Coma/stupor

Question 0

Stupor

Answer 0

Purposeful response only with intense stimulation

Deep stupor - very intense noxious -> poorly directed response
Persistent drowsiness - stimulus -> purposeful but intermittent

vs Sleep - arouse to persistent alert wakefulness

Question 1

Coma

Answer 1

Cannot be aroused to purposeful movement

Light -> can elicit reflexes
Deep - no response

Ddx:
Hysterical (psych) - normal EEG and nystagmus
Neuromuscular -
 - NMJ - MS, Rx
 - peripheral nerves - GBS, porphyria
 - pontine - ie "locked in"

Question 2

“Locked in” syndrome

Answer 2

Isolated pontine lesion (hemorrhage, infarct, demyelination)

Awake, awarer, respond to commands
Auditory intact (lateral vs medial arteries)
Vertical, convergence, opening intact (midbrain)

Question 3

Overview of consciousness

Answer 3

Cortex - awareness, higher functions
- diffuse depression = “encephalopathy” (metabolic toxic)
- can have vegetative state if reticular intact
Reticular activating system - rostral pons, caudal midbrain -> dienceph
- necessary for cortical function
- more resistant to metabolic/toxic encephalopathies
- direct - ischemia/infarct, hemorrhage, neoplasm, abcess, trauma
- compression - uncal transtentorial herniation
- unilateral cortical? -> rostral-caudal deterioration

Question 4

Emergency eval of altered mental

Answer 4

Airway, blood pressure
Temperature
Meningeal - rigidity, Brudzinski's sign (knee and hip flexion)
Tympanic membrane - trauma, infection
Glucose, D5W, thiamine
Naloxone, flumazenil, seizures
ABG, CMP, LFT, tox

Exam - LOC, resp, pupil, vestibular, motor

CT - trauma, suspect mass or CVA
LP - if infection suspected, worsens herniation
EEG - not routine, ?hysterical, ?persistent alpha waves (no change with stimulus vs awake)

Question 5

Eval of coma

Answer 5

GCS vs FOUR scale - LOC, motor, verbal, resp, reflexes

LOC/motor - commands -> localize -> withdraw

• dienceph> decorticate (assym, first on damaged side)
• mesen/pons> decerebrate
• lower pons/medulla> flaccid (time and extent proportional to location)
• late> hyper-reflexia, spastic, primitive

Resp - primary medullary control with input

• cortical dep> yawn, sigh
• dienceph/mesen/diffuse cortical > Cheynes-Stokes
• lower mesenceph/upper pons > centeral hypervent (-> alkalosis)
• lower pons> ataxic (irreg irreg + hypervent + apneustic)
• medulla> depression -> apnea

Pupils

• dienceph (hypothal)> miosis, reactive (lose SNS)
• caudal dienceph, rostral midbrain> sluggish (pretectal)
• midbrain> mydriasis, non-reactive (CN 3)
• below midbrain> midposition, non-reactive (CN3 and SNS)
• isolated pontine/medulla, narcotic > small, reactive

Vestibular

• cortex > lose fast nystagmus (tonic deviation)
• midbrain > disconjugate
• lower pons > no vestibular response (CN 6, PPRF)

Question 6

Rostro-caudal deterioration

Answer 6

Expanding brain (edema) or mass (hemorr, tumor, abcess/mass)

Lateral sensory or motor

• > dienceph
• > midbrain
• > uncal/transtentorial herniation - often 2ndary hemorrhage -> damage midbrain/RAS -> irreversible coma
• > pons -> medulla

Progression of sx:

• LOC -> stupor -> coma
• resp -> Cheyne-Stokes -> hypervent -> ataxic -> depression
• pupils -> small reactive -> dilated nonreact -> midposition nonreact
• VOR -> lose fast -> lose slow
• motor -> localize -> withdraw -> decort -> decerebrate