Head and Neck - Lec 5
what are the 3 causes/mechanisms of intracranial pressure
1. blockage of CSF in subarachnoid space 2. blood build up in other meningeal spaces (epidural,arachnoid,pia) 3. infection/inflammation of CSF
what 3 things does obstructive hydropcephalus cause
1. build up of CSF 2. increased volume in cranium 3. increased intracranial pressure
how can a meningioma cause morbidity
1. compress cranial contents 2. invade orbit cavity 3. compress dural venous sinus
what is in BSCB
1. endothelial cells with tight junctions 2.pericytes 3.astrocyte end feet 4.basal membrane
components of blood csf barrier
1. epithelial cells w/tight junction
what are the 3 components of the uvea
1. iris 2. ciliary body 3.choroid
what are the 2 components of the blood aqueous barrier
1. iris (endo) 2. ciliary body (epi)
if there is an uninterrupted aneurysm of posterior communicating artery, symptoms?
1. pain-CN 5 2. dilated pupil- CN 3 3. diplopia- CN 3 4. ptosis
where are the 2 barriers of blood csf barrier
1. physical (tight junctions & choroid epith) 2. enzymatic barrier (mechanisms)
what is terson's syndrom
1. pre-retinal hemorrhage 2. papilledema (bilateral) 3. intracranial hemorrhage
components of BBB
1.endothelial with tight junction 2.end feet of astrocytes 3.pericytes 4. basal membrane
how many barriers in BRB, what are they
2, inner and outer
what % of people die if not treated in 48 hours
20!
what CN is involved with posterior communicating artery
3
the headache is involved with what CN
5
what CN is involved w/ increased intracranial pressure
6
what is blood spinal cord barrier similar to and why
BBB both in CNS
herination of temporal lobe (uncus) over free edge tentorium compresses what nerve
CN3
if there is an uninterrupted aneurysm of posterior communicating artery, what nerve affected
CN3
what is double vision of subarachnoid caused by
CN3 if compressed by aneurysm of posterior communicating artery CN6 if compressed by pressure
if bleeding in trauma what kind of scan
CT scan
where does lumbar puncture need to happen
L3-L4 (subarachnoid space)
blood clot
MRI
if tumor block CSF what scan
MRI
any increased intracranial pressure can cause
RAS, compression of reticular activating system
what is idiopathic intracranial hypertension
a disease/cause which is unknown why
what is a meningioma
a tumor of the meninges
where do meningiomas typically trail/ can be found
along dura, dural tail
epidural hematoma can be fatal in how long
an hour
how is a subarachnoid hematom/hemmorhage caused
aneurysm
when orbital cavity is the main site of a meningioma where does it arise from
arachnoid
what kind of blood is a subarachnoid hematom/hemmorhage
arterial
what kind of blood is in an epidural hematoma/hemmorhage
arterial
what is reticular formation
awakened/conscious
aside from the optic disc being pushed foward papilledema is also caused by
axoplasmic stasis and extrusion from the cell membrane
where are tight junctions in BBB
between endothelial and capillaries
hemmorage
bleeding
subarachanoid is due to
bleeding of ruptured aneurysm
where is a epidural hematoma
bleeding on top of dura (between dura and skull)
what is a venous sinus thrombosis
bloot clot in DVS,
what does meningitis result in
breakdown of CSF barrier/ infection into CSF
what is the job of external cortical veins
bring venous blood to dural venous sinus
at what level is BBB found
capillary
what level is blood csf barrier
capillary
where is epidural hematomas mainly seen
children
where is CSF made
choroid plexus
BCSFB occurs at
choroid plexus epithelium
what produces epithelium
ciliary body epithelium
is a ventricle is compressed it causes
compression of CSF and obstructive hydrocephalus
what is RAS in charge of
consciousness
parasympathetic cause pupils to
constrict
overtime with compression of CNIII
damaged parasym so not dilating and droopy lid
if you have epidural hematoma would the pupil be dilated or constricted
dilated
so if parasympathetic isn't working due to compression from epidural hematoma
dilated pupils
compression of CN3 causes
dilation of pupil
where is RAS
dorsal brainstem
what does venous sinus thrombosis block
drainage of venous blood and CSF
what type of cells does BBB have
endothelial cells
what comprises inner BRB
endothelium w/ TJ, pericyte,astrocyte
which 2 hematomas cause CN3 palsy
epidural and subarach (but they are different)
if you seen a midline shift what does that mean
epidural hematoma
what comprises outer BRB
epith w/ TJ
where are tight junctions in BCSFB
epithelial and choroid plexus
where do you find epithelial
external surface of bodies and internal organs
what is the dural fold of a meninge
falx cerebri
is a epidural hematoma/hemmorhage fast or slow bleeding
fast
aqueous is where
fluid in the anterior chamber
where does middle meningeal artery enter skull
foramen spinosum
damage to internal cortical bridges leads where
great vein of galen
what are the possible symptoms of intracranial pressure
headaches, vomiting, nausea, pulsing sound, double vision because of increased cranial pressure
where are the dural venous sinuses
in dural fold of meninges of falx cerebri
how are they different?
in epidural (pterion hit, middle meningeal damage, midline shift, uncus,brainstem moves, parasym affected, CN3 impacted) but in subarach (due to aneurysm, PCOM affected)
is dural venous sinus is blocked what happens
increase in pressure and increase in CSF
if we see optic disc margins and axoplasmic stasis what does it sugggest
increased intracranial pressure and papilldema
what is meningitis
inflammation of meninges
where do you find endothelial cells
inside blood vessels
where is CSF produced (ventricles)
lateral, 3, and 4
where is choroid plexus present in (ventricles?)
lateral,3 and 4
if you have a subdural hematoma and headache that is due to
meningeal irritation of CN 5
what is the most important symptom of meningitis
neck stiffness
do every brain tumor cause increased brain pressure
no
does a unruptured aneurysm cause papildema
no
does every meningioma cause increased cranial pressure
no
does pituitary tumor cause increased pressure , or compress CSF
no
is subdural a real space usually
no
would damage to internal cortical bridges cause a subdural hematoma
no
can the subdural hematoma cross the midline , why
no dural fold
function of BBB
not allow solutes from blood to cross into fluid of CNS; prevent toxins from entering the brain
who does subdural hematoma typically occur in
older adults/ people on blood thinners
where is CSF located concerning the eyes
optic nerve sheath
meninges surround the optic nerve so we can have a
optic nerve sheath meningioma
what is an important eye finding of increased brain pressure
papilledema
what can cross BBB
passive diffusion/ selective transport (glucose, water,AAs)
what cannot cross BBB
pathogens, solutes in the blood, hydrophilic molecules into CSF
choroid plexus is highly vascularized
pia
where is CSF produces in vascularized....
pia/ choroid plexus
hematoma
pool of blood
where does middle meningeal artery become encased
pterion
where is middle meningeal artery encased on the external skull
pterion
where is outer BRB
retinal pigment epithelium
what does increased intracranial pressure mean
rise in pressure, inside the skull
what does a subdural hematoma usually result from
rupture of extern cortical bridging veins
what are hematomas or hemorrhages caused b
ruptured blood vessels
what symptoms does subdural hematoma have
same as epidural just slower
what are the symptoms of this
same as others
what happens if there is a ruptured aneurysm of posterior communicating artery
same things as above AND subarachnoid hemorrhage (papilldema)
how is blood CSF barrier similar to BBBB
selective diffusion, remove, prevent
blood csf barrier function
separate blood from getting into CSF
what if you see a child/infant with subdural hematoma
shaken baby syndrome (retinal hemorrhages)
is a subdural hematoma/hemmorhage fast or slow
slow
how can we check intracranial pressure
spinal tap or lumbar puncture cause CNS includes spinal cord
what lies superior to the temporal fossae and extends to the zygomatic arch
superior temporal line
what is papilledema
swelling of optic nerves in BOTH eyes
what is the opening for the brainstem
tentorial notch
if you get hit in the pterion what happens
the bone will rupture the middle meningeal and result in a epidural hematoma
if the middle meningeal artery causes a epidural hematoma then...
the temporal lobe will herniate over the tentorial margin
where does a meningioma invade our orbital cavity
through superior orbital fissure
what does a capillary have in the brain vs. in general
tight junction, pericytes, astrocytes, basal membrane
what is the function of the blood barriers
to protect the brain
where else is BBB found
transition from arterioles to venules
what causes epidural hematoma/hemmorhage
trauma
what causes subdural hematoma/hemmorhage
trauma
what is the most medial projection of the temporal lobe
uncus
where does subdural hematoma happen
under dura between arachnoid
what kind of blood is subdural hematoma/hemmorhage
venous
where does herniating brain move toward
weakest area/biggest openings: foramen magnum and tentorial notch (opening for brainstem)
when does the epidural become a real space
when there is bleeding
meningiomas are easier to see in MRIs with or without contrast
with!
who does this condition affect mainly
women of child bearing age or above ideal body weight
can a meningioma cause morbidity
yes
could there be a midline shift in subdural hematoma
yes
does a ruptured aneurysm cause papilledema
yes
is papilledema a medical emergency
yes
is an arterial bleed quick? if so, why?
yes under high pressure
can increased brain pressure be life threatening
yes!!
do BCSFB and BBB have TJ
yes, both do
does a epidural hematoma cross the midline
yes, but doesnt often
can a subdural hematoma be fatal
yes, but slower
can we have meningioma of falx cerebri
yes, compresses DVS and causes papilledema
is there meninges in the orbit
yes, optic nerve from dura inner layer (meningeal)
is there CSF around optic nerve
yes, subarachnoid space