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Brain Death

  1. Definition. Death is recognized as occurring when there is irreversible cessation of all brain function. A brain insult sufficient to cause complete loss of cerebral function should be docu­mented, if possible.
  2. Approach to the patient
    1. Physical examination.
      1. Pupillary responses are absent,
      2. Eye movements cannot be elicited by the vestibulo­ ocular reflex or by irrigating the ears with cold water.
      3. The corneal reflex is absent
      4. Gag reflex is absent, and there is no facial or tongue movement.
    2. Apnea test. Patients have no respiratory function. An apnea test should be performed to ascertain that no respirations occur at a PaCO2 level of at least 60 mm Hg. The oxygenation should be maintained as the PaCO2 is allowed to rise. The inability to develop respiration is consistent with medullary failure.
    3. Exclusionary criteria. A diagnosis of brain death cannot be made in the setting of drug intoxication, hypothermia (defined as a core temperature of <32°C), or severe hypotension (i.e., shock).
    4. Confirmatory tests. These tests are usually not necessary to diagnose brain death but can be used if doubt exists or if local statutes require them.
      1. An EEG does not demonstrate any physiologic brain activity.
      2. Tests to assess cerebral blood flow fail to show cerebral perfusion.
        1. Period of observation. Periodic evaluation is necessary before a diagnosis of brain death can be made, unless there is gross evidence of a no survivable insult to the brain.
        2. Two evaluations (6 to 12 hours apart) are usually sufficient to support a diagnosis of brain death declaring brain death.

Fig: Examination of brainstem reflexes in coma. Midbrain and third nerve function are tested by pupillary reaction to light, pontine function by spontaneous and reflex eye movements and corneal responses, and medullary function by respiratory and pharyngeal responses. Reflex conjugate, horizontal eye movements are dependent on the medial longitudinal fasciculus (MLF) interconnecting the sixth and contralateral third nerve nuclei. Head rotation (oculocephalic reflex) or caloric stimulation of the labyrinths (oculovestibular reflex) elicits contraversive eye movements. (Ref. Hari. 18th ed., Pg- 2250)

Extra Edge: Blink (Corneal) reflex is used to asses mid pontine lesion (AIIMS Nov 2012)


Extra Edge  (Ref. Hari. 18th ed., Pg- 2250)

  1. Decorticate rigidity and decerebrate rigidity, or "posturing," describe stereotyped arm and leg movements occurring spontaneously or elicited by sensory stimulation.
  2. Flexion of the elbows and wrists and supination of the arm (decortication) suggests bilateral damage rostral to the midbrain, whereas extension of the elbows and wrists with pronation (decerebration) indicates damage to motor tracts in the midbrain or caudal diencephalon.

Table - Paraneoplastic Syndromes





Subacute cerebellar degeneration

i. Hodgkin lymphoma
ii. Breast
iii. SCLC (small cell lung cancer)

iv. neuroblastoma

Limbic encephalitis; brainstem encephalitis


ii. Neuroblastoma
iii. Testicular

Subacute sensory neuropathy


ii. Neuroblastoma

Opsoclonus myoclonus

i. Neuroblastoma
ii. Breast

Retinal degeneration


Stiff-man syndrome


Lambert-Eaton myasthenic Syndrome


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