Determinants and Assessment of Cerebral Tissue Perfusion

Components of consciousness

arousal (alertness)content (awareness)

arousal (alertness)

-Patients ability to respond (eye opening) - can have eyes open , primal instinct, but not know their name-Maintaining wakefulness-Evaluates Brainstem-GCS is most frequently used tool to identify changes in arousal

content (awareness)

Assessment of cognitive component of consciousness - higher level of functioning, evaluation to person, place, and timeEvaluates the cerebral hemispheresOrientation to person place and time

In depth Clinical Assessment

•Beyond the assessment of arousal and content, a more in depth neurological assessment includes•Assessment of pupillary and oculomotor reactions, vital signs, and cranial nerve reflexes

respirations

the most valuable information because it can be correlated with anatomic level of dysfunction; medulla controls respiratory rhythm and pattern. when respirations are affected, the medulla is affected.

cheyne stokes respirations

a regular crescendo-decrescendo pattern with increasing then decreasing rate and depth of respirations followed by a period of apnea; hyperventilation with periods of apnea

central neurogena hyperventilation

A sustained pattern of rapid, regular, deep respirations (hyperpnea)

apneustic breathing

Prolonged inspiration with a pause at full inspiration followed by expiration and a possible pause following expiration; full inspiration and full expiration

cluster breathing

Clusters of several breaths with irregular periods of apnea between clusters

ataxic respirations

respirations that are completely irregular in pattern and depth with irregular periods of apnea

pupillary reactions

provide information about the location of lesions or mass effect from cerebral edema resulting in increased ICP; ICP can compress cranial nerves, resulting in abnormal pupil reaction to light

constricted pupils

can indicate pons lesions or opiate drug overdose

dilated fix pupils

emergency action required, indicative of ischemia or anoxia, late indication of brain anoxia**could also be on cocaine/ meth

unilaterally dilated and fixed pupil

may indicate compression of the oculomotor nerve (CNIII) on the same side (ipsilateral) as the lesion; one is dilated one is constricted, when compressing CN3, no constriction and dilation, lesion on ipsilateral (same) side

Oculomotor Responses

2 reflexes used to determine brain stem integrity-Oculovestibular reflex (caloric)-Oculocephalic reflex (doll's eyes)2 reflexes used to determine brain stem integrity-Oculovestibular reflex (caloric)-Oculocephalic reflex (doll's eyes)-Tests cranial nerves•III—oculomotor - dolls•IV—trochlear - dolls•VI—abducens - dolls•VIII—acoustic - caloric

Doll's eyes present

eyes move right in relation to head moving left; NORMAL. if the doll's eyes are absent, eyes do not move in relation to the head. direction of vision follows head to the left = ABNORMAL

oculovestibular reflex (cold caloric test)

cold water in ear canal causes nystagmus . A is normal, eyes look at it, CN 8 is ok .B and C are abnormal; one looks straight, the other looks sidewaysC = CN 8 not working , brain stem injury

Abnormal Posturing

•In response to noxious stimuli indicates either dysfunction of either the cerebral hemispheres or the brainstem.

decorticate posturing

•- after something like a sternal rub-Abnormal flexion - arms up to chest, flexed, legs extend and rotate internally ; can be reversible-Indicates cerebral hemisphere dysfunctionupper arms move upward to the chest; elbows, wrists, and fingers flex; legs extend with internal rotation; feet flex.

decerebrate posturing

-Abnormal extension; arms extended by sides, jaw clenched, neck extended, feet plantar flexed-Indicates brainstem dysfunction-More ominous signneck is extended with jaw clenched; arms pronate and extend straight out; feet are plantar flexed

Criteria For Brain Death

•Completion of all appropriate diagnostic and therapeutic procedures with no possibility of brain function recovery - dolls eyes, caloric test, etc•Unresponsive coma•No spontaneous respiration - have to be no a vent bc not initiating breaths•No brain stem function (ocular or caloric)•Isoelectric (flat) EEG•Persistence of these signs for an appropriate observation period

Dementia

•A group of conditionsin which cortical functionis decreased,impairing cognitive skills and motor coordination•Issues with memory are common and include short-term memory losses as well as confusion of historical events•Behavioral and personality changes interfere with relationships, work, and activities of daily living•Causes: vascular disease (e.g., atherosclerosis), infections, toxins, and genetic conditionsdoesnt mean they have alzheimer's ; umbrella term for alzheimer's vascular, lewy body, and frontotemporal

Alzheimer's Disease

•Most common form of dementia•Brain tissue degenerates and atrophies, causing a steady decline in memory and mental abilities•The exact etiology is unknown, but associated with three pathologic characteristics-Amyloid plaques mix with a collection of additional proteins, neuron remnants, and other nerve cell pieces-Neurofibrillary tangles - abnormal collections of a protein called tau that clumps together, cause thickening, neuron gets diseased, loss of connection between neurons-Connections between neurons responsible for memory and learning are lost; neurons cannot survive when their connections to other neurons are lost; neurons are basically dyingPlaques and debris get caught in neurons2 causes = amyloid plaques and neurofibrillary tangles

alzheimer's risk factors and complications

•Not a part of normal aging, but risk increases with age•Rates are higher in women•Rates may be higher in those persons with less education for unknown reasons•Additional risk factors: family history, hypertension, hypercholesterolemia, diabetes mellitus, and history of traumatic brain injury•Prevalence and mortality rates are on the rise d/t people living longer•Complications: infections (primarily pneumonia and urinary tract infections), injuries related to falls, malnutrition, dehydration, and decubitus ulcerssedentary, afraid t leave their house, sit, lie down, as neurons die, the brain shrinks, can see on MRI or CT

Alzheimer's Disease Manifestations

•Insidious onset•Course may extend 10-20 years•Include: memory loss, problems with abstract thinking, difficulty finding the right word to express thoughts or even follow conversations, difficulty reading and writing, disorientation (even in familiar surroundings), loss of judgment, difficulty performing familiar tasks, personality changes, hallucinations, and incontinence of bowel or bladder4 categories of symptoms = 1. Cognition = mental declines, confusion, memory loss, inability to recognize common things like family, behavior change2. Behavior changes =3. Mood = depressed, angry, mean4. Full body = incontinence of bowel and bladder, loss of appetite

alzheimer's disease dx

•Diagnosis is often difficult and often involves ruling out other conditions•Diagnosis: history, physical examination (including a neurologic assessment and mental status evaluation), head computed tomography, head magnetic resonance imaging, and head positron emission tomography (iv glucose see uptake)

alzheimers disease tx

-No cure for AD, nor are there any therapies that will slow the progression-Medications to manage symptoms and maximize functioning:-Other strategies: memory aids (e.g., calendars), nutritional support, physical exercise, cognitive activities, safety precautions (e.g., supervision and removing clutter), maintaining a calm environment, social interactions, coping strategies, and supportMeds just slow the process, dont cure anything, decline leads to inability to carry out simple task

Seizure Disorder

•Seizure -Seizures are changes in the brain's electrical activity. This can cause dramatic, noticeable symptoms or even no symptoms at all. Neurons misfire•The symptoms of a severe seizure are often widely recognized, including violent shaking and loss of control.•Can occur secondary to trauma, hypoglycemia, electrolyte disorders, acidosis, infection, tumors, or chemical ingestion (e.g., medications, illicit drugs, and alcohol)

2 Types of seizures

Based on the type of behavior and brain activity, seizures are divided into two broad categories:-Generalized and-Partial (also called local or focal).Classifying the type of seizure helps doctors diagnose whether or not a patient has epilepsy.

6 types of Generalized seizures(Produced by the entire brain)

grand mal or generalized tonic clonic - unconsciousness, convulsions, muscle rigidityabsence - brief loss of consciousnessmyoclonic - sporadic (isolated) jerking movements, maybe just of their hand or somethingclonic - repetitive jerking movementstonic - muscle stiffness rigidityatonic - loss of muscle tone

grand mal seizure

•In this type of seizure, the patient loses consciousness and usually collapses.•The loss of consciousness is followed by generalized body stiffening ("tonic") for 30 to 60 seconds, then by violent jerking ("clonic" phase) for 30 to 60 seconds, after which the patient goes into a deep sleep (the "postictal" or after-seizure phase).•injuries and accidents may occur, such as tongue biting and urinary incontinence.

Partial (focal) seizure

•All seizures are caused by abnormal electrical disturbances in the brain. this is when seizures occur when this electrical activity remains in a limited area of the brain.can be divided into simple - not affecting awareness or memory and complex - affecting awareness or memory of events before, during, and immediately after the seizure and affecting behavior•Usually last just a few seconds•Some people may experience auras (unusual sensations just prior to an impending seizure) that are actually simple focal seizures in which the person maintains consciousness•Seizure characteristics tend to be similar with every seizure

simple focal seizure

Individual remains conscious but experiences unusual feelings or sensations that can take many forms (e.g., sudden and unexplainable feelings of joy, anger, sadness, or nausea; hear, smell, taste, see, or feel things that are not real)

complex focal seizure

Individual has changes in or loss of consciousness, producing a dreamlike experience; may display strange, repetitious behaviors (e.g., blinking, twitching, moving one's mouth, walking in a circle) called automatisms

seizure diagnosis

history (including a description of the seizure activity if possible), physical examination, head computed tomography, head magnetic resonance imagining electroencephalogram (EEG) - measures brain waves and indicates sz

seizure treatment

-During a seizure, positioning the individual on his or her side, protect head, do not force items in between the individual's teeth, do not restrain the individual, manage airway, oxygen therapy, muscle relaxants, anti-seizure agents, and allow to sleep following the seizure-For epilepsy, anti-seizure agents, surgical resection or transaction, wear a medical-alert bracelet, and avoid precipitating factors (e.g., sleep deprivation, alcohol, illicit drugs, and excessive stimuli)Don't want to intrude or force anything ; loosen tight clothingTriggers = sleep deprivation, alcohol, elicit drugs, excessive stimuli like bright lights and loud noises

Autoregulation

•Brain Regulates its own perfusion by this. Other organs do too, has ability to make sure perfusion is proper.•Amount of Blood Flow through the brain•Ability to self regulate is lost with head injured patients as long as MAP is between 60 to 150. will always have enough oxygenated blood . If MAP is outside this range, NOT enough oxygen to the brain

ICP and CPP

•2 pressures within the cranial vault that significantly impacts neurological status

ICP

intracranial pressure; the pressure exerted by the soft contents within the cranial vault against the cranial bones; closed system

CPP

•cerebral perfusion pressure; the amount of pressure used in providing blood flow to the brain. Need this in order for blood to get up to the brain. CPP = MAP - ICP•Normal is 60-100•The pressure gradient is necessary to drive blood from the aorta into the cranial vault•Space Occupying Lesion (SOL) ↑ ICP and ↓ CPP•↑ ICP = ↓ LOCICP pushes down on the blood trying to flow up to the brainAn ICP of 10, MAP of 100. 100-10 = CPP of 90. if MAP decreases and or ICP increases, CPP decreases and brain isnt perfusing properlyAs ICP increases, LOC decreases

Intracranial Vault Contents

•Brain Volume Remains Relatively Stable; cant make it bigger or smaller-Brain - 80 percent-Blood -10 percentCSF -10 percentVault has limited space. Volume of each compartment stay relatively stable; no room for a space occupying lesion, bleed, or blood clot; anything else coming in increases pressure in brain

Monro-Kellie Hypothesis

•A change in volume of any one of these components must be accompanied by a reciprocal change in one or both of the other components•If not, increased ICP occursBrain cavity can compensate to a certain point; when decompensation begins, pressure increasesFirst thing to change is CSF leaving head. Second is the blood starts moving out, decreased blood flow to the head. When mass gets so big, pts neuro status decompensates, increased ICP.

Intracranial Pressure (ICP)

•The combination of 3 intracranial component volumes form the total intracranial volume and ICP•Normal ranges: 0-15 mm Hg ; we all have a little pressure especially form coughing or sneezing or something like that•> 15 = sustained increase•> 20 = focal areas of ischemia•> 40 = global ischemia•> 50 life threatening•↑ ICP = ↓ O2•Treat > 20 mm Hg

Causes of Increased Intracranial Pressure

Include any dynamic that cause changes in the cranial vault volume (CSF, brain, blood)1. increased CSF volume - hydrocephalus2. increased brain tissue volume - ischemia and necrosis, infection, hemorrhage, tumor, edema3. increased blood volume (cerebral vasodilation) - things that cause cerebral arteries to dilate; acidosis - keep in alkalotic side if on vent**, high arterial PaCO2, hypoxia4. increased intra thoracic or intra abdominal pressure - coughing, straining (valsalva), suctioning, PEEP, hip flexion - someone sitting in chair increases pressure in the abdomen5. decreased cerebral venous drainage - supine position with HOB flat, neck flexion or rotation

s/s of increased ICP

•Headache•Nausea/vomiting•Decline of LOC, drowsiness•Confusion•Agitation•Seizures - can occur during any insult to the CNS•Neck Stiffness/back pain•↓ GCS (↓ LOC)•3Rd nerve Compression (oculomotor)•Cushings Triad (Severe)-Hypertension (Wide)-Bradycardia- Irregular REspiration

cushings triad

very late sign, body trying as hard as it can to increase blood flow to the brain; BP goes up, wide pulse pressure, medulla oblongata compressed = bradycardia. Also irregular respiration, brain herniation down the back of the neck, very ominous sign****hypertension with wide pulse pressure, bradycardia, irregular respiration

cerebral edema

•Increase in the fluid content of brain tissue•Results in increased brain tissue volume•It occurs after brain insult from trauma, infection, toxins, hemorrhage, tumor, hypoxia, infarction.•Leads to increased ICP and causes herniation

Herniation

•Feared complication of increased ICP•Refers to displacement of brain tissue

Hyprocephalus

•Excess fluid within the cerebral ventricles caused by interference of the CSF, of ten caused by defective reabsorption or increased CSF production•May develop from infancy to adult.•Various types•Normal pressure hydrocephalus (NPH)-Dilation of the ventricles without increased pressure-Occurs later in life-Ventricles are enlarged and CSF is minimally elevated-Often idiopathic•CM: triad: Confusion, gait disturbance, incontinence. (symptoms from too much fluid in there)

Parkinson's Disease

•Progressive condition involving the destruction of the substantia nigra in the brain•Results in a lack of dopamine•When approximately 80% of the dopamine-producing cells are destroyed, movement issues that typically include tremors (involuntary shaking) of the hands and head develop•The tremors may disappear or decrease when the body part is moved intentionally•Cause: unknown•For unknown reasons, more common in men and those living in rural areas

Parkinson's Symptoms

•tremor of the hands, arms, legs, jaw and face•bradykinesia or slowness of movement•rigidity or stiffness of the limbs and trunk•postural instability or impaired balance and coordination

parkinson's diagnosis and treatment

•Diagnosis: history, physical examination (including neurologic assessment), and other tests to rule out other conditions.•Treatment:-No cure-Medications (e.g., levadopa and dopamine agonists)-Physical and occupational therapy along with assistive devices-Coping strategies, support, proper nutrition, and adequate rest can promote and maintain overall health