29. Central Nervous System Pathology Flashcards
What is acute purulent meningitis?
Purulent leptomeningeal inflammation due to bacteria.
Which organism is responsible of acute purulent meningitis in neonates?
Group B streptococci, Escherichia coli.
Which organism is responsible of acute purulent meningitis in infants and children?
Haemophilus influenza.
Which organism is responsible of acute purulent meningitis in adolescents and young adults?
Neisseria meningitidis.
Which organism is responsible of acute purulent meningitis in elderly?
Streptococcus pneumoniae and Listeria monocytogenes.
What are two sequelae due to organization of purulent exudate and fibrosis?
Hydrocephalus and cranial nerve impairment (neural deafness).
Which part of the brain does mycobaterial meningoencephalitis affect?
Basal surface of the brain.
Which type of mycobateria causes meningoencephalitis? Which one in AIDS patients?
Usually by Mycobacterium tuberculosis or atypical mycobateria. Mycobacterium avium-intracellulare (MAI) in AIDS patients.
What is the normal value of proteins (mg/dL) in cerebrospinal fluid?
15-45.
What is the normal value of pressure (cm H2O) in cerebrospinal fluid?
70-180.
What is the normal lymphocyte count in cereborspinal fluid?
Less than five.
What is the normal value of glucose (ug/dL) in cerebrospinal fluid?
45-85 (50-70% glycemia)
In which type of meningitis do we see normal values of glusose in CSF?
Aseptic (viral).
Which types of meningitis do we see moderate 100-1000 lymphocyte count?
Aseptic (viral) and Granulomatous (mycobacterial/fungal).
What are 4 clinical presentations of viral encephalitides?
- Perivascular cuffs.
- Microglial nodules.
- Neuron loss.
- Neuronophagia.
What is a characteristic presentation of Herpes simplex type 1 viral encephalitis?
Hemorrhagic necrosis of temporal lobes.
What micro presentation is characteristic of Rabies encephalitis?
Negri bodies in hippocampal and Purkinje neurons.
What are 5 anthropod-borne viral encephalitides?
- St. Louis
- California
- Eastern equine
- Western Equine
- Venezuelan
What does HIV cerebral involvement lead to?
AIDS-dementia complex.
What micro presentation do we see in HIV-related encephalitides?
Microglial nodules and diagnostic mutlinucleated giant cells.
What does spinal involvement of HIV lead to?
Vacuolar myelopathy similar to vitamin B12 deficiency-associated subacute combined degeneration.
What virus is related to Progressive multifocal leukoencephalopathy (PML)?
JC virus (John Cunningham).
What 3 micro presentations do we see in Progressive multifocal leukoencephalopathy?
- Demyelination.
- Lymphohistiocytic
- Astrogliosis.
What happens to astrocytes in Progressive multifocal leukoencephalopathy? What happens to oligodendrocytes?
Astrocytes acquire bizarre shapes. Oligodendrocytes in active lesions contain intranuclear inclusions.
What are the 4 most common fungi involved in fungal meningoencephalitis?
- Candida
- Aspergillus
- Cryptococcus
- Mucor
What two species of fungi have a penchant for marked tropism for blood vessels?
Aspergillus and Mucor. They can cause vasculitis, rupture of blood vessels and hemorrhage.
What type of meningoencephalitis does Cryptococcus cause and what type of lesions?
It causes diffuse meningoencephalitis: invasion of the brain through Virchow-Robin and soap bubble lesions.
What does toxoplasmosis cause in the brain?
Cerebral abscess with central necrosis and chronic inflammation.
What do we find in MRI/CT scan of someone with toxoplasmosis?
Characteristic ring-enhancing lesions.
What is the cause of Creutzfeldt-Jakob disease (CJD)?
Caused by prion protein (PrP) that has turned from its normal conformation of alpha-helix PrP(C) to beta-pleated PrP(SC).
What gene and which chromosome is the agent that causes Creutzfeldt-Jakob disease?
The prior protein is encoded by a single-exon gene on chromosome 20.
What change does Creutzfeldt-Jakob disease cause in the brain?
Spongiform change by fine vacuolization of the neuropil in the gray matter (especially the cortex) due to large membrane-bound vacuoles within neuronal processes.
What percentage of Creutzfeldt-Jakob disease are sporadic? How many are by familial?
85% are sporadic, 15% are familial.
Which disease causes Subacute Spongiform Encephalopathy (SSE)?
Kuru in the Fore tribe in New Guinea due to the consumption of infected brains.
What is another name for Global cerebral ischemia?
Diffuse ischemic encephalopathy.
What are 3 vulnerable places in the brain for global cerebral ischemia?
Purkinje neurons, hippocampus CA1 (Sommer sector) and pyramidal neurons of cortex.
What type of strokes are the most frequent?
Infarctions (85% of all stroke cases).
What is the percentage of all infarctions caused by hemorrhage?
15% of all stroke cases.
Which type of emboli causes the majority of emboli occlusions?
By thromboemboli from cardiac chambers, less frequently due to atheroemboli.
At what time do we see liquefactive necrosis after cerebral infarction?
2-3 weeks after the cerebral infarction.
What is the most frequent predisposing condition for intracerebral (intraparenchymal) hemorrhage?
Hypertension.
What are the symptoms of intracerebral hemorrhage?
Severe headache, frequent nausea/vomiting, steady progression of symptoms over 15-20 minutes and coma.
Which is the most frequent artery involved in epidural hemorrhage?
Middle meningeal artery.
Which type of brain herniation does epidural hemorrhage lead to if not promptly evacuated?
Usually subfalcine.
What is the “talk-and-die syndrome” and in which pathology does it present?
It is the lucid interval before loss of consciousness seen in epidural hemorrhage.
What is the cause of epidural hemorrhage?
Virtually traumatic, associated with skull fractures, due to tear of dural arteries, most frequently middle meningeal artery.
What is the cause of subdural hemorrhage?
Usually (in contrast to epidural which is virtually) traumatic, caused by the rupture of bridging veins (from cerebral convexities to sagittal sinus).
What are the symptoms of subdural hemorrhage?
Headache, drowsiness, focal neurologic deficits, sometimes dementia. Recurs frequently.
What is the most frequent cause of subarachnoid hemorrhage?
Ruptured berry aneurysms.
What are the symptoms of subarachnoid hemorrhage?
Sudden (“thunderclap”) headache, nuchal rigidity, and neurological deficits on one side, and stupor.
What is a berry aneurysm?
Thin-walled sacular outpouchings, consisting of intima and adventitia only.
What is the most frequent site of berry aneurysm?
Anterior circle of Willis at branching points.
What are 3 pathologies associated with berry aneurysms?
- Marfan syndrome.
- Ehlers-Danlos type 4.
- Adult polycystic kidney disease.
What is the prognosis after a berry aneurysm rupture?
1/3 die, 1/3 recover, 1/3 rebleed.
What is a concussion?
Change in the momentum of the head (impact against a rigid surface).
What are the clinical manifestations of a concussion?
Loss of consciouness and reflexes, temporary respiratory arrest, and amnesia for the event.
What is a contusion?
Impact of parts of the brain against the inner calvarial surfaces. Causes bruising to the brain resulting from tissue and vessel disruption.
Describe the site of injury of a contusion.
Crests of orbital gyri in frontal and temporal poles.
What are “Coup” and “contrecoup” and when do we see them?
Coup: site of injury
Contrecoup: site of diametrically opposite.
They both develop when the head is mobile at the time of impact in contusions.
What happens in an acute contusion?
Hemorrhage of brain tissue in wedge-shaped area.
What happens in subacute contusions?
Necrosis and liquefaction of brain.
What happens in remote contusions?
Depressed area of cortex with yellow discoloration (“plaque jaune”)
What is diffuse axonal injury?
Injury to the white matter due to acceleration/deceleration. It causes damage to axons at the nodes of Ranvier with impairment of axoplasmic flow.
What five sites of the brain does diffuse axonal injury has a predilection for?
- Corpus callosum.
- Periventricular white matter.
- Hippocampus
- Cerebral peduncles.
- Cerebellar peduncles.
What micro presentations does diffuse axonal injury cause?
Axonal swellings appreciable in the white matter.
What is the clinical presentation of diffuse axonal injury?
Coma after trauma without evidence of direct parenchymal injuries.
What does the prognosis of diffuse axonal injury depend on?
Related to the duration of coma.
What do lesions to the thoracic segments or below cause?
Paraplegia.
What do lesions to cervical segments cause?
Tetraplegia.
What do lesions above C4 cause and why?
Respiratory arrest due to paralysis of diaphragm.
What is another name for Subfalcine herniation?
Cingulate gyrus herniation.
What happens in a Subfalcine herniation?
Cingulate gyrus is displaced underneath the falx to the opposite side. Causes compression of anterior cerebral artery.
What is another name for Transtentorial herniation?
Uncal herniation.
What is acute aseptic meningitis and what micro presentation do we see?
Leptomeningeal inflammation due to viruses (enterovirus most frequent). Lymphocytic infiltration of leptomeninges and superficial cortex.
What happens in a transtentorial hernia?
Uncus of the temporal lobe is displaced over the free edge of the tentorium. Compression of the third nerve; pupillary dilation on the same side, infacrt in dependnt territory.
What happens in the advanced stages of transtentorial herniation?
Durret hemorrhage within the central pons and midbrain.
What is Cerebellar tonsillar?
Displacement of cerebellar tonsils through the foramen magnum.
What happens in the compression of medulla?
Cardiorespiratory arrest.
What is anencephaly?
Absence of cranial vault; incompatible with life -babies soon die after birth.
What is spina bifida?
Bony defect of the vertebral arch.
What is meningocele?
Bony defect with outpouching of the meninges.
What is meningomyelocele?
Defective formation of the bony arch with cystic outpouching of meninges, spinal cord, and spinal roots.
What is myelocele?
Defective bony arch with complete exposure of spinal cord.
Which neural defect does not lead to increas in alfa-fetoprotein during pregnancy?
Spina bifida occulta.
What is Anorld-Chiari malformation?
It is faulty craniospinal junction, resutling in small posterior fossa with: (4)
- Downward displacement of cerebellar vermis and medulla.
- Compression of the fourth ventricle.
- Obstruction hydrocephalus.
- Frequent lumbar meningomyelocele.
What other pathology is Arnold-Chiari malfomation is associated with?
Syringomyelia.
Which type of Arnold-Chiari malformation is the most common?
Type 1
Which type of Arnold-Chiari malformation is the most symptomatic?
Type 2.
Which type of Arnold-Chiari malformation is the one with downward displacement of cerebellar tonsils?
Type 1.