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
- Diverticulum of a malformed brain tissue through a defect in the cranium
- Usually in the posterior fossa
- Can occur across cribriform plate in anterior fossa
Encephalocele
Asymptomatic bony defect (spina bifida occulta) to a severe malformation with a flattened disorganized spinal cord segment associated with an overlying meningeal outpouching
Spina bifida
Small brain; associated with chromosome abnormalities, fetal alcohol syndrome, and viral infection acquired in utero (HIV-1)
Microencephaly
Large brain
Megalencephaly
Decreased number of gyri
Lissencephaly
Complete absence of gyri
Agyria
numerous small, irregularly formed cerebral convolutions
Polymicrogyria
abnormal clusters of neurons in inappropriate locations along normal migratory routes; they are commonly associated with epilepsy
Neuronal heterotopias
incomplete separation of the cerebral hemispheres; associated with midline facial abnormalities (cyclopia)
Holoprosencephaly
absent white matter bundles
Agenesis of the corpus callosum
small posterior fossa with misshapen cerebellar tonsils
which shows Hydrocephalus; lumbar myelomeningocele
C
low-lying cerebellar tonsils extending into the vertebral canal
which is Clinically silent or present with CSF flow obstruction
Chiari type I malformation
enlarged posterior fossa; absent cerebellar vermis; cystic dilatation of the 4th ventricle
which shows Brainstem nuclei dysplasias
Dandy-Walker malformation
- Hypoplasia of cerebellar vermis with misshapen brainstem
- “molar tooth sign” on imaging
Joubert syndrome
Nonprogressive neurologic motor deficits (dystonia, spasticity, ataxia/athetosis, paresis) occurring during prenatal and perinatal periods
Cerebral palsy
occurs between the thalamus and caudate nucleus; may remain small and localized or can extend into the ventricular system
Germinal matrix haemorrhage
supratentorial periventricular white matter ischemic infarcts
Periventricular leukomalacia
cystic lesions throughout cerebral hemispheres in extensive ischemic damage; involves both gray and white matter
Multicystic encephalopathy
mushroom-shaped gyri with thinned-out, gliotic stalks
Ulegyria
ischemic neuronal loss and gliosis in the basal ganglia and thalamus associated with aberrant and irregular myelin formation
Status marmoratus
- displaced skull fracture: fracture in which bone is displaced into the cranial cavity by a distance greater than the thickness of the bone
- Accidental falls tend to involve the occiput
- Trauma occurring as a consequence of syncope tends to involve the frontal skull
Trauma: Skull Fracture
clinical syndrome of altered consciousness secondary to head injury
CONCUSSION
old traumatic lesions present as depressed, retracted, yellowish brown patches involving the ___
crests of gyri (plaque jaune)
Findings: axonal swelling
About half of patients who develop coma shortly post-trauma
DIFFUSE AXONAL INJURY
- Usually associated with skull fracture (in adults)
- accumulation of arterial blood between the dura and the skull
- rapidly evolving neurologic symptoms (often after a short lucid period) that require intervention
EPIDURAL HEMATOMA
- May follow minor trauma
- accumulation of venous blood between the dura and the arachnoid
- slowly evolving neurologic symptoms, often with a delay from the time of injury
SUBDURAL HEMATOMA
Spinal Cord Injury: with lesions at C4 and above, respiratory compromise due to diaphragm paralysis
Cervical vertebrae: quadriplegia
Thoracic vertebrae or below Spinal Cord injury
paraplegia
