head and neck lecture 14 Flashcards
where do epidural hematomas occur
bleeding on top of dura (bw dura and skull)
What is the weakest part of the skull?
pterion
where is pterion bone
in the temporal fossa on external skull
at the location of the pterion, but on the internal skull is where which artery travels encased in bone
middle meningeal artery
what are the 2 reasons why the skull is most likely to fracture at the pterion
bone is thinner here (middle meningeal travels thru it) and it’s an articulation of multiple bones
where do the middle meningeal artery come from
foramen spinosum
what foramina does the middle meningeal artery travel to first to enter the skull
foramen spinosum
can you see the middle meningeal artery itself in the dura
yes
if there is a fracture in the pterion the middle meningeal artery could tear and bleed into the cranial cavity into the _______ causing an _________
epidural space
epidural hematoma
an epidural hematoma occurs bw
the dura and the skull
epidural hematoma is most likely seen in
kids who have a head injury with fracture of the temporal bone
in theory, can an epidural hematoma cross the midline bc it is located bw the dura and the skull
yes but since dura is tightly adherent to the adjacent skull near suture lines, it doesnt usually cross suture lines
separates right and left halves of the brain
falx cerebri
if the middle artery bleeds into the epidural space (epidural hematoma) the _____________ will herniate over the tentorial margin
temporal lobe
what is the most medial projection of the temporal lobe
uncus
the herniating brain will towards the weakest areas (biggest openings)
tentorial notch
forament magnum
the ______ is found in the core of the brainstem
reticular formation
the reticular formation is responsible for
the awakened state = consciousness
in an epidural hematoma, the medulla and cerebellum will move towards the weakest area
foramen magnum compressing the medulla with its vital centers
where is the reticular formation found
in dorsal brainstem
herniation of the temporal love (uncus) over the free edge of tentorium compresses CN 3 causing a
dilated pupil
what should pupils do when you shine light into eyes
constrict
what should eyes do in dim
dilate
a compressive CN 3 palsy can present initially as just a
dilated pupil
what fibers travel outside of CN 3
parasympathetic nervous fibers
epidural hematoma affects
middle meningeal artery = arterial blood under high pressure
subdural hematoma affecs
bridging veins = venous blood under less pressure
- slower bleed than arterial blood
patients with a subdural hematoma may not become symptomatic until
a few weeks after an episode of trauma
where does a subdural hematoma take place
beneath the dura, bw the dura and arachnoid (in subdural space)
in a subdural hematoma, is it venous or arterial blood
since arteries do not travel in the subdural space, this is not an arterial bleed
it is venous blood
does a subdural hematoma cross midline
it can not because the falx cerebri doesn’t let it cross to the other side
a subdural hematoma is the collection of blood between
the inner layer of dura and the arachnoid
what causes a subdural hematoma
a rupture of the cortical bridging veins
subdural hematomas are most common in
-pt treated with anticoagulants
- elderly and alcoholics with atrophy
if subdural hematomas are not treated they can damage the
reticular activating system
subdural hematomas occur due to tearing of _____ that are transporting venous blood from the cortex to the DVS
external cortical bridging veins
subdural hematomas occur due to
trauma
external cortical (bridging) veins drain into
the superior saggital sinus
internal cortical veins drain into the great vein of galen. would damage to the inernal cortical cause a subdural hematoma
no
what are the signs/symptoms of a SDH
-severe headache
-vomiting
-dizziness
-sudden weakness arm or leg
dilated pupil
RAS compromised:
decreased consciousness
confusion
inability to wake up
the headache associated with a SSH is due to
meningeal irritation innervated by CN 5
who is most at risk for a SDH
people who are fragile
-the elderly
- infants
- anyone who sustains severe head trauma
______ is the occurrence of a vitreous hemorrhage in association with intracranial hemorrhage and elevated ICP
terson syndrome
subarachnoid hemorrhage causes increased
intracranial pressure and papilledema
the most common presenting problem from an aneurysm is
rupture with bleeding in subaraachnoid space
symptoms of SAH
bad headache
nausea/vomiting
dizziness
neck pain
pulsitile tinnitus
double vision
does an unruptured aneurism cause papilledema
no
only a ruptered aneurysm can cause papilledema
aside from the optic disc being pushed forward… papilledema is also caused by
axoplasmic stasis and extrusion from the cell membrane
what can cause papilledema
anything that causes increased ICP
bleeding
tumors blocking CSF flow
blood clots in dural venous sinuses blocking CSF flow
a subdural hemorrhage causes
increased intracranial pressure and papilledema
is a SDH a fast or slow bleed
slow bleed
optic disc could look normal after trauma even if they do have SDH
is a SAH bleed fast or slow
a fast arterial bleed
pt may develop papilledema more quickly
the most common presenting problem from an aneurysm is _______ and _________ into subarachnoid space
rupture and bleeding
obstructive hydrocephalus
build up of CSF
increased volume of cranial cavity
increased intracranial pressure
intracranial mass can compress _______ and cause increased intracranial pressure and papilledema
dural venous sinuses
a mass of meninges. it tends to trail along the dura, causing a dural trail
meningioma
venous sinus thrombosis is a blood clot in
the dural venous sinuses
venous sinus thrombosis blocks drainage of
venous blood AND CSF
-CSF can’t drain out of cranial cavity and leads to increased intracranial pressure
idiopathic intracranial hypertension - possible mechanism
increased pressure in the venous system keeps CSF from draining
meningitis
inflammation of the meninges
what symptom is seen with meningitis
neck pain / stiffness
just like with the optic nerve, there is only _____ layer of dura surrounding the spinal cord
one
around the spinal cord there is
arachnoid and pia and therefore a subarachnoid space
