What are the symptoms of brain death?

Symptoms of Brain Death

Brain death is characterized by complete loss of consciousness, absence of all brainstem reflexes, and apnea (inability to breathe spontaneously), representing irreversible cessation of all brain function including the brainstem. 1

Core Clinical Findings

1. Coma

• Complete loss of consciousness, vocalization, and volitional activity 1
• Absence of responsiveness to any stimuli, including painful stimuli 1
• Lack of spontaneous motor activity (though spinal reflexes may still be present) 1

2. Absence of All Brainstem Reflexes

• Pupillary abnormalities:

  • Midposition or fully dilated pupils that do not respond to light 1
  • Fixed pupils typically in midsize or dilated position (4-9 mm) 1

• Ocular reflexes:

  • Absent corneal reflexes (no eyelid movement when cornea is touched) 1
  • Absent oculocephalic ("doll's eye") reflexes 1
  • Absent oculovestibular (caloric) responses (no eye movement when ice water is instilled into ear canal) 1

• Bulbar reflexes:

  • Absent gag and cough reflexes, even with tracheal suctioning 1
  • Absence of movement of facial and oropharyngeal muscles 1
  • Absent sucking and rooting reflexes (in infants) 1

3. Apnea

• Complete absence of respiratory effort despite adequate stimulus 1, 2
• Verified through formal apnea testing:
  • Patient is preoxygenated with 100% oxygen
  • Ventilator is disconnected
  • CO₂ allowed to rise (PaCO₂ >60 mmHg confirms valid test) 1, 2
  • No respiratory movements observed despite this intense respiratory stimulus 2

Confirmation Requirements

1. Exclusion of Confounding Conditions

• Normal body temperature (>32.5°C) 1
• Absence of CNS depressants, neuromuscular blocking agents, or other drugs that could mask brain function 1
• No severe metabolic disturbances 1

2. Establishing Irreversibility

• Persistence of clinical findings for an observation period (typically 6-24 hours) 1
• Shorter observation periods may be acceptable if irreversibility can be confirmed by ancillary tests 1

3. Ancillary Tests (when clinical examination is limited or uncertain)

• Cerebral blood flow studies (catheter angiography, CT angiography) showing cerebral circulatory arrest 3
• Electroencephalography (EEG) showing electrocerebral silence 4
• Other tests: perfusion scintigraphy, transcranial Doppler 3

Important Clinical Considerations

• Brain death determination requires strict adherence to established protocols to prevent diagnostic errors 5
• The use of checklists and standardized processes is recommended 5
• Documentation should reference clinical examination criteria, any laboratory testing performed, and determination of irreversibility 1
• Confirmation by a second physician is prudent and required by law in some jurisdictions 1

Common Pitfalls

• Failure to adequately exclude reversible causes of coma 6
• Improper apnea testing technique leading to hypoxemia or hemodynamic instability 2
• Misinterpretation of spinal reflexes as evidence of brain function 1
• Inadequate observation time in cases where the etiology of brain injury is uncertain 1
• Failure to recognize drug intoxication or hypothermia as confounders 4

Brain death determination is a complex process that requires thorough understanding of neurophysiology and careful clinical assessment. When properly diagnosed, brain death represents a condition that cannot be reversed by any medical or surgical intervention 6.