CNS Flashcards
- shrinkage of cell body
- ## pyknosis of the nucleusdisappearance of the nucleolus
- loss of Nissl substance,
intense cytoplasmic eosinophilia
Acute injury: “Red Neurons”
Loss of synapses → cell death and reactive gliosis
SUBACUTE AND CHRONIC INJURY: “DEGENERATION”
hypertrophy and hyperplasia response to injury
ASTROCYTES
- proliferate
- develop elongated nuclei
- form aggregates around small foci of tissue necrosis (microglial nodules)
- congregate around cell bodies of dying neurons (neuronophagia)
MICROGLIA
Excess fluid accumulation in the brain parenchyma
Cerebral edema
Pathyway of Cerebral edema
in which there is an↑ in ECF and vascular permeability → ↑ intercellular fluid
Conditions include:
Localized: adjacent to inflammation and neoplasm
Generalized: global ischemic injury
Vasogenic
- Excess fluid accumulation in the ventricular system
- Mostly due to impaired flow and resorption of CSF
- Rarely due to CSF overproduction secondary to tumors
- Increased volume of CSF expands the ventricles and can elevate the intracranial pressure
- When hydrocephalus occurs before cranial suture closure, the head is enlarged; hydrocephalus after bone fusion leads to ventricular expansion and increased intracranial pressure without a change in head circumference
Hydrocephalus
Pathway of Cerebral Edema in which there is ↑ intracellular fluid due to cell membrane injury
Conditions include:
Generalized hypoxic ischemic injury
Metabolic derangement
CYTOTOXIC
A focally obstruted ventricular system that is caused from mass in the 3rd ventricle and aqueductal stenosis
NON-COMMUNICATING
(OBSTRUCTIVE) HYDROCEPHALUS
It is a ventricular system communicate with subarachnoid space and enlargement of entire ventricular system that si caused from CSF overproduction due to choroid plexus tumor and arachnoid fibrosis due to minigitis
COMMUNICATING HYDROCEPHALUS
There is an↑ CSF as compensation to decreased parenchymal mass
HYDROCEPHALUS EX VACUO
Displacement of brain tissue past rigid dural folds (the falx and tentorium) or through openings in the skull because of increased intracranial pressure
Herniation
↑ intracranial ____ → ↑ intracranial ____ → herniation
- volume
- pressure
The herniating part is cingulate gyrus and the hernation is under the falx cerebri. The compressed structures are the anterior cerebral artery and branches which produces secondary infarcts (focal neurologic deficits)
SUBFALCINE (CINGULATE) HERNIATION
The herniating part is medial aspect of temporal lobe and the hernation is across tentorium cerebelli. The compressed structures are the CN III; posterior cerebral artery; contralateral cerebral peduncle which produces CN III: Pupillary dilation; posterior cerebral artery: territorial infrct; contralateral cerebral peduncle: hemiparesis ipsilateral to lesion; and Duret hemorrhages.
TRANSTENTORIAL HERNIATION
The herniating part is cerebellar tonsils and the hernation is through foramen magnum. The compressed structure is the brainstem which produces cardiac and respiratory depression
TONSILLAR HERNIATION
- Failure of the closure of anterior neural tube
- Absence of most of brain and calvarium
- Area cerebrovasculosa: flattened remnant of disorganized brain tissue
Anencephaly
- Extension of the spinal cord and meninges through a defect in vertebral column
- Meningocele: meninges only
Myelomeningocele