Disorders of Consciousness - Exam 3 Flashcards
What is consciousness?
Consciousness is a state of awareness to environment and self with a responsiveness to stimuli
aka you know where and who you are
How is consciousness achieved and maintained?
Via action of the neurons that make up the Ascending Reticular Activating System (ARAS) in the brainstem and cerebral cortex
What makes up the reticular system?
Ascending reticular activating system (ARAS)
Descending reticulospinal tracts
Where does the ARAS originate? Where does it go? What does it control?
originates in the upper pons and midbrain
projecting to the thalamus and hypothalamus and extending to the cerebral cortex, controlling levels of alertness
Where does the descending reticulospinal tract travel? Does it affect consciousness?
travels downward into the spinal cord and modulates spinal reflex activity
does NOT affect consciousness
What does damage to the descending reticulospinal tract lead to?
Damage leads to loss or diminished reflexes
________ is the outer layer of the cerebral hemispheres consisting of grey matter and controls the content of consciousness. What is it responsible for?
Cerebral cortex
self-awareness, language, reasoning, spatial relationship, integration and emotions
What is the difference between consciousness and unconsciousness?
conscious: Awake, aware, alert and RESPONSIVE to stimuli with FAST neuronal activity
unconscious: unaware and unresponsive to stimuli resulting from damage to the ARAS and/or the cerebrum with DIMINISHED transmission of signals from the ARAS to the cerebrum
**What are the 5 levels of consciousness?
What is included in the primary survey of an unconscious patient? Then what do you do?
Circulation
Airway
Breathing
then vitals and secondary survey
aka need to check pulse and then get vitals
What are the first 4 steps in the evaluation of the unconscious patient?
primary survey
vital signs and secondary survey
brief history
initial PE: any evidence of trauma? neuro eval, glasgow coma score
What is included in circulation when talking about the primary survey?
circulation is check pulse
then BP
then is the rhythm regular?
What do you do if a pt does NOT have spontaneous respiration or ineffective respirations? What step? what survey?
need to provide assisted ventilation with bag-mask with supplemental oxygen +/- intubation with vent support
Airway breathing of the Primary survey
**What is the normal range for MAP? How do you calculate MAP?
70-100
What is considered severe hypertension is terms of MAP? What is considered hypotension?
MAP> 130mmHg
hypotension MAP less than 70
If MAP is less than 70, what do you do?
give fluids first then vasopressors to try and raise BP
Why would an ammonia level be high in an unconscious patient?
high ammonia makes you think cirrhosis of the liver
What are the 3 initial managements you need to consider EARLY on when the cause of unconsciousness is not known?
**What extra step needs to be taken when administering thiamine? What vitamin? What dz are you trying to treat?
Administer before or with glucose
vit B1
Wernicke encephalopathy
When evaluating the unconscious patient, _____ is super important. Give the 3 options
timing!
abrupt
gradual
fluctuating
What does abrupt timing of unconsciousness make you think? (give time frame) gradual? (give time frame) fluctuating?
abrupt: subarachnoid hemorrhage, seizure, cardiac arrhythmia
abrupt is measured in seconds
gradual: infectious, space occupying lesion
gradual is measured in hours to days
fluctuating: recurring seizures, subdural hematoma, metabolic disorders
What does unconsciousness with focal neurologic changes make you think?
structural lesion with mass effect or stroke
What does unconsciousness with HA and vomiting make you think?
intracranial hemorrhage, increased ICP
What does unconsciousness with palpitations/chest pain/SOB make you think?
arrhythmia
What does unconsciousness with fever or recent illness make you think?
infection/sepsis
What does unconsciousness with recent confusion/delirium make you think?
metabolic process, drug, alcohol, poison
What does unconsciousness with dizziness/lightheaded make you think?
hypotension, stroke, arrhythmia, hypoxia
What is the empiric treatment for unconsciousness, febrile and possible infection?
ceftriaxone and vancomycin
acyclovir
What is the empiric tx for unconsciousness due to BZD overdose? What do you need to make sure of? Why?
Flumazenil
they have a positive history of BZD overdose because flumazenil is dangerous because it can induce seizures
What is the empiric tx for unconsciousness due to possible poison ingestion? What is the associated timeframe?
Gastric lavage/activated charcoal
only within the last hour
What is the empiric tx for unconsciousness due to increased intracranial pressure?
Glucocorticoids
Mannitol
Position head of bed elevated 30°
What is the empiric tx for unconsciousness due to non-convulsive seizures?
Lorazepam
Phenytoin or equivalent
What would be some PE findings that would indicate cerebral cortex injury or ARAS injury?
hemotympanum, external signs of trauma
Skin: jaundice, track marks, ecchymosis
heart: arrhythmias
What do nonreactive pupil suggest? What cranial nerve?
nonreactive - suggests that the lesion is in the upper brainstem
CN III
What do reactive pupils suggest?
widespread structural lesions or metabolic suppression of the cerebral hemispheres
What CN does the corneal reflex test test?
CN V
What CN does the oculocephalic reflex test? Describe it. What is a normal test? abnormal? When is it CI?
CN III, IV, VI)
Head is abruptly rotated from one side to the other in a horizontal plane
normal: eyes will stay fixed on the object
abnormal: eyes will remain mid-position
CI: in C-spine trauma
What is the alternative to oculocephalic reflex? When would you use it? Describe the test. What is a normal response?
Oculovestibular reflex : cold caloric stimuli
when the C-spine is not cleared
cold saline/water is inserted into the ear canal
Normal response - eyes moving to irrigated (ipsilateral) side followed by brisk horizontal nystagmus back to contralateral ear
During the cold caloric stimuli, what does eyes move slowly toward ipsilateral side indicate?
Cortical damages with intact brainstem
During the cold caloric stimuli, what does eyes remain fixed without reflexive movement indicate?
Cortical and brainstem damage
How should you check CN IX and X?
gag reflex
non-intubated - tongue depressor
should cause involuntary gagging
intubated - deep suction should produce cough reflex
What is cheyne-stokes respirations? What does it indicate?
a pattern of progressive hyperpnea, followed by brief apnea
indicative of lower medullary dysfunction
What is apneustic breathing? What does it indicate?
prolonged inspiratory phase or end-inspiratory pause followed by quick partial expirations;
aka small spurts of exhalation
higher medullary dysfunction
What are the 4 areas that can be used to elicit painful stimulation?
sternal rub
supra ocular pressure
jaw angle pressure
medial trapezius pinch
What are the 4 possible responses to central painful stimulation?
localized - UE movement toward the painful stimuli - indicates lesser depth of coma
flexor posturing (decorticate)
extensor posturing (decerebrate)
no response
Describe deCORticate rigidity
Abnormal flexor posturing of the limbs
aka hands into the CORe
Describe decerebrate rigidity
An extended posturing: upper-extremity extension, adduction, and pronation together with lower-extremity extension and plantar flexion
What does bilateral posturing indicate?
large structural lesion with mass effect or metabolic disorders
What does unilateral/asymmetric posturing indicate?
structural disease on the contralateral cerebral hemisphere or brainstem
Which one is more severe, decorticate rigidity or decerebrate rigidity? What does each indicate?
decerebrate rigidity is worse
Decorticate - damage to upper midbrain
Decerebrate - damage to lower midbrain and upper pons
What is the Glasgow Coma Scale? What are the 3 categories?
assesses coma severity on a 3-15 scale, according to three categories of responsiveness
eye opening
motor
verbal responses
Glasgow Coma Scale less than 8, what do you need to do? What age range is the scale indicated for?
score less than 8, need to intubate
age: only good for 18+ years old
**What is the Glasgow Coma Scale? Need to know scores and what each one means
What is the lowest you can get on the Glasgow Coma scale?
lowest is 3, NOT 0
What should be included in the diagnostic evaul of an unconscious pt?
EKG
head CT w/o
lumbar puncture and CSF analysis
When would you want to order an EMERGENT head CT in an unconscious pt?
focal neurologic signs, papilledema or fever
When would you want to order a EMERGENT lumbar puncture and CSF analysis?
if the CT scan shows fever, elevated WBC, meningismus
Which is more sensitive for a subarachnoid hemorrhage if it has been greater than 6 hours since onset, a LP or CT?
greater than 6 hours of onset, LP is more sensitive than CT
When is a LP CI?
cerebral edema/increased ICP
When is an EEG used? What is it?
utilized if concern for non-convulsive seizure as the cause for diminished consciousness
uses sensors to evaluate the electrical activity of the neurons in the brain
What does an evoked-potential study tell you? How does it work?
results reveal the time it takes for an electrical impulse to get from one location to another after stimulation
utilizes visual, auditory, and somatosensory (touch) stimulation to assess electrical signals to the brain
______ is the most sensitive imaging of the brain. _____ is first line
Brain MRI
CT is first line because it can be performed faster than MRI
What are the 3 pathophys processes that can lead to an altered state of consciousness?
What is the technical definition of a coma? what are the 2 highlighted key words?
A sleep-like state with no purposeful response to the environment and from which the patient cannot be aroused for > 1 hour
no PURPOSEFUL response
cannot be aroused for > 1 hour
aka eyes are closed and do NOT open spontaneously, no verbal communication, no movement even when painful stimuli is applied
What is Psychogenic Unresponsiveness? What 3 conditions is it associated with?
A prolonged, motionless, dissociative attack in which the patient has absent or reduced response to external stimuli
schizophrenia (catatonic type), somatoform disorders
malingering
What does the neuro exam reveal in Psychogenic Unresponsiveness? What is the confirmatory test?
symmetrically decreased muscle tone, otherwise normal
cold caloric testing reveals a normal response
What is a Persistent Vegetative State (PVS)? What two things will be present?
A state of wakefulness but not awareness lasting > 1 month
Spontaneous eye opening and sleep–wake cycles but unable to comprehend nor produce language
What is the pathophys behind Persistent Vegetative State (PVS)?
intact brainstem and autonomic function but severe bilateral hemispheric damage
What is the prognosis of someone recovering from a Persistent Vegetative State (PVS)? give specific timeframes
Recovery is exceedingly rare among patients in a PVS from a medical cause (e.g., anoxic brain injury) if PVS last > 3 months and from a TBI if lasting > 12 months
What is Locked-In syndrome? What things are present?
Patients are awake, alert and fully aware of their surroundings, however they are mute and quadriplegic
Decerebrate posturing or flexor spasms may be seen, Voluntary eye opening, vertical eye movements and/or ocular convergence are preserved
What is the pathophys behind locked-in syndrome? What is it often due as a result from?
acute destructive lesions (eg, infarction, hemorrhage, demyelination, encephalitis) involving the VENTRAL PONS and sparing the tegmentum (ventral part of the midbrain)
often an embolic occlusion of the basilar artery
Define brain death? What can NOT be present
Irreversible cessation of all brain function is required for a diagnosis. COMPLETE UNRESPONSIVENESS to speech and painful stimuli
The presence of seizures or decorticate/decerebrate posturing is incompatible with brain death
What must be absent in order to be considered absent brainstem reflexes?
Pupillary, corneal, and oropharyngeal responses are absent; EOM is absent with doll’s head or cold caloric testing, respiratory response is absent
What qualifies as irreversibility of brain dysfunction?
etiology of coma must be known and correlate with clinical presentation and prognosis must be irreversible
What are the 3 diagnostic options regarding EEGs that confirms a brain death diagnosis?
6 hrs with isoelectric (flat) EEG
12 hrs w/o EEG
24 hrs for anoxic brain injury w/o EEG
_____ is important in long term management of a coma. They are at an extremely high risk for ______
Maintain airway/adequate respirations
extremely high risk for aspiration
What is the prognosis for a coma? What is the timeframe?
Patients either recover or evolve into brain death, a persistent vegetative or minimally conscious state
Coma is a transitional state that rarely lasts more than SEVERAL WEEKS, except in cases of ongoing sedative therapies or protracted sepsis.
practice the 4 GCS cases in lecture!!!
do it!!
