Disorders of Consciousness Flashcards by Thao Hoang

what is consciousness?

a state of awareness to environment and self with a responsiveness to stimuli

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How is consciousness achieved and maintained?

Via action of the neurons that make up the Ascending Reticular Activating System (ARAS) in brainstem and cerebral cortex

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what is the reticular system?

a set of interconnected neurons in the brain stem consisting of 2 neurologic pathways

Ascending reticular activating system (ARAS)
Descending reticulospinal tracts

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which part of the reticular system originates in the upper pons and midbrain, projecting to the thalamus and hypothalamus and extending to the cerebral cortex, controlling levels of alertness

Ascending reticular activating system - ARAS

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which part of the reticular system
travels downward into the spinal cord and modulates spinal reflex activity
Doesn’t affect consciousness
Damage leads to loss or diminished reflexes

Descending reticulospinal tracts

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the outer layer of the cerebral hemispheres consisting of grey matter and controls the content of consciousness

Cerebral cortex

self-awareness, language, reasoning, spatial relationship, integration and emotions

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what is the difference between conscious and unconscious?

Conscious
- Awake, aware, alert and responsive to stimuli or in a normal state of sleep but responsive to stimuli
- Fast neuronal activity can be found all over the brain and signals can be passed between areas of the ARAS
Unconscious
- unaware and unresponsive to stimuli resulting from damage to the ARAS and/or the cerebrum
- A diminished transmission of signals from the ARAS to the cerebrum

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evaluation of an unconscious pt

Primary Survey (C-A-B)
- Circulation
- Airway
- Breathing
Vital Signs and Secondary Survey
brief history
- events surrounding loss of consciousness
initial PE
- General - evidence of trauma
- Neurologic Evaluation - CN deficits, Glasgow Coma Score

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circulation in a primary survey of an unconscious pt involves?

check pulse

No Pulse - start CPR
Pulse present = maintain circulation
- Is BP normal?
— Yes = No further intervention
— No = Treat appropriately (see later slide)
- Is rhythm regular?
— Obtain EKG to confirm

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Airway/Breathing in a primary survey of an unconscious pt involves?

Spontaneous regular respirations = monitor
No spontaneous respiration or ineffective respirations = provide assisted ventilation
- Mouth-to-mouth/mask (in the field)
- Bag-mask with supplemental oxygen
- May require intubation / ventilator support

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how to conduct Vital Signs and Secondary Survey of an unconscious pt?

BP/pulse (circulation)
- Tx severe HTN (MAP >130 mmHg)
- Tx hypotension (MAP < 70 mmHg)
Respirations/pulse ox (airway/breathing)
- Maintain airway, clear any secretions
- Administer oxygen or mechanical ventilation if needed
Temperature
- Treat hyperthermia or hypothermia

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how to calculate MAP?

= (SBP + 2*DBP)/3

normal = 70-100mmHg

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initial management for unconscious pt?

Obtain IV access and labs
- CBC, glucose, electrolytes, BUN/Cr, LFTs , PT,, ABG, drug screen, ETOH, ammonia
when cause is still unknown, IV and monitor for improvement:
- 50% dextrose in water (D50W), 50 mL x 3-5 min - only if hypoglycemic
- Thiamine 100 mg by slow bolus injection
— Wernicke encephalopathy - MUST before or with glucose
- Naloxone - OD

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if the onset/timing of the event for the unconscious pt was abrupt, what is the likely cause?

subarachnoid hemorrhage, seizure, cardiac arrhythmia

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if the onset/timing of the event for the unconscious pt was gradual, what is the likely cause?

infectious, space occupying lesion

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if the onset/timing of the event for the unconscious pt was fluctuating, what is the likely cause?

recurring seizures, subdural hematoma, metabolic disorders

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if the associated sx of the unconscious pt involved focal neurologic changes
what could be the cause?

structural lesion with mass effect or stroke

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if the associated sx of the unconscious pt involved HA and vomiting
what could be the cause?

intracranial hemorrhage, increased ICP

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if the associated sx of the unconscious pt involved palpitations/chest pain/SOB
what could be the cause?

arrhythmia

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if the associated sx of the unconscious pt involved fever or recent illness
what could be the cause?

infection/sepsis

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if the associated sx of the unconscious pt involved recent confusion/delirium
what could be the cause?

metabolic process, drug, alcohol, poison

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if the associated sx of the unconscious pt involved dizziness/lightheaded
what could be the cause?

hypotension, stroke, arrhythmia, hypoxia

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what empiric tx is for possible infection for an unconscious pt?

ceftriaxone and vancomycin
acyclovir

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what empiric tx is for possible ingestion for an unconscious pt?

Flumazenil (BZD overdose)
Narcan (opiate overdose)
Gastric lavage/activated charcoal

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what empiric tx is for possible increased ICP for an unconscious pt?

Glucocorticoids Mannitol Position head of bed elevated 30°

what empiric tx is for possible nonconvulsive seizures for an unconscious pt?

Lorazepam Phenytoin

Look for clues to etiology during a PE of an unconscious pt:

HEENT: hemotympanum, external signs of trauma Skin: jaundice, track marks, ecchymosis Heart: arrhythmia Is there a focal neurologic abnormality on exam? Is the loss of consciousness caused by a cerebral cortex injury or ARAS injury?

for a valid and complete a focused neurologic examination you must d/c what?

sedatives

nonreactive pupils in a unconscious pt suggests that the lesion is where?

upper brainstem

if an unconscious patient has reactive pupils, what does that suggest?

**widespread structural lesions** or **metabolic suppression** of the cerebral hemispheres

what are "doll eyes" in an unconscious pt?

- Head is abruptly rotated from one side to the other in a horizontal plane - Normal response - eyes move opposite direction of head movement - _contraindicated in C-spine trauma_

what is an alternative option to test oculovestibular reflex when C-spine is not cleared

cold caloric stimuli - cold saline/water is inserted into the ear canal (_must have intact TM and clear canals_) - **Normal response** - _eyes moving to irrigated (ipsilateral) side_ followed by brisk horizontal nystagmus back to contralateral ear

if an unconscious pt is non-intubated, how could you test their gag reflex? what if theyre intubated?

tongue depressor intubated - deep suction = cough reflex

what type of respiration is a pattern of progressive hyperpnea, followed by brief apnea? what does this mean?

Cheyne-Stokes respirations Indicative of lower medullary dysfunction

what type of respiration is prolonged inspiratory phase or end-inspiratory pause? what does this mean?

Apneustic breathing higher medullary dysfunction

ways to assess motor in a neuro exam of an unconscious pt?

assess for spontaneous movement muscle tone arm drop

ways to do Central painful stimulation in an unconscious pt? responses?

1. sternal rub, supra ocular pressure, jaw angle pressure, medial trapezius pinch 2. possible responses - localized - UE movement toward the painful stimuli - indicates lesser depth of coma - flexor posturing (decorticate) - extensor posturing (decerebrate) - no response

Abnormal flexor posturing of the limbs upper-extremity adduction and flexion at the elbows, wrists, and fingers, together with lower-extremity extension, which includes extension and adduction at the hip, extension at the knee, and plantar flexion and inversion at the ankle what type of pain response is this

Decorticate Rigidity

An extended posturing: upper-extremity extension, adduction, and pronation together with lower-extremity extension and plantar flexion what type of pain response is this?

Decerebrate Rigidity

pt displays bilateral posturing of Decerebrate Rigidity what does this indicate?

**large structural lesion** with mass effect or **metabolic disorders**

pt displays unilateral/asymmetrical posturing of Decerebrate Rigidity what does this indicate?

**structural disease on contralateral** cerebral hemisphere or brainstem

difference between Decerebrate vs Decorticate

1. Decerebrate - damage to lower midbrain and upper pons - indicative of a more severe injury 2. Decorticate - damage to upper midbrain

how to assess peripehral painful stimulation for unconscious pt?

1. nail bed pressure 2. assesses sensory and motor pathways - does patient grimace? - does patient attempt to pull away from pain?

assesses coma severity on a 3-15 scale, according to three categories of responsiveness what is this scale?

Glasgow Coma Scale (GCS) eye opening motor verbal responses

diganostic evaluations for an unconscious pt?

1. EKG 2. Head CT scan w/o contrast 3. LP and CSF analysis - CI - cerebral edema/increased ICP 4. Electroencephalography (EEG) - uses sensors to evaluate the electrical activity of the neurons in the brain 5. Evoked-potential studies

A head CT w/o contrast is prioritized as emergent in an unconscious pt if they have signs of:

focal neurologic signs papilledema fever

LP and CSF analysis is prioritized as emergent in an unconscious pt if they have signs of:

fever, elevated WBC, meningismus

LP and CSF analysis is - more sensitive for subarachnoid hemorrhage (SAH) than CT if onset is what time?

> 6 hrs onset

which diagnostic evaluation is utilized if concern for non-convulsive seizure as the cause for diminished consciousness

Electroencephalography (EEG)

which diagnostic evaluation is quick and effective in looking for hemorrhage, neoplasm, abscesses, signs of trauma, causes of increased ICP

head CT without contrast

what diagnostic evaluation utilizes visual, auditory, and somatosensory (touch) stimulation to assess electrical signals to the brain

Evoked-potential studies results reveal the time it takes for an electrical impulse to get from one location to another after stimulation

additional evaluations for an unconscious pt?

1. Other laboratory tests - blood cx, adrenal and thyroid tests, coagulation tests, carboxyhemoglobin, specific drug concentrations 2. Brain MRI - most sensitive imaging of the brain - displays information earlier than CT - can assess for a variety of underlying CNS etiologies - second-line to CT d/t length of time to complete the procedure

3 pathophysiological processes can lead to altered state of consciousness

1. Lesions that **damage the RAS** in the upper midbrain or its projections 2. **Destruction of both cerebral hemispheres** 3. **Suppression of reticulocerebral function** by drugs, toxins, or metabolic derangements such as anoxia, uremia, hypo-/hyperglycemia and hepatic failure

A sleep-like state with no purposeful response to the environment and from which the patient cannot be aroused for > 1 hour

Coma - Eyes are closed and do not open spontaneously -Lacking verbal communication - No purposeful movement of the face or limbs - Verbal stimulation produces no response - Painful stimulation may produce no response or nonpurposeful reflex movements mediated through spinal cord or brainstem pathways

A prolonged, motionless, dissociative attack in which the patient has absent or reduced response to external stimuli Presentation ranges from stupor or catatonia to functional coma

Psychogenic Unresponsiveness associated w/ schizophrenia (catatonic type), somatoform disorders (conversion disorder or somatization disorder) or malingering

confirmatory test for Psychogenic Unresponsiveness

cold caloric testing reveals a normal response

A state of wakefulness but not awareness lasting > 1 month Spontaneous eye opening and sleep–wake cycles Unable to comprehend (this is an area of debate) nor produce language, lacks purposeful motor responses

Persistent Vegetative State (PVS)

pathophys of Persistent Vegetative State (PVS)

intact brainstem and autonomic function but **severe bilateral hemispheric damage**

Prognosis of Persistent Vegetative State (PVS)

Recovery is exceedingly rare among patients in: * PVS from a medical cause (eg, anoxic brain injury) * PVS last > 3 months * TBI if lasting > 12 months

Patients are awake, alert and fully aware of their surroundings, however they are mute and quadriplegic

Locked-In Syndrome Decerebrate posturing or flexor spasms may be seen Voluntary eye opening, vertical eye movements and/or ocular convergence are preserved

pathophys of locked-in syndrome

acute destructive lesions of **ventral pons** and *sparing tegmentum* (ventral part of the midbrain) - often an embolic occlusion of the basilar artery

Irreversible cessation of all brain function is required for a diagnosis Complete unresponsiveness to speech and painful stimuli Absent brainstem reflexes

Brain Death _etiology of coma must be known_ and correlate with clinical presentation and _prognosis must be irreversible_

Diagnostic confirmation for brain death

6 hrs with isoelectric (flat) EEG 12 hrs w/o EEG 24 hrs for anoxic brain injury w/o EEG

Long Term Management for coma

1. Manage underlying etiology 2. Maintain airway/adequate respirations - intubation required if: --- apnea, upper airway obstruction, hypoventilation, or emesis --- the patient is at high risk for aspiration

Disorders of Consciousness Flashcards

(64 cards)