Patho: Neuro-Brain

what is gray matter and its’ prupose?

- Nerve cell bodies, dendrites, and bundles of axons that serves to process information

What is white matter and its’ function?

Myelinated processes that allow
communication between gray
matter and the rest of the body

What does the frontal lobe control?

• motor control (premotor cortex)

• problem solving (prefrontal area)

• speech production (broca’s area)

what does the parietal lobe control?

touch perception (somatosensory cortex)

body orientation and sensory discrimination

What does the occipital lobe control?

sight (visual cortex)

visual reception and interpretation

What does the temporal lobe control?

-auditory processing (hearing)

-language comprehension (Wernicke’s area)

memory/information retrieval

What is the function of the midbrain?

controls involuntary eye movements and reflexes related to visual and audio information

What is the function of pons?

-relays messages from cortex to the cerebellum

-REM sleep (dreams)

-

What is the function of the medulla oblongata?

-regulates RR,HR, sleeping, digestion

-regulates muscle tone and movement

-initiates reflexes such as vomiting, swallowing, gagging, sneezing, coughing, and hiccuping

what is a stroke (CVA)?

Sudden death of brain tissue due to
a lack of oxygen when blood flow to
the brain is impaired (by blockage
or blood vessel rupture)

what are types of strokes?

ischemic (blockage)

hemorrhagic (rupture)

what are risk factors for stroke?

• hypertension

• diabetes

• obesity

• arterio/atherosclerosis

• -previous CIA/TIA

• -atrial fibrillation

• -age

• -genetics

• -sleep apnea

• 
  

Are most strokes ischemic or hemmorhagic?

ischemic - 87%

what are the warning signs of a stroke?

B: balance

E: eyes

F: face

A: arms

S: speech

T: time

describe the difference between a hemorrhagic stroke and an ischemic stroke?

Hemorrhagic: Caused by the rupture of a blood vessel in the brain, leading to bleeding into the intracranial
cavity and brain tissue death.

Ischemic: Caused by a blockage in a
blood vessel in the brain, leading to the
hypoxia and death of brain tissue distal
to the blockage

what are bleeding causes of a hemorrhagic stroke?

• increased ICP

• compression of brain tissue

• decreased cerebral perfusion

What is an intracerebral hemorrhage?

• when bleeding occurs directly into the brain tissue

What is a subarachnoid hemorrhage?

• when bleeding occurs directly in the subarachnoid

• - considered a neurologic emergency

What are the causes of a subarachnoid hemorrage?

• trauma

• arteriovenous malformation (AVM)

• ruptured intracranial aneurysm ( most common)

what are causes of an intracerebral hemmorage?

• - most common cause is chronic hypertension

• other causes include cerebral amyloid angiopathy, brain tumors, coagulation disorders, trauma, cocaine or illicit drug use

what are symptoms of hemorrhagic strokes?

• thunderclap headache

• contralateral hemiplegia

• LOC

• increased intracranial pressure

• coma/death/posturing (without treatment)

• spasticity

What are arteriovenous malformation (AVM)?

• form a tangled mass of dilated blood vessels that are fragile

• - capillary network is missing

• - usually present at birth but symptoms often appear before 30

describe AVM before rupture

• often asymptomatic

• - may cause chronic headache

• - seizures (20% of cases)

describe AVM after rupture

• subarachnoid or intracerebral hemorrhage

• - symptoms depend on location and size

What is an intracranial aneurysm?

• weakened area of a cerebral artery that balloons outward

• - major concern is rupture which leads to bleeding into subarachnoid space

what are facts of ishemic strokes?

Interruption of larger arteries causes greater damage

• Collateral circulation mediates outcomes

• Clinical presentation varies based on the functional role of the affected part of the brain

what are types of ishemic strokes?

thrombotic stroke

embolic stroke

lacunar stroke (small vessel disease)

What is a thrombotic stroke?

• stroke caused by blood clot forming within a cerebral artery

• - forms mostly in middle cerebral artery (MCA)

what does a thrombotic stroke commonly develop from?

atherosclerosis

What is an embolic stroke?

when an embolus blocks a cerebral blood vessel

• - most often from heart, aorta, or common carotid artery

what is the most common cause/source of an embolic stroke?

atrial fibrillation

Why is a recurrent stroke more common from an embolic stroke?

the embolic source continues to exist

what does a lacunar stroke (small vessel disease) cause?

small ischemic lesions deep in the brain but not the cortex

• 
  

what is a lacunar stroke associated with?

cerebral small vessel disease and untreated hypertension

how may a lacunar stroke present itself?

• - pure motor deficits

• - sensory deficits

• -silent

What is a Transient Ischemic Attack (TIA)?

a warning sign

• - temporary interruption of blood flow to the brain

• - caused by cellular hypoxia without cell death so it is NOT a mini stroke

describe facts of a TIA

• considered a medical emergency and a warning sign of future stroke

• - 7-17% will have a stroke within 3 months of TIA

• - symptoms last less than 24 hours

what is the gold standard for any stroke patient?

rapid head CT to determine the origin

how can you determine the type of stroke?

• sudden headache

• agitation

• eye gaze impairment

• mydriatic pupils

• - the percentage of the symptoms are higher in hemorrhagic stroke

describe what happens to the cells during a stroke + ischemia

1. 1. lack of oxygen + glucose leads to a halt in ATPP production

2. 2. no ATP means cellular Na+/K+ pumps fail and intracellular Na+ builds up

3. 3. excess Na+ pulls water into cells causing them to swell and rupture

4. 4. meanwhile, distressed cells also release large amounts of glutamate, leading to neural excitotoxicity

5. 5. excess Ca+ is pulled into cells too leading to various problems like phospholipase activation, mitochondrial swelling, and apoptosis

How can a stroke cause brain swelling?

• - the blood-brain barrier becomes leaky

• - fluid moves into brain tissue (vasogenic edema)

• - brain tissue swells

• - intracranial pressure increases

What is a cerebral edema?

increased fluid in brain tissue

What are the effects/ where does a cerebral edema occur?

• - can occur inside cells or between cells

• - causes brain tissue swelling

• 
  

Why is cerebral edema so dangerous?

• - it compresses blood vessels

• -decreased oxygen delivery to brain tissue

• - increases intracranial pressure

• - can lead to brain herniation

what is increased ICP?

increase in the pressure inside the skull

what are the levels of normal and increased ICP?

normal: 5-15 mmHg

increased: >20-25 mm Hg

how can ICP rise?

from increases in brain tissue (cerebral edema or tumor), blood ( hemorrhage) , and CSF (hydrocephalus)

What is inside the skull?

brain, cerebral spinal fluid, blood

What does the Monro-Kellie Doctrine state?

states that the total volume of brain tissue, blood, and cerebrospinal fluid within the rigid adult skull is constant; an increase in one component should cause a decrease in another or intracranial pressure rises

what are examples conditions that increase the amount of space being occupied inside the skull, causing the other components (brain tissue, blood, or CSF) to shift to compensate.

–Hemorrhage causes CSF and brain matter to shift

–Increased CSF (hydrocephalus) causes blood and brain tissue shift

–Tumor causes blood, CSF, and brain matter to shift

What is herniation?

medical emergency where increased ICP causes brain tissue to move from its normal position in the skull into an area of less pressure

why is herniation important?

it can cause extreme deficits if left untreated

what should you monitor during a herniation?

Monitor for Cushing’s Triad:

•Hypertension (systolic)

•Bradycardia

•Irregular breathing

What are common post stroke defecits?

Neurological impairments vary in :

–Physical (motor/sensory)

–Cognition

–Mood (emotion, behavior)

What is Agnosia?

The inability to recognize or identify an object despite intact sensory function

• -individual can see, hear, or feel the object but can’t identify it

List and describe the different types of agnosia

–Tactile agnosia: cannot identify an object by touch

–Visual agnosia: cannot recognize an object by sight

–Auditory agnosia: cannot recognize sounds

What is dysphagia?

difficulty swallowing food or liquids

What is aphasia?

difficulty comprehending or expressing a language

What is the difference between the Broca’s area vs Wernicke’s area

broca: focuses on language production ( expressive)

wernicke: focuses on speech comprehension ( receptive)

Describe the outcomes of a left hemisphere stroke

•Right side hemiparesis or hemiplegia

•Speech, reading and writing deficits

•Difficulty with analytical thinking

•Frustrated, angry, depressed, cautious, slow to move

Describe the outcomes of a right hemisphere stroke

•Left side hemiparesis or hemiplegia

•Hearing deficit, spatial or temporal deficits

•Lack of facial recognition

•Euphoric, impulsive, denial of deficits, poor judgment

What can post-cva patients develop?

• -uti’s

• -depression

• -falls

• -pneumonia

• -PEs

• -DVTs

What is the ischemic core?

art where the stroke hits; where the brain tissue is destined to die

Describe the time increments of tissue and survival

1-60 seconds: loss of consciousness

2-4 minutes: glycogen and glucose stores are exhausted

4-5 minutes: cellular ATP stores are depleted, brain likely damage likely

6-10 minutes: brain damage highly likely

10+ minutes: irreversible brain damage (biological death)

How do you treat a stroke treatment?

•Goal is to RESTORE PERFUSION through clot busting drug- (Intravenous tissue-type plasminogen activator- tPA), surgical intervention, and/or supportive measures

What is meant by the window of opportunity for perfusion:

Critical time period during which the penumbra is at risk is when neurological deficits created by ischemia can be partly or completely reversed by restoring perfusion to the ischemic yet viable brain tissue.

What is the time frame for protecting the penumbra?

3 hours (4.5 hours in appropriate canidates) from symptom onset by giving tPA

what is TPA?

tissue plasminogen activator

• - converts plasminogen to plasmin, which breaks down the fibrin in blood clots, but it isn’t without risks

How do you treat a hemorrhagic stroke?

•Goal is to STOP THE BLEEDING through surgical intervention, B/P control, and ICP prevention and/or management

What are the protective brain structures

skull, meninges, cerebral spinal fluid, and blood brain barrier

Describe the meninges

• cover brain ( dura matter, arachnoid matter, pia mater)

What is the function of cerebral spinal fluid?

–Bathes brain, provides a cushion and nourishment

–Produced by choroid plexus in brain ventricles

What is a TBI

injury to the brain caused by an external force

What is common causes of TBI?

falls, motor vehicle accidents, firearm-related injuries, assualts

Why is TBI important?

Major cause of disability and death

Describe the types of TBI

Primary injury: Damage occurring at the moment of impact

•Caused by a direct external force

•Brain damage happens immediately

Secondary injury: Damage that develops later from swelling, hypoxia, or increased ICP

what are contributors to secondary TBI?

•Inflammation

•Cerebral edema (swelling)

•Increased intracranial pressure (ICP)

•Decreased oxygen delivery

•Decreased cerebral blood flow

What are the primary causes/sources of TBI?

1. - concussion

2. - coup-contrecoup injury

3. - intracranial hemorrhage/hematomas

What is a concussion?

•A form of mild traumatic brain injury caused by the transfer of energy (usually from an impact) to brain tissue

Describe the effects of a concussion

•Produces functional deficits without detectable structural damage

•Axonal injury is likely to be major contributor to altered cognitive function

•Repeated concussions can result in more prolonged recovery

What are common symptoms of a concussion?

nausea/vomiting, confusion, blurry vision, dizziness, or sleep disturbances

Describe the process of a concussion

Impact → brain moves → axons/cell membranes are stressed → cellular communication and metabolism become disrupted → temporary neurologic symptoms

What is a coup-contracoup injury?

•The brain is injured on opposite sides following a sudden impact or deceleration.

What are coup-contracoup injuries caused by?

MVCs, falls, and assaults.

Describe an epidural hematoma

•Fast, arterial bleed

•May show dilated pupil on one side

•May have initial LOC, return, then collapse again (“transient lucidity” or “lucid interval”)

•Headache, vomiting, weakness, walking/speaking difficulty, seizures

• blood collects between the skull and the dura matter

describe a subdural hematoma

•Slow, venous bleed

•Slow or delayed deterioration of consciousness; may be mistaken for stroke

•Many symptoms are the same as an epidural hematoma, but the onset is much slower

• - Blood collects between the dura and arachnoid mater

describe a subarachnoid hematoma

blood collects between the arachnoid at pia

describe a intraparenchymal hematoma

blood collects within the brain tissue itself

What happens when ICP > MAP

brain can no longer received enoigh oxygen

• sympathetic and parasympathetic nervous system activates

What is a Decorticate reflex? What does this indicate problems with?

where the arms are like C’s and move toward the cord

cervical spinal tract or cerebral hemisphere

What is a Decerebrate reflex? What does it indicate problems with?

extensor/ arms are like E’s

• Problems with the midbrain or pons

What is unilateral dilation?

problem with CN III)

•Compression of nerve on same side of herniation/mass

•Pupil might first take on an ovoid shape

What are constricted pupils?

pupils (pinpoint pupils)

–Hypothalamic lesion

–Certain drugs (ex. opiates)

What are bilateral, fixed and dilated pupils

•Ominous

•Suggests serious brainstem damage