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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
Parenchymal Infections Poliomyelitis
• 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
26
Progressive Multifocal Leukoencephalopathy • Viral encephalitis caused by a polyomavirus (JC virus (unrelated to Creutzfeldt-Jacob disease))
• 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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Progressive Multifocal Leukencephalopathy • Occurs almost exclusively in immunosuppressed individuals
• 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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Subacute Sclerosing Panencephalitis • A rare, progressive clinical syndrome
• 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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Subacute Sclerosing Panencephalitis | • The disease stems from a persistent, but non- productive infection of the CNS by an altered measles virus
• 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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Demyelinating Disease
Multiple Sclerosis
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Multiple Sclerosis: Epidemiology • F>M
• 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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MS: Pathogenesis • Not clearly understood
* 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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MS: Morphology • Plaques present in white matter – Active plaques: active myelin breakdown with abundant macrophages, perivascular lymphocytes, and reactive astrocytes
• Four different types of active plaques – Inactive plaques: astrocytic proliferation and gliosis
34
MS: Clinical Findings | • CSF: mildly increased protein with oligoclonal bands
• 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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MS: Clinical Findings | • Involvement of the brain stem produces cranial nerve signs, ataxia, nystagmus
• Acute or insidious onset • MBS (myelin basic protein): may be present in CSF during active lesions
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MS: Clinical Findings • Common manifestations:
– Visual disturbances – paresthesias – spasticity of one or more extremities – speech disturbances – gait abnormalities
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MS: Prognosis | • Clinical course is unpredictable
• Over time, there is a gradual, often step- wise, accumulation of neurologic deficits
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Degenerating Diseases
Alzheimer Disease Parkinsonism Huntington Disease
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Degenerating Diseases
• Characterized by the progressive loss of neurons with associated secondary white matter changes • Neuronal loss is selective • Arise without a clear inciting event
40
Alzheimer Disease | • Most common cause of dementia in the elderly
• Patients rarely symptomatic before the age of 50 • Most cases are sporadic • ~ 10% are familial
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Hemorrhage Subarachnoid Hemorrhages and Ruptured Saccular (Berry) Aneurysms
• Usually result from rupture of an aneurysm (saccular) or less frequently an A-V malformation
42
Alzheimer Disease
* 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
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Alzheimer Disease: Pathogenesis and Genetics
• 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
Alzheimer Disease: Pathogenesis and Genetics • Geneticfactors – Familial cases exist – Mutations in 4 genetic loci have been linked conclusively to familial AD
• 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
Alzheimer Disease: Pathogenesis • Study of the familial forms:
– 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
Alzheimer Disease: Pathogenesis • APP can also be cleaved by α- secretase and γ-secretase – This yields a different peptide which is not pathogenic
• 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
Alzheimer Disease: Tau Protein
* 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
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Alzheimer Disease: Tau Protein • Tau :
– An intracellular protein involved in the assembly of intra-axonal microtubules – Seen in other neurodegenerative disorders, neoplasms, and hamartomas
49
AD: Morphology • Corticalatrophy • Neurofibrillary tangles – Bundles of filaments in the cytoplasm of neurons – Hyperposphorylated tau
* Senileplaques(neuriticplaques) – Silver-staining neuritic processes surrounding a central amyloid core • Amyloid angiopathy • Granulovacuolar degeneration * Some cases have lewy bodies
50
AD: Clinical Presentation | • Slow but relentless course
* 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
Fronto temporal Dementias
• 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
Frontotemporal Dementias with Tau Mutations
• 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
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Frontotemporal Dementias with Tau Mutations • Pick Disease: Morphology
– 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
Frontotemporal Dementias with Tau Mutations • Pick Disease: Microscopic changes – Neuronal loss most severe in the outer three layers of the cortex
• 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
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Parkinsonism • Idiopathic Parkinson disease
* Progressive supranuclear palsy | * Corticobasilar degeneration • Multiple system atrophy • Postencephalitic parkinsonism • Multiple system atrophy (MSA)
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Parkinsonism: Clinical Findings • Diminished facial expression
• Stooped posture • Slowness of voluntary movement, festinating gate • Rigidity, “pill-rolling” tremor
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Parkinsonism | • TRAP
– Resting tremor – Cogwheel rigidity – Bradykinesia or akinesia – Impairment in posture and equilibrium
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Idiopathic Parkinson Disease
• Appears later in life • May include dementia in addition to the movement disorder
59
Parkinson Disease: Pathogenesis • Most cases are sporadic
– 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
Parkinson Disease Pathogenesis
• 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
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Parkinson Disease: Morphology • Pallor of the substantia nigra and locus ceruleus due to the loss of pigmented neurons
* Lewy bodies: intracytoplasmic, eosinophilic inclusions, composed of the presynaptic protein α-synuclein * Lewy neurites: dystrophic neurites that also contain abnormally aggregated α-synuclein
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Parkinson Disease: Diagnosis • Clinical diagnosis
– Must rule out toxic exposure or other known etiology • No definitive laboratory or neuroimaging study is pathognomonic
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Parkinson Disease: Clinical Features
• Treatment with L-dopa does not reverse the morphologic changes or arrest the progress of the disease • 10 – 15% develop dementia
64
Huntington Disease • Autosomal dominant
• Progressive movement disorders and dementia • Histologically, degeneration of striatal neurons • Relentlessly progressive • Average course of ~ 15 years to death
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Huntington Disease: Morphology
• 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
Huntington Disease: Molecular Genetics • The HD gene: – Located on 4p16.3, the huntingtin gene
• 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
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Huntington Disease: Clinical Course
• Age of onset most commonly in the 4th and 5th decades • Motor symptoms typically precede cognitive impairment.
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Toxic and Acquired Metabolic Diseases
Vitamin Deficiencies Neurologic Sequelae of Metabolic Disturbances
69
Vitamin Deficiencies
Thiamine (Vitamin B1) | Vitamin B12
70
Thiamine Deficiency | • Causes wet and dry beriberi (discussed in nutrition lecture)
• 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
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Wernicke-Korsakoff Syndrome
• 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
Wernicke-Korsakoff Syndrome – Ataxia
• 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
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Wernicke-Korsakoff Syndrome | – Disturbances of Consciousness and Mentation
• 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
Wernicke-Korsakoff Syndrome | •Most patients respond to thiamine administration
– 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
Vitamin B12 Deficiency
• Can cause anemia • Can have severe and potentially irreversible effects on the CNS
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Vitamin B12 Deficiency • Causes – Gastric Disorders • Pernicious anemia • Gastrectomy syndromes
– Intestinal diseases • Competing intestinal flora and fauna – Acquired Immunodeficiency Syndrome – Pancreatic disease – Dietary Deficiency
77
Vitamin B12 Deficiency • Morphology-CNS Lesions
– 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
Vitamin B12 Deficiency • Clinical Signs and Symptoms – Peripheral neuropathy
• Numbness, tingling, and slight ataxia in the lower extremities • Disturbances of vibratory sense and proprioception • May progress to spastic weakness or complete paraplegia
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Vitamin B12 Deficiency • Clinical S & S
– Neurologic syndrome can occur in the absence of megaloblastic anemia – Dementia mimicking Alzheimer disease – Neuropsychiatric disease • Psychotic depression, paranoid schizophrenia, frank psychosis – “Megaloblastic madness”
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Vitamin B12 Deficiency • Treatment
– Parenteral Vitamin B12 injections – With prompt vitamin replacement, symptoms improve – Can be permanent if deficiency has been present for a long time
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CNS Tumors
Gliomas
82
Astrocytoma
* Diffuse astrocytoma | * Pilocytic astrocytoma
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Diffuse Astrocytoma
• ~80% of adult primary brain tumors • Late middle age • Typically found in the cerebral hemispheres • Signs & symptoms: – Seizures, headaches, focal neurologic deficits
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Diffuse Astrocytma
• 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
Morphology
• Infiltrative growth pattern • Fibrillary background of astrocytic processes • Hypercellular with nuclear pleomorphism
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Grading
Three grading: – Low-grade astrocytoma – Anaplastic astrocytoma: increased anaplasia, mitoses, vascular proliferation – Glioblastoma multiforme: necrosis with pseudopalisading of tumor cells
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Prognosis
• Low-grade lesion may remain stable for years but eventually progress • High-grade (glioblastoma):
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Pilocytic Astrocytoma
• 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
Meningiomas
• 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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