Coma and Brain Death

Authors: Flaherty, Alice W.; Rost, Natalia S.

Title: Massachusetts General Hospital Handbook of Neurology, The, 2nd Edition

Copyright 2007 Lippincott Williams & Wilkins

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Coma and Brain Death

A. See also

Trauma, p. 119.

B. Levels of decreased consciousness

• 1. Confusion: Decreased attention but relatively normal alertness.

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• 2. Drowsiness: (~lethargy, somnolence). Arouses to voice and can respond verbally.

• 3. Stupor: (~obtundation). No response to voice, no spontaneous speech. Incomplete but purposeful response to pain.

• 4. Coma: Nonpurposeful or no response to pain ( unarousable unresponsiveness ).

C. Other alterations in consciousness

see p. 42.

D. Initial coma evaluation

CPR if needed IV access draw labs (include tox screen, ?carbon monoxide level) give dextrose, thiamine, naloxone do coma exam (see below) treat suspected high ICP, meningitis, or seizures get head CT treat metabolic problems.

E. Coma exam

VS (and note pattern of breathing), cardiac rhythm, response to voice, lids (spontaneously closed?), pupils, eye movements (spontaneous, doll's, calorics), corneals, grimace to nasal tickle, gag, cough, motor response to pain, tone (lift and drop arm), reflexes.

• 1. Decorticate posturing (lesion is above midbrain):

  • a. Arm: Flexed elbow, wrist, fingers.

  • b. Leg: Extended and internally rotated leg, with plantar flexion.

• 2. Decerebrate posturing (lesion is above medulla):

  • a. Head: Clenched jaw, extended neck.

  • b. Arm: Adducted and internally rotated shoulder, extended elbow, pronated wrist, flexed fingers.

  • c. Leg: Extended and internally rotated leg, plantar flexion.

F. Glasgow Coma Scale (GCS)

Range 3-15 (pt. gets 3 points for just being there). GCS <8 is indication for intubation and poor prognosis.

Table 4. Glasgow Coma Scale.

Points	Eye Opening	Verbal	Motor
6			Obeys
5		Oriented	Localizes pain
4	Spontaneous	Confused	Withdraws to pain
3	To speech	Inappropriate	Flexion (decort.)
2	To pain	Unintelligible	Extensor (decereb.)
1	None	None	None

G. Causes of coma with normal head CT

• 1. Drug overdose or reaction: Especially sedatives, anticholinergics, and poisons, but also including neuroleptic malignant syndrome.

• 2. Anoxia or ischemia: Cardiac arrest, brainstem stroke, fat or cholesterol emboli, DIC, thrombotic thrombocytopenic purpura, vasculitis.

• 3. Trauma: Diffuse axonal injury, bilateral isodense SDH, high ICP.

• 4. Metabolic encephalopathy: Low or high glucose, low or high Na, high Ca, alkalosis or acidosis, hypercapnia, adrenal crisis, low or high thyroid, uremia, high ammonia, thiamine deficiency, hyperthermia or hypothermia.

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• 5. Infection or inflammation: Meningitis, encephalitis, sepsis, cerebritis (SLE), sarcoidosis, Beh et's, etc.

• 6. Seizure disorder: Nonconvulsive status epilepticus, postictal state.

• 7. Central pontine myelinolysis: see p. 197. Usually presents as mutism, oculobulbar palsies, quadriparesis. After rapid Na correction.

H. Prognosis in nontraumatic coma

• 1. Confounding factors: All drug effects, reversible metabolic factors, and hypothermia must be corrected first.

• 2. Prognosis by etiology: Those with hepatic cause do best, hypoxic-ischemic intermediate, vascular worst.

• 3. Prognosis by neurological exam:

  • a. Day of presentation: Look for corneal, pupillary, and oculocephalic (doll's) or caloric test responses.

    • 1) 1 of 3 absent: 95% of pts. vegetative or badly disabled.

    • 2) 2 of 3 absent: 99% of pts. vegetative or badly disabled.

  • b. Day 1:

    • 1) Spontaneous eye movements: 99% of pts. who do not have spontaneous conjugate roving eye movements or better will be vegetative or severely disabled.

    • 2) Motor withdrawal: Of pts. with spontaneous eye movements but no purposeful withdrawal to pain, 90% will be vegetative or severely disabled.

  • c. Day 3:

    • 1) Motor withdrawal: Of pts. with no purposeful withdrawal to pain, 100% will be vegetative or severely disabled.

    • 2) Spontaneous eye opening: Of pts. who withdraw but keep eyes closed, 80% will be vegetative or severely disabled.

  • d. Day 7:

    • 1) Spontaneous eye opening: Of pts. who withdraw but keep eyes closed, 100% will be vegetative.

    • 2) Obeying commands: Of pts. with spontaneous eye opening who do not follow commands, about 80% will be vegetative or severely disabled.

  • e. Day 14:

    • 1) Abnormal oculocephalic reflex:

      • a) Not following commands or opening eyes spontaneously: 100% vegetative.

      • b) Following commands or opening eyes spontaneously: 80% vegetative or severely disabled.

    • 2) Normal oculocephalic reflex: Only 20% will be severely disabled or worse.

I. Vegetative state

Similar to coma but pt may have sleep-wake cycles and eye opening to auditory stimuli, with no awareness of environment or self, no ability to communicate, and no purposeful motor activity.

J. Brain death

An attending must see the pt before he is declared brain dead. If there may be litigation about the death, get legal counsel first. The following criteria should be met:

• 1. Known cause.

• 2. No masking conditions: No hypothermia (<32 C), CNS depressants, nl electrolytes.

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• 3. No evidence of brainstem function:

  • a. Reflexes: No pupillary, corneal, oculovestibular, gag, cough, or other brainstem reflexes.

  • b. No motor response to deep central pain: There should be neither decerebrate nor decorticate posturing, but spinal reflexes including flexor withdrawal ( triple flexion ) can be seen after brain death, as well as deep tendon reflexes. There should be no change in heart rate to pain.

• 4. Apnea test: Criteria are no spontaneous breaths and pCO₂ >60 (unreliable in pt with COPD and CO₂ retention).

  • a. Preoxygenate: 15 min of ventilation with 100% O₂ beforehand. Need pCO₂ <45 and normal pH before further testing.

  • b. Disconnect ventilator; give O₂ 8-12 L/min by tracheal cannula; observe for spontaneous breaths.

  • c. Draw ABG after about 8-10 min (depends on pt stability).

  • d. Terminate test if:

    • 1) pCO₂ >60: Positive for brain death.

    • 2) Pt breathes: Negative.

    • 3) Systemic instability: Hypotension, cardiac arrhythmia, or O₂ saturation <80%: inconclusive test.

• 5. Observation period: Use clinical judgment. Recommendations:

  • a. 24 h: For anoxic brain injury and no confirmatory tests.

  • b. 12 h: For clearly irreversible condition, no confirmatory tests.

  • c. 6 h: For clearly irreversible condition, confirmatory tests.

• 6. Optional confirmatory tests (not necessary):

  • a. Flat EEG: Isoelectric at high gain.

  • b. Absent cerebral blood flow: e.g., an ICP > SBP for 1 hour or transcranial ultrasound showing reversible flow velocities.

K. Organ and tissue donation

• 1. Eligibility criteria: Candidates may be any age. Next of kin does not disapprove (this may hold even if pt. had an organ donor card). There are additional exclusion criteria not listed (e.g. HIV infection), but call the transplant coordinator and let them decide.

  • a. Organ donation: Brain dead, intact circulation, ventilated.

  • b. Tissue donation: Anyone with irreversible absence of respiration and circulation.

• 2. Transplant coordinator: Call early, 1-800-446-6362, even if you have not yet asked the family. You can ask afterwards; the organ bank will not approach the family without your permission.

• 3. When and how to ask the family: In some states, you ask all families of eligible donors about organ donation. Especially in ICUs, the nurses have had much experience with this. Ask their advice, if possible.

• 4. Management after brain death for organ donation: The transplant team will help once the pt. is declared brain dead. Before that, of course, you should treat pts. with their best interest in mind only.