Vascular Malformations
• Three groups:

A

– Arteriovenous malformations

– Cavernous angiomas
– Capillary telangiectasias

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8
Q

Hypertensive Cerebrovascular Disease

A

Lacunar Infarcts
Slit Hemorrhages

Hypertensive Encephalopathy

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9
Q

Lacunar Infarcts

A

•Hypertension affects the deep penetrating arteries supplying the basal ganglia, hemispheric white matter, and brain stem
• Vessels develop arteriolar sclerosis,some become occluded
• Smallcavitaryinfarcts(lacunes)
• Occur in the lenticular nucleus, thalamus, internal capsule, deep white matter, caudate nucleus, and pons

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10
Q

Lacunar Infarcts

• May be clinically silent or cause severe neurologic impairment

A

• Morphology:
– Cavities of tissue loss with scattered fat-laden macrophages

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11
Q

Slit Hemorrhages

• Rupture of small penetrating vessels with the development of small hemorrhages

A

• Hemorrhage reabsorbs in time leaving a slit-like cavity and hemosiderin laden macrophages

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12
Q

Hypertensive Encephalopathy

• Diffuse cerebral dysfunction

A

– Headache
– Confusion
– Vomiting
– Convulsions
– May lead to coma

• Treatment: rapid therapeutic intervention to lower intracranial pressure

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13
Q

Vascular (Multi-Infarct)

Dementia

A

• Occurs in those who suffer multiple bilateral gray matter infarcts and white matter infarcts over the course of months/years

• Caused by multifocal vascular disease
– Cerebral atherosclerosis
– Vessel thrombosis or embolization
– Cerebral arteriolar sclerosis

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14
Q

CNS Infections: Routes of Entry

A
  • Hematogenous spread
    • Direct implantation (traumatic, iatrogenic)
  • Local extension (sinuses, cranial bones)
    • Via the peripheral nervous system
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15
Q

Acute Pyogenic Meningitis: Causative Organisms

A

• Neonates: Escherichia coli, group B streptococci
• Infants & children: Haemophilus influenzae, streptococcus pneumoniae
• Adolescents & young adults: Neisseria meningitidis
• Elderly: streptocccus penumoniae, Listeria monocytogenes

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16
Q

Acute Pyogenic Meningitis: Clinical Findings

A
  • Symptoms: headache, photophobia, irritability, clouding of consciousness, neck stiffness
  • CSF: cloudy/purulent, increased pressure, increased neutrophils, increased protein, decreased glucose
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17
Q

Acute Pyogenic Meningitis: Morphology

A

• Prominent meningeal vessels
• Neutrophils in subarachnoid space
• Inflammatory cells may infiltrate the leptomeningeal blood vessels
• Chronic adhesive arachnoiditis

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18
Q

Chronic Meningoencephalitis

A

Tuberculous Meningitis

Neurosyphilis

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19
Q

Tuberculous Meningitis

• Symptoms: headache, malaise, mental confusion, vomiting

A

• CSF: mononuclear cells, increased protein, normal or moderately decreased glucose
• Gelatinous or fibrinous, basally located exudate

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20
Q

Tuberculous Meningitis

• Granulomatous inflammation with caseous necrosis & obliterative endarteritis

A

• Tuberculoma: well circumscribed intraparenchymal mass
• AIDS patients: TB & Mycobacterium avium-intracellulare complex infections

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21
Q

Neurosyphilis

• Tertiary stage of syphilis

A

• Meningeal neurosyphilis: chronic meningitis with obliterative endarteritis& a perivascular plasma cell infiltrate
• Paretic neurosyphilis: invasion of the brain by treponemal organisms with brain atrophy & resultant severe dementia

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22
Q

Neurosyphilis

• Tabes dorsalis:

A

damage to dorsal root sensory nerves with impaired sensation & absence of deep tendon reflexes
– Loss of proprioception
– Charcot joint

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23
Q

Brain Abcess
• Streptococci & Staphylococci are the primary causative organisms

A

• May arise from direct implantation, local extension, or hematogenous spread
• Predisposing factors: acute bacterial endocarditis, cyanotic congenital heart disease, and chronic pulmonary sepsis

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24
Q

Brain Abcess
• Discrete lesions with central liquifactive necrosis surrounded by a fibrous collagen capsule and edema

A

• Treated with antibiotics and surgery
• Predisposing conditions
– Acute bacterial endocarditis
– Right-to-left shunt

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25
Q

Parenchymal Infections

Poliomyelitis

A

• Poliovirus: enterovirus that has been controlled by immunization
• Specificallyattackslowermotorneurons producing a flaccid paralysis with muscle wasting and hyporeflexia
• Postpolio syndrome: late neurologic syndrome characterized by progressive weakness associated with decreased muscle bulk and pain

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26
Q

Progressive Multifocal
Leukoencephalopathy

• Viral encephalitis caused by a polyomavirus (JC virus (unrelated to Creutzfeldt-Jacob disease))

A

• Infects and kills oligodendrocytes
• Nuclear viral inclusions in oligodendrocytes
• Demyelination is principal effect
• Occurs in immunosuppressed individuals
• Focal, progressive neurologic symptoms

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27
Q

Progressive Multifocal Leukencephalopathy
• Occurs almost exclusively in immunosuppressed individuals

A

• Most people have serologic evidence of exposure by the age of 14
– Primary infection is asymptomatic
– PML results from the reactivation of the virus
• Morphology: ill-defined white matter injury
– Ranging in size from millimeters to large confluent regions

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28
Q

Subacute Sclerosing Panencephalitis
• A rare, progressive clinical syndrome

A

• Characterized by:
– Cognitive decline
– Limb spasticity
– Seizures
• Typically occurs in children or young adults months or years after an initial early-age acute infection with measles

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29
Q

Subacute Sclerosing
Panencephalitis

• The disease stems from a persistent, but non- productive infection of the CNS by an altered measles virus

A

• Morphology:
– Widespread gliosis and myelin degeneration
– Viral inclusions
– Variable inflammatory infiltrate of white and gray
matter
– Neurofibrillary tangles
• Disease persists in non-vaccinated populations

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30
Q

Demyelinating Disease

A

Multiple Sclerosis

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31
Q

Multiple Sclerosis: Epidemiology
• F>M

A

• Frequency increases with increasing distance from the equator
• Increased incidence in first-degree relatives
• Increased risk with HLA-DR2
• Most common demyelinating disease
• Young adults

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32
Q

MS: Pathogenesis
• Not clearly understood

A
  • Indirect evidence points to an autoimmune disorder
    – CD4+ and CD8+ lymphocytes are found in the lesions
    – Antibody-mediated injury also seems to play a role
    – HLA-DR2 gives increased risk
  • 15 fold higher risk when the disease is present in a 1st degree relative
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33
Q

MS: Morphology

• Plaques present in white matter
– Active plaques: active myelin breakdown with abundant macrophages, perivascular lymphocytes, and reactive astrocytes

A

• Four different types of active plaques
– Inactive plaques: astrocytic proliferation and gliosis

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34
Q

MS: Clinical Findings

• CSF: mildly increased protein with oligoclonal bands

A

• Antibodies against myelin oligodendrocyte glycoprotein and myelin basic protein
• Unilateral visual impairment is a common presentation
• Protean manifestations
• Relapsing and remitting flare-ups, episodes of neurologic deficit during variable intervals of time, followed by gradual, partial remission

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35
Q

MS: Clinical Findings

• Involvement of the brain stem produces cranial nerve signs, ataxia, nystagmus

A

• Acute or insidious onset
• MBS (myelin basic protein): may be present in CSF during active lesions

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36
Q

MS: Clinical Findings
• Common manifestations:

A

– Visual disturbances
– paresthesias
– spasticity of one or more extremities
– speech disturbances
– gait abnormalities

37
Q

MS: Prognosis

• Clinical course is unpredictable

A

• Over time, there is a gradual, often step- wise, accumulation of neurologic deficits

38
Q

Degenerating Diseases

A

Alzheimer Disease
Parkinsonism
Huntington Disease

39
Q

Degenerating Diseases

A

• Characterized by the progressive loss of neurons with associated secondary white matter changes
• Neuronal loss is selective
• Arise without a clear inciting event

40
Q

Alzheimer Disease

• Most common cause of dementia in the elderly

A

• Patients rarely symptomatic before the age of 50
• Most cases are sporadic
• ~ 10% are familial

41
Q

Hemorrhage

Subarachnoid Hemorrhages and Ruptured Saccular (Berry) Aneurysms

A

• Usually result from rupture of an aneurysm (saccular) or less frequently an A-V malformation

42
Q

Alzheimer Disease

A
  • manifests with the insidious onset of impaired higher intellectual function and altered mood, and behavior
  • Later, there is progression to disorientation, memory loss, and aphasia
    – Findings indicative of severe cortical dysfunction
  • Over another 5 to 10 years
    – Patient becomes profoundly disabled, mute, and immobile
43
Q

Alzheimer Disease: Pathogenesis
and Genetics

A

• Number of neurofibrillary tangles correlates better with clinical impairment

• Biochemical markers that correlate with the degree of dementia:
– Loss of choline acetyl-transferase
– Synaptophysin immunoreactivity
– Amyloid burden

44
Q

Alzheimer Disease: Pathogenesis and Genetics

• Geneticfactors
– Familial cases exist

– Mutations in 4 genetic loci have been linked
conclusively to familial AD

A

• Chromosome 21: a locus encoding amyloid precursor protein
(APP)
• Chromosome 14: mutation in presenilin 1gene
• Chromosome1:mutation in presenilin2gene
• Late onset AD asociated with the expression of the ε4allele of apolipoprotein E, encoded on chromosome 19

45
Q

Alzheimer Disease: Pathogenesis

• Study of the familial forms:

A

– Supports a model in which a peptide Aβ (beta amyloid)
– This is created when the transmembrane protein amyloid precursor protein (APP) is sequentially claeved
• β-amyloid converting enzyme (BACE)
• γ-secretase

46
Q

Alzheimer Disease: Pathogenesis

• APP can also be cleaved by α- secretase and γ-secretase
– This yields a different peptide which is not pathogenic

A

• Mutations in APP or in components of γ- secretase (presenilin-1 or presenilin-2) lead to familial AD
– Increase the rate at which Aβ is generated

47
Q

Alzheimer Disease: Tau Protein

A
  • The presence of Aβ also leads to hyperphosphorylation of the neuronal microtubule binding tau
  • This causes tau to redistribute from axons into dendrites and cell bodies, where it aggregates into tangles
48
Q

Alzheimer Disease: Tau Protein
• Tau :

A

– An intracellular protein involved in the assembly of intra-axonal microtubules

– Seen in other neurodegenerative disorders, neoplasms, and hamartomas

49
Q

AD: Morphology

• Corticalatrophy
• Neurofibrillary tangles
– Bundles of filaments in the cytoplasm of neurons
– Hyperposphorylated tau

A
  • Senileplaques(neuriticplaques)
    – Silver-staining neuritic processes surrounding a central amyloid core
    • Amyloid angiopathy
    • Granulovacuolar degeneration
  • Some cases have lewy bodies
50
Q

AD: Clinical Presentation

• Slow but relentless course

A
  • Symptomatic course running 10 years
  • Initial symptoms:
    – Forgetfulness and other memory disturbances
  • Progression:
    – Language and math deficits
  • Final stages:
    – Incontinent, mute, unable to walk
51
Q

Fronto temporal Dementias

A

• A group of disorders classified together because they shared clinical features
– Progressive deterioration of language
– Personality changes
• Degeneration and atrophy of the temporal and frontal lobes
• Several of these disorders share the accumulation of tau-containing deposits

52
Q

Frontotemporal Dementias with Tau Mutations

A

• Pick Disease
– Lobar atrophy
– Rare, distinct, progressive dementia
– Presents with the early onset of behavioral and personality changes
– Usually sporadic, but some familial cases exist

53
Q

Frontotemporal Dementias with Tau Mutations

• Pick Disease: Morphology

A

– Pronounced, frequently asymmetric atrophy of the frontal and temporal lobes
– Conspicuous sparing of the posterior two thirds of the superior temporal gyrus
– Atrophy may be severe

• Gyri reduced to a wafer-thin (knife edge) appearance

54
Q

Frontotemporal Dementias with Tau Mutations

• Pick Disease: Microscopic changes
– Neuronal loss most severe in the outer three layers of the cortex

A

• Pick cells—characteristic swelling of cells
• Pick bodies—round to oval filamentous inclusions
– Filaments are similar to those in AD
– Contain 3R tau
– Do not survive the death of the neuron

55
Q

Parkinsonism

• Idiopathic Parkinson disease

A
  • Progressive supranuclear palsy

* Corticobasilar degeneration
• Multiple system atrophy
• Postencephalitic parkinsonism
• Multiple system atrophy (MSA)

56
Q

Parkinsonism: Clinical Findings

• Diminished facial expression

A

• Stooped posture
• Slowness of voluntary movement, festinating gate
• Rigidity, “pill-rolling” tremor

57
Q

Parkinsonism

• TRAP

A

– Resting tremor
– Cogwheel rigidity
– Bradykinesia or akinesia
– Impairment in posture and equilibrium

58
Q

Idiopathic Parkinson Disease

A

• Appears later in life
• May include dementia in addition to the movement disorder

59
Q

Parkinson Disease: Pathogenesis

• Most cases are sporadic

A

– Both autosomal dominant and autosomal recessive forms of the disease exist
– Point mutations and duplications of the gene encoding α-synuclein (protein involved in synaptic transmission) cause the AD form of PD

60
Q

Parkinson Disease Pathogenesis

A

• Degeneration of dopaminergic neurons of the substantia nigra
• Associated with a reduction in the striatal dopamine content
• Severity of the motor syndrome is proportional to the dopamine deficiency

61
Q

Parkinson Disease: Morphology

• Pallor of the substantia nigra and locus ceruleus due to the loss of pigmented neurons

A
  • Lewy bodies: intracytoplasmic, eosinophilic inclusions, composed of the presynaptic protein α-synuclein
  • Lewy neurites: dystrophic neurites that also contain abnormally aggregated α-synuclein
62
Q

Parkinson Disease: Diagnosis

• Clinical diagnosis

A

– Must rule out toxic exposure or other known etiology
• No definitive laboratory or neuroimaging study is pathognomonic

63
Q

Parkinson Disease: Clinical
Features

A

• Treatment with L-dopa does not reverse the morphologic changes or arrest the progress of the disease
• 10 – 15% develop dementia

64
Q

Huntington Disease

• Autosomal dominant

A

• Progressive movement disorders and dementia
• Histologically, degeneration of striatal neurons
• Relentlessly progressive
• Average course of ~ 15 years to death

65
Q

Huntington Disease: Morphology

A

• Degenerationofstriatalneurons
• Small brain
• Atrophy of the caudate nucleus and putamen
• Secondary atrophy of the globuspallidus
• Dilation of the lateral and third ventricles
• Atrophy of the frontallobe,less oftenofthe parietal lobe, and occasionally the entire cortex

66
Q

Huntington Disease: Molecular Genetics

• The HD gene:
– Located on 4p16.3, the huntingtin gene

A

• Encodes a protein: huntingtin
– Trinucleotide repeat disease
• CAG trinucleotide repeat expansions
• Occur during spermatogenesis
• Paternal transmission is associated with earlier onset
in the next generation

67
Q

Huntington Disease: Clinical
Course

A

• Age of onset most commonly in the 4th and 5th decades
• Motor symptoms typically precede cognitive impairment.

68
Q

Toxic and Acquired Metabolic Diseases

A

Vitamin Deficiencies
Neurologic Sequelae of Metabolic Disturbances

69
Q

Vitamin Deficiencies

A

Thiamine (Vitamin B1)

Vitamin B12

70
Q

Thiamine Deficiency

• Causes wet and dry beriberi (discussed in nutrition lecture)

A

• Wernicke-Korsakoff Syndrome

– Wernicke encephalopathy
• Nystagmus, abducens and conjugate gaze palsies, ataxia of gait, and mental confusion

– Korsakoff syndrome
• Amnesic state
• Retentive memory is impaired out of proportion to
other cognitive functions

71
Q

Wernicke-Korsakoff Syndrome

A

• In thiamine deficiency, Wernicke encephalopathy occurs first, followed by Korsakoff syndrome

• Clinical features
– Oculomotor abnormalities
• Nystagmus
—both horizontal and vertical, mainly evoked by gaze
• Weakness or paralysis of the lateral rectus muscles
• Weakness or paralysis of conjugate gaze

72
Q

Wernicke-Korsakoff Syndrome
– Ataxia

A

• Is one of stance and gait
• In acute stage of the disease—the patient may not be
able to stand or walk without support
• Wide-bases stance
• Slow, uncertain, short-stepped gait

73
Q

Wernicke-Korsakoff Syndrome

– Disturbances of Consciousness and Mentation

A

• Several types of disturbed mentation and consciousness can occur, most commonly global confusional state
• Minimal spontaneous speech

– Amnesic State
• Defect in both learning (anterograde amnesia) and loss of past memories (retrograde amnesia)
• Confabulation: may be seen in both the initial phase (confusion) and the convalescent phase

74
Q

Wernicke-Korsakoff Syndrome

•Most patients respond to thiamine administration

A

– Ocular recovery often begins in hours (diagnostic)
– Improvement in ataxia is delayed

• 40% recover completely, the rest not at all
– Global confusion, apathy, drowsiness recede
– 20% recover completely or almost so from the memory disorder, the rest are left with permanent disability

75
Q

Vitamin B12 Deficiency

A

• Can cause anemia
• Can have severe and potentially irreversible effects on the CNS

76
Q

Vitamin B12 Deficiency

• Causes

– Gastric Disorders
• Pernicious anemia
• Gastrectomy syndromes

A

– Intestinal diseases
• Competing intestinal flora and fauna

– Acquired Immunodeficiency Syndrome
– Pancreatic disease
– Dietary Deficiency

77
Q

Vitamin B12 Deficiency
• Morphology-CNS Lesions

A

– Demyelination of the dorsal and lateral tracts of the spinal cord
– Since ascending and descending tracts involved, designated: subacute combined degeneration of the spinal cord
– Recent evidence links low cobalamin status with brain volume loss and cerebral white matter lesions

78
Q

Vitamin B12 Deficiency
• Clinical Signs and Symptoms – Peripheral neuropathy

A

• Numbness, tingling, and slight ataxia in the lower extremities
• Disturbances of vibratory sense and proprioception
• May progress to spastic weakness or complete paraplegia

79
Q

Vitamin B12 Deficiency
• Clinical S & S

A

– Neurologic syndrome can occur in the absence of megaloblastic anemia
– Dementia mimicking Alzheimer disease
– Neuropsychiatric disease
• Psychotic depression, paranoid schizophrenia, frank psychosis
– “Megaloblastic madness”

80
Q

Vitamin B12 Deficiency
• Treatment

A

– Parenteral Vitamin B12 injections
– With prompt vitamin replacement, symptoms improve
– Can be permanent if deficiency has been present for a long time

81
Q

CNS Tumors

A

Gliomas

82
Q

Astrocytoma

A
  • Diffuse astrocytoma

* Pilocytic astrocytoma

83
Q

Diffuse Astrocytoma

A

• ~80% of adult primary brain tumors
• Late middle age
• Typically found in the cerebral hemispheres
• Signs & symptoms:
– Seizures, headaches, focal neurologic deficits

84
Q

Diffuse Astrocytma

A

• Diffuse or infiltrative growth pattern
• Divided into histologic grades based on the degree of differentiation
• Tend to become less differentiated over time
• Mutations in TP53 (p53) and Rb genes as well as gain of function mutations in PI3K pathways have central roles in tumorigenesis

85
Q

Morphology

A

• Infiltrative growth pattern
• Fibrillary background of astrocytic processes
• Hypercellular with nuclear pleomorphism

86
Q

Grading

A

Three grading:

– Low-grade astrocytoma
– Anaplastic astrocytoma: increased anaplasia, mitoses, vascular proliferation
– Glioblastoma multiforme: necrosis with pseudopalisading of tumor cells

87
Q

Prognosis

A

• Low-grade lesion may remain stable for years but eventually progress
• High-grade (glioblastoma):

88
Q

Pilocytic Astrocytoma

A

• Tumor of children and young adults
• Cerebellum is the most common location
• Cystic lesions with a mural nodule
• Microcystic lesions with Rosenthal fibers
• Behave in a benign fashion in the majority of cases

89
Q

Meningiomas

A

• Predominately benign tumor of adults
• Attached to dura
• Arise from the meningothelial cells of the arachnoid
• Compress underlying brain
• Slow growing

Pathology (15 decks)

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