The Central Nervous System

Question 1

General response of neurons to injury.

Answer 1

Acute: Intense eosinophilia (red neuron); Chronic: cell loss

Question 2

General response of astrocytes and microglia to injury.

Answer 2

Astrocytes: Hyperplasia, hypertrophy; with accumulation of GFAP; Microglia: proliferation

Question 3

It is the accumulation of excess fluid within the brain parenchyma. The brain is softer than normal and often appears to “overfill” the cranial vault. In generalized edema the gyri are flattened, the intervening sulci are narrowed, and the ventricular cavities are compressed; can be vasogenic (occurs when the integrity of the normal blood-brain barrier is disrupted; with increased vascular permeability, fluid shifts from the vascular compartment into the intercellular spaces of the brain), or cytotoxic (due to an increase in intracellular fluid secondary to neuronal, glial, or endothelial cell membrane injury, as might be encountered in an individual with a generalized hypoxic/ischemic insult or with exposure to some toxins).

Answer 3

Cerebral edema

Question 4

Refers to the accumulation of CSF leading to dilation of the ventricular system; can be noncommunicating (from an obstacle or disruption of flow seen most commonly at the foramen of Monroe or aqueduct of Sylvius), or communicating (due to reduced resorption of CSF; all of the ventricular system is enlarged).

Answer 4

Hydrocephalus

Question 5

Effect of increased intracranial pressure from an increase in volume of any intracranial component; may lead to vascular compromise, infarction, additional swelling and herniation; has several types including, subfalcine, transtentorial, and tonsillar.

Answer 5

Herniation

Question 6

This leads to accumulation of blood between the dura and the skull; the expanding hematoma has a smooth inner contour that compresses the brain surface; clinically, patients may experience a lucid interval between the moment of trauma and development of neurologic symptoms; bleeding source usually arterial (from middle meningeal artery in pterion fractures); on imaging, typically shows a lentiform bleed.

Answer 6

Epidural hematoma

Question 7

This leads to accumulation of blood in the subdural space; bleeding is usually venous (from injury to bridging veins); usually observed in extremes of ages; can be chronic; on imaging, typically shows a crescent-shaped bleed.

Answer 7

Subdural hematoma

Question 8

In the setting of this condition, the brain is swollen, with wide gyri and narrowed sulci; the cut surface shows poor demarcation between gray and white matter; results from generalized reduction of cerebral perfusion, usually below systolic pressures of less than 50mmHg.

Answer 8

Global cerebral ischemia

Question 9

Neurons most sensitive to ischemia.

Answer 9

Pyramidal layer of hippocampus (CA1: Sommer sector), cerebellar Purkinje cells, pyramidal cells of cerebral cortex

Question 10

Results from cerebral artery occlusion, either thrombotic or embolic; and hemorrhagic or nonhemorrhagic; nonhemorrhagic infarcts show liquefactive necrosis of the brain parenchyma.

Answer 10

Focal cerebral ischemia

Question 11

Injury to small perforating vessels in the form of sclerosis due to hypertension; morphologically, small, cavitary infarcts (lacunes).

Answer 11

Lacunar infarcts

Question 12

Injury to small perforating vessels, in the form of rupture of small vessels due to hypertension; morphologically, tissue destruction, pigment-laden macrophages and gliosis.

Answer 12

Slit hemorrhages

Question 13

Bleeding secondary to rupture of small intraparenchymal vessel; nontraumatic; most common cause of deep parenchymal hemorrhage is hypertension; commonly affects the basal ganglia (putamen), thalamus, and pons.

Answer 13

Hypertensive intraparenchymal hemorrhage

Question 14

Intraparenchymal hemorrhage affecting the leptomeninges and cortex; due to deposition of amyloid in small to medium-sized leptomingeal and cortical vessels.

Answer 14

Cerebral amyloid angiopathy-associated intraparenchymal hemorrhage

Question 15

Patients with this type of intracranial hemorrhage complains of having “the worst headache I’ve ever had”/ thunderclap headache; the most frequent cause is rupture of saccular berry aneurysm; most common location is ACA-ACoA junction (40%).

Answer 15

Subarachnoid hemorrhage

Question 16

A vascular malformation wherein the involved vessels resemble a tangled network of wormlike vascular channels; microscopically, they are enlarged blood vessels separated by gliotic tissue, often with evidence of prior hemorrhage; common location vessels involved are of the subarachnoid space and brain.

Answer 16

Arteriovenous malformation

Question 17

Most common demyelinating disorder; characterized by distinct episodes of neurologic deficits, separated in time, attributable to white matter lesions that are separated in space; affected areas show multiple, well-circumscribed, slightly depressed, glassy, gray-tan, irregularly shaped lesions, termed “plaques”; common initial manifestation is unilateral involvement of the optic nerve (optic or retrobulbar neuritis).

Answer 17

Multiple sclerosis

Question 18

CSF findings in Multiple sclerosis.

Answer 18

Moderate pleocytosis, mildly elevated protein, increased IgG (oligoclonal)

Question 19

Clinically present with bilateral optic neuritis and spinal cord demyelination; associated with antibodies against aquaporin-4.

Answer 19

Neuromyelitis optica (NMO)

Question 20

Demyelinating disorder associated with rapid correction of hyponatremia.

Answer 20

Central pontine myelinolysis (CPM)/Osmotic demyelination syndrome (ODS)

Question 21

It is the most common cause of dementia in the older adults, characterized by presence of plaques composed of A_ amyloid, and neurofibrillary tangles composed of Tau proteins.

Answer 21

Alzheimer disease (AD)

Question 22

Loss of dopaminergic neurons in substantia nigra; triad of tremor, rigidity and bradykinesia; there are single or multiple, intracytoplasmic, eosinophilic, round to elongated inclusions that often have a dense core surrounded by a pale halo or Lewy bodies, composed of _-synuclein aggreagates.

Answer 22

Parkinson disease (PD)

Question 23

Accumulation of Lewy bodies in basal nucleus of Meynert leads to this condition:

Answer 23

Lewy body dementia

Question 24

This is the most common form of neurodegeneration affecting the motor system; characterized by muscle atrophy and hypereflexia due to loss of both upper and lower motor neurons.

Answer 24

Amytropic lateral sclerosis (ALS)

Question 25

Psychotic symptoms or ophthalmoplegia on a background of acute alcoholism; reversible with thiamine administration; morphologically, hemorrhage and necrosis of the mamillary bodies and the walls of the third and fourth ventricles

Answer 25

Wernicke syndrome

Question 26

Short-term memory disturbances and confabulation on a background of chronic alcoholism; not reversible with thiamine administration; morphologically, cystic space with hemosiderin-laden macrophages in dorsomedial nucleus of the thalamus.

Answer 26

Korsakoff syndrome

Question 27

Degeneration of posterolateral cord tracts due to abnormal myelin formation associated with Vitamin B12 deficiency; clinically, sensory disturbance and ataxia in LEs that leads to spastic paralysis and paraplegia.

Answer 27

Subacute combined degeneration

Question 28

Cytogenetic origin is astrocytes; forms include: Pilocytic (WHO I/IV) (common in children), Well-differentiated (WHO II/IV), Anaplastic (WHO III/IV) and glioblastoma (WHO IV/IV) (Note: the rest except pilocytic astrocytoma are called infiltrating astrocytomas, and are common in adults).

Answer 28

Astrocytoma

Question 29

Histologic criteria for the diagnosis of glioblastoma.

Answer 29

Necrosis and endothelial proliferation

Question 30

Cytogenetic origin is oligodendrocytes; forms include: Well-differentiated (WHO II/IV), and Anaplastic (WHO III/IV); histologically characterized by round tumor cells with cytoplasmic halos (“fried-egg appearance) supplied a by network of anastomosing capillaries with calcifications.

Answer 30

Oligodendroglioma

Question 31

Common location of this tumor is near 4th ventricle during the first two decades of life, and intraspinal in adults; cytogenetic origin is ependymal cells; tend perivascular pseudorosettes on histologic examination.

Answer 31

Ependymoma

Question 32

Often located midline in the cerebellum in children, and lateral in adults; on histology, lesion is extremely cellular with sheets of anaplastic (small blue) cells; can also form Homer-Wright rosettes; essentially a primitive neuroectodermal tumor (PNET); radiosensitive.

Answer 32

Medulloblastoma

Question 33

Most common form of primary CNS lymphoma.

Answer 33

DLBCL

Question 34

Cytogenetic origin is arachnoid meningothelial cells; varied histologic patterns include syncytial, fibroblastic, transitional, psammomatous and secretory (associated with pseudopsammoma bodies); grades include: Typical (WHO I/IV), Atypical (WHO II/IV); and Anaplastic (Malignant) (WHO III/IV).

Answer 34

Meningioma

Question 35

Sharply demarcated masses, often at the junction of gray and white matter, usually surrounded by a zone of edema; usual sources are lung, breast, skin (melanoma), kidney, and GIT, and choriocarcinomas.

Answer 35

Metastases