Lecture 1: Blood Supply and Ventricular System Flashcards
CSF is similar to blood ultrafiltrate and contains higher/lower cocentrations of which molecules?
Higher concentrations:
- Sodium
- Chloride
- Magnesium
Lower concentrations:
- Potassium
- Calcium
- Glucose
- Protein
What produces the CSF and primarily in which ventricles?
- Choroid plexus
- Primarily in lateral ventricles and 4th ventricle
What are the 4 ventricles and where are they found?
- 2x lateral ventricles –> in each cerebral hemisphere
- 3rd ventricle —> between thalami
- 4th ventricle –> between cerebellum and pons
What is the general flow of CSF starting in the lateral ventricles all the way to the superior sagittal sinus?
Hydrocephalus is an increase in cerebral mass/size due to presence of excessvie CSF where?
Ventricular system, subarachnoid space, or both!
External hydrocephalus is also know as what; there is an excessive accumulation of CSF where; what are the size of the ventricles like?
- Communicating hydrocephalus
- Excessive CSF in the subarachnoid space
- Normal ventricle size
- Compression of CNS
What are the 2 types of external hydrocephalus; commonly caused by?
- Supratentorial external hydrocephalus = above the tentorium cerebelli
- Most commonly associated w/ senile atrophy of the cortex (i.e., Alzheimer’s disease) - Infratentorial external hydrocephalus = below the tentorium cerebelli
What type of hydrocephalus is shown here?
Supratentorial external hydrocephalus
Internal hydrocephalus is also known as what; what is occuring?
- Noncommunicating hydrocephalus
- CSF produced in the ventricular system does NOT drain into the subarachnoid space
- Results in dilation of the ventricles proximal to the obstruction
3rd ventricle choroid plexus ependyoma causes an obstruction of?
- Interventricular foramen
- CSF backs up into lateral ventricles
Midbrain astrocytoma is causes an obstruction of?
- Cerebral aqueduct
- CSF backsup into the 3rd and lateral ventricles
Arnold-Chiari malformation or Dandy-Walker Cyst causes an obstruction of?
- Median and Lateral aperatures
- CSF backs up into 4th, 3rd, and lateral ventricles
With communicating hydrocephalus CSF can move where, but not move where, which results in a combination of which 2 hydrocephalus?
- CSF can move through the ventricular system into the infratentorial subarachnoid space
- CSF cannot circulate over the cerebrum to be resorbed at the arachnoid villi near the superior sagittal sinus
Results in:
- Hypertrophy of ventricles (internal hydrocephalus)
- Accumulation of CSF in the infratentorial space (infratentorial external hydrocephalus)
Communicating hydrocephalus is caused by an obstruction of; what causes this obstruction?
- Obstruction of narrow space between the tentorial notch and midbrain
- Adhesions of fibrosis in subarachnoid space from —>
- Previous inflammation - infantile meningitis
- Cerebral edema
- Uncal herniation
What are the clinical signs of hydrocephalus in infants/young children versus adults?
- Increased intracranial pressure is partially/completely compensated via enlargement of cranial sutures (children)
- In adults, sutures are fused —> prevent head enlargement, but there is still increased intracranial pressure
Why is Papilledema one of the clinical signs of hydrocephalus/increased intracranial pressure?
- Optic sheath surrounds the optic nerve and inside the sheath is the subarachnoid space
- If CSF increases within subarachnoid space, there will be increased pressure on the optic nerve and can lead to the optic disc bulging out
- One of the key signs of hydrocephalus
What are 3 of the clinical signs of hydrocephalus?
- Papilledema
- Internal strabismus/abducens (CN VI) palsy
- Mental retardation
Where is the internal venous plexus of Batson located, where does it receive drainage from and where does it empty?
- Receives drainage from veins in the spinal cord
- Located in the EPIDURAL space
- Empties into the intervertebral veins and then segmental veins
The internal cerebral vein is located where, receives drainage from what and empties into which vein?
- Runs next to the parahippocampal gyrus
- Receives thalamostriate and anterior septal veins
- Drains into the Great Vein of Galen
Which veins drain into the Great Vein of Galen and where does this vein drain?
- Receives the Internal Cerebral VeinandBasal Vein of Rosenthal
- Drains into the Straight Sinus
What is the significance of an occlusion to the Great Vein of Galen? What structures may be compressed in a Great Vein Varix?
- Occlusion is usually fatal, as it drains the deep cerebrum
- Great vein varix –> may compress the pineal body and posterior commissure
Where does the superior sagittal sinus drain versus the straight sagittal sinus?
- Superior sagittal sinus usually drains into the right transverse sinus
- Straight sinus usually drains into the left transverse sinus
Thrombosis of superior sagittal sinus or right transverse sinus leads to?
Cortical ischemia and/or necrosis
Thrombosis of straight sagittal sinus or left transverse sinus usually results in?
- Ischemia and/or necrosis of deep cerebrum
- Usually fatal
What 3 locations is the blood brain barrier absent?
1) Pineal body
2) Area Postrema
3) Median eminence of the hypothalamus
The ICA and vertebral arteries pierce which layer and then run into which space before giving off cerebral arteries?
- Pierce the dura
- Run in subarachnoid space
Cerebral arteries run in the subarachnoid space before giving off branches that penetrate where; what are these branches surrounded by?
- Branches penetrate into brain parenchyma
- Surrounded by Virchow-Robin space (perivascular space) and Pia mater
What are the 4 branches off the ICA which supply the anterior circulation?
1) Opthalmic artery
2) Anterior Choroidal artery
3) Anterior Cerebral artery
4) Middle Cerebral artery
Which artery is frequently a cause of vacular insufficiency to globus pallidus and hippocampus in elderly?
Anterior Choroidal artery
What 5 areas are supplied by the anterior choroidal artery; why is this artery clinically significant?
- The choroid plexus of the lateral ventricle
- Internal capsule
- Basal ganglia
- Thalamus
- Rostral midbrain
*Prone to thrombosis due to long course in subarachnoid space
Which nerves does the anterior cerebral artery run next to?
Olfactory and optic nerves
Which areas are supplied by the Anterior Cerebral artery?
- Anterior 2/3 of the medial side and supero-lateral portion of the hemisphere
- Paracentral lobule region
Occlusion of the Anterior Cerebral artery will affect which region of the brain and cause what downstream problems?
- Will affect blood supply to the paracentral lobule region (motor and sensory to LE)
- Contralateral paresis and/or parasthesia of the leg and foot
What branches does the Anterior Cerebral artery give off; including thre 2 cortical branches?
- Recurrent Artery of Heubner
- Anterior Communicating artery
Cortical branches:
1 ) Anterior Pericallosal artery
2) Callosomarginal artery
Where do the medial and lateral striate/thalamostriate arteries arise from and what do they supply?
- Middle Cerebral artery
- Supply Internal CapsuleandCorpus Striatum + Thalamus
What does the Central/Rolandic artery off the MCA supply?
Primary motor and somesthetic cortices
What do the frontal branches off the MCA supply?
- Premotor and Prefrontal Cortices
- Broca’s speech area in dominant hemisphere (usually left)
What do the parietal branches off the MCA supply?
Association cortex
What do the temporal branches off the MCA supply?
Primary auditory cortex
What does the angular artery off the MCA supply?
- Supramarginal and angular regions
- Wernicke’s area in dominant hemisphere (left usually)
What occurs with occlusion of the Central artery off of the MCA?
Contralateral spastic paralysis and/or paresthesia of the head and upper 1/2 of the body
What occurs with occlusion of the frontal branches off of the MCA?
- Broca’s Aphasia = expressive language disorder
- Can hear and comprehend, however cannot respond appropriately
- Frustrating problem in initiation of speech motor patterns
What occurs with occlusion of the parietal branches off the MCA?
Variety of interpretive disorders including body neglect, agnosia, and apraxia
What occur with occlusion of the temporal branches off the MCA?
Difficulty localizing sounds
What occurs with occlusion of the angular artery off the MCA?
- Wernicke’s Aphasia = Receptive language disorder
- Fluent in speech, however lacks content or meaning in spoken and written comprehension
- Circumlocute w/ inappropriate word choices and new word creation
Where does the Anterior Spinal artery arise from and what does it supply?
- From the Vertebral artery
- Supplies most of the central gray matter and anteromedial portion of white matter
Where do the Posterior Spinal arteries arise from and what do they supply?
- Branch off the vertebral or PICA
- Supply dorsal roots and about 75% of posterior columns
- Along with radicular arteries they supply peripheral margins of the cord
Spinal cord trauma may interrupt blood flow to spinal cord especially if supplied by 2 arterial supplies, most frequently occurs adjacent to enlargements at which vertebral levels?
- C2-3
- T1-4
- L1
What is the major supply to the inferior 2/3 of the spinal cord, where does this artery arise from and what artery does it contribute to?
- Great Anterior Artery or Adamkiewicz
- Arises from: left inferior intercostal or superior lumbar arteries
What may compromise the Great Anterior Artery of Adamkiewicz and what does this cause?
- Secondary to thoracolumbar fracture or surgical repair of AAA
- Results in ischemic necrosis of the spinal cord (partial or complete transection)
What causes Central Cord Syndrome?
- Disruption of blood flow to the Anterior Spinal artery
- Thrombosis or hyperextension injury of the neck
- Ischemia of the central region of the spinal cord
Which deficits or other clinical outcomes may result from Central Cord Syndrome; which extremities most affected?
- Central necrosis and cavitation of the spinal cord
- Sensory and motor deficits to upper extremities > LE’s
- Distal musculature > proximal musculature
What 3 areas does the PICA supply?
- Posterior inferior portion of cerebellum
- Posterolateral aspect of the medulla
- Choroid plexus of the 4th ventricle
What does occlusion of the PICA lead to?
Lateral medullary syndrome/Wallenburg syndrome
Where is the AICA located and what CN’s and other structure is it next to?
- Located in the Pontobulbar sulcus
- Next to CN VI, VII, and VIII and the Flocculus of the Cerebrum
What 3 things does the AICA supply?
1) Anteror inferior portion of Cerebellum
2) Superior and Middle Cerebellar peduncles
3) Part of brainstem
The superior cerebellar artery is located posterior to which CN?
CN III
The superior cerebellar artery supplies what 3 regions?
- Superior lateral portion of cerebellum
- Deep cerebellar nuclei
- Part of pons and midbrain
The labyrinthine artery is a branch off of and is the main artery to?
- Branch of Basilar artery or off AICA
- Main artery to the internal ear
What is Labyrinthinitis and what does it cause?
- Atherosclerosis or inflammation of the Labyrinthine Artery resulting in irritation of the vestibulo-cochlear apparatus
- Disrupts equilibrium and/or hearing
What do the Pontine branches off the Basilar artery supply and what type of pattern do these branches distribute in?
- Medial and lateral aspects of the pons
- Distribute to regions of the brainstem in a “pie wedge” pattern
What is supplied by the Penetrating branches, Temporal branches, Parieto-occipital artery, Calcarine artery, and Posterior Pericallosal artery all coming from the Posterior Cerebral artery?
Penetrating branches: internal capsule, thalamus, choroid plexus of the lateral ventricle, and upper midbrain
Temporal branches: inferior temporal cortex
Parieto-occipital artery: visual association corex
Calcarine artery: primary visual cortex
Posterior pericallosal artery: anastomoses w/ anterior pericallosal artery of the anterior cerebral artery
What may causes PCA occlusion and what does it result in?
- Thrombosis or compression due to uncal herniation
- Causes: ischemic necrosis of the primary visual cortex
- Contralateral homonymous hemianopsia w/ macular sparing
What causes a falx herniation and what occurs; what are the clinical symptoms?
- Unilateral space-occupying lesion present –> Cingulate Gyrus can herniate
- Pushes beneath the free edge of Falx Cerebri
- Headache, contralateral leg weakness, may not present clinical deficits
What causes an Uncal herniation (tentorial); what happens?
- Unilateral space-occupying lesion is present —> Uncus can herniate
- Pushes through tentorial notch (opening in tentorium cerebelli)
What are the early clinical signs of Uncal herniation; what about when there is midbrain involvement?
- Early sign: unilateral dilating pupil (CN III compression) = oculomotor nerve palsy = closed eyelid, deviation of eye down/out and pupil dilation
- Midbrain involvement: contralateral hemiparesis and respiratory compromise
- Kernohan’s notch
An uncal herniation causes pressure on the ipsilateral brainstem leading to; if the increases pressure pushes the brainstem into tentorium cerebelli what is observed?
- Pressure on ipsilateral brainstem = contralateral limb weakness
- Referred to as Kernohan’s Notch or a False Localizing Sign
- Brainstem pushed into tentorium cerebelli = ipsilateral limb weakness (to space-occupying lesions)
What occurs in a Tonsilar herniation and why are they so serious?
- Cerebellar tonsils herniate through foramen magnum
- Compress medulla and lead to respiratory arrest = fatal
A patient comes in after a traumatic incident and is initially unconcious but then has a rapid recovery. After a few hours pass neurologic symptoms begin, what do you suspect?
- Epidural Hematoma
- Rupture of the Middle Meningeal A.
A rupture of the middle meningeal artery is a high pressure bleed and what space does this bleeding expand and what does this hematoma press on; what is the treatment for epidural hematoma?
- Expands the epidural space, pushes the dura mater from the bone creating a blood filled space
- Hematoma presses upon cerebral hemisphere; uncal herniation compression of midbrain
- Progressive decrease in level of conciousness
- Treatment = evacuation of hematoma
What pathology is shown here?
- Epidural hematoma
- Has a “lens” look to it
What is a Subdural Hematoma and why do they become more likely to occur in older patients?
- Head trauma causes veins to rupture as they cross the subdural space
- Veins vulnerable to sheer forces between movement of the brain versus dura; veins become stretched as we age and are more susceptible to rupture
- Ruptured vein —> blood slowly accumulates in subdural space
What is seen clinically with Subdural Hematoma’s and how are they differentiated from Epidural Hematoma’s?
- Same symptoms as epidural hematomas, however more insidious
- Delayed due to slower pooling of blood
- Can have more acute onset
- Lethargy, seizures, or headaches
What pathology is this?
- Subdural hematoma
All major blood vessels suppying the CNS run in the subarachnoid space with surrounding CSF; what is seen clinically with a Subarachnoid Hemorrhage?
- Rupture = presence of RBC’s in the CSF
- To sample the CSF –> Lumbar Puncture at L4-L5
