Coma: Difference between revisions

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==Definition==
==Background==
*State of reduced alertness and responsiveness from which the patient cannot be aroused
*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<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)
*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===
*[[Stroke]] (ischemic or hemorrhagic)
*[[Intracranial hemorrhage]] ([[subdural hematoma]], [[epidural hemorrhage]], [[subarachnoid hemorrhage]])
*[[Elevated intracranial pressure]] / [[herniation syndromes]]
*Brain tumor with mass effect
*[[Cerebral venous sinus thrombosis]]
*[[Brain abscess]]
*[[Hydrocephalus]]
*Traumatic brain injury
 
===Diffuse/Metabolic Causes===
*[[Hypoglycemia]] — most important to rule out immediately
*Drug overdose / poisoning (opioids, benzodiazepines, barbiturates, alcohols)
*[[Hepatic encephalopathy]]
*[[Uremia]]
*[[Sepsis]] / systemic infection
*[[Meningitis]] / [[Encephalitis]]
*[[Nonconvulsive status epilepticus]]
*[[DKA]] / [[HHS]]
*[[Hypothermia]] / [[hyperthermia]]
*[[Hyponatremia]] / [[hypernatremia]]
*[[Carbon monoxide toxicity]]
*[[Hypertensive encephalopathy]]
*Anoxic brain injury (post-cardiac arrest)
*[[Wernicke encephalopathy]]
*[[Myxedema coma]] / [[thyroid storm]]
 
==Evaluation==
*Immediate:
**ABCs — secure airway if GCS ≤8 (intubate)
**[[Finger stick glucose]] — treat [[hypoglycemia]] immediately
**Rapid vitals including temperature
*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):
**Head of bed 30°
**[[Mannitol]] or [[hypertonic saline]]
**Emergent neurosurgical consultation
**See [[Elevated intracranial pressure]]
 
==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==
==See Also==
*[[Altered Mental Status]]
*[[Altered mental status]]
*[[Persistent Vegetative State]]
*[[Altered mental status (peds)]]
*[[Elevated intracranial pressure]]
*[[Herniation syndromes]]
*[[Glasgow Coma Scale]]
*[[Nonconvulsive status epilepticus]]
*[[Hypoglycemia]]
 
==External Links==
 
==References==
<references/>


[[Category:Neurology]]
[[Category:Neurology]]
[[Category:Critical Care]]
[[Category:Symptoms]]
[[Category:Symptoms]]

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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