Comment on the significance of the following signs in a patient  on whom you are performing brain death testing:


a) a generalised tonic clonic seizure
b) slow drifting of one eye away from the ear in which cold water is injected during caloric testing
c) flexion of the arm at the elbow following imposition of a painful  stimulus to the nail bed on that side
d) sitting up during apnoea testing
e) an increase in pulse from 70 bpm to 110 bpm during apnoea testing

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College Answer

With each of these signs, clearly indicate if they are compatible or not with the diagnosis of brain death and provide a brief explanation  for your answer.

a) generalised tonic clonic seizure

the patient must have intact neural connections to have a grand mal fit - brain death can not be present

b) slow drifting of one eye away from the ear in which cold water is injected during caloric testing

any eye movement in response to caloric testing signifies the presence of some reflex arc function. Brain death cannot be diagnosed

c) flexion of the arm at the elbow following imposition of a painful stimulus to the nail bed on that side this may represents a spinal reflex. It does not influence a diagnosis of brain death

d) sitting up during apnoea testing
this represents another spinal reaction to the acidosis which occurs with hypercarbia and is termed the Lazarus sign. It usually really unsettles nursing staff and is inevitably very disturbing to relatives. However it is compatible with a diagnosis of brain death .

e) an increase in pulse from 70 bpm to 110 bpm during apnoea testing Hypercarbia (which occurs during apnoea testing) results in endogenous adrenaline release. An change in pulse rate and blood pressure is common during apnoea resting and is not incompatible with brain death

Discussion

The ANZICS Statement on Death and Organ Donation is again the primary source for this answer. Specifically, I direct the reader to Page 22 of the most recent version, where sections 2.2.3 and 2.2.4 discuss observations which are compatible and incompatible with drain death.

To simplify revision, I will quote some of them here.

Observations compatible with brain death:

  • Spinal reflexes in response to noxious stimulus:
    • Extension-pronation movements of the upper limbs
    • Nonspecific flexion of the lower limbs
    • Undulating toe reflex
    • Lazarus sign
    • Deep tendon reflexes
    • Plantar responses (flexor or extensor)
    • "Respiratory-like movements" without much of a tidal volume
    • Head turning
  • Sweating
  • Blishing
  • Tachycardia
  • Normal blood pressure in absence of vasopressors
  • Absence of diabetes insipidus

Observations incompatible with brain death:

  • Extensor posturing (decorticate)
  • Flexor posturing (decerebrate)
  • True extensor or flexor responses to painful stimuli
  • Seizures

For a more comprehensive overview, a good (ancient) article from the Acta Neurochirurgica describes what the authors have quaintly termed "Spinal Man", a species of human bereft of higher cortical function, which is a creature reliant purely on spinal reflexes.

Additionally, a more recent article discusses the various physiological responses to apnoea testing, including all the various cardiovascular derangements which occur.

Thus:

a) - a seizure - rules out brain death

b) - a positive caloric reflex - is a brainstem reflex which is still working, and it rules out brain death

c) - arm flexion to ipsilateral painful stimulus - could be a spinal reflex, and does not rule out brain death. 

d) - a Lazarus sign - does not rule out brain death

e) - a hypercapnea-associated catecholamine surge - can occur with zero cerebral input, and does not rule out brain death.

References

References

ANZICS Death and Organ Donation Committee, THE ANZICS STATEMENT ON DEATH AND ORGAN DONATION Edition 3.2 2013

 

McNair, N. L., and K. J. Meador. "The undulating toe flexion sign in brain death." Movement disorders 7.4 (1992): 345-347.

 

Jørgensen, E. O. "Spinal man after brain death." Acta neurochirurgica 28.4 (1973): 259-273.

 

Ropper, Allan H. "Unusual spontaneous movements in brain‐dead patients."Neurology 34.8 (1984): 1089-1089.

 

Heytens, Luc, et al. "Lazarus sign and extensor posturing in a brain-dead patient: case report." Journal of neurosurgery 71.3 (1989): 449-451.

 

Lang, C. J. G., and J. G. Heckmann. "Apnea testing for the diagnosis of brain death." Acta neurologica scandinavica 112.6 (2005): 358-369.