Lecture 3: Disorders of Consciousness Flashcards
Define consciousness
State of awareness to environment and self with a responsiveness to stimuli
What system controls consciousness and where is it located?
- Ascending reticular activating system (ARAS)
- Originates in the upper pons and midbrain
- Extending to the brainstem and cortex
Controls the level of alertness
What mainly composes the cerebral cortex?
Grey matter
What causes unconsciousness?
Damage to the (ascending reticular activating system) ARAS or cerebrum.
Slow impulses.
Sleep does not qualify since you still are responsive.
What are the 5 LOCs? (image)
ALOSC
Sound, touch, pain
Alphabetical up to coma
What is in the primary survey of a patient?
- Circulation (carotid)
- Airway
- Breathing
Easier to just remember ABCs
What is considered severe MAP in regards to an unconscious patient?
MAP > 130
How do you calculate MAP?
(SBP + 2(DBP))/3
1 2 3
1 systolic
2 diastolics
3 divisions
If we have an unconscious patient, what 3 things can we administer IV?
- Dextrose for hypoglycemic patients.
- Thiamine (with or before glucose) for Wernicke encephalopathy
- Naloxone (Opiate OD)
All of these are generally not harmful.
Thiamine helps glucose uptake, and it has no harmful effects to someone who is not thiamine deficient.
What conditions would cause immediate onset unconsciousness?
- SAH
- Seizure
- Cardiac arrhythmia
When can flumazenil be used?
CONFIRMED BZD OD
What empiric ABX could be used for an unconscious patient?
- Rocephin + Vanco
- Acyclovir
For increased ICP, what meds can we use?
- Glucocorticoids
- Mannitol
- Position head of bed to 30deg
For non-convulsive seizures, what are some meds we can use?
- Lorazepam
- Phenytoin or equivalent
What does a focal neurologic abnormality suggest for underlying etiology on an unconscious patient?
Structural lesion
What skin finding can suggest IVDU?
Track marks
What does pupil reactivity tell you about potential lesion location?
A non-reactive pupil suggests upper brainstem lesion.
What are doll’s eyes/oculocephalic reflex?
An abnormal reflex means the eyes will remain midline as they are moved. (The eyes will NOT stay fixed)
DO NOT USE IF C-SPINE TRAUMA IS SUSPECTED.
Involves head turning
What is the alternative to testing the oculocephalic reflex? When do we use it?
- Cold caloric stimuli
- Used when C-spine is NOT cleared.
- Cold saline into ear should cause ipsilateral eye movement, but nystagmus will go back towards opposite ear. (Normal test)
Tests the oculovestibular reflex.
Intact brainstem will allow the ipsilateral movement.
However, cortical damage will delay the return.
Abnormal Response = no turning towards the ear being irrigated.
How do you test the gag reflex (9&10) in an intubated patient?
Deep suction should cause a cough.
Describe Cheyne-stokes respirations.
- Progressive Hyperpnea followed by brief apnea
- Indicative of lower medullary dysfunction
Describe apneustic breathing.
- Prolonged inspiratory phase or end-inspiratory pause
- Higher medullary dysfunction
A = apex = higher medullary
What test can be used to assess muscle tone in an unconscious patient?
- Arm drop test.
- A truly unconscious patient will hit themselves in the face if the hand is dropped on top.
- A malingering patient will avoid hitting themselves even if they are “unconscious”
Describe decerebrate posturing.
Decerebrate: extensor posturing
Cerebrate has a lot of Es, and so does extensor.
Considered the more severe of the two posturings.
Damage to Lower midbrain and upper pons.
Describe decorticate posturing.
Flexor posturing
Decorticate is pulling to the CORe
Damage to upper midbrain
What are the 3 categories of the GCS?
- Eye opening Response
- Verbal Response
- Motor Response
3-15
Minor: 13-15
Mod: 9-12
Severe: 3-8
When is a CT head w/o con considered an emergent scan to order?
- Focal neurologic deficits
- Papilledema
- Fever
When is a LP considered emergent post CT scan?
- Fever
- Elevated WBCs
- Meningismus
CI in cerebral edema or increased ICP.
What etiology is EEG primarily used to look for?
Nonconvulsive seizures resulting in diminished consciousness.
What do evoked potentials measure?
How long it takes from an impulse to get from one location to the other.
What is the most sensitive imaging modality of the brain?
MRI Brain
2nd-line bc it takes a long time.
What are the 3 pathophysiological processes that can result in unconsciousness?
- Lesions that damage the RAS in the midbrain or its projections
- Destruction of large portions of both cerebral hemispheres
- Suppression of reticulocerebral function.
What is a coma?
Sleep-like state with No purposeful response and patient cannot be aroused for >1 hour
What is psychogenic unresponsiveness?
- Prolonged, motionless, dissociative attack
- Absent or reduced response to external stimuli
Neuro disorders usually. Dx of exclusion!!!!
Underlying etiologies: schizo (catatonia), conversion disorder, somatoform disorder, or malingering
How is psychogenic unresponsiveness confirmed?
Cold caloric testing with a normal response.
What is a persistent vegetative state?
- State of wakefulness but not awareness lasting > 1 month
- Intact brainstem and autonomic function
- Severe, bilateral hemispheric damage.
When is prognosis poor for a persistent vegetative state?
- Medically caused with state > 3 months
- TBI induced > 12 months
What is locked-in syndrome?
- Awake, fully alert, fully aware
- Mute, quadriplegic
- Decerebrate posturing or flexor spasms can be seen.
- Voluntary eye movements.
Brain awake but nothing can move
What is the underlying pathophysiology that leads to locked-in syndrome?
- Acute, destructive lesions involving ventral pons but sparing the tegmentum.
- Often due to embolic occlusion of basilar artery
there is a house episode on this if you’re interested
What is the description for brain death?
- Irreversible cessation of all brain function.
- Complete unresponsiveness to speech and painful stimuli
- Absent brainstem reflexes
- Etiology must be known and prognosis irreversible.
What is the diagnostic criteria for brain death?
- 6 hrs with isoelectric/flat EEG
- 12 hrs w/o EEG
- 24 hrs for anoxic brain injury w/o EEG
How do we manage coma long-term?
- Manage underlying etiology
- Maintain airway/adequate respirations
GCS Mnemonic
- E: eyes shut (1)
- Y: Y shaped pain (2)
- E: ear piercing (3)
- S: spontaneous (4)
- V: Voiceless (1)
- O: Obscure, incomprehensible (2)
- I: Inappropriate but comprehensible (3)
- C: Confused but able to answer (4)
- E: Elegant (5)
- O: Obey Verbal (6)
- L: Localizes to pain (5)
- D: draws away from pain (4)
- B: bends on pain (3)
- E: extends on pain (2)
- N: No motor response (1)
EYES VOICE OLDBEN
Just remember that OLDBEN starts at 6.
