NEUROLOGICAL PROGNOSTICATION AFTER CARDIAC ARREST 

INTRODUCTION

Neurological prognostication refers to prediction of long-term neurological outcome in comatose survivors after return of spontaneous circulation (ROSC) following cardiac arrest.

Immediately after ROSC, coma and absent brainstem reflexes usually represent transient post-ischemic brain dysfunction — not brain death — hence Brain Stem Death protocol must be delayed


WHY PROGNOSTICATION IS COMPLEX

Post-cardiac arrest brain injury involves:

Primary Injury

  • Global cerebral ischemia during arrest

Secondary Injury

  • Reperfusion injury
  • Cytotoxic edema
  • Excitotoxicity
  • Inflammation
  • Mitochondrial failure

👉 Neurological recovery is time-dependent
👉 Sedation, metabolic derangements, hypothermia may mask neurological signs


WHEN TO PERFORM PROGNOSTICATION

Guideline Recommendation

👉 According to ERC 2021 / ESICM / AHA 2020

Definitive prognostication ≥ 72 HOURS after ROSC

OR

≥ 72 HOURS after rewarming

(in patients treated with targeted temperature management – TTM)

Why 72 Hours?

  1. Sedative drugs may persist
  2. TTM delays drug metabolism
  3. Neurological recovery is delayed
  4. Prevents false pessimism


PATIENTS ELIGIBLE FOR PROGNOSTICATION

Must have:

✔ Persistent coma
✔ GCS Motor ≤ 3
✔ Absence of confounders


MAJOR CONFOUNDERS (MUST BE EXCLUDED)

Drug related

  • Sedatives
  • Opioids
  • Neuromuscular blockers

Metabolic

  • Severe electrolyte abnormality
  • Hypoglycemia
  • Hepatic encephalopathy
  • Uremia

Physiological

  • Hypothermia
  • Shock
  • Severe hypoxia
  • Severe hypotension


OUTCOME DEFINITIONS

Good Neurological Outcome

  • CPC 1–2 (Cerebral Performance Category)

Poor Neurological Outcome

  • CPC 3–5
    • Severe disability
    • Vegetative state
    • Brain death
    • Death


CORE PRINCIPLE

👉 Multimodal Prognostication is Mandatory

Never rely on a single test


PROGNOSTICATION MODALITIES


1️⃣ CLINICAL EXAMINATION

Pupillary Reflex

Bilateral absence at ≥72 hours

  • Strong predictor of poor outcome
  • False positive rate ≈ 0–5%


Corneal Reflex

Absent bilaterally

  • Highly specific for poor prognosis


Motor Response

Motor score ≤3

(Abnormal flexion or worse)

  • Used as screening marker
  • Alone NOT sufficient


Status Myoclonus

Early generalized myoclonus (<48 hr)

  • Suggests severe injury
  • Especially if:
    • Continuous
    • Associated with burst suppression EEG

⚠ Exception:

  • Lance-Adams syndrome (late action myoclonus → good outcome possible)


2️⃣ ELECTROPHYSIOLOGY

Somatosensory Evoked Potentials (SSEP)

Bilaterally absent N20 cortical response

👉 One of the MOST RELIABLE predictors

  • Very high specificity (>95%)
  • Not affected by sedation
  • Should be performed ≥24–72 hours


Electroencephalography (EEG)

Highly malignant patterns:

✔ Suppressed background
✔ Burst suppression
✔ Generalized periodic discharges on suppressed background
✔ Non-reactive EEG


Favorable EEG Features:

✔ Continuous background
✔ EEG reactivity
✔ Normal sleep patterns


3️⃣ NEUROIMAGING

CT Brain

Poor prognostic signs:

✔ Diffuse cerebral edema
✔ Loss of grey-white differentiation
✔ Effacement of sulci
✔ Reduced GWR (Grey-White Ratio)


MRI Brain

Diffusion-Weighted Imaging (DWI)

Poor prognostic signs:

✔ Extensive diffusion restriction
✔ Cortical laminar necrosis
✔ Basal ganglia injury

👉 MRI is more sensitive than CT


4️⃣ BIOMARKERS

Neuron Specific Enolase (NSE)

Elevated NSE levels:

  • Marker of neuronal injury
  • Serial measurement preferred

Typical poor prognostic indicator:

👉 NSE > 60 µg/L at 48–72 hr
(Exact threshold varies between guidelines)


Emerging Biomarkers

  • Neurofilament light chain
  • S100B protein

(Not yet standard)



Poor Prognosis Likely if ≥2 Strong Predictors Present

Strong Predictors:

✔ Absent pupillary reflex
✔ Absent corneal reflex
✔ Bilateral absent SSEP N20
✔ Highly malignant EEG pattern
✔ NSE markedly elevated
✔ Severe cerebral edema on imaging


SPECIAL CLINICAL SIGNS

Post-Anoxic Status Epilepticus

Poor prognosis if:

✔ Refractory seizures
✔ Associated malignant EEG

But:

  • Treat aggressively
  • Some patients recover


Brainstem Dysfunction

Signs include:

✔ Absent brainstem reflexes
✔ Absent respiratory drive

Very poor prognosis


SELF-FULFILLING PROPHECY PROBLEM

Early WLST based on premature assessment:

➡ Artificially increases mortality
➡ Overestimates poor prognosis

Hence guidelines insist:

👉 Multimodal + delayed assessment


WITHDRAWAL OF LIFE-SUSTAINING THERAPY (WLST)

Should be considered only if:

✔ Multiple concordant poor prognostic markers
✔ No confounders
✔ Discussion with family
✔ Ethical and institutional policy compliance