Question 16

List the clinical signs and tests used for neuro-prognostication after cardiac arrest and discuss their limitations.

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College answer

Not available.


The question did not ask for "advantages and disadvantages", they only wanted limitations. Thus, a mangled truncated version of summary the table from the neuroprognostication chapter is offered here.

Predictors of Poor Outcome in Comatose Survivors of Cardiac Arrest
Predictive sign or investigation Limitations and confounding factors
Absent pupillary reflex
  • Sedation
  • Hypothermia
  • Paralysis
  • Presence of shock
  • Metabolic derangements, eg. acidosis
Absent corneal reflex
Extensor motor response, or worse
  • High false positive rate (~50%)
Myoclonic status epilepticus
  • Interpreter-dependent
  • Findings may be subtle
  • Paralysis interferes with interpretation
Somatosensory evoked potentials:
absence of the N20 component
Burst suppression on EEG
  •  Poor predictive value; cannot be used for prognostication on its own.
Absence of EEG reactivity, or "malignant" EEG pattern
  • Confounded by sedation and hypothermia
Neuron-specific enolase
CT brain
  • If performed too early, the CT may not demonstrate any findings.
MRI brain
  • If performed too late, the MRI may not demonstrate any findings.


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