Chapter 28: The CNS - Intro Flashcards
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
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
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!
What type of injury is associated with localized vs. generalized vasogenic edema?
- Localized: adjacent to inflammation or neoplasms
- Generazlied: follow ischemic injury
What is the most common cause of noncommunicating (obstructive) hydrocephalus in the neonate/infant?
Aqueductal stenosis
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
What 2 congenital conditions cause ventricular system obstruction?
1) Acqueductal stenosis
2) Dandy-Walker malformation
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!!!
Herniation is displacement of brain tissue due to _____ or ______
Mass effect or Increased intracranial pressure
What is diffuse vs. focal mass effect that is associated with herniation?
- Diffuse: generalzied brain edema
- Focal: tumors, abscesses, or hemorrhages
Subfalcine herniation involves displacement of the _______ under the _______
Cingulate gyrus under the falx cerebri
A subfalcine herniation may lead to compression of the ________ artery leading to infarction
Anterior Cerebral artery (ACA)
What symptoms would result from Subfalcine herniation with compression of the ACA?
Contralateral lower extremity weakness
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
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”
What are Duret hemorrhages and are a result of what?
- Progression of transtentorial herniation producing secondary hemorrhagic lesions in the midbrain and pon
- “Flame-shaped” lesions
Why is it crucial to exam the eyes of a patient you expect to be suffering from increased intracranial pressure?
Look for papilledema
What are congenital causes of hydrocephalus?
- Intrauterine infections (TORCH)
- Agenesis/atresia/stenosis
- Arnold chiari malformations
- Dandy walker syndrome
- Cranial defects: Achondroplasia and Craniostenosis
Which rare type of brain tumor leads to increased CSF production, thus causing increased ICP and hydrocephalus?
Choroid Plexus Papilloma/Carcinoma
What is the most common parasitic nervous system disease in the world and can lead to hydrocephalus?
- Cysticercosis
- Taenia Solium (pork tapeworm)
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
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
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.
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
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)
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)
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
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
Perinatal ischemic lesions of the cerebral cortex leading to thinned-out, gliotic gyri is known as?
Ulegyria
Diastatic fracture
Fracture that crosses a suture
If the head is immobile at the time of trauma, what time of injury will be found?
Only a coup injury
Clinical term for altered consciousness secondry to a head injury typically brough about by a change in momentum of the head
Concussion
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
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
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
Diffuse axonal injury is best demonstrated using what lab techniques/stains?
- Silver impregnantion (silver stain)
- Immunoperoxidase stains for amyloid precursor protein and α-synuclein
As many as 50% of individuals who develop coma shortly after trauma, even without cerebral contusions, are believed to have?
Diffuse axonal injury
Sudden onset of severe headache (“worst headache of my life”), often with rapid neurologic deterioration is consistent with a _________ hemorrhage
Subarachnoid
Secondary injury associated seen in subarachnoid hemorrhage is often associated with what?
Vasospasm
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
What type of hematoma is associated with rupture of the bridging veins?
Subdural hematoma
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
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
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
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
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
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
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
Border zone (“watershed”) infarcts are usually seen after ________ episodes
Hypotensive
Which pattern of injury is seen in the cerebral neocortex following global ischemia?
Pseudolaminar necrosis
What are the subacute changes seen 24 hours to 2 weeks after global ischemia?
- Tissue necrosis
- Influx of Macrophages and Reactive gliosis (10 days)
- Vascular proliferation
Following global ischemia you see ______ of the gyri and _____ of the sulci
- Widening of the gyri
- Narrowing of the sulci
*Edema
Global cerebral ischemia occurs after which events?
Cardiac arrest, shock, or severe hypotension
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)
Which artery is most frequently affected by embolic infarction?
MCA — direct extension of the internal carotid artery
Widespread hemorrhagic lesions involving the white matter are characteristic of embolization of _______ after trauma
Bone marrow
Most common sites for thrombotic occlusions in the brain
- Carotid bifurcation
- Origin of MCA
- Either end of Basilar artery