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anoxic/hypoxic encephalopathy

Etiology: 1) cardiac arrest 2) respiratory failure 3) catastrophic stroke 4) poisoning a) carbon monoxide poisoning b) drug overdose 5) head trauma Pathology: 1) hippocampal pyramidal neurons selectively vulnerable [4] - CA1 region most vulnerable [5] 2) cererbellar Purkinje cells selectively vulnerable [4] 3) diffusely affects neocortex [2,4] 4) thalamus consistently injured [2] 5) neurons of the nucleus accumbens relatively spared [3] 6) in neonatal anoxia, periventricular white matter is also selectively vulnerable [4] 7) calcium channels and excitatory glutamate receptors are implicated in hypoxic/anoxic brain damage [4] 8) hypoglycemia & ATP deficiency implicated Clinical manifestations: 1) progression through the Glasgow coma scale within seconds to minutes 2) 98% of patients with Glasgow coma scale < 5 remain die or remain comatose after 2 weeks 3) other signs/symptoms* associated with poor prognosis a) absent corneal reflexes b) absent pupillary reaction to light c) absent withdrawal to pain d) absent motor responses * 24 hours after onset Laboratory: 1) markedly elevated neuron-specific enolase (> 33 ug/L) or serum S-100 associated with poor prognosis Radiology: 1) CT or MRI for the evaluation of stroke or head trauma if indicated 2) PET scan may play a role in the future Management: 1) specific measures for specific etiology 2) supportive care for 3-5 days or longer 3) induced hypothermia may improve morbidity & mortality if insult is removed 4) prognosis - not immediately apparent - supportive care for 3-5 days or longer may be needed prior to establishing irreversibility

General

anoxia hypoxia

References

  1. UpToDate 14.2 http://www.utdol.com
  2. Adams JH et al, The neuropathology of the vegetative state after an acute brain insult. Brain 2000, 123:1327 PMID: 10869046
  3. Huang KW, Zhao Y Selective sparing of human nucleus accumbens in aging and anoxia. Can J Neurol Sci 1995, 22:290 PMID: 8599772
  4. Cervos-Navarro J and Deimer NH, Selective vulnerability in brain hypoxia. Crit Rev Neurobiol 1991, 6:149 PMID: 1773451
  5. Ng T et al, Changes in the hippocampus and the cerbellum resulting from hypoxic insults: frequency and distribution. Acta Neuropathol (Berl) 1989, 78:438 PMID: 2782053
  6. Medical Knowledge Self Assessment Program (MKSAP) 18, American College of Physicians, Philadelphia 2018
  7. Vrselja Z, Daniele SG, Silbereis J at el Restoration of brain circulation and cellular functions hours post-mortem. Nature. volume 568, pages 336-343 (April 17, 2019) PMID: 30996318 https://www.nature.com/articles/s41586-019-1099-1 - Farahany NA, Greely HT, Giattino GM Part-revived pig brains raise slew of ethical quandaries. Nature. volume 568, (April 17, 2019) PMID: 30996311 https://www.nature.com/articles/d41586-019-01168-9 - Youngner S, Hyun I Pig experiment challenges assumptions around brain damage in people. Nature. volume 568, (April 17, 2019) PMID: 30996309 https://www.nature.com/articles/d41586-019-01169-8