1
Q
Layers Protecting the Brain
A
SCALP
- Skin
- subcutaneous Connective tissue
- galea Aponeurotica
- Loose areolar connective tissue
- Pericraneium (periosteum)
2
Q
Meninges
A
“PAD” the brain
- Pia Mater
- Arachnoid Mater
- Dura Mater
3
Q
Dura Mater
A
-Outermost
-Thickest/Toughest Membrane
-Means “Tough Mother”
-Peforated for cranial Nerves/Blood Vessels
Two Layers
-Periosteal: External
-Meningeal: Internal
Dural Inflodings
-Falx Cerebri
-Tentorium Cerebelli
(Both made from meningeal layer)
4
Q
Falx Cerebri
A
Fold that extends into the longitudinal fissure (separates R/L hemispheres)
5
Q
Tentorium Cereeblli
A
(in the back) fold that divides the occipital lobe from the cerebellum (separates cerebral hemispheres)
-Tentorial Notch: Opening in tentorium that the midbrain passes through
6
Q
Separation of the dura layers
A
Dural Venous SInuses which mainly drain blood via the sigmoid sinus into the internal jugular vein
7
Q
These folds can cause damage to the brain during high velocity impact
A
Falx Cerebri: Damage to the Corpus Callosum
Tentorium Cerebelli: Damage to midbrain, vessels, CN3
8
Q
Epidural Space
A
- Epi= Above (btw skull and dura)
- Contains: Middle Meningeal Artery
- If ruptured: Epidural Hematoma (result of temporal bone fracture)
9
Q
Epidural Hematoma
A
- Result of temporal bone fracture
- Initially asymptomatic but within hours: Increased ICP, herniation, death
10
Q
Middle Meningeal Artery (Epidural Space)
A
-Branches odd the external carotid artery
Enters space through the foramen spinosum
-Supplies the dura
11
Q
Subdural Space
A
- Sub=Below (btw dura and arachnoid)
- Contains: Bridging veins (susceptible to shearing forces bc brain moves; crescent shaped
- Bridging Veins: Cross the subdural space and drain into venous sinuses
- If ruptured: Subdural hematoma
12
Q
Subdural Hematoma
A
-Chronic (elderly, shrinking brain) and acute (high velocity impacts/trauma)
13
Q
Arachnoid Mater
A
- Delicate membrane lying between pia (internally) and dura (externally)
- Adheres to dura mater
- Arachnoid granulations
- Impermeable (doesn’t allow fluid to pass)
- Perforated to allow CN & BV to pass-through
14
Q
Arachnoid Granulations
A
Serve as one way valve to the dural sinus
15
Q
Subarachnoid Space
A
- Between the Arachnoid and Pia Mater
- Has trabeculae that suspend the brain
- CSF Circulation
- Contains major arteries of the brain
16
Q
Subarachnoid Hemorrhage
A
-Buildup of blood into the CSF
-Cause severe headaches
Hemorrhages can be:
-Traumatic: Ruptured vessels that bleed in the space (more common, no vasospasm seen)
-Non-traumatic: (spintaneous) Arterial aneurysm that bleeds in the space
17
Q
Non-Tramatic Subarachnoid Hemorrhage
A
- Spontaneous
- Arterial aneurysm that bleeds in the space
- A-comm=30%, P-comm= 25%, MCA= 20%
- Atroveneous malformation 4-5% of cases
- Sudden headache
- Delayed cerebral vasospasm: arteries realize they’re bleeding and constrict too much leading to ishemic stroke (if not monitored could lead to infarct)
18
Q
Pia Mater
A
- Thinnest/most delicate
- Highly vascular; impermeable
- Adheres to brain tissue (contours of the brain)/spinal cord
- Extends out from spinal cord to help anchor it to the dura by dentate ligaments
19
Q
What can happen when we get hemorrhages in the brain?
A
Herniations
20
Q
Herniation
A
When mass effect is severe enough to push intracranial strictures from one compartment to another Types: -Subfalcine Herniation -Central Herniation -Transtentorial Herniation -Tonsillar Herniation
21
Q
Subfalcine Herniation
A
Cingulate gyrus gets pushed under the falx cerebri
-Usually from unilateral pressure
22
Q
Central Herniation
A
Central downward displacement of the brainstem
23
Q
Uncal Transtentorial Herniation
A
Medial aspect of the temporal lobe (uncus) is pushed inferiorly against tentorium cerebelli
24
Q
Tonsillar Herniation
A
Cerebellar tonsils get pushed down into foramen magnum
-Life threatening because it compresses the brainstem (regulates respirations and BP)
25
Ventricles
- 2 Lateral Ventricles: Telencephalon
- 1 Third Ventricle: Diencephalon
- Cerebral Aqueduct: Mesencephalon
- 1 Fourth Ventricle: Metencephalon/Myelencephalon
26
Chroid Plexus/CSF Production
- Occurs in the choroid plexus of each ventricle
- Made of ependymal cells and choroid epithelial cells which produce CSF (constantly!)
- Create a pressure gradient (80-180mm of water = normal)
- Cilia assist in circulating CSF
27
CSF Normal Values
- Normal Volume: 150cc; 20cc/hour; about 500cc/day
- Infant 10-100mm of water
- Normal Adult: 80-180mm of water
- Obese Adult: up to 280mm of water
- Appearance: Sparkling clear; not cloudy or colored with abnormal cells
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CSF Functions
- Buoyancy
- Cushioning
- Cleaning
- Ionic Balance
29
CSF Flow
1. Choroid Plexus
2. Lateral Ventricles
3. Interventricular Foramen (aka Foramen of Monroe)
4. 3rd Ventricle
5. Cerebral Aqueduct
6. 4th Ventricle
7. Foramen of Luschka/Magendie
8. Spinal Cord
9. Subarachnoid Space
10. Arachnoid Granulations (reabsorbed through these)
11. VDural enous Sinus
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CSF diffuses through _____ & is reabsorbed into the _____?
- Arachnoid Granulations
| - Venous System
31
The veins of the brain empty into...
Sinuses
32
Sinuses
-Formed by the 2 layers of the dura
-No halves in sunuses
-Drainage occurs from the superior sagittal sinus into the transverse sinuses and sigmoid sinus
-Major sinuses that feed into the internal Jugular Vein
Superior:
-Confluence SInus
-Superior Sagittal Sinus
-Transverse Sinus
-Sigmoid Sinus
-Cavernous Sinus
Deep
-Vein of Galen
-Straight Sinus
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Sigmoid Sinus
Exits skull through jugular foramen
34
Superior Sagittal Sinus (superior)
Big one on top
35
Inferior Sagittal SInus (superior)
Runs along the bottom edge of the falx cerebri heading back towards the tentorium cerebelli where it becomes the straight sinus and joins with the superior sagittal sinus
36
Confluence of the Sinuses (SIS) (superior)
AKA: Torcular Herophili
- Area where the superior & inferior sagittal, occipital & straight sinusus comverge and are drained by the transverse sinus
- At the confluence, they head down the sigmoid sinus then into the IJV
37
Cavernous Sinus (superior)
-Sits on the sella turcica of the skull
-ICA runs through here
-Uses the Superior Petrosal & inferior petrosal sinuses to drain into the transverse sinus
Surrounds the:
-Pituitary gland
-CN 3, 4, 5, &6
An abnormality in venous return can compress the CN's or IC artery
38
Straight Sinus (deep)
Formed by the inferior sagittal sinus and the vein of galen
39
Sagittal SInus Thrombosis
Obstruction of venous drainage which causes an increase in ICP
- Common after birth
- Brain decreases BP which decreases cerebral perfusion and can lead to an infarct
- Delta sign: Superior sagittal sinus will be black on scans
40
Foramen of Monro (interventicular foramen)
-Connects lateral ventricles to the 3rd ventricle
41
Cerebral Aqueduct
Connects 3rd and 4th ventricles; Travels through midbrain
42
Foramen of Magendie
Connects 4th ventricle medially to the SC
| -Magendie=Medial
43
Foramen of Luschka
Connects 4th ventricle laterally to the SC
| -Luschka=Lateral
44
Increased ICP (Disorders of CSF System)
-Can occur with any increase in size of any structure
Symptoms
-Headache
-Nasea
-Bradycardia
-Hypertension
-Loss of Consciousness
-Papilledema (optic disk pushed forward, CN2)
-Cushings Triad: HTN, Bradycardia, irregular respirations
(minto compenation can be made by body decreasing CSG andd blood volume without much rise in ICP)
45
Increased ICP Treatment
- Elevating bed to 30° to promote drainage
- Medications
- Shunts: Placed in lateral ventricle
- Hemicarniectomy: Removal of 1/2 the skyll overlying mass lesion to allow for surgery
- Craniotomy: Drill holes in the skull then saw the piece of skull off (bone flap) to allow the brain to swell and perform procedure (bone flap stored in storage or patients abdominal wall unil replaced)
- Lumbar Puncture: allows to check CSF
46
Hydrocephalus (Disorders of CSF System)
-Dialation/ Enlargement of the ventricled due to accumulation of fluid in the brain
Causes
-Blocked CSF circulation
-Impeded CSF absorption
-Too much production
Result:
-Ventricles push (pressure on corticobulbar & corticospinal tracts causing increased spacity/weakness
47
Hydrocephalus Treatment
- Drainage of Fluid: Burr hole in in cranium to drain fluid
- Shunt: Shunt tubing passes from lateral ventricle out of the skull then tunneled back through the skin into the peritoneal cavity of the abdomen
- Endoscopic surgery
48
Cisterns
Openings in the subarachnoid space that are filled with CSF
-Cisterna Magna (cerebellar medullary cistern): Between cerebellum and medulla near foramen magnum
Others:
-Pontine Cistern
-Interpeduncular Cistern
-Lumbar Cistern
49
Perimesencephalic Cisterns
- Ambient Cistern
- Quadrigeminal Cistern
- Interpeduncular Cistern
- Premedullary Cistern
- (Pre)Pontine Cistern
- Lumbar Cistern
50
Ambient Cistern
Located lateral to the midbrain
51
Quadrigeminal CIstern
Posterior to the midbrain, breneath the posterior portion of the corpus callosum
52
Interpeduncular CIstern
Ventral surface of midbrain
53
Premedullary Cistern
Anterior to Medulla
54
Pontine (prepontine) Cistern
Ventral (anterior) to the pons
55
Lumbar Cistern
-Located in lumbar portions of the spinal cord
-Contains cauda equina
-Important location for lumbar puncture/spinal tap occurs here at L4-L5
-Allows to check CSF
Positioned in side lying with legs flexed
-Punture is made below L3 (L4/L5)
56
Venous Drainage Purpose
CSF diffuses through Arachnoid granulations and is reabsorbed into the venous system
57
Venous Drainage Flow
1. Arachnoid Granulation
2. Venous Sinus
3. Confluence of Sinuses (superior, inferior, & straight)
4. Transverse Sinus
5. Sigmoid Sinus
6. Internal Jugular Vein
58
Blood Brain Barrier
Function: To protect the brain
-Allows only certain subsances to get through the barrier (tight junction btw endothelial cells that line capillary walls
Get through mostly by active tansport: Lipid soluble substances can cross easily
-Water-soluble substances do not
59
Circumventricular Organs
Areas of the brain that are not protected by the BBB
| -Median eminence and neurohypophysis (involves in the regulation and release of putuitary hormones)
60
Higher Uptake into Brain (Blood Brain Barrier)
- Thiopental (anesthetic)
- Sulfonamide
- Tetracyclines
- Atropine
- Glucose
- L-DOPA
- O2&CO2
61
Lower Uptake into Brain (Blood Brain Barrier)
- Phenobarbital (anticonvulsant)
- Norepinephrine
- Dopamine
- Penicilin
62
L-DOPA (Blood Brain Barrier)
-Treatment for Parkinsons disease which can easily cross barrier
-Dopamine alone requires higher amounts since it has a lower uptake into the brain
(Higher Uptake into Brain)
63
Headaches
Typically benign but can be life threatening
-No pain receptors in the brain so caused by mechanical traction, inflammation, or irritation of structures (meninges)
Types
-Migraine
-Cluster Headache
-Tension Headache
-Side of Headache
(watch out for explosive headaches, usually indicates a medical incident (subarachnoid hemorrhage or stroke)
64
Migraine (Vascular Headaches)
- All over brain
- Vary in length of time (usually last 30min-24hrs, can reoccur once every few years to several times a week)
- Painful
- Sensitive to light, sounds, and sudden movemt
- Sometimes have an aura (warning that it is coming)
- Nausea and vomiting may occur
- Women are more prone to migraines
- Thought to have a genetic basis (family related)
65
Cluster Headache (Vascular Headaches)
- Intense headaches that are focal (specific area)
- Occur once to several times a day over a few weeks
- Localized behind eyes
- Shorter
- Very intense
- More common in men
66
Tension Headache (Headaches)
- Stress related headache that feels like a steady dull ache
| - Tight hair/headband
67
Side of Headache= (Headaches)
= Side of pathology
68
Ischemic Strokes
- Occurs when there is not enough BS to the area of the brain which leads to cell death
- 3rd leading cause of death (80-85% of strokes)
- Major cause of permanent disability
- Blocked Artery (embolic or thrombic)
- More common
- Embolism causes large vessel infarcts > w/ sudden onset of maximal deficits
- Small Vessel Infarcts (Lacunar Infarcts) > seen in chronic hypertension: Usually affects the deep structures of the hemisphere and brainstem
- Thrombosis occassionally occurs in large proximal vessels
69
Embolic (Ischemic Stroke)
Clot within an artery that travels in the blood stream until it becomes lodged
- Caused by cardiac related A-fib or MI
- Abrupt onset
- Usually cause a large vessel infarct
- Common site of occlusion- ICA or MCA
70
Thrombic (Ischemic Stroke)
Blood clot forms in the artery that supplies blood to the brian
- Usually due to athersclerosis
- Abrupt or slow onset
- Usually smaller vessels
- Common site of occlusion- Vertebral, basilar, MCA
- Less common
71
Hemorrhagic Stroke
-Weak part of vessel rupture (15-20% of strokes)
-Usually in younger patients
-Intracerebral/subarachnoid hemorrhage
-Artery Breaks
-Higher Mortality rate (lowest mortality rate seen with smaller lacunar infarct)
-But better outcomes (because blood is reabsorbed & younger)
Causes:
-Aneurysm
-HTN
-Trauma to the head
-Bleeding disorder
72
Circle of Willis
73
Anterior Circulation
Supplied by the Internal Carotid Artery (ICA)
-ACA: Ant. Comm. A.
-MCA: Post.Comm. A.
Aorta> Brachiocephalic A> Common Carotid A. & Subclavian A > ICA & ECA (common carotid)
74
Middle Cerebral Artery (MCA)
-Most common
Superior Division
-Supplies above the sylvian fissure to include the frontal love
Inferior Division
-Supplies below the sylvian fissure, including lateral tempotal and some parietal lobe
-Also incdues globus pallidus and caudate nucleus (part of BG)
75
Anterior Cerebral Atrery (ACA)
-Supplies anterior medial surface of frontal to anterior parietal lobes; imc;ides anterior limb of internal capsule, BG (putamen, caudate nucleus)
76
Anterior Communicating Artery (A-comm)
Posterior circulation: Supplied by the vertebral arteries
| -Subclavian A.> Vertebral A.> Basilar A.
77
Posterior Cerebral Artery (PCA)
Inferior and medial temporal lobes and occipital lobes
| -Includes: Thalamis & posterior limb of internal capsule, splenium of corpus callosum
78
Vertebral Arteries
Posterior spinal artery (2x)
Anterior spinal artery (1)
Posterior inferior cerebellar artery (PICA): Cerebellum & Medulla
79
Spinal Cord Circulation
```
2 Posterior Spinal Arteries
-Branch off vertebral artery
-Smaller
-Supply 1/3rd the SC
1 Anterior Spinal Artery
-Branch off the vertebral artery
-Bigger
-Supply 2/3rd the SC
```
80
Basilar Artery
Anterior Inferior Cerebellar Artery (AICA)
-Anterior & Inferior portions of cerebellum
Superior Cerebellar Artery (SCA)
-Superior portion of cerebellum
81
Cortical Stroke Syndormes
- Middle Cerebral Artery (feeds laterally: arm and face)
- Anterior Cerebral Artery (feeds anterior: legs)
- Posterior Cerebral Artery (feeds posterior: vision)
82
Left Superior MCA
- Right Face & Arm Weakness (in some cases sensory loss)
| - Brocas Aphasia
83
Right Superior MCA
- Left Face & Arm Weakness
| - Left Hemineglect (to a variable extent)
84
Left Inferior MCA
- Wernicke's Aphasia
| - Right Visual Field Deficits
85
Right Inferior MCA
- PROFOUND Left Hemineglect
- Left Visual Field Deficits
- Right Gaze
86
Left Deep Territory MCA
- Right Pure Motor Hemiparesis
| - Larger Infarcts may produce "cortical” deficits (such as aphasia)
87
Right Deep Territory MCA
- Left Pure Motor Hemiparesis
| - Big Infarct leads to left hemineglect
88
Left Stem MCA
- R. Hemiplegia
- R. Hemianesthesia
- R. Homonymous Hemianopia
- Global Aphasia
- L. Gaze at Onset
89
Right Stem MCA
- L. Hemiplegia
- L. Hemianesthesia
- L. Homonymous Hemianopia
- Profound L. Hemineglect
- R. Gaze at Onset
90
Left ACA
- Right LE weakness and sensory loss
- Transcortical Motor Aphasia
- Variable Frontal Lobe Dysfunction (release signs)
91
Right ACA
- Left LE weakness and sensory loss
- Left Hemineglect
- Variable Frontal Lobe Dysfunction (release signs)
92
Left PCA
- R. Homonymous Hemianopia
- L. Occipital cortex: Alexia w/o agraphia
- L. Thalamus & Internal Capsule: Aphasia
93
Right PCA
- L. Homonymous Hemianopia
| - Smaller Branches: Sensory loss & hemiparesis
94
Watershed Infarcts
A blood flow blockage that is localized to the border zones between territories of 2 major arteries in the brain
- ACA-MCA
- MCA-PCA
95
ACA-MCA Watershed
- Occlusion of internal carotid artery (ICA) or drop in BP in a patient with carotid stenosis can cause this watershed infarct (bc both are fed by carotid)
- Proximal arm and leg weakness (both R&L)
- On the dominant (L) side= Transcortical Aphasia
96
MCA-PCA Watershed
-DIsturbances of higher-order visual processing
97
Brainstem Strokes
-Worse prognosis for survival or recovery
-May involve coma, lesions of CN, lesions of descending motor or ascending sensory pathways
Characterized by "the 4 D's with crossed findings"
-Diplopia
-Dysarthria
-Dysphagia
-Dizziness
98
"The 4 D's" (Brainstem Strokes)
- Diplopia
- Dysarthria
- Dysphagia
- Dizziness
99
Locked in Syndrome
A medical condition, usually resulting from a stroke that damages part of the brainstem
-The body and most of the facial muscles are paralyzed but consciousness remains and the ability to perform certain eye movements is preserved
Causes/Symptoms/Deficits that occur:
-Bilateral weakness of UE, LE, and face
-Lateral gaze weakness
-Dysarthria
100
Foramen of Monro (interventicular foramen)
-Connects lateral ventricles to the 3rd ventricle
101
Anterior Communicating Artery (A-comm)
Posterior circulation: Supplied by the vertebral arteries
| -Subclavian A.> Vertebral A.> Basilar A.
102
2 Posterior Spinal Arteries
- Branch off vertebral artery
- Smaller
- Supply 1/3rd the SC
103
CVA
Traumatic event involving the arterial supply to the brain which may be caused by vascular changes in primary arteries supplying the brain
-Causes death to brain cells due to lack of O2
104
Infarct
-An area of coagulation necrosis in a tissue due to local ischemia resulting from obstructionof circulation to area (cell death)
By a thrombus or an embolism
-Thrombus: An aggression of platelets and fibrin causing vascular obstuction at the point of its formation (narrowing)
-Embolism: Sudden blocking of an artery by a clot or foreign material which has been brough to the site of lodgemont. (the clot/foreign material is so big that it bloscks the small vessel)
105
Aneurysm
A sac formed by the dialation of the artery or vein (ballooning)
-Aneurysm are diagnosed with an angiogram
106
Transient Ishemic Attack (TIA)
Events that are caused by arterial blood vessel changes which cause brief periods of noticeable neurologic changes, breif loss of vision, numbness in hands and feet, followed by complete recovery in most cases
-Usually <10 minutes
-15% will have a CVA; hald of which occur within the first 48 hours
-Persistent. deficits within 3 months
Causes
-Embolus temporarily occludes BV
-Thrombus formation on blood vessel wall
107
Aphasia
Loss of language (receptive or expressive)
108
Aphasia
Difficulty performing certain learned movements w/o loss of power, sensation, or coordination
109
Agnosia
Loss of the ability to recognize the importance of sensory stimuli
-Ex. Tactile agnosia= The inability to recognize familar objects by touch
110
Rule of 2's
- 2% of. body weight is your brain
- Brain uses 20% of the O2 takes in
- Brain uses 25% of the gluscose
111
Risk Factors: Ischemic Stroke
- Hypertension
- Diabetes
- High Cholesterol
- Smoker
- Positive family history
- Cardiac disease
- Prior history of stroke or other vascular disease
112
Treatment: Ischemic Stroke
Acute Management
- Early intervention= Better outcomes
- History, exam, rule of hemorrage w/ CT
- Tissue Plasminogen (tPA) w/in the first 4.5 hours of stroke onset if ishemic infart
- DO NOT give to hemmorhagic (would cause more bleeding)
113
PT &. OT Role in Ischemic Strokes
- Neuroplasticity: How the brain can adapt/recover from a stroke
- Work to recover function and decrease risk factors because they are at risk of having another one
114
Carotid Stenosis: Atherosclerosis
Stenosis of ICA
- Thrombi embolizes > causing a TIA or infarct
- MCA Symptoms: Contralteral face-arm or face-arm-leg weakness, sensory changes, visual field deficits, aphasia, or neglect
- ACA. Symptoms: Contralateral Leg Weakness
- Opthalmic Symptoms: Ipsilateral monocular visual loss (amauosis fugax), Severity determined by doppler US or angiography (gold standard)
115
Treatment of Carotid Stenosis/Athersclerosis
- Carotid Endartectomy: Expose the carotid, clamp it., then clean out the atheromatous material
- Angioplasty
- Stenting: Push material out of the way and place stent
116
Carotid Dissection (dissection of carotid arteries or vertebral arteries)
Vessel dissects and blood burrows into the vessel wall that has a small tear
-Patient explains it as a pop or turbulent sound when their heart beats
Causes
-Trauma to head or neck
-Flap protrudes into vessel
Diagnosis: MRI/MRA or CT of neck
Treatment: Anticoagulant
