Neurology Powepoint Flashcards
What structures protect the brain & spinal cord
Meninges, Subarachnoid space, & Epidural Space
What structure makes up the Meninges?
Outer to inner: Dura, Arachnoid, & Pia mater
What are the major devisions of the brain?
Cerebrum (cerebral cortex), Cerebellum, Brainstem, & Limbic System
Cerebrum (cerebral cortex) is responsible for
Higher functions
The Cerebellum is responsible for
Voluntary movement & balance
The brainstem controls
Basic life functions like HR & breathing
The Limbic system manages
Emotions, Memories & Arousal
What are the loves of the brain?
Frontal, Parital, Temporal & Occipital
Frontal lobe involves
Problem solving, movement, reasoning & speech
Parietal lobe is responsible for
Sensory processing & spatial orientation
Temporal lobe is responsible for
Hearing, memory & language
Occipital lobe is responsible for
Visual Processing
What are the functions of the Cerebellum?
Coordinates voluntary movements (walking & writing)
Maintains balance & posture
Fine tunes motor skills
The Thalamus is the
Relay center (relayed to cerebral cortex)
EXCEPT SMELL
The Hypothalamus controls
Autonomic functions & endocrine system
The Epithalamus is involved in
Sleep- wake cycles & Limbic system connections
What are structures of the Limbic system?
Thalamus, Hypothalamus, Amygdala & Hippocampus
The Limbic system is considered a
Transitional region between die cephalon & cerebral hemispheres
Amygdala functions
Emotional processing
Hypothalamus function
Hunger, thirst, temperature & circadian rhythms
Hippocampus function
Memory formation & storage
What are the structures of the Brainstem
Midbrain, Pons & Medulla
Functions of the Midbrain
Visual & Auditory processing & motor control
Functions of the Pons
Regulates sleep & Arousal (RAS)
The Medulla Oblongata controls
HR, RR & Reflexes
Neurons are the
Basic functional units of the brain
The brain receives what percentage of cardiac output
20%
What is the primary regulator of blood flow within the CSF?
CO2
CO2 is a potent
Vasodilator in the CNS
The brain receive blood supply from which 2 arteries?
Internal Carotid (anterior circulation) 80%
Vertebral (posterior circulation) 20%
What are the 3 major paired arteries that perfuse the cerebellum & Brainstem
Posterior Inferior
Anterior Inferior
Superior cerebellar
All 3 of the paired arteries that perfuse the cerebellum & brainstem originate from the
Basilar Artery
The Circle of Willis is
Collateral blood flow
The BBB is permeable to
Water
CO2
O2
Lipid Soluble substances
BBB is impermeable to
Plasma Protein
Non-lipid soluble large substance
CSF protects
The brain & spinal cord
How much CSF circulates in the ventricles & subarachnoid space?
125-150 mL
How much CSF produced daily?
600mL
What structure produces the majority of CSF?
Choroid Plexus
Slowing of EEG & CBF value
20-25mL/100g/min
Flattening of EEG & CBF values
15-20mL/100g/min
Irreversible brain damage & CBF values
<10mL/100g/min
Autoregulation defiinition
Brains ability to maintain constant blood flow despite changes in SBP
Autoregulation is effective between
60-150mmHg MAP
High BP can lead to increased
Cerebral Perfusion
Hemorrhage
Low BP can cause
Insufficient blood flow to the brain, leading to ischemia or stroke
Hypercapnia (slow breathing), increased CO2 causes
Vasodilation
Increasing CBF
Hypocapnia (fast breathing) low CO2 levels cause
Vasoconstriction
Decreased CBF
Hypoxia will trigger
Vasodilation will occur to increase blood flow
Hyperoxia can
Reduce CBF
Hypercapnia & Hypoxia will cause
Vasodilation
Increasing CBF
Hypocapnia & Hyperoxia will cause
Vasoconstriction
Decreased CBF
With Autoregulation, MAPs below 60 will cause
Vasodilation
Ischemia
With Autoregulation, MAPs above 150 will cause
Vasoconstriction
Edema
Hemorrhage
BBB distribution
Nitric Oxide (NO) will cause
Vasodilation that increases CBF
Adenosine, which is released during metabolic, promotes
Vasodilation
Increased ICP will _____ the pressure gradient for blood flow, leading to ________ CBF & potential ischemia
Reduce
Decreased
Hypothermia will _____ CMRO2 & _______ CBF
Decrease
Decrease
Hyperthermia will ______ metabolic demands, leading to ____ CBF
Increase
Increase
What happens with aging & Autoregulation
Diminished Autoregulation & Increased Vascular Resistance
What diseases can impair CBF regulation
Atherosclerosis
HTN
Diabetes
Autoregulation alters cerebrovascular resistance (CVR) within
5-60 seconds
CBF is ____ dependent
Pressure dependent
What are the 3 mechanisms of Autoregulation
Myotonic Mechanism
Metabolic mechanism
Neuronal Mechanism
What is the myogenic mechanism of Autoregulation
Smooth muscle in blood vessel walls contract or relax
What is the metabolic mechanism of Autoregulation
Changes in metabolic activity (CO2 or O2 levels) influence vasoconstriction or vasodilation
What is the neuronal mechanism of Autoregulation
Neuronal signals from SNS
What happens when Autoregulation fails
Hypoperfusion or hyperperfusion
High blood viscosity can
Decrease CBF
Lower blood viscosity can
Increase CBF
Traumatic brain injury impairs
Autoregulation by causing fluctuations in CBF, CMRO2 & CVR
Stroke can cause
Direct vascular damage to blood vessels
Increased CBF, CVR, & decreased CMRO2 (caused by inflammatory process)
Think of decreased food to brain
Ischemia can lead to increased
Oxidative stress, further damaging vascular endothelium
Chronic HTN will shift the Aitoregulation curve to the
RIGHT, meaning higher pressures are needed to maintain constant CBF
Increased ICP can
Reduce CPP, impairing autoregulation
Inhalation agents can
Impair Autoregulation
Cause direct dilation (cerebral)
Increase cerebral blood volume
Can increase ICP
IV anesthetics can
Preserve Autoregulation
Vasodilators & vasoconstriction can affect
Cerebral vasodilation & autoregulation
Normal ICP
7-15 mmHg
When is ICP monitoring initiated?
> 20mmHg
What is severe ICP
> 40mmHg
What is the most accurate way to monitor ICP levels?
Invasively with an intraventricular catheter
GOLD STANDARD
Where is the subarachnoid bolt placed?
Between the brain & arachnoid mater
When monitoring ICP, epidural sensors are placed
Between the skull & dura mater
What are non invasive measures for ICP monitoring
Funduscopy
Transcranial Doppler Ultrasound
Funduscopy examines
Optic nerve pressure in relation to ICP monitoring
Transcranial Doppler Ultrasound ( measuring ICP), measures
Blood flow Velocity in the Middle Cerebral Artery
When it comes to Transcranial Doppler Ultrasound…what is P1, P2 and P3
P1= Percussion Wave; Arterial Pulsation & reflects transmission of systolic pressure wave from the heart to the intracranial space
P2= Tidal wave; reflects brains compliance or brains ability to accommodate changes in volume; represents CSF pressure
Elevated P2= decreased brain compliance (may be due to swelling or mass effect
P3= Dictotic Wave; associated with closure of aortic valve
Signs & symptoms of ICP elevation
Depressed LOC
N/V/HA
Blurred vision
Diplopia
Confusion
Dilated pupils
Ataxia
Weakness
Behaviors problems
Increased ICP can lead to
Herniation syndromes which can cause brain tissue shifting related to compartmentalized pressure gradients
What is Cushings Triad?
Associated with increased ICP:
Increased Arterial BP associated with Bradycardia
Irregular RR
Widening Pulse Pressure
(Can have HTN)
What is normal CPP
60-80mmHg
How can you calculate CPP?
MAP-ICP
What’s important to know about calculating CPP
Either take MAP-ICP
OR
CVP
(Which ever is higher)
What is the most preferred way to monitor CPP
Magnetic Resonance Perfusion (MRP)
Transcranial Doppler Ultrasonography measures
Velocity ( only flow velocity)
Negative movement (away from probe) suggests stenosis,emboli or vasospasm
How can we invasively monitor cerebral perfusion (CMRO2)?
Jugular bulb venous oximetry
Cerebral Microdilaysis
SjVO2, in preference to Jugular bulb venous oximetry, is indicative of
Global oxygen
Cerebral Microdialysis measures
Glucose
Pyruvate
Lactate
Glutamate
Glycerol
A 20% decrease from baseline Cerebral Oximetry is indicative of
Decreased outcomes
What is normal Cerebral O2?
60-80%
What’s important to know when monitoring cerebral perfusion (CMRO2)
Need to know baseline
Autoregulation impairment can cause
Increased CBF & ICP
Some inhalation agents can increase
CMRO2, which can lead to increased CBF & ICP (more pronounced with Nitrous Oxide)
Sevo, ISO & Des will_________ CMRO2
Decrease
Cerebral vasodilation will ______ICP
Increase
Inhalation agents can disrupt BBB, potentially leading to
Cerebral edema & increased ICP
Nitrous oxide will________ CMRO2
Increase
______can decrease the brains metabolic rate, thus reducing oxygen & glucose consumption
Hypothermia
Use of anesthetics & sedatives can ___________ & ________
Decrease brain activity & metabolic demand
Medications used to dilate blood vessels will
Improve blood flow & increase CBF
Avoid hyperventilation (decrease in CO2) to prevent
Vasoconstriction
What medications can be used to decrease cerebral edema
Mannitol (0.5-1.5g/kg)
OR
Hypertonic Saline (3% starting at 50-100cc/hr)
Hypertonic may be more effective than Mannitol for brain relaxation
What head position can decrease ICP?
Elevating the head
Drugs like ________can minimize excitotoxicity (they reduce glutamate-mediated excitotoxicity)
NMDA Receptor Antagonists
Ketamine/ Mg
Which medications are useful in neuroprotection?
CCB
Growth Factors
What is the gold standard for diagnosis & treatment of brain tumors?
Biopsy
What determines the morbidity of brain tumors
Size
Rate of Growth
Proximity to structures
Invasion of structures
Disruption of BBB
Vasogenic Edema
Persistence of edema after resection
Impaired Autoregulation in parenchyma surrounding
The professor in class stated what 2 major things determine brain tumors morbidity
Type & Growth Rate
Glial cells provide
Support & nourishment to neurons
What are Oligodendrocytes?
Cells responsible for forming the myelin sheath in the CNS
What is the purpose of Ependymal cells
Line the ventricles of the brain & spinal cord
Which brain tumor type is usually slow growing & often benign
Meningiomas
Pituitary gland is responsible for
Hormone production
Why contrary rumors cause visual disturbances?
Proximity to optic nerve
Which brain tumor class is aggressive & the most common
Glioblastoma Multiforme (most deadly)
Which brain tumor is common in children
Medulloblastomas, develops in cerebellum (area responsible for balance & coordination)
Type of Primitive Neuroectodermal Tumor (PNET)
What is the most common type of Schwannoma?
Vestibular Schwannoma
Can lead to hearing loss & balance problems
How to manage hemodynamics with brain surgery
Avoid HTN, since it may increase bleeding & brain edema
What medications can be used in hemodynamic monitoring during brain surgery?
Short active Beta Adrenergic Antagonists like Esmolol, labetalol, nicardipine or clevidipine
PEEP should not exceed
10cmH2O
Which surgery is commonly related to VAE?
Posterior Fossa Tumors
Posterior Fossa Tumors can cause
Altered Respiratory patterns
Cardiac Dysrhythmias
Cranial nerve dysfunction
What can be used for VAE detection?
Precordial Doppler
Transesophageal Echocardiogram
How to manage VAE
Notify surgeon to flood field
100% oxygen
Aspirate through CVC positioned at the junction of the superior vena cava & right atrium
Supportive care
Vasopressors, fluids & Inotropes
If possible, place head at level of heart
Stop use of nitrous oxide to prevent increase in air bubble
Consider PEEP cautiously as it can exacerbate systemic HOTN
Blood sugar range
90-180
Use short acting agents
IntraOperative hyperglycemia is associated with
Increased postop infections
How to treat hypoglycemia
50% Dextrose 20-50mL
Hyperglycemia effects on blood vessels
Damage to small blood vessels
Decreased O2 supply
All leads to cell death
Hypoglycemia effects in the brain
Lack of energy to brain
Leads to irreversible cognitive damage
How can coughing & vomiting be managed
Low dose Remi
IV intratracheal lidocaine
Zofran
What medication needs to be avoided in lymphoma patients & post pituitary surgery
Dexamerhasone due to diagnostic interference & hypothalamic pituitary adrenal axis suppression
What is Electroencephalography (EEG)
Monitoring brain electrical activity to detect abnormal patterns, ischemia or seizure
Motor evoked potentials monitors
Response in muscles to brain stimulation
Assess motor pathways
SSEP assesses
Sensory pathways by stimulating peripheral nerves
Most common
BAEPs (CN 8) assesses
Auditory pathways
Common during surgery near brainstem
Small latency increases with deep anesthesia or cold irrigation fluids
VEPs assess
Visual pathway integrity
Electromyography (EMG) detects
Abnormal muscle activity & provides information on nerve function
Mannitol should be used cautiously in patients with
CHF
Renal Failure
Pulmonary Edema
Maintain brain volume & ICP with mild
Hyperventilation ( will cause hypocapnia, which will cause constriction & decrease CBF
During brain surgery, it’s best to avoid increases in ICP until the
Dura is opened
When can gas be used during surgery?
Once monitoring is done
Maintain fluid balance with
Dextrose free iso osmolar crystalloids or colloids
What causes an increased risk of VAE
Operative site is above the level of the right atrium with open, non collapsible venous channels
VAE occurs in
30-75% of all sitting posterior fossa surgeries
Air entrainment can cause
Impaired gas exchanges
Intrapulmonary shunting
Hypoxemia
Decreased end expired CO2
Potential arrhythmias
Decreased CO
Severe pulmonary HTN
Hemodynamic collapse
Precordial Doppler can detect
0.25mL of air in the heart
Qualitative Monitor
TEE is more sensitive for detecting VAE but more
Cumbersome & invasive
Quantitative
What medications need to be used cautiously due to neurological assessment
Narcotics
What are some common concerns with pituitary surgery
Endocrinopathy manifestations
Electrolyte disturbances
Risk of Cabernous sinus
Carotid artery injury
Prop assessment of visual fields
Hormone disturbances Risk
Acromegaly can cause
Difficult airway management
Risks hypertrophic cardiomyopathy
Cartilage is stenosed
What is Cushing syndrome
Hypercortisolism
Glucose intolerance
Increased skin fragility
HTN
With TSH Secreting Tumors, ensure
Euthyroid state before surgery
Pituitary surgery places a patient at increased risk for what 2 things
SIADH
DI
How to manage SIADH?
Water Restriction
Demeclocycline (tetracycline ABX inhibiting ADH action in renal tubules)
Desmopressin
How to manage DI
Fluid & electrolyte replacement
HALLMARK IS POLYURIA WITH DILUTE URINE
What can prevent CSF leaks
Use of lumbar subarachnoid catheter
SIADH can lead to
Intravascular volume overload
Hypothermia
Extracellular body water is usually normal
What things should be considered when a patient comes in for a Ventriculoperitoneal (VP) shunt
Can’t control airway (are often lethargic & have swallowing difficulties)
Considered a full stomach
RSI them especially with revisions
Which part is painful during VP surgery
Tunneling of catheter
During VP surgery, what needs to happen to pass the shunt
Keep ETCO2 low
Chiari malformation is when the
Cerebellar tonsils descend into the spinal canal
Deep brain Stimulation requires
MAC/local/patient cooperation during electrode placement to assess functional response
(General during battery placement)
What grading system assesses clinical symptoms of a cerebral aneurysm surgery
Hunt & Hess Grading Scale
(Intubate with Grade 3)
Which grading system assesses GCS & motor deficits
World Federation of Neurological Surgeons Grading Scale
Diameter of an aneurysm is linked to
Rebleeds and those larger than 6mm generally require surgical treatment
Size of a small aneurysm?
Giant?
Small <10mm
Giant >24mm
What are the symptoms of SAH?
Severe HA
N/V
Photophobia
Seizures
Focal Deficits
Altered consciousness
How is SAH diagnosed
Non contrast head CT
What are risk factors of SAH?
> 40years
Female
Smoking
HTN
Connective Tissue Disorders
Circle of Willis is where
85% of aneurysm occur
10% arise from vertebrobasilar system
Which aneurysm must you clip?
Multisaccular
Large with wide neck
Near major vascular structures
(Cannot be coiled if neck is too wide)
Multiple aneurysms are associated with
Polycystic kidney disease
What are considerations for the rupturned aneurysms
Risk of rebleeding
Cerebral vasospasm can occur within 72 hrs up to 14days
Hydrocephalus
Cardiac dysfunction
Neurogenic pulmonary edema
Seizures
When should treatment happen for SAH
Within first 48 hours & before increased risk of cerebral vasospasm
During surgical clipping, SBP should be maintained at
<160, can change once clip is secured
Verapamil will
Directly stop a spasm
Saccular aneurysms are usually amenable to
Clipping
How is Burst Suppression used during clipping
Used during exposure
Achieved with Prop
Additional pressors may be needed to maintain CPP
Adenosine is given for
Circulatory collapse
It also decompresses the aneurysm sac for safe clipping w/o prolonged HOTN
International subarachnoid aneurysm trial has better
Outcomes in patients with coiling vs clipping
Clipping or coiling involves giving heparin, so what should be available
Protamine 50-100mg
Coiling in aneurysm with clover shape can cause
Coil migration
What are the clinical presentation of AVMs
Cerebral Hemorrhage
HA
Seizures
Signs of cerebral ischemia due to steal effect
What is the grading system for AVMs
Spetzler Martin Geading System which is based on size, eloquence of adjacent brain & pattern of venous drainage
AVMs are graded through levels
1-5 with higher grades indicating higher surgical risks
Normocapnia is a level of
PaCO2 35-45mmHg
What is possible with Chiari Decompression
Back of neck is painful
CSF leak possible since it is close to brainstem
When managing stroke, onset of s/s can o onset of treatment should be
Within 4 hours, but before 9 hours for ischemic stroke
Challenges of carotid endarterectomy
COPD
Not cooperative
Uncompensated CHF
RLS
What are the clinical manifestations of Hyper Perfusion syndrome
HA
HTN
Seizures
Focal neurological deficit
What are the risk factors for Hyper Perfusion Syndrome
Severe carotid stenosis
Poor BP control
GA
Lack of antihypertensive therapy post discharge
Chronic high grade carotid stenosis leads to
Reduced cerebral perfusion & compensatory vasodilation of cerebral vessels
Once perfusion is restored after endarterectomy,
The normal blood flow exceeds the capacity previously dilated cerebral vessels to autoregulate, leading to hyperperfusion
Due to prolonged ischemia & endothelial damage, the auto regulatory mechanisms are
Impaired, unable to constrict appropriately in response to increased perfusion pressure
Hyperperfusion can lead to
Mechanical stress & inflammation causing disruption of BBB, resulting in NT in edema & hemorrhage (due to fluid & protein leak)
Potential hemorrhage
Hyperperfusion & BBB disruption will trigger
Release of inflammatory cytokines & oxidative stress
This will exacerbate endothelial injury & neuronal damage
What are the procedures for epilepsy
Temporal lobectomy with amygdalohippocampectomy & less invasive SEEG
Antiepileptics can
Increase metabolism of muscle relaxants, opioids & dex requiring higher doses of
With TBI, maintain CPP
Above 60mmHg & avoid excessive HTN
What is Moyamoya disease
Progressive cerebrovascular disease characterized by stenosis or occlusion of arteries at the base of the brain
Hypothermia can cause
Coagulation problems
Me Fort fractures occurs when
The midface separates from the skull base due to blunt force trauma
Type 1 Le Fort fx
Horizontal injury
Type 2 Le Fort
Pyramidal injury
Type 3 Le Fort
Extensive transverse injury
Le Fort fx can
Obstruct the airway/aspiration risk due to full stomach risk
Cause significant bleeding
Nerve damage
Hematoma formation
Ocular complication
