CH 14--Nervous System 1/Increased Intracranial Pressure, Cerebral Edema, Hydrocephalu Flashcards
A—-Central Nervous System
- Cerebral hemishperes
- Brain stem
- Cerebellum
- Spinal CORD
B—-Peripheral Nervous System
- Cranial NERVES
- Spinal NERVES
KNOW
Diseases of the nervous system
2 main groups
1—____________–Both the nervous system & other organs, as infections
2—_______–Unique conditions to the nervous system, as the diseases of the myelin and degeneration of neurones
Systemic
Localized
REACTIONS OF CNS CELLS TO INJURY Cells of the CNS 5 main groups 1-- Neurons 2-- Neuroglial cells 3-- Microglial cells 4-- Connective tissue 5-- Blood vessels
KNOW
5 Cells of the CNS
1–NEURONS
•Nerve cells = ________ cells of the nervous system
•Cytoplasmic extensions: axons and dendrites
a. The neuron is a pyramidal cell with a rounded nucleus
and prominent nucleolus. The granularity of the cytoplasm is imparted by rough endoplasmic reticulum (Nissl substance).
b. In DISEASES they undergo the following CHANGES:
–SWELLING of the neuron
–DISPLACEMENT of the nucleus to the periphery of the cell
–Intraneuronal body formation, notably the neurofibrillary
tangle
–Chromatolysis (pale cytoplasm due to the dispersal of the Nissl bodies) when the axon is injured
–Fragmentation and phagocytosis of distal portion of the
axon (WALLERIAN degeneration)
–If the axon is myelinated, the myelin sheath undergoes
fragmentation and phagocytosis. This is followed by
regeneration that may produce a PAINFUL MASS =
“__________ _____________”
basic
Traumatic Neuroma
5 Cells of the CNS
2—Neuroglial cells
Includes:
1. Oligodendroglia (oligodendrocyte)
A—-OLIGODENDROGLIA
The most vulnerable glial cells to ischemia
Present between axons in the white matter, and
around neurones in the gray matter
Produce the ______ _________ in the CNS
Pathological changes manifest as demyelinating
diseases
2. ASTROCYTE
A—Stellate cells with processes that form a _________ for the other brain cells
B—seen In:
The gray matter “protoplasmic astrocytes”
The white matter “fibrous astrocytes”
Both types have “_______-________”
(expanded foot processes) (end feet)
Part of the blood brain barrier
in case of injury produces glial fibers (cytoplasmic processes) resulting in “_______” which is similar to fibrosis in other tissues
C—ASTROCYTES
Pathological changes include:
Eosinophilic hyaline cytoplasm
Glial scars (a network of astrocytes with no collagen
formation)
myelin sheath
framework
Sucker-feet
gliosis
5 Cells of the CNS
3–MICROGLIA
Histiocytes of the CNS
Function is _____________
Pathological changes = Nuclei become elongated to form nodules around the necrotic neuron
****NOT COVERED:
4– Connective tissue
5– Blood vessels
Phagocytosis
COMMON PATHOPHYSIOLOGIC COMPLICATIONS
CNS diseases can lead to clinical complications such as:
- Increased INTRACRANIAL pressure
A—-most commonly caused by:
1 Space occupying lesions in the _______ ______; as tumors or abscesses
2 Hemorrhages
3 Brain edema
4 HYDROCEPHALUS
***Increased intracranial pressure may lead to Herniation of the brain tissue from one cranial compartment into another.
cranial cavity
COMMON PATHOPHYSIOLOGIC COMPLICATIONS
CNS diseases can lead to clinical complications such as:
- Cerebral herniation
Types: - ________________ (uncinate) herniation
- ________________ herniation
- ________________ (cingulate) herniation
TRANSTENTORIAL
Tonsillar
Subfalcine
3 TYPES OF Cerebral herniation
THE MAJOR HERNIATIONS ARE:
- Transtentorial (uncinate) Herniation
= Herniation of the medial portion of the temporal lobe (uncus) through the tentorium cerebelli
“_______ _________ __________”
A—-Manifestations
COMPRESSION of the midbrain produces loss of consciousness
COMPRESSION of the oculomotor nerve produces an
ipsilateral pupillary constriction followed by dilatation
COMPRESSION of the Aqueduct of Sylvius leading to
hydrocephalus, which results in further increase in the
intracranial pressure and further Herniation.
Tentorial Pressure Cone
3 TYPES OF Cerebral herniation
- Tonsillar Herniation
A–Herniation of the cerebellar tonsils through the _________ _________
B–________ ________ due to the compression of the medulla oblongata and the respiratory center
foremen Magnum
Sudden death
3 TYPES OF Cerebral herniation
- Subfalcine (cingulate) Herniation
A–Herniation of the cingulate gyrus under the falx cerebri tothe opposite side
B–May cause__________ of the anterior cerebral artery
rupture
COMMON PATHOPHYSIOLOGIC COMPLICATIONS
- Cerebral edema
Features:
Brain is sensitive to small volume changes:
1. absence of lymphatics
2. surrounded by bony skull
KNOW
COMMON PATHOPHYSIOLOGIC COMPLICATIONS
- Cerebral edema
2 Types:
1 - _______ edema: Extracellular accumulation of fluid due to its leakage across damaged wall (necrotic)
2. _________ edema: Intracellular accumulation of fluid e.g. ischemia, toxin = impair cell wall function.
Vasogenic
Cytotoxic
COMMON PATHOPHYSIOLOGIC COMPLICATIONS
CNS diseases can lead to clinical complications such as:
Hydrocephalus
Definition: Excessive accumulation of _____ leading to
dilatation of the ventricles
CSF
COMMON PATHOPHYSIOLOGIC COMPLICATIONS
CNS diseases can lead to clinical complications such as:
Hydrocephalus
- NON-communicating (obstructive!!):
CSF can NOT reach ________ due to OBSTRUCTION
in ventricular system:
A * Congenital:
- stenosis of aqueduct of Sylvius
- Arnold-Chiari malformation + displacement
of cerebellar tonsil into cervical canal
B * Inflammation:
- meningitis
- cerebral abscess
C * Tumors:
- ependymoma
- medulloblastoma
D * Intracranial hemmorrhage
——————————————————————– - COMMUNICATION hydrocephalus:
CSF passes normally out of _________.
The block is IN the subarachnoid space
Either:
i. INCREASE CSF production (tumors of choroid plexus)
ii. DECREASE CSF absorption (dural sinus thrombosis)
subarachnoid
ventricles
