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Page 1: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Chapter 14

Page 2: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Level of Consciousness“ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration of the individual’s condition”

Table 14-3 Levels of Altered Consciousness

Page 3: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Alterations in Cognitive NetworksFull consciousness: awareness of self and

the environment

Arousal: state of awakenessMediated by the reticular activating system

Content of Thought: all cognitive functionsAwareness of self, environment and affective states (moods)

Page 4: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Alterations in ArousalCauses Table 14-1 & 14-2

StructuralDivided by location above or below tentorial plate

MetabolicPsychogenic

Page 5: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Alterations in ArousalPathological processes

Infectious, vascular, neoplastic, traumatic, congenital, degenerative, polygenic

MetabolicHypoxia, electrolyte disturbances, hypoglycemia, drugs and toxins

Page 6: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Alterations in Arousal“range from slight drowsiness to coma”

Coma – produced by eitherBilateral cerebral hemisphere damage or

suppressionBrain stem* lesions or metabolic

derangement that damages and suppresses the reticular activating system

*midbrain, medulla, pons (Figure 12-5)

Page 7: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration
Page 8: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Alterations in Arousal• Clinical manifestations : critical for evaluation

“extent of brain dysfunction”“index for identifying ↑ or ↓ CNS function”1) Level of consciousness2) Pattern of breathing

- Post hyperventilation apnea (PHVA) - Cheyne–Stokes respiration (CSR)

3) Pupillary changes (size and reactivity)4) Oculomotor response (position and reflexes)5) Motor response (skeletal muscle)

Page 9: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration
Page 10: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

President Lincoln April 14, 1865

Page 11: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Pathway of the bullet

Page 12: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Clinical Manifestations

Page 13: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration
Page 14: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Clinical Manifestations

Page 15: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Clinical Manifestations

Page 16: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Decorticate & Decerebrate

Page 17: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Brain Death“never recover nor maintain internal

homeostasis”

Total Brain Death – criteria (5): (cerebrum, brain stem & cerebellum)

Completion of all appropriate and therapeutic procedures

Unresponsive coma (absence of motor and reflex responses)

No spontaneous respirations (apnea)

Page 18: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Brain death – criteria

No ocular responsesIsoelectric EEG: 6 to 12 hours without hypothermia/depressant drugs

Page 19: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Cerebral Death “death exclusive of brain stem and

cerebellum”

No behavioral or environmental responsesBrain continues to maintain internal

homeostasisSurvivors

ComaVegetative state (“wakeful unconscious state”)Minimal conscious state

Locked-in syndrome

Page 20: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Seizures “Sudden, transient alteration of brain

function caused by an abrupt explosive disorderly discharge of cerebral neurons”

Alteration in brain function (transient)Altered level of arousal

Convulsion – seizure with tonic-clonic movement

Epilepsy – seizures recur without treatment (5 to 10/1000)

Page 21: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration
Page 22: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Conditions - Seizures

Cerebral lesions

Biochemical disorders

Cerebral trauma

Epilepsy

Page 23: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Seizures Partial (focal/local)

Simple, complex, secondary, generalized

Generalized (bilateral/symmetric)

Unclassified

Page 24: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Seizures Epileptogenic focus

Group of neurons that appear to be hypersensitive to sudden depolarizationHyperthermia, hypoxia, hypoglycemia,

hyponatremia, sensory stimulation and certain sleep phases

Aura – partial seizure precedes generalized

Prodroma – early manifestation – hours to days before

Page 25: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Seizures Tonic – contraction

Excitation spreads to subcortical, thalamic and brain stem areas

Loss of consciousness

Clonic – relaxationInhibitory neurons of cortex, anterior

thalamus and basal ganglia

Page 26: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Alterations in Awareness

MemoryRetrograde amnesia – past memoriesAntegrade amnesia – new memoriesTemporary or permanent (severe head injury or

Alzheimer disease)

Executive attention deficits Inability to maintain sustained attention Inability to set goals Working memory deficitTable 14-6 Clinical manifestations

Page 27: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Memories:amygdala hippocampus thalamus prefrontal cortex

Page 28: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Data Processing Deficits Agnosia – failure to recognize the form

and nature of an object: CVATactile, visual, auditory

Dysphasia – inability to arrange words in logical order: CVA (middle cerebral artery-L cerebral hemisphere)

Expressive – cannot find words, difficulty writing (Broca’s area)

Receptive – language is meaningless (inappropriate words, neologisms) – Wernicke

Page 29: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration
Page 30: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Data Processing Deficits

Dementia*Progressive failure of cerebral functions

that is not caused by an impaired level of consciousness

↓ orienting, memory language and executive attention networks

Table 14-13 Comparison of Delirium & Dementia

Page 31: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

DementiaDegeneration of neurons

Compression-space occupying lesion

Atherosclerosis

Genes-Alzheimer & Huntington diseases

CNS infection –HIV, Creutzfeldt-Jakob

“nerve cell damage and brain atrophy”

Page 32: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Alzheimer Disease (AD)

Familial onset

Early-onset-chromo mutations # 21 (very rare)

Late onset-90% cases ? Chromo #19*

TheoriesMutation for encoding amyloid precursor proteinAlteration in apolipoprotein E*Loss of neurotransmitter of choline

acetyltransferase

Page 33: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Alzheimer Disease (AD)Neurofibrillary tangles

Senile plaques

Clinical manifestationsForgetfulness, emotional upset, disorientation,

confusion, lack of concentration, decline in abstraction, problem solving and judgment

Diagnosis – R/O other causes

Page 34: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration
Page 35: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Burden of Alzheimer’s Disease5.4 million Americans 16 million by 20506th leading cause of death:#prevented, cured, slowed>/= 65y/o average survival: 4-8 yrs, may up to 20yrsCaregivers burden: 60% emotional stress

: 30%depressedCost 2011: $183 billion $1 trillion by 2050

J.Alzheimer’s Assoc. March 2011

Page 36: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Know the SignsMemory loss that disrupts daily lifeTrouble planning or solving problemsDifficulty completing tasksConfusion with time or placeTrouble understanding images and spatial

relationshipsNew problems with speaking or writing wordsMisplacing things and inability to retrace

stepsDecreased or poor judgment

Page 37: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Know the SignsSocial withdrawal Change in mood or personality

Review Table 14-14

Page 38: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Cerebral Hemodynamics

CBF – blood flow

CPP – perfusion pressure

CBV – blood volume

Cerebral oxygenation – “critical factor”

Page 39: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Injury States↓ cerebral perfusion

Normal perfusion but ↑ intracranial pressure (ICP)

↑ cerebral blood volume

SO: “must maintain CPP and control ICP”

Page 40: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Increased Intracranial Pressure (IICP)

↑ intracranial content, edema, excess CSF or hemorrhage

Normal 5 to 15 mmHg

Stages 1-4 (Figure 14-10)Stage 1 vasoconstriction and external

compression of venous system - ↓ ICP (autoregulation)

Stage 2

Page 41: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration
Page 42: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

GeneralAutoregulation - blood vessel

diameter to maintain a constant blood flow is lost with ↑ ICP

↑ vasoconstriction to elevate BP > ICPa) ↓O2 ↑CO2 → deterioration

b) small pupils, neurologic hyperventilation, widened pulse pressure and ↓HR

Local vasodilation 2° to ↑ CO2 →↑ BV →↑↑ ICP → approaches SBP - ↓ perfusion with severe hypoxia/acidosis

IICP – not evenly distributed throughout the cranial vault

Page 43: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration
Page 44: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Cerebral Edema• Increase in the fluid (intracellular or extracellular)

within the brain (↑ volume)

• Results: trauma, infection, hemorrhage, tumor, ischemia, infarct or hypoxia

1) Vasogenic: BBB is disrupted - ↑ plasma protein to extracellular space - ↑ ICP

2)Cytotoxic: toxic factors → failure NA-K+ transport system: K+ out, H2O in

3)Ischemic (infarction): vasogenic and cytotoxic → cell necrosis → lysosomes → BBB↑

4)Interstitial (hydrocephalus): ↑ volume about ventricles

Page 45: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Hydrocephalus (Types Table 14-16)

Excess fluid within the cranial vault, subarachnoid space or both

Caused by interference in CSF flow

↓ reaborption↑ fluid productionObstruction

Infancy through adulthood

Page 46: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Spinal Shock “complete cessation of spinal cord function

below the lesion”

• Complete flaccid paralysis

• Absence of reflexes

• Marked disturbance of bowel and bladder function

• Days to weeks– Return of spinal reflexes → hyperactive

→ spasticity, rigidity

Page 47: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Michael J Fox

Page 48: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Parkinson Disease After age 40 – peak onset 58 – 62 years

107 to 187 per 100,000

Severe degeneration of the basal ganglia involving dopaminergic nigrostriatal pathwayDopamine: inhibitory neurotransmitterAcetylcholine: stimulatory neurotransmitter

IMBALANCE of” neurotransmitters motor modulation”

Ach________________Dopamine

Page 49: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Parkinson Disease

Page 50: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Parkinson Disease Clinical manifestations

Tremor at restRigidity (muscle stiffness)Bradykinesia (poverty of movement)Postural disturbanceDysarthria (uttering of words)Dysphagia (difficulty swallowing)Progressive dementia

Page 51: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration
Page 52: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration
Page 53: Chapter 14. Level of Consciousness “ the most critical clinical index of nervous system function, with changes indicating either improvement or deterioration

Parkinson Disease