Lecture 3: Disorders of Consciousness

Question 1

Define consciousness

Answer 1

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

Question 2

What system controls consciousness and where is it located?

Answer 2

• Ascending reticular activating system (ARAS)
• Originates in the upper pons and midbrain
• Extending to the brainstem and cortex

Controls the level of alertness

Question 3

What mainly composes the cerebral cortex?

Answer 3

Grey matter

Question 4

What causes unconsciousness?

Answer 4

Damage to the (ascending reticular activating system) ARAS or cerebrum.

Slow impulses.

Sleep does not qualify since you still are responsive.

Question 5

What are the 5 LOCs? (image)

Answer 5

ALOSC

Sound, touch, pain

Alphabetical up to coma

Question 6

What is in the primary survey of a patient?

Answer 6

• Circulation (carotid)
• Airway
• Breathing

Easier to just remember ABCs

Question 7

What is considered severe MAP in regards to an unconscious patient?

Answer 7

MAP > 130

Question 8

How do you calculate MAP?

Answer 8

(SBP + 2(DBP))/3

1 2 3

1 systolic
2 diastolics
3 divisions

Question 9

If we have an unconscious patient, what 3 things can we administer IV?

Answer 9

• 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.

Question 10

What conditions would cause immediate onset unconsciousness?

Answer 10

• SAH
• Seizure
• Cardiac arrhythmia

Question 11

When can flumazenil be used?

Answer 11

CONFIRMED BZD OD

Question 12

What empiric ABX could be used for an unconscious patient?

Answer 12

• Rocephin + Vanco
• Acyclovir

Question 13

For increased ICP, what meds can we use?

Answer 13

• Glucocorticoids
• Mannitol
• Position head of bed to 30deg

Question 14

For non-convulsive seizures, what are some meds we can use?

Answer 14

• Lorazepam
• Phenytoin or equivalent

Question 15

What does a focal neurologic abnormality suggest for underlying etiology on an unconscious patient?

Answer 15

Structural lesion

Question 16

What skin finding can suggest IVDU?

Answer 16

Track marks

Question 17

What does pupil reactivity tell you about potential lesion location?

Answer 17

A non-reactive pupil suggests upper brainstem lesion.

Question 18

What are doll’s eyes/oculocephalic reflex?

Answer 18

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

Question 19

What is the alternative to testing the oculocephalic reflex? When do we use it?

Answer 19

• 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.

Question 20

How do you test the gag reflex (9&10) in an intubated patient?

Answer 20

Deep suction should cause a cough.

Question 21

Describe Cheyne-stokes respirations.

Answer 21

• Progressive Hyperpnea followed by brief apnea
• Indicative of lower medullary dysfunction

Question 22

Describe apneustic breathing.

Answer 22

• Prolonged inspiratory phase or end-inspiratory pause
• Higher medullary dysfunction

A = apex = higher medullary

Question 23

What test can be used to assess muscle tone in an unconscious patient?

Answer 23

• 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”

Question 24

Describe decerebrate posturing.

Answer 24

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.

Question 25

Describe decorticate posturing.

Answer 25

Flexor posturing | Decorticate is pulling to the CORe ## Footnote Damage to upper midbrain

Question 26

What are the 3 categories of the GCS?

Answer 26

* Eye opening Response * Verbal Response * Motor Response | 3-15 ## Footnote Minor: 13-15 Mod: 9-12 Severe: 3-8

Question 27

When is a CT head w/o con considered an emergent scan to order?

Answer 27

* Focal neurologic deficits * Papilledema * Fever

Question 28

When is a LP considered emergent post CT scan?

Answer 28

* Fever * Elevated WBCs * Meningismus | CI in cerebral edema or increased ICP.

Question 29

What etiology is EEG primarily used to look for?

Answer 29

Nonconvulsive seizures resulting in diminished consciousness.

Question 30

What do evoked potentials measure?

Answer 30

How long it takes from an impulse to get from one location to the other.

Question 31

What is the most sensitive imaging modality of the brain?

Answer 31

MRI Brain | 2nd-line bc it takes a long time.

Question 32

What are the 3 pathophysiological processes that can result in unconsciousness?

Answer 32

1. Lesions that damage the RAS in the midbrain or its projections 2. Destruction of large portions of both cerebral hemispheres 3. Suppression of reticulocerebral function.

Question 33

What is a coma?

Answer 33

Sleep-like state with **No purposeful response** and patient **cannot be aroused for >1 hour**

Question 34

What is psychogenic unresponsiveness?

Answer 34

* Prolonged, motionless, dissociative attack * Absent or reduced response to external stimuli | Neuro disorders usually. Dx of exclusion!!!! ## Footnote Underlying etiologies: schizo (catatonia), conversion disorder, somatoform disorder, or malingering

Question 35

How is psychogenic unresponsiveness confirmed?

Answer 35

Cold caloric testing with a normal response.

Question 36

What is a persistent vegetative state?

Answer 36

* State of wakefulness but not awareness lasting > 1 month * **Intact brainstem** and autonomic function * **Severe, bilateral hemispheric damage.**

Question 37

When is prognosis poor for a persistent vegetative state?

Answer 37

* Medically caused with state > 3 months * TBI induced > 12 months

Question 38

What is locked-in syndrome?

Answer 38

* Awake, fully alert, fully aware * Mute, quadriplegic * Decerebrate posturing or flexor spasms can be seen. * Voluntary eye movements. | Brain awake but nothing can move

Question 39

What is the underlying pathophysiology that leads to locked-in syndrome?

Answer 39

* Acute, destructive lesions involving **ventral pons but sparing the tegmentum**. * Often due to embolic occlusion of basilar artery ## Footnote there is a house episode on this if you're interested

Question 40

What is the description for brain death?

Answer 40

* Irreversible cessation of all brain function. * Complete unresponsiveness to speech and painful stimuli * Absent brainstem reflexes * Etiology must be known and prognosis irreversible.

Question 41

What is the diagnostic criteria for brain death?

Answer 41

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

Question 42

How do we manage coma long-term?

Answer 42

* Manage underlying etiology * Maintain airway/adequate respirations

Question 43

GCS Mnemonic

Answer 43

* 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 ## Footnote Just remember that OLDBEN starts at 6.