A17. Examination of the unconscious patient

• Differentiate between cardiac, metabolic, and neurological causes
  • Most unconscious patients have underlying cardiac or metabolic problem; neurologic cause of unconsciousness is rare
  • Cardiac causes of unconsciousness
    • Most common
    • Suspicious features
      • Low heart rate
      • Low blood pressure
      • Abnormal ECG
  • Endogenous metabolic causes of unconsciousness
    • Etiology
      • Metabolic acidosis
      • Hypoglycaemia
      • Hyperglycaemic crisis
      • Hepatic encephalopathy
      • Uraemia
      • Hypercapnia
    • Suspicious features
      • Abnormal blood sugar
      • Kussmaul breathing (quick and deep)
      • Abnormal odour of breath
      • Hypotonia
      • Hyporeflexia
  • Exogenous metabolic causes of unconsciousness (intoxication)
    • Etiology
      • Opioids
      • Benzodiazepines
      • Alcohol
    • Suspicious features
      • Drugs or needles around the patient
      • Needle marks on the patient’s arms
      • Slow, superficial breathing
      • Extreme miosis (pinpoint pupils)
      • Low blood pressure
  • Neurological causes of unconsciousness
    • Etiology
      • Brainstem lesion (of the ascending reticular activating system)
        • Increased ICP -> foramen magnum herniation
        • Brainstem stroke
        • Trauma
      • Bilateral thalamus lesion
        • There’s a relatively frequent malformation where both thalami receive blood from same artery -> prone to bilateral ischaemia
      • Bilateral frontal lobe lesion
    • Suspicious features
      • Abnormal pupillary light reflex
        • Unilateral dilated fixed pupil – CN III palsy
        • Bilateral dilated fixed pupils – tectal lesion or atropine
        • Midpoint fixed pupils – midbrain lesion
        • Pinpoint fixed pupils – pons lesion, opioids
        • Small reactive pupils – thalamus lesion or metabolic
      • Abnormal conjugation
        • Conjugated and deviated eyes (deviate ipsilateral to cortical lesion)
        • Dysconjugated eyes (brainstem or CN III, IV, VI lesion)
        • Skew deviation (brainstem lesion)
      • High blood pressure
        • Increased ICP -> Cushing reflex
      • Decorticate posturing
        • Flexed elbows, adducted arms, flexed fingers and wrists
        • Indicates damage above the red nucleus, e.g. rostral midbrain, thalamus, internal capsule, hemispheres
      • Decerebrate posturing
        • Upper and lower extremities extended and internally rotated
        • Indicates damage below the red nucleus, e.g. caudal midbrain or pons
      • Absent oculocephalic reflex (brainstem lesion) (see topic 3)
      • Absent corneal reflex
      • Absent cough reflex (lower brainstem lesion)
      • Hyperreflexia
• History
  • From relatives or other witnesses
  • Did patient have any symptoms right before loss of consciousness?
  • Was loss of consciousness abrupt or gradual?
  • Patient’s recent health
  • Patient’s functional status
  • Previous medical history
  • Medication use
• Examination
  • General examination
    • ABC (airways, breathing, circulation)
      • Are the airways obstructed?
      • Breathing
        • Cheyne-Stokes breathing -> brainstem lesion, heart failure
        • Slow, superficial breathing -> drugs, narcotics
        • Quick, superficial breathing -> brainstem lesion
        • Kussmaul breathing -> acidosis, hyperglycaemic crisis
      • Circulation
        • Pulse
        • Temperature
          • Hyperthermia -> infection, heat stroke
          • Hypothermia -> cold exposure, sepsis, CNS disease
        • Skin colour
        • Blood pressure
          • Hypertension -> CNS haemorrhage
          • Hypotension -> circulatory shock
    • Smell of breath
      • Alcohol, ketone bodies, liver failure, uraemia, …
    • Bruises which can suggest a fall
  • Neurological examination
    • Determine Glasgow coma scale score
      • To what degree is the patient arousable?
        • Shout to them
        • Induce pain
          • Press on the exit point of the ophthalmic nerve
          • Press on fingernail
      • Observe eye opening, movement, and verbal response
    • Examination of meningeal signs (see topic 1)
      • Only examined if cervical trauma can be excluded
      • Meningeal signs can be present in subarachnoid haemorrhage
    • Examination of cough reflex
      • By suction or inserting endotracheal tube
    • Examination of pupil and pupillary reflexes
      • Unilateral, maximally dilated
      • Bilateral, maximally dilated
      • Mid-dilated, does not react to light
      • Tiny pinpoint pupils
      • Horner syndrome (see topic 41)
    • Examination of position of eyes
      • Conjugate deviation
      • Dysconjugate deviation
      • Skew deviation
    • Examination of spontaneous eye movements
      • Downward deviation of eyes
      • Repetitive horizontal movements
    • Examination of reflex eye movements
      • Oculocephalic (doll’s eyes) reflex
      • Oculovestibular reflex
    • Examination of corneal reflex
    • Examination of muscle tone
    • Examination of fundus
      • Papilloedema
      • Haemorrhage
    • Examination of pyramidal signs