Jim Exam 4 Neuropathology

Corpus callosum

What is this structure?

Caudate

What is this structure?

Putamen

What is this structure?

Amydgala

What is this structure?

Globus pallidus

What is this structure?

Hippocampus

What is this structure?

Mammillary bodies

What are these structures?

Corpus callosum

What is this structure?

Midbrain

What is this structure?

Pons

What structure is this?

Medulla

What structure is this?

Cerebellum

What structure is this?

4th Ventricle

What structure is this?

Corpus collosum

What structure is a large, thick band of nerve fibers that connects the two hemispheres of the brain?

Hippocampus

What is a crucial part of the limbic system located in the temporal lobe and functions in short-term and long-term memory?

Mamillary bodies

What are the paired brainstem nuclei on the posteroinferior aspect of the hypothalamus that play a role in memory recollection?

Basal ganglia

What is the group of nuclei in the central area of the brain that receives input from the cortex and functions to control conscious and proprioceptive movements?

Cerebellar Purkinje cells

What is the unique population of neurons in the cerebellum that function in regulating and coordinating motor movements?

Complete or partial absence of the corpus callosum

What is agenesis of the corpus callosum?

Yes, anterior commissure can assume interhemispheric tasks due to plasticity

Can agenesis of the corpus callosum be asymptomatic and why?

It is displaced downward

What happens to the cingulate gyrus in callosal agenesis?

Increased volume of cerebrospinal fluid within the ventricular system

What is hydrocephalus?

In the ventricles, not the brain parenchyma (fluid in the parenchyma is cerebral edema

Where is the excess fluid in hydrocephalus located?

Headache, behavioral change, lethargy, delayed development

What are common clinical signs of hydrocephalus?

Ventricular dilation upstream from a blockage of CSF outflow

What is noncommunicating hydrocephalus?

Congenital malformations, tumors, or certain infections

What causes noncommunicating hydrocephalus?

CSF accumulation from impaired absorption or excess production affecting all ventricles

What is communicating hydrocephalus?

Ventricular enlargement secondary to loss of brain parenchyma from atrophy

What is hydrocephalus ex vacuo?

Accumulation of fluid within the brain parenchyma

What is cerebral edema?

Inflammation, ischemia, toxic injury, or space-filling lesions like tumors

What are typical causes of cerebral edema?

Increased vascular permeability

What drives cerebral edema formation at the vascular level?

Swollen flattened gyri, narrowed sulci, compressed ventricles

What are gross features of generalized cerebral edema?

Brain herniation

What is a major risk of severe cerebral edema?

Subfalcine herniation

What kind of herniation is this?

Transtentorial herniation

What kind of herniation is this?

Tonsillar herniation

What kind of herniation is this?

Cingulate gyrus pushed under the falx due to unilateral hemispheric expansion

What is subfalcine herniation?

Anterior cerebral artery

Which artery can be compressed in subfalcine herniation?

Medial temporal lobe forced against the tentorial edge

What is transtentorial (uncal) herniation?

Oculomotor nerve (CN III) with ipsilateral blown pupil due to impaired ocular reflexes

Which cranial nerve is compressed in transtentorial/uncal herniation and what is the sign?

Posterior cerebral artery causing ischemia of primary visual cortex

Which artery may be compressed in transtentorial/ uncal herniation and what results?

Compression of the contralateral cerebral peduncle against the tentorium

How can uncal herniation produce ipsilateral hemiparesis?

Loss of consciousness

What can occur when the brainstem is compressed in transtentorial herniation?

Duret hemorrhages

With which hemorrhage is transtentorial/uncal herniation classically associated?

Linear or flame-shaped hemorrhages in midbrain and pons from downward displacement in uncal herniation

What is a Duret hemorrhage?

Tearing of basilar artery branches entering the pons along the midline

What vessel disruption underlies Duret hemorrhage?

Poor, indicating severe brainstem injury

What is the prognosis with Duret hemorrhages?

Altered consciousness, respiratory irregularities, autonomic instability

What symptoms suggest brainstem involvement in Duret hemorrhage?

Cerebellar tonsils displaced through the foramen magnum

What is tonsillar herniation?

Brainstem compression causing respiratory and cardiac failure

What are life-threatening consequences of tonsillar herniation?

1) Trauma with contusions

2) Hemorrhagic transformation of ischemic infarct

3) Cerebral amyloid angiopathy

4) Hypertension

5) Tumors (primary or metastatic)

What are common etiologies of intraparenchymal hemorrhage?

Selective involvement of gyri

What are the features of intraparenchymal hemorrhage due to trauma (contusions)?

Petechial hemorrhages in a previously ischemic territory due to reperfusion injury

What are the features of intraparenchymal hemorrhage due to ischemia (hemorrhagic conversion of ischemic infarct)?

Lobar hemorrhages involving subcortical white matter with possible extension into subarachnoid space

Due to amyloid deposition making vessel walls fragile

What are the features of intraparenchymal hemorrhage due to cerebral amyloid angiopathy?

Hemorrhage is centered in the deep white matter, thalamus, basal ganglia, brainstem with possible intraventricular extension

What are the features of intraparenchymal hemorrhage due to hypertension?

Minute aneurysms / microaneurysms in the brain that occur in small penetrating vessels that can rupture and cause intraparenchymal hemorrhage

What are Charcot-Bouchard aneurysms?

High-grade gliomas and certain metastases

Which tumors commonly bleed within brain parenchyma?

1) Acute hypertensive encephalopathy

2) Intraparenchymal/lobar hemorrhage

3) Arteriosclerosis

4) Charcot-Bouchard aneurysms

5) Rupture of berry aneurysms

6) Lacunar infarcts

7) Predilection for vessels involving the basal ganglia

8) Atherosclerosis

9) Subarachnoid hemorrhage

10) Cerebral edema

11) Petechiae and necrosis of arterioles in the gray and white matter

List CNS findings associated with systemic hypertension

Trauma or rupture of vascular abnormalities such as saccular aneurysm or AVM

What are common causes of subarachnoid hemorrhage?

Sudden severe headache ("thunderclap

headache) and rapid neurologic decline with risk of vasospasm from blood in CSF

What clinical presentation suggests aneurysmal subarachnoid hemorrhage?

Venous bleeding from torn bridging veins often after minor trauma with slow progression

What is the usual mechanism of subdural hematoma?

Early clot draws in water and enlarges into a mass-like lesion

Why can a subdural hematoma enlarge over time?

Laceration of the middle meningeal artery associated with skull fracture (usually due to trauma)

What causes an epidural hematoma?

Brief lucid interval followed by rapidly evolving neurologic deterioration

What is the classic course of an epidural hematoma?

Amyloid-β derived from APP proteolysis

What amyloid species is usually deposited in cerebral amyloid angiopathy (CAA)?

Cortical and leptomeningeal vessels

Which vessels are primarily involved in CAA?

CAA is cortical and leptomeningeal whereas arteriosclerosis predominates in deep structures like basal ganglia

How does CAA differ from hypertensive arteriosclerosis in distribution?

Makes vessel walls rigid and fragile increasing hemorrhage risk

How does amyloid deposition affect vessel integrity in CAA?

Lobar hemorrhages and microhemorrhages in cortex

What hemorrhage pattern is typical of CAA?

Congo red with apple-green birefringence under polarized light

What stain highlights amyloid in CAA?

Hemorrhagic parenchymal injury with edema from rapid tissue displacement

What is a cerebral contusion?

Orbitofrontal surfaces and temporal tips over rough skull base

Where are contusions most common and why?

Contusion at the site of head impact

What is a coup injury?

Contusion opposite the site of impact due to rebound

What is a contrecoup injury?

Wedge-shaped reddish purple lesion widest at point of impact

What are gross features of an acute contusion?

Neuronal injury and hemorrhage

What are microscopic features of an acute contusion?

Yellow brown discoloration from hemosiderin with firmer tissue due to fibrosis

What are gross features of a remote contusion?

Hemosiderin deposition with neuronal loss and chronic inflammation with lymphocytes and macrophages

What are microscopic features of a remote contusion?

Eye opening verbal response and motor response

What does the Glasgow Coma Scale assess?

Upper midbrain damage with flexed arms and extended legs

What does decorticate posturing indicate anatomically?

Upper pontine damage with extended rigid arms and legs

What does decerebrate posturing indicate anatomically?

Widespread white matter tract injury from shearing between brain regions

What is diffuse axonal injury?

Coma due to widespread disconnection

What is a clinical consequence of diffuse axonal injury?

Small cavitary infarct due to occlusion of a single penetrating artery

What is a lacunar infarct?

Basal ganglia, thalamus, internal capsule, deep white matter, and pons

Where do lacunar infarcts most commonly occur?

Yes they can be clinically silent or produce focal deficits

Can lacunar infarcts be asymptomatic?

Global brain dysfunction from malignant hypertension with raised intracranial pressure

What is acute hypertensive encephalopathy?

Headache confusion vomiting seizures and possible coma

What are clinical features of acute hypertensive encephalopathy?

Embolism thrombosis and global ischemia

What are the main mechanisms leading to cerebral infarct?

Post-MI mural thrombus, atrial fibrillation, and valvular disease

What are common cardiac sources of cerebral emboli?

Via paradoxical embolism through a right-to-left shunt

How can a DVT cause a brain embolus?

Middle cerebral artery

Which artery is most frequently occluded by emboli?

Carotid bifurcation, origin of MCA, and ends of basilar artery

Where do thrombotic occlusions most often form in the cerebrovasculature?

Severe hypotension in cardiac arrest or shock

What causes global cerebral ischemia without focal occlusion?

Infarct in border-zone regions most distal to arterial supply during global hypoperfusion

What is a watershed infarct?

Red neurons with cytoplasmic eosinophilia and edema followed by neutrophil infiltration

What are early histologic changes after acute infarct?

Liquefactive necrosis resolving to a cystic cavity with macrophage cleanup

What is the end stage of infarct evolution after weeks?

Penetrating arterioles develop atherosclerosis and occlude

How does hypertension lead to lacunar infarcts pathologically?

Sensory disturbances

What deficits can lacunar infarcts in the thalamus cause?

Internal capsule

What deep white matter tract is critical for motor and sensory transmission, and is often affected by lacunar infarcts?