Neuropathology III Flashcards
what are the different classifications of traumatic brain injuries (TBI)?
- Skull fracture
- Epidural/subdural/sub-arachnoid hemorrhage
- Parenchymal/intraventricular hemorrhage
- Parenchymal injury ( Contusion /lacerations)
- Diffuse Axonal Injury (DAI)
what are the common causes of secondary brain injury?
brain swelling (edema)
systemic complications (shock, hypotension etc)
what are the two ways a traumatic brain injury can occur?
direct impact
movement of brain inside the cranium
How are skull fractures classified and what are their key features?
they are classified by configuration or pattern, can be open, closed, or displaced and do not always indicate brain damage
*Communicating fractures may lead to intracranial infection
what is an epidural hematoma and where do most causes occur?
TBI that occurs due to collection of blood between the dura and the skull seen in only 2% of TBI cases
- more than 50% of them occur in the temporal parietal region
- damage to the middle meningeal artery
What causes subdural hematoma and where does the bleeding occur?
caused by rupture of bridging veins between the dura and arachnoid, leading to blood collection under the dura covering the brain surface
What are the types and mortality rate of subdural hematoma (SDH)?
can be acute, subacute, or chronic (>3 weeks); acute SDH occurs in 12–29% of severe TBI cases with a 40–60% mortality rate
Who is at greater risk for SDH and how does it present?
Elderly individuals are more at risk due to age-related cerebral atrophy, which stretches veins; SDH presents with progressive neurological signs
what is a subarachnoid hemorrhage?
61% of TBI due to rupture of cortico-meningeal vessels leading to an increase in intracranial pressure (ICP) and to acute hydrocephalus
what can cause vascular spasms in subarachnoid hemorrhages?
hemoglobin released from RBCs in the subarachnoid space
what are contusions?
bruises on the brain caused by trauma involved in damage to brain tissue (neural parenchyma) and small blood vessels, leading to localized bleeding and swelling
where do contusions mainly occur?
most common sites are the underside of the frontal and temporal lobes at the crests (tops) of gyri, unlike ischemic brain injuries which affect the depths (sulci) of the brain
What is a coup brain contusion and when does it occur?
brain injury that occurs directly under the site of impact, usually when the head is stationary and struck by an object — for example, during an assault
What is a contrecoup contusion and what causes it?
happens on the opposite side of the brain from the impact, caused when a moving head suddenly hits a surface, like in a fall or motor vehicle accident (MVA)
What are remote contusions and how do they appear?
old brain bruises that appear yellow-brown due to hemosiderin deposits in macrophages, often located in the inferior frontal and temporal lobes
What is an acute concussive injury and how often does it lead to prolonged symptoms?
mild traumatic brain injury that is usually self-limited, but 10–30% of cases can result in prolonged symptoms.
what are the symptoms of acute concussive injury ?
Loss of consciousness
Amnesia Headache
Slow reaction time
Irritability
Emotional lability
Sleep disturbance
What is Post-Concussive Syndrome (PCS)?
condition where concussion symptoms last longer than 3 months, including issues like headaches, memory problems, and fatigue.
What is Diffuse Axonal Injury (DAI) and what commonly causes it?
traumatic brain injury from shearing forces—commonly due to high-speed motor vehicle accidents—that damage white matter tracts in the brain.
What is Chronic Traumatic Encephalopathy (CTE) and how is it diagnosed?
a progressive brain condition from repeated head injuries, seen in contact sport athletes, and is only diagnosed postmortem by detecting Tau deposits in brain tissue
What are the two types of cerebral edema and how does cerebral edema appear?
- vasogenic and cytotoxic edema
- the brain shows flattened gyri, narrowed sulci, compressed ventricles, and indistinct gray-white matter junctions
What is vasogenic edema and what causes it?
most common type of cerebral edema, caused by blood-brain barrier (BBB) disruption, leading to an increase in extracellular fluid due to increased vascular permeability and impaired resorption from limited lymphatic drainage.
What is cytotoxic edema and how does it occur?
involves increased intracellular fluid due to cell membrane injury, often from hypoxia, ischemia, or metabolic disturbances
what is a herniation?
physical displacement of brain tissue from one compartment to another due to increased intracranial pressure
What is subfalcine herniation and what is its clinical consequence?
occurs when the cingulate gyrus is pushed under the falx cerebri, which can compress the anterior cerebral artery, potentially leading to infarction in that vascular territory
What is uncal herniation and how does it occur?
happens when the medial temporal lobe is displaced from the middle to the posterior fossa through the tentorial opening, potentially compressing critical structures like the oculomotor nerve (CN III) and posterior cerebral artery
What is a Duret hemorrhage and what causes it?
brainstem hemorrhage, typically located in the midbrain, caused by transtentorial herniation compressing small penetrating arteries, leading to central brainstem bleeding
What is tonsillar herniation and why is it dangerous?
Tonsillar herniation is when the cerebellar tonsils are displaced downward through the foramen magnum, compressing the medulla and potentially leading to fatal disruption of cardiac and respiratory centers
What is hydrocephalus?
accumulation of excess cerebrospinal fluid (CSF) in the brain’s ventricular system, leading to increased intracranial pressure and potential damage to brain tissues
What causes communicating (non-obstructive) hydrocephalus?
caused by impaired CSF absorption in the subarachnoid space, often due to scarring (e.g., from meningitis) or malfunctioning arachnoid granulations, despite no blockage within the ventricles
What causes non-communicating (obstructive) hydrocephalus?
caused by a physical blockage within the ventricular system (e.g., tumors, congenital malformations) that prevents CSF from flowing normally, leading to buildup upstream of the obstruction
