Key Takeaways
- Approximately 1.5 million people in the United States experience traumatic brain injury annually, with up to 50,000 resulting in coma states lasting more than 24 hours
- Global incidence of coma due to stroke is estimated at 150-250 cases per 100,000 population per year in high-income countries
- In the EU, the annual incidence of coma from severe traumatic brain injury (GCS ≤8) is about 10-15 per 100,000 inhabitants
- Traumatic brain injury is the cause in 40% of coma cases in young adults aged 15-24 in the US
- Anoxic brain injury from cardiac arrest accounts for 25% of non-traumatic comas in adults
- Metabolic disturbances, including electrolyte imbalances, cause 15-20% of all coma presentations in emergency departments
- Glasgow Coma Scale (GCS) score of 3-5 indicates deep coma with 80% mortality risk without intervention
- Pupils fixed and dilated bilaterally in coma suggest brainstem herniation in 90% of cases
- Absent corneal reflex in comatose patients indicates pontine involvement >95% specificity
- Supportive hyperosmolar therapy with mannitol reduces ICP by 20-30% in 70% cytotoxic edema comas
- Targeted temperature management at 32-36°C improves neurologic outcomes in 40-50% post-cardiac arrest comas
- Barbiturate coma (pentobarbital) controls refractory ICP in 60-80% pediatric TBI cases
- Mortality in untreated bacterial meningitis coma is 70-90%, drops to 20% with timely antibiotics
- GCS 3-5 at admission predicts 90% mortality in severe TBI coma patients
- Post-anoxic coma with absent pupillary response at 72h has 100% false positive rate for awakening
Coma causes vary widely with traumatic brain injury and stroke being most common globally.
Causes and Etiology
- Traumatic brain injury is the cause in 40% of coma cases in young adults aged 15-24 in the US
- Anoxic brain injury from cardiac arrest accounts for 25% of non-traumatic comas in adults
- Metabolic disturbances, including electrolyte imbalances, cause 15-20% of all coma presentations in emergency departments
- Drug and alcohol intoxication leads to 10-15% of coma cases, with opioids being the most common in recent years
- Stroke (ischemic and hemorrhagic) is responsible for 20% of coma etiologies in patients over 65
- Central nervous system infections (meningitis, encephalitis) account for 10% of pediatric comas worldwide
- Hepatic encephalopathy from liver failure causes 5-10% of comas in hospitalized patients
- Seizure-related (status epilepticus) etiologies make up 8-10% of coma admissions
- Hypoglycemia is the cause in 4-6% of emergency coma cases, particularly in diabetics
- Neoplastic causes (brain tumors, metastases) account for 3-5% of structural comas
- Carbon monoxide poisoning causes 2-3% of toxic comas, often misdiagnosed initially
- Autoimmune encephalitis (e.g., anti-NMDA receptor) causes 1-2% of new-onset comas in young adults
- Snakebite neurotoxins lead to coma in 10-15% of severe envenomations in endemic areas
- Hyperthermia/heat stroke accounts for 1% of summer coma cases in temperate climates
- Uremic toxins from renal failure cause 2-4% of metabolic comas
- Myxedema coma from hypothyroidism: less than 1% but 25-50% mortality
- Addison's disease crisis: hypocortisolism causes 20% of acute cases to present in coma
- Wernicke's encephalopathy from thiamine deficiency leads to coma in 10-20% untreated alcoholics
- Cerebral malaria parasites sequester in brain vessels, causing 80% of severe pediatric malaria comas
- Non-convulsive status epilepticus underlies 20% of unexplained comas in ICU
- Basilar artery occlusion stroke causes locked-in syndrome mimicking coma in 70% of cases
- Guillain-Barré syndrome with bulbar involvement leads to coma via respiratory failure in 5%
- Japanese encephalitis virus neurotropism causes coma through brainstem inflammation in 50%
- Traumatic epidural hematoma rapidly progresses to coma in 50-70% if untreated
- Herpes zoster ophthalmicus can lead to contralateral hemiplegia and coma via vasculitis
- Lithium toxicity causes coma in 10-20% of severe overdoses (>2.5 mmol/L)
Causes and Etiology Interpretation
Clinical Features and Diagnosis
- Glasgow Coma Scale (GCS) score of 3-5 indicates deep coma with 80% mortality risk without intervention
- Pupils fixed and dilated bilaterally in coma suggest brainstem herniation in 90% of cases
- Absent corneal reflex in comatose patients indicates pontine involvement >95% specificity
- Decerebrate posturing on GCS assessment correlates with midbrain dysfunction in 85% of traumatic comas
- EEG burst suppression pattern in anoxic coma predicts poor outcome with 100% specificity at day 3
- FOUR Score (Full Outline of UnResponsiveness) outperforms GCS in intubated patients by 20% accuracy
- Absent N20 somatosensory evoked potential (SSEP) waveform predicts death in post-anoxic coma with 99% specificity
- CT head showing midline shift >5mm in coma indicates surgical emergency in 95% TBI cases
- CSF opening pressure >40 cmH2O in comatose meningitis patients suggests bacterial etiology 80%
- Hyperglycemia >300 mg/dL in coma prompts immediate metabolic screening in 70% reversible cases
- Absent oculocephalic reflex (doll's eyes) localizes lesion to pons in 90% of structural comas
- Serum ammonia >200 µmol/L in suspected hepatic coma confirms encephalopathy in 95%
- MRI diffusion restriction in bilateral basal ganglia suggests CO poisoning in 80% comas
- Bispectral index (BIS) <40 in sedation-adjusted coma predicts awakening delay >7 days 75%
- Pronounced periodic complexes on EEG in herpes encephalitis coma have 90% specificity
- GCS motor score ≤2 at 72 hours post-injury predicts poor outcome in 90% TBI comas
- Serum sodium <120 mmol/L in coma indicates severe hyponatremia, treatable cause in 60%
- Absent pupillary light reflex with preserved corneal reflex suggests midbrain-sparing lesion 85%
- Continuous EEG monitoring detects non-convulsive seizures in 20% of unexplained comas
- Thyroxine <3 µg/dL and hypothermia <32°C confirm myxedema coma in 95% cases
- Carboxyhemoglobin >25% on co-oximetry diagnoses CO-induced coma accurately 100%
- Cortisol <5 µg/dL post-ACTH stimulation confirms Addisonian coma etiology 98%
- Creatinine >10 mg/dL with asterixis indicates uremic coma in ESRD patients 90%
- Anti-NMDA receptor antibodies positive in 80% of young female autoimmune coma cases
- Parasitemia >5% with hypoglycemia confirms severe falciparum malaria coma 85%
- Delta ratio >2 on arterial blood gas distinguishes metabolic from respiratory acidosis in coma
- Intracranial pressure >20 mmHg on monitor requires intervention in 95% comatose TBI
- Intravenous thiamine reversal of ophthalmoplegia and confusion diagnoses Wernicke's coma 90%
Clinical Features and Diagnosis Interpretation
Incidence and Prevalence
- Approximately 1.5 million people in the United States experience traumatic brain injury annually, with up to 50,000 resulting in coma states lasting more than 24 hours
- Global incidence of coma due to stroke is estimated at 150-250 cases per 100,000 population per year in high-income countries
- In the EU, the annual incidence of coma from severe traumatic brain injury (GCS ≤8) is about 10-15 per 100,000 inhabitants
- Pediatric coma incidence from non-traumatic causes like meningitis is around 5-10 per 100,000 children under 5 years annually worldwide
- In low-income countries, coma from cerebral malaria affects approximately 1-2% of all malaria cases, equating to over 200,000 pediatric cases yearly
- The prevalence of persistent vegetative state post-coma in the US is about 10,000-25,000 adults and 4,000-10,000 children
- Coma from drug overdose accounts for 15-20% of all coma admissions in urban US hospitals, with over 100,000 cases yearly
- Incidence of hypoglycemic coma in diabetics is 1.2-4.6 per 100 patient-years in type 1 diabetes populations
- In Australia, heatstroke-induced coma occurs in 0.5-1 per 100,000 population during extreme heat waves
- Post-cardiac arrest coma prevalence is 50-80% of out-of-hospital cardiac arrest survivors immediately post-resuscitation
- Worldwide, hepatic encephalopathy leading to grade IV coma (deep coma) occurs in 30-40% of acute liver failure cases
- In the UK, coma from status epilepticus has an incidence of 10-20 per 100,000 per year
- Neonatal hypoxic-ischemic encephalopathy causing coma affects 1-8 per 1,000 live births in term infants globally
- Coma from carbon monoxide poisoning in the US: about 50,000 emergency visits yearly, 400 deaths
- In India, snakebite envenomation leads to coma in 10-20% of severe cases, with 50,000 deaths annually
- Alcohol withdrawal delirium tremens progressing to coma occurs in 5% of severe cases, affecting 1-2% of hospitalized alcoholics
- Traumatic coma from road traffic accidents: 40-50% of severe TBI cases in Europe, incidence 5-10 per 100,000
- Myxedema coma incidence is 0.2 per 100,000 per year in the US, mostly elderly females
- In sub-Saharan Africa, bacterial meningitis causes coma in 20-30% of cases, incidence 50 per 100,000 children
- Post-anoxic coma after near-drowning: 10-20% of pediatric submersion victims develop prolonged coma
- Coma from Guillain-Barré syndrome (respiratory failure variant) in 20-30% of severe cases, incidence 1-2 per 100,000 yearly
- In the US, opioid-induced coma contributes to 70,000 overdose deaths yearly, with many surviving in coma states initially
- Encephalitis from herpes simplex leads to coma in 70% of untreated cases, incidence 1-3 per million
- Diabetic ketoacidosis coma in 10-25% of pediatric presentations
- In elderly populations, stroke-induced coma rate is 15-20% of hemorrhagic strokes
- Traumatic brain injury coma in military personnel: 20-30% of blast injuries lead to immediate coma
- Addisonian crisis causing coma in 20-30% of acute adrenal insufficiency cases
- In Europe, subarachnoid hemorrhage coma in 20% of cases, incidence 6-10 per 100,000
- Uremic encephalopathy coma in end-stage renal disease pre-dialysis: 10-20% incidence
- Global annual cases of coma from Japanese encephalitis: around 10,000-15,000
Incidence and Prevalence Interpretation
Prognosis and Outcomes
- Mortality in untreated bacterial meningitis coma is 70-90%, drops to 20% with timely antibiotics
- GCS 3-5 at admission predicts 90% mortality in severe TBI coma patients
- Post-anoxic coma with absent pupillary response at 72h has 100% false positive rate for awakening
- Hepatic coma grade IV has 80% 30-day mortality despite optimal therapy
- 50% of cardiac arrest comas awaken within 72h if EEG shows reactive background
- Pediatric TBI coma recovery to mRS 0-3 in 60% if GCS motor >5 at day 7
- Myxedema coma mortality reduced from 50% to 20-30% with IV thyroid hormone therapy
- Absent SSEP N20 at day 3 post-arrest predicts no recovery in 99% anoxic comas
- Cerebral malaria coma in children <5y: 15-20% mortality, 10% neurologic sequelae
- Opioid overdose coma survival 90% with naloxone, but 20% hypoxic brain injury persistent
- Status epilepticus coma >24h duration: 40% mortality, 30% permanent disability
- Guillain-Barré coma (ventilatory failure): 80% full recovery, 5% mortality
- HSV encephalitis coma treated early: 50% good outcome, untreated 90% mortality
- Uremic coma dialysis: 70% awaken within 48h, 10% permanent damage
- CO poisoning coma with LOC >6h: 30% persistent vegetative state risk
- Autoimmune encephalitis coma: 80% recover to independence with immunotherapy
- Hypoglycemic coma <24h: 95% full recovery, >24h: 20% cognitive deficit
- Decompressive craniectomy in TBI coma: shifts mortality from 80% to 50%
- Addisonian crisis coma: mortality <5% with prompt steroids, 50% untreated
- Wernicke's coma treated: 20% mortality, 80% recover; untreated 10-20% death
- Snakebite neurotoxic coma with antivenom: 90% survival, 20% sequelae
- Bacterial meningitis coma: 30% mortality adults, 10% children with steroids
- Persistent vegetative state after coma: 50% die within 1y, 30% minimally conscious transition
- Malignant MCA stroke coma: 80% mortality medically, 40% with hemicraniectomy
Prognosis and Outcomes Interpretation
Treatment and Management
- Supportive hyperosmolar therapy with mannitol reduces ICP by 20-30% in 70% cytotoxic edema comas
- Targeted temperature management at 32-36°C improves neurologic outcomes in 40-50% post-cardiac arrest comas
- Barbiturate coma (pentobarbital) controls refractory ICP in 60-80% pediatric TBI cases
- Continuous veno-venous hemodiafiltration corrects uremic coma metabolites in 90% within 48 hours
- High-dose steroids (dexamethasone 10mg IV) reverse spinal cord compression coma in 70% tumor cases
- Lactulose 30ml QID reduces ammonia by 50% in 80% hepatic encephalopathy grade III-IV comas
- IV acyclovir 10mg/kg q8h improves survival from 20% to 70% in HSV encephalitis coma
- Benzodiazepines (lorazepam 0.1mg/kg) terminate status epilepticus coma in 80% within 10 min
- 50% dextrose IV reverses hypoglycemic coma (<40mg/dL) in 95% non-diabetic cases immediately
- Hypertonic saline 3% bolus reduces ICP by 5-10 mmHg in 75% hyponatremic comas
- IV immunoglobulin 0.4g/kg/day x5 days improves Guillain-Barré coma recovery in 85%
- N-acetylcysteine infusion prevents hepatic coma progression in 85% paracetamol overdoses
- Plasmapheresis removes autoantibodies in 70% autoimmune encephalitis comas
- Hyperbaric oxygen at 2.5 ATA x90min accelerates carboxyhemoglobin clearance by 50% faster
- IV hydrocortisone 100mg q6h with fludrocortisone reverses Addisonian coma in 90% within 24h
- Levothyroxine 500mcg IV loading dose improves GCS by 3 points in 60% myxedema comas
- Decompressive craniectomy reduces mortality by 20-30% in malignant MCA stroke comas
- Continuous EEG-guided propofol infusion controls non-convulsive status in 90% ICU comas
- Artesunate IV 2.4mg/kg reduces mortality by 35% in cerebral malaria comas
- Thiamine 500mg IV x3 days prevents progression in 95% Wernicke's comas
- Antivenom within 6 hours reverses neurotoxic coma in 80% snakebite cases
- Pronestyl (procainamide) infusion terminates hyperthermic fasciculations leading to coma recovery 70%
- Mechanical ventilation with PaCO2 35-40 mmHg optimizes cerebral perfusion in 85% comas
- Ketamine infusion avoids hypotension in refractory ICP comas unlike propofol 50% better
- RIFampin adjunctive therapy improves bacterial meningitis coma outcomes by 20%
Treatment and Management Interpretation
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