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Neuro: Clin Med IIB > Disorders of Consciousness > Flashcards

Disorders of Consciousness Flashcards

1
Q

what is consciousness?

A

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

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2
Q

How is consciousness achieved and maintained?

A

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

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3
Q

what is the reticular system?

A

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

  1. Ascending reticular activating system (ARAS)
  2. Descending reticulospinal tracts
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4
Q

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

A

Ascending reticular activating system - ARAS

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5
Q

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

A

Descending reticulospinal tracts

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6
Q

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

A

Cerebral cortex

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

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7
Q

what is the difference between conscious and unconscious?

A
  1. 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
  2. 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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8
Q

evaluation of an unconscious pt

A
  1. Primary Survey (C-A-B)
    - Circulation
    - Airway
    - Breathing
  2. Vital Signs and Secondary Survey
  3. brief history
    - events surrounding loss of consciousness
  4. initial PE
    - General - evidence of trauma
    - Neurologic Evaluation - CN deficits, Glasgow Coma Score
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9
Q

circulation in a primary survey of an unconscious pt involves?

A

check pulse

  1. No Pulse - start CPR
  2. 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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10
Q

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

A
  1. Spontaneous regular respirations = monitor
  2. 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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11
Q

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

A
  1. BP/pulse (circulation)
    - Tx severe HTN (MAP >130 mmHg)
    - Tx hypotension (MAP < 70 mmHg)
  2. Respirations/pulse ox (airway/breathing)
    - Maintain airway, clear any secretions
    - Administer oxygen or mechanical ventilation if needed
  3. Temperature
    - Treat hyperthermia or hypothermia
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12
Q

how to calculate MAP?

A

= (SBP + 2*DBP)/3

normal = 70-100mmHg

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13
Q

initial management for unconscious pt?

A
  1. Obtain IV access and labs
    - CBC, glucose, electrolytes, BUN/Cr, LFTs , PT,, ABG, drug screen, ETOH, ammonia
  2. 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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14
Q

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

A

subarachnoid hemorrhage, seizure, cardiac arrhythmia

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15
Q

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

A

infectious, space occupying lesion

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16
Q

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

A

recurring seizures, subdural hematoma, metabolic disorders

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17
Q

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

A

structural lesion with mass effect or stroke

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18
Q

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

A

intracranial hemorrhage, increased ICP

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19
Q

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

A

arrhythmia

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20
Q

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

A

infection/sepsis

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21
Q

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

A

metabolic process, drug, alcohol, poison

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22
Q

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

A

hypotension, stroke, arrhythmia, hypoxia

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23
Q

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

A

ceftriaxone and vancomycin
acyclovir

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24
Q

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

A

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

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25
Q

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

A

Glucocorticoids
Mannitol
Position head of bed elevated 30°

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26
Q

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

A

Lorazepam
Phenytoin

27
Q

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

A

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?

28
Q

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

A

sedatives

29
Q

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

A

upper brainstem

30
Q

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

A

widespread structural lesions or metabolic suppression of the cerebral hemispheres

31
Q

what are “doll eyes” in an unconscious pt?

A
  • 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
32
Q

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

A

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
33
Q

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

A

tongue depressor
intubated - deep suction = cough reflex

34
Q

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

what does this mean?

A

Cheyne-Stokes respirations
Indicative of lower medullary dysfunction

35
Q

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

what does this mean?

A

Apneustic breathing
higher medullary dysfunction

36
Q

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

A

assess for spontaneous movement
muscle tone
arm drop

37
Q

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

A
  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
38
Q

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

A

Decorticate Rigidity

39
Q

An extended posturing: upper-extremity extension, adduction, and pronation together with lower-extremity extension and plantar flexion

what type of pain response is this?

A

Decerebrate Rigidity

40
Q

pt displays bilateral posturing of Decerebrate Rigidity

what does this indicate?

A

large structural lesion with mass effect or metabolic disorders

41
Q

pt displays unilateral/asymmetrical posturing of Decerebrate Rigidity

what does this indicate?

A

structural disease on contralateral cerebral hemisphere or brainstem

42
Q

difference between Decerebrate vs Decorticate

A
  1. Decerebrate - damage to lower midbrain and upper pons
    - indicative of a more severe injury
  2. Decorticate - damage to upper midbrain
43
Q

how to assess peripehral painful stimulation for unconscious pt?

A
  1. nail bed pressure
  2. assesses sensory and motor pathways
    - does patient grimace?
    - does patient attempt to pull away from pain?
44
Q

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

what is this scale?

A

Glasgow Coma Scale (GCS)
eye opening
motor
verbal responses

45
Q

diganostic evaluations for an unconscious pt?

A
  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
46
Q

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

A

focal neurologic signs
papilledema
fever

47
Q

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

A

fever, elevated WBC, meningismus

48
Q

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

A

> 6 hrs onset

49
Q

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

A

Electroencephalography (EEG)

50
Q

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

A

head CT without contrast

51
Q

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

A

Evoked-potential studies

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

52
Q

additional evaluations for an unconscious pt?

A
  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
53
Q

3 pathophysiological processes can lead to altered state of consciousness

A
  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
54
Q

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

A

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
55
Q

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

A

Psychogenic Unresponsiveness

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

56
Q

confirmatory test for Psychogenic Unresponsiveness

A

cold caloric testing reveals a normal response

57
Q

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

A

Persistent Vegetative State (PVS)

58
Q

pathophys of Persistent Vegetative State (PVS)

A

intact brainstem and autonomic function but severe bilateral hemispheric damage

59
Q

Prognosis of Persistent Vegetative State (PVS)

A

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
60
Q

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

A

Locked-In Syndrome

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

61
Q

pathophys of locked-in syndrome

A

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

62
Q

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

A

Brain Death
etiology of coma must be known and correlate with clinical presentation and prognosis must be irreversible

63
Q

Diagnostic confirmation for brain death

A

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

64
Q

Long Term Management for coma

A
  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

Neuro: Clin Med IIB (13 decks)

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