Coma: Difference between revisions

(Comprehensive expansion: EM-focused approach with AEIOU-TIPS, structured DDx, key exam findings, coma cocktail, and herniation management)
(Add verified PubMed references (PMIDs 24767707, 33218655))
 
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==Background==
==Background==
*Coma is a state of unresponsiveness from which the patient cannot be aroused, even with vigorous stimuli
*Coma is a state of unresponsiveness from which the patient cannot be aroused, even with vigorous stimuli<ref>Edlow JA, et al. Diagnosis of reversible causes of coma. Lancet. 2014;384(9959):2064-76. PMID 24767707</ref>
*Defined as GCS ≤8 or inability to follow commands, speak, or open eyes
*Defined as GCS ≤8 or inability to follow commands, speak, or open eyes<ref>Karpenko A, Keegan J. Diagnosis of Coma. Emerg Med Clin North Am. 2021;39(1):155-172. PMID 33218655</ref>
*Requires dysfunction of '''both cerebral hemispheres''' or the '''reticular activating system''' (brainstem)
*Requires dysfunction of both cerebral hemispheres or the reticular activating system (brainstem)
*Coma is a medical emergency — rapid assessment and stabilization take priority while pursuing diagnosis
*Coma is a medical emergency — rapid assessment and stabilization take priority while pursuing diagnosis
*The mnemonic '''AEIOU-TIPS''' helps recall the differential:
*The mnemonic AEIOU-TIPS helps recall the differential:
**'''A''' — Alcohol, Acidosis
**A — Alcohol, Acidosis
**'''E''' — Endocrine, Electrolytes, Encephalopathy
**E — Endocrine, Electrolytes, Encephalopathy
**'''I''' — Insulin (hypoglycemia, DKA, HHS)
**I — Insulin (hypoglycemia, DKA, HHS)
**'''O''' — Opiates, Overdose, Oxygen (hypoxia)
**O — Opiates, Overdose, Oxygen (hypoxia)
**'''U''' — Uremia
**U — Uremia
**'''T''' — Trauma, Temperature
**T — Trauma, Temperature
**'''I''' — Infection (meningitis, encephalitis, sepsis)
**I — Infection (meningitis, encephalitis, sepsis)
**'''P''' — Psychiatric (rare, diagnosis of exclusion), Poisoning
**P — Psychiatric (rare, diagnosis of exclusion), Poisoning
**'''S''' — Stroke, Seizure (nonconvulsive status), Shock
**'''S''' — Stroke, Seizure (nonconvulsive status), Shock


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*No eye opening, verbal response, or motor response to command
*No eye opening, verbal response, or motor response to command
*Key exam components:
*Key exam components:
**'''Pupils:''' Bilateral fixed/dilated (anoxic brain injury, sympathomimetic), bilateral pinpoint (opioids, pontine lesion), unilateral fixed/dilated (uncal herniation, CN III compression)
**Pupils: Bilateral fixed/dilated (anoxic brain injury, sympathomimetic), bilateral pinpoint (opioids, pontine lesion), unilateral fixed/dilated (uncal herniation, CN III compression)
**'''Eye movements:''' Oculocephalic reflex (doll's eyes), oculovestibular reflex (cold calorics); absent = brainstem dysfunction
**Eye movements: Oculocephalic reflex (doll's eyes), oculovestibular reflex (cold calorics); absent = brainstem dysfunction
**'''Motor response:''' Purposeful withdrawal, flexion posturing (decorticate), extension posturing (decerebrate), flaccid
**Motor response: Purposeful withdrawal, flexion posturing (decorticate), extension posturing (decerebrate), flaccid
**'''Breathing pattern:''' Cheyne-Stokes (bilateral hemispheric or early transtentorial), central hyperventilation (midbrain), ataxic/apneustic (medulla/pons)
**Breathing pattern: Cheyne-Stokes (bilateral hemispheric or early transtentorial), central hyperventilation (midbrain), ataxic/apneustic (medulla/pons)
**'''Signs of trauma:''' Battle sign, raccoon eyes, hemotympanum, scalp lacerations
**Signs of trauma: Battle sign, raccoon eyes, hemotympanum, scalp lacerations


==Differential Diagnosis==
==Differential Diagnosis==
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==Evaluation==
==Evaluation==
*'''Immediate:'''
*Immediate:
**ABCs — secure airway if GCS ≤8 (intubate)
**ABCs — secure airway if GCS ≤8 (intubate)
**[[Finger stick glucose]] — treat [[hypoglycemia]] immediately
**[[Finger stick glucose]] — treat [[hypoglycemia]] immediately
**Rapid vitals including temperature
**Rapid vitals including temperature
*'''Focused workup:'''
*Focused workup:
**CBC, BMP, LFTs, ammonia, lactate, VBG/ABG
**CBC, BMP, LFTs, ammonia, lactate, VBG/ABG
**Toxicology screen (urine drug screen, serum ethanol, salicylate, acetaminophen levels)
**Toxicology screen (urine drug screen, serum ethanol, salicylate, acetaminophen levels)
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**Coagulation studies (PT/INR) if bleeding or liver disease suspected
**Coagulation studies (PT/INR) if bleeding or liver disease suspected
**Thyroid function (TSH) if no clear cause identified
**Thyroid function (TSH) if no clear cause identified
*'''Imaging:'''
*Imaging:
**'''CT head without contrast''' — first-line; rules out hemorrhage, mass, hydrocephalus, herniation
**CT head without contrast — first-line; rules out hemorrhage, mass, hydrocephalus, herniation
**Consider CTA head/neck if large vessel occlusion or vascular dissection suspected
**Consider CTA head/neck if large vessel occlusion or vascular dissection suspected
**MRI if CT negative and structural cause still suspected
**MRI if CT negative and structural cause still suspected
*'''Other:'''
*Other:
**[[Lumbar puncture]] if meningitis/encephalitis suspected (after CT, if safe)
**[[Lumbar puncture]] if meningitis/encephalitis suspected (after CT, if safe)
**[[EEG]] for suspected nonconvulsive status epilepticus
**[[EEG]] for suspected nonconvulsive status epilepticus
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==Management==
==Management==
*'''Stabilize first:'''
*Stabilize first:
**Airway protection — intubate if GCS ≤8 or unable to protect airway
**Airway protection — intubate if GCS ≤8 or unable to protect airway
**IV access, continuous monitoring
**IV access, continuous monitoring
**Treat [[hypoglycemia]] immediately with dextrose
**Treat [[hypoglycemia]] immediately with dextrose
*'''Empiric interventions ("coma cocktail"):'''
*Empiric interventions ("coma cocktail"):
**[[Dextrose]] (D50) if glucose unknown or low
**[[Dextrose]] (D50) if glucose unknown or low
**[[Thiamine]] 100 mg IV (give before or with glucose to prevent [[Wernicke encephalopathy]])
**[[Thiamine]] 100 mg IV (give before or with glucose to prevent [[Wernicke encephalopathy]])
**[[Naloxone]] 0.4-2 mg IV if opioid overdose suspected (pinpoint pupils, respiratory depression)
**[[Naloxone]] 0.4-2 mg IV if opioid overdose suspected (pinpoint pupils, respiratory depression)
**[[Flumazenil]] — generally '''avoided''' in undifferentiated coma (risk of seizures in benzodiazepine-dependent patients)
**[[Flumazenil]] — generally avoided in undifferentiated coma (risk of seizures in benzodiazepine-dependent patients)
*'''Treat underlying cause''' once identified
*Treat underlying cause once identified
*'''Herniation management''' if signs present (unilateral dilated pupil, posturing):
*Herniation management if signs present (unilateral dilated pupil, posturing):
**Head of bed 30°
**Head of bed 30°
**[[Mannitol]] or [[hypertonic saline]]
**[[Mannitol]] or [[hypertonic saline]]

Latest revision as of 10:42, 22 March 2026

Background

  • Coma is a state of unresponsiveness from which the patient cannot be aroused, even with vigorous stimuli[1]
  • Defined as GCS ≤8 or inability to follow commands, speak, or open eyes[2]
  • Requires dysfunction of both cerebral hemispheres or the reticular activating system (brainstem)
  • Coma is a medical emergency — rapid assessment and stabilization take priority while pursuing diagnosis
  • The mnemonic AEIOU-TIPS helps recall the differential:
    • A — Alcohol, Acidosis
    • E — Endocrine, Electrolytes, Encephalopathy
    • I — Insulin (hypoglycemia, DKA, HHS)
    • O — Opiates, Overdose, Oxygen (hypoxia)
    • U — Uremia
    • T — Trauma, Temperature
    • I — Infection (meningitis, encephalitis, sepsis)
    • P — Psychiatric (rare, diagnosis of exclusion), Poisoning
    • S — Stroke, Seizure (nonconvulsive status), Shock

Clinical Features

  • No eye opening, verbal response, or motor response to command
  • Key exam components:
    • Pupils: Bilateral fixed/dilated (anoxic brain injury, sympathomimetic), bilateral pinpoint (opioids, pontine lesion), unilateral fixed/dilated (uncal herniation, CN III compression)
    • Eye movements: Oculocephalic reflex (doll's eyes), oculovestibular reflex (cold calorics); absent = brainstem dysfunction
    • Motor response: Purposeful withdrawal, flexion posturing (decorticate), extension posturing (decerebrate), flaccid
    • Breathing pattern: Cheyne-Stokes (bilateral hemispheric or early transtentorial), central hyperventilation (midbrain), ataxic/apneustic (medulla/pons)
    • Signs of trauma: Battle sign, raccoon eyes, hemotympanum, scalp lacerations

Differential Diagnosis

Structural Causes

Diffuse/Metabolic Causes

Evaluation

  • Immediate:
  • Focused workup:
    • CBC, BMP, LFTs, ammonia, lactate, VBG/ABG
    • Toxicology screen (urine drug screen, serum ethanol, salicylate, acetaminophen levels)
    • Serum osmolality and osmolar gap
    • Blood cultures if infection suspected
    • Coagulation studies (PT/INR) if bleeding or liver disease suspected
    • Thyroid function (TSH) if no clear cause identified
  • Imaging:
    • CT head without contrast — first-line; rules out hemorrhage, mass, hydrocephalus, herniation
    • Consider CTA head/neck if large vessel occlusion or vascular dissection suspected
    • MRI if CT negative and structural cause still suspected
  • Other:
    • Lumbar puncture if meningitis/encephalitis suspected (after CT, if safe)
    • EEG for suspected nonconvulsive status epilepticus
    • ECG — arrhythmia or toxicologic cause

Management

  • Stabilize first:
    • Airway protection — intubate if GCS ≤8 or unable to protect airway
    • IV access, continuous monitoring
    • Treat hypoglycemia immediately with dextrose
  • Empiric interventions ("coma cocktail"):
    • Dextrose (D50) if glucose unknown or low
    • Thiamine 100 mg IV (give before or with glucose to prevent Wernicke encephalopathy)
    • Naloxone 0.4-2 mg IV if opioid overdose suspected (pinpoint pupils, respiratory depression)
    • Flumazenil — generally avoided in undifferentiated coma (risk of seizures in benzodiazepine-dependent patients)
  • Treat underlying cause once identified
  • Herniation management if signs present (unilateral dilated pupil, posturing):

Disposition

  • All comatose patients require ICU admission
  • Emergent neurosurgical consultation for surgical lesions (EDH, SDH with mass effect, hydrocephalus)
  • Neurology consultation for suspected nonconvulsive status epilepticus or unexplained coma

See Also

External Links

References

  1. ↑ Edlow JA, et al. Diagnosis of reversible causes of coma. Lancet. 2014;384(9959):2064-76. PMID 24767707
  2. ↑ Karpenko A, Keegan J. Diagnosis of Coma. Emerg Med Clin North Am. 2021;39(1):155-172. PMID 33218655
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