Week 0: PATHOLOGY [part 1] Flashcards
occurs when the medial aspect of the temporal lobe is compressed against the free margin of the tentorium.
Transtentorial (uncinate, mesial temporal) Herniation
When the extent of herniation is large
enough the contralateral cerebral peduncle may be compressed,
resulting in hemiparesis ipsilateral to the side
of the herniation; the compression in the peduncle in
this setting is known as the
Kernohan Notch
Progression
of transtentorial herniation is often accompanied by secondary
hemorrhagic lesions in the midbrain and pons,
termed
Duret Hemorrhages
accumulation of excess fluid within
the brain parenchyma.
Cerebral edema
is an increase in
CSF volume within all or part of the ventricular system
Hydrocephalus
severe malformation
with a flattened, disorganized segment of
spinal cord, associated with an overlying meningeal
outpouching.
Spinal dysraphism or spina bifida
spinal dysraphism that is asymptomatic bony defect
spina bifida occulta
extension
of CNS tissue through a defect in the vertebral
column
myelomeningocele
applies when there is only
a meningeal extrusion
meningocele
refers to a diverticulum of malformed
brain tissue extending through a defect in the cranium.
encephalocele
overall recurrence rate for a neural tube defect
in subsequent pregnancies has been estimated at
4 to 5 percent
malformation of the anterior end of the
neural tube, with absence of most of the brain and calvarium.
anencephaly
flattened remnant of disorganized
brain tissue with admixed ependyma, choroid
plexus, and meningothelial cells
area cerebrovasculosa
The absence of cortical gyri defines this abnormality,
lissencephaly
characterized by small, unusually
numerous, irregularly formed cerebral convolutions.
polymicrogyria
a spectrum of malformations characterized
by incomplete separation of the cerebral hemispheres
across the midline.
holoprosencephaly
Holoprosencephaly is
associated with ____________ as well as other genetic syndromes.
trisomy 13
absence of the white matter
bundles that carry cortical projections from one hemisphere
to the other
agenesis of the corpus callosum
bat wing deformity on radiologic imaging
misshapen lateral ventricles d/t agenesis of the corpus callosum
consists of a small posterior fossa, a misshapen midline
cerebellum with downward extension of vermis through
the foramen magnum (Fig. 28-7), and, almost invariably,
hydrocephalus and a lumbar myelomeningocele
Arnold-Chiari malformation (Chiari type II malformation)
less severe disorder in
which low-lying cerebellar tonsils extend down into the
vertebral canal
Chiari type I malformation
characterized by an enlarged
posterior fossa. The cerebellar vermis is absent or present
only in rudimentary form in its anterior portion
Dandy Walker Malformation
hypoplasia
of the cerebellar vermis with apparent elongation
of the superior cerebellar peduncles and an altered
shape of the brainstem;
Joubert’s Syndrome
Molar Tooth sign on imaging
Joubert’s syndrome
characterized by expansion of the
ependyma-lined central canal of the cord
Hydromyelia
formation of a fluid-filled cleft-like cavity in the
inner portion of the cord
Syringomyelia
formation of a fluid-filled cleft-like cavity in the
inner portion of the cord that extends to the brainstem
Syringobulbia
histologic appearance is destruction of the adjacent gray and white matter,
surrounded by a dense feltwork of reactive gliosis
neurologic malformations in general
Infarcts may occur in the supratentorial periventricular
white matter
perventricular leukomalacia
The principal functional unit of the central nervous system
CNS
Neuron
Neurons requires a continuous supply of ___ and _____ for its metabolic needs
glucose and oxygen
spectrum
of changes that accompany acute CNS hypoxia/ischemia or
other acute insults and reflect the earliest morphologic markers
of neuronal cell death (
acute neuronal injury/ red neurons
morphologic patterns of red neurons
enlargement of the cell body, pyknosis of the nucleus, disappearance of the
nucleolus, and loss of Nissl substance, with intense eosinophilia
of the cytoplasm.
axonal reaction to injury is manifested by
enlargement and
rounding up of the cell body, peripheral displacement of the
nucleus, enlargement of the nucleolus, and dispersion of Nissl
substance from the center to the periphery of the cell (central
chromatolysis).
may occur as a manifestation of
aging, when there are intracytoplasmic accumulations complex lipids (lipofuscin), proteins, or carbs
neuronal inclusions
Abnormal intranuclear inclusion seen in herpetic infection
Cowdry body
Abnormal intranuclear inclusion seen in rabies infection
Negri body
most important histopathologic indicator of
CNS injury, regardless of etiology
Gliosis
These cells have multipolar, branching cytoplasmic pro
cesses
that emanate from the cell body and contain glial
fibrillary acidic protein (GFAP),
Astrocytes
they contribute to barrier functions controlling the flow of macro
molecules
between the blood, the cerebrospinal fluid (CSF) and the brain
Astrocytes
are thick, elongated,
brightly eosinophilic, irregular structures that occur
within astrocytic processes, and contain two heat-shock
proteins (αB-crystallin and hsp27) as well as ubiquitin
Rosenthal fibers
are mesoderm-derived phagocytic cells that
serve as the resident macrophages of the CNS.
Microglia
the ciliated columnar epithelial cells
lining the ventricles
ependymal cells
an increase in intracellular fluid secondary
to neuronal, glial, or endothelial cell membrane
injury, as might be encountered in someone with a generalized
hypoxic/ischemic insult or with a metabolic
derangement that prevents maintenance of the normal
membrane ionic gradient
Cytotoxic edema
occurs especially
around the lateral ventricles when an increase in intravascular
pressure causes an abnormal flow of fluid from the
intraventricular CSF across the ependymal lining to the
periventricular white matter.
Interstitial Edema (hydrocephalic edema)
if the ventricular system is obstructed and does not
communicate with the subarachnoid space, as may occur
because of a mass in the third ventricle, it is called
non communicating or obstructive hydrocephalus
ventricular system is in communication
with the subarachnoid space, and there is enlargement of
the entire ventricular system.
Communicating Hydrocephalus
compensatory increase in ventricular
volume secondary to a loss of brain parenchyma.
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
occurs when unilateral or assymetric expansion of a cerebral hemisphere displaces the cingulate gyrus under the falx
Subfalcine (cingulate) herniation
