CNS Infections Flashcards
What composes the CNS?
Brain, Spinal Cord
Function of CNS?
master controller and coordinator of almost
all bodily functions
What encloses the brain?
cranial meninges
(membranous covering) and neurocranium (bony
case)
3 parts of the brain?
cerebrum,
cerebellum, and the brain stem
What is the cerebrum?
Main brain parenchyma
What composes the meninges?
Calvaria and duria
Parts of cerebral cortex observed when meninges are removed?
Gyri, sulci, fissures
Differentiate gyri, sulci, fissures
Gyri (folds), sulci (grooves), fissures (clefs)
membranous coverings of the
brain that lie internal to the cranium
cranial meninges
Three membranous connective tissues of meninges (describe).
1) Dura matter/dura: outermost layer; tough,
thick, external fibrous layer
2) Arachnoid matter: middle layer; thin and
intermediate
3) Pia mater/pia: innermost layer; delicate
internal vasculated layer
Name for arachnoid and pia mater (and why)
Leptomeninges (associated together)
Separates pia mater from arachnoid mater
Subarachnoid space
What is contained in subarachnoid space?
CSF
clear liquid, similar to blood plasma in
constitution
CSF
CSF function
provides nutrients, but it has less
protein and a different ion concentration as
compared to the blood plasma
Separates cerebral hemispheres; within longitudinal fissure
Falx cerebri
What is falx cerebri?
continuation of the dura
mater, lying within the great longitudinal fissure
Divided into different lobes with different functions
Cerebrum
When cerebrum lobe functions
are disrupted, they are ___.
correlated to the location of
a corresponding neurological deficit at the brain
clear liquid that fills the subarachnoid space of the central nervous system; Continuously generated and reabsorbed
CSF
Production of CSF made in ___.
choroid plexus and
ependymal cells in the ventricles of the brain
Amount of CSF produced
400 to 500 mL/day
Contains choroid plexus
Ventricles
Site of CSF reabsorption
arachnoid villi
Functions of CSF
Provides buoyant force
■ CSF surrounds the brain
■ It dissipates a lot of downward force that
would normally act on the organ → hence it reduces the stress on the brain and allows for it to maintain its shape
○ Protects the brain from damage secondary to sudden head movement → acts as a cushion and shock absorber
○ Regulates intracranial pressure
○ Clears CNS metabolites → since CSF is circulated, traveling through the different ventricles of the brain
Cells in CNS? (NGMAO)
Neurons, Glial cells (Oligoendrocytes, Astrocytes, Microglia)
function as tissue macrophages within the
CNS; resident dendritic cells in the CNS
Microglia
Structures for protection of brain (NMBB)
Neurocranium, Meningeal barrier, Blood-brain barrier, Blood-CSF barrier
One of most important sites for the control of the CNS microenvironment in homeostasis
Blood-Brain Barrier
Blood-Brain Barrier composed of?
endothelial cells of the blood
vessels
Location of endothelial cells?
inline or near the astrocytes, neurons, and pericytes
How is pathogen penetration prevented in BBB
mechanical separation by the presence of specialized endothelial cells tightly attached to each other
Mortality in CNS infections?
100%
Mortality depends on what?
Agent, age, immune status of individual
Tropism or preponderance
in invading neural tissue
neurotropism
CNS infections categorized according to?
location
CNS Infections (MERMBFR):
Meningitis, Encephalitis, Rhomboencephalitis, Myelitis, Brain Abscess, Focal Lesions, Radiculitis
localized
infection; associated with
immunocompromised individuals
Focal lesions and brain abscess
Locations of brain abscess:
Directly on brain parenchyma; depending on location with regards to dura
intracranial focal collection of
purulent material located between
the dura mater and arachnoid
matter
Subdural empyema/abscess
intracranial focal collection of
purulent material located between the
cranium and the dura
Epidural abscess
Inflammation of the brain parenchyma
Encephalitis
Clinical manifestations of Encephalitis (ADLPUSFFHNV)
○ Altered mental status (decreased level of
consciousness, lethargy, personality change,
unusual behavior) lasting at least 24 hours,
○ Seizures, and/or
○ Focal neurologic signs,
○ Fever, headache, nausea, and vomiting
Inflammation of the meninges
Meningitis
Clinical Manifestations of Meningitis (FHNVPS)
○ Fever
○ Headache
○ Nausea
○ Vomiting
○ Photophobia
○ Stiff neck aka nuchal rigidity
Difference of meningitis vs encephalitis
Non altered sensorium
Brainstem encephalitis
Rhomboencephalitis
Clinical Manifestations of rhomboencephalitis (MTACRSC)
(mainly involved with balance
and respiratory functions)
○ Myoclonic jerks, tremor, ataxia, cranial nerve
involvement, respiratory abnormalities, shock,
and coma
Inflammation of the spinal cord
Myelitis
Clinical Manifestation of Myelitis (WBFR)
Weakness, bladder dysfunction, flaccid
paralysis, and reduced or absent reflexes
Inflammation of the nerve roots
Radiculitis
Clinical Manifestations of Radiculitis (WSDD)
Weakness, shooting pain, dysesthesia, and
diminished reflexes
Why is diagnosis of CNS based on diagnostic tests?
A lot of pathogens infect different parts of CNS
