Coma

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Coma
ICD-10	R40.2
ICD-9	780.01

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

In medicine, a coma (from the Greek Template:Polytonic koma, meaning deep sleep) is a profound state of unconsciousness. A comatose patient cannot be awakened, fails to respond normally to pain or light, does not have sleep-wake cycles, and does not take voluntary actions. Coma may result from a variety of conditions, including intoxication, metabolic abnormalities, central nervous system diseases, acute neurologic injuries such as stroke, and hypoxia. It may also be deliberately induced by pharmaceutical agents in order to preserve higher brain function following another form of brain trauma, or to save the patient from extreme pain during healing of injuries or diseases. A coma may also result from immense head trauma caused by something like a car accident or a series of very severe concussions. The underlying cause of the coma is bilateral damage to the Reticular formation of the midbrain, which is important in regulating sleep .

Differential Diagnosis of Causes of Coma

(Most common causes)

• Cerebral masses
• Diabetic coma
• Encephalitis
• Encephalomyelitis
• Endocrine encephalopathies
• Heart failure
• Head trauma
• Heatstroke
• Hepatic encephalopathy
• End stage renal disease
• Intoxication
• Poisoning
• Pulmonary embolism
• Psychoses
• Subarachnoid hemorrhage
• Syncopes

By organ system

Cardiovascular	Heart attack, Heart failure, Malignant hypertension, Shock, Ventricular fibrillation, Very low blood pressure, Cardiac dysrhythmias, Endocarditis, Rheumatic Fever
Chemical / poisoning	1,1-Dimethylhydrazine poisoning, 2-Methyl-4-Chlorophenoxyacetic Acid poisoning , Acetone poisoning, Acetylene poisoning , Ackee Fruit Food poisoning , Acrolein poisoning, Acute Chemical poisoning -- Varnish makers' and painters' Naptha, Acute xylene poisoning, Aftershave poisoning, Alcohol intoxication, Aldrin poisoning, Alicyclic hydrocarbons poisoning, Allethrin poisoning, Amanita polypyramis poisoning, Amidithion poisoning, Amiton poisoning, Ammonium Bifluoride, Ammonium Sulfamate poisoning, Anchovy (clupeotoxin) poisoning , Aniline poisoning, Antifreeze poisoning, Amyl Alcohol, Aristolochic acid, Arsenic, Apricot seed poisoning, Azinfos-methyl poisoning, Azinphos-ethyl poisoning, Azinphosmetile poisoning, Azothoate poisoning, Benoxafos poisoning, Bentazon poisoning, Benzene toxicity, Beta ketothiolase deficiency, Bird cherry seed poisoning, Bitter almond seed poisoning, Black henbane poisoning, Black jetbead poisoning, Blue-ringed octopus poisoning, Boric Acid, Box Jellyfish poisoning, Bromide toxicity, Bromoform poisoning, Butyl Alcohol poisoning, Camphor, Cannabinoids, Carbamate insecticide poisoning, Carbaryl, Carbinoxamine, Carbon monoxide poisoning, Carbon Tetrachloride, Carbophenothion, Celandine poisoning, Cherry laurel seed poisoning, Cherry seed poisoning, Chlophedianol toxicity, Chloral hydrate poisoning, Chlorate salts poisoning, Chlorfenvinphos poisoning, Chloromethane poisoning, Chloropyrifos poisoning, Chlorpyrifos poisoning, Chokecherry seed poisoning, Christmas Cherry poisoning, Chromium poisoning, Clupeotoxism, Cobra poisoning, Cocaine, Common poppy poisoning, Cone shell poisoning, Copper toxicity, Coumaphos poisoning, Cresols poisoning, Cresylic acid poisoning, Cyanide poisoning, Daphne poisoning, Darvocet overdose, Death Angel poisoning, Death Camas poisoning, Demethyldiazepam toxicity, Demeton-O-methyl poisoning, Demeton-S-methyl poisoning, Demeton-S-methylsulphon poisoning, Devil's trumpet poisoning, Dialifos poisoning, Diazinon poisoning, Dichloralphenazone poisoning, Dichloronaphthoquinone poisoning, Dichlorvos poisoning, Dicrotophos poisoning, Dieldrin poisoning, Diethylene Glycol poisoning, Dimethoate poisoning, Dimethyl Phthalate poisoning, Dinitrocresol poisoning, Dinitrophenol poisoning, Di-n-Octyl phathalate poisoning, Dioxathion poisoning, Disulfoton poisoning, Endothion poisoning, English Ivy poisoning, English Laurel poisoning, Ethchlorvynol poisoning, Ethion poisoning, Ethoate-methyl poisoning, Ethoprophos poisoning, Ethylene Glycol poisoning, Ethyl-guthion poisoning, Etrimfos poisoning, Eucalyptus Oil poisoning, Fenchlorphos poisoning, Fenitrothion, Fensulfothion, Fenthion poisoning, Fire cherry poisoning, Fonophos poisoning, Formaldehyde poisoning, Formothion poisoning, Funnel Web spider poisoning, Hair Bleach, Hair Dye, Heptenophos poisoning, Hexachlorobutadiene poisoning, Hyacinth bean poisoning, Imazapyr poisoning, Iodofenphos poisoning, Japanese pagoda tree poisoning, Jessamine poisoning, Jimsonweed poisoning, 1,2-Dichloromethane, Cadmium, Degreasing solvents, Dichloroacetylene, Diethylene glycol, Ethylene glycol ethers, Gasoline, Germanium, Glue solvent vapors, Heavy metals, Herbicide, Hexachloro-1,3-butadiene, Hydrocarbons, Lead, Lantana poisoning, Lead poisoning, Lobelia poisoning,Loquat poisoning, Lupine poisoning, Mercury, Methanol, Methemoglobin-producing agents, Mayapple poisoning, Mecarbam, Mephenoxalone,Metaldehyde, Methacrifos, Methamidophos, Methaqualone, Methidathion, Methyl Bromide, Methyprylon, Mexican tea poisoning, Nabilone, Naked brimcap poisoning, Omethoate poisoning, Organophosphate insecticide poisoning, Oxydeprofos poisoning, Oxydisulfoton poisoning, Parathion poisoning, Pentachlorophenol poisoning, Phorate poisoning, Phosalone poisoning, Phosdrin poisoning, Phosmet poisoning, Phosphamidon poisoning, Phoxim poisoning, Phthalthrin poisoning,Pirimiphos-methyl, Poison hemlock poisoning, Polyethylene Glycol -- Low Molecular Weight, Primiphos methyl, Profenofos,Propoxur, Prothidathion poisoning, Prothoate poisoning, Pyrimidifen poisoning, Pyrimitate poisoning, Paint thinners, Paints, Paraquat ochratoxin A, Perchloroethylene, Platinum, Silicon compounds, Silver, Solvents, Styrene,Uranium, Quinalphos poisoning, Quintiofos poisoning, Ramelteon poisoning, Sardine poisoning (clupeotoxin), Selenious Acid, Slickhead poisoning (clupeotoxin), Sodium Monofluoroacetate, Sophamide, Sulfotep poisoning, Systemic monochloroacetate poisoning, Tapioca poisoning, Terbufos poisoning, Tetraethyl Pyrophosphate poisoning, Tetrahydrocannabinol, Tetramethrin poisoning, Tetramethylenedisulfotetramine poisoning, Thallium sulfate, Thiometon, Thornapple poisoning, Tolclofos methyl poisoning, [Toluene]], Thallium, Toluene, Trichloroethane, Trichloroethylene, Triazophos poisoning, Triazotion poisoning, Trichloroethane, Triclofos, Triethylene Glycol, Trifenfos, White snakeroot poisoning, Wild cherry seed poisoning, Wild Lima bean poisoning
Dermatologic	No underlying causes
Drug Side Effect	No underlying causes
Ear Nose Throat	No underlying causes
Endocrine	ACTH resistance, Addison's Disease, Diabetic coma, Diabetic ketoacidosis, Functioning pancreatic endocrine tumor, Hyperosmolar non-ketotic diabetic coma, Hyperparathyroidism, Hypoglycemia, Hypothyroidism, Insulinoma, Metastatic insulinoma, Multiple endocrine neoplasia type 1, Multiple endocrine neoplasia type 2, Multiple endocrine neoplasia type 3, Thyroid gland failure, X-linked adrenoleukodystrophy -- Addison disease only, Pituitary apoplexy, Congenital Hyperinsulinism, Hyperinsulinism due to glucokinase deficiency, Hyperinsulinism due to glutamodehydrogenase deficiency, Pheochromocytoma crisis
Environmental	Altitude sickness, Comly syndrome, Dehydration, Heat stroke, Hyperbaric sickness, Hypothermia, Mountain sickness, Near-drowning, Suffocation, High altitude cerebral edema
Gastroenterologic	End Stage Liver Failure, Hepatitis, Progressive familial intrahepatic Cholestasis 2, progressive familial intrahepatic Cholestasis 3, Hepatic encephalopathy
Genetic	2-methylbutyryl-coenzyme A dehydrogenase deficiency, 3 alpha methylcrotonyl-Coa carboxylase 1 deficiency, 3 alpha methylcrotonyl-coa carboxylase 2 deficiency, 3-methylcrotonyl-CoA carboxylase deficiency, Arginosuccinic aciduria, Carbamoyl-phosphate synthase 1 deficiency, Carnitine deficiency (systemic), Carnitine transporter deficiency, Citrullinemia I, Citrullinemia II, Congenital Hyperinsulinism, Flavoprotein deficiency, Fructose-1,6-bisphosphatase deficiency, hereditary, Fructose-1-phosphate aldolase deficiency, hereditary, Fumarase deficiency, Glycine synthase deficiency, HMG-CoA lyase deficiency, Holocarboxylase synthetase deficiency, Hyperinsulinism due to glucokinase deficiency, Hyperinsulinism due to glutamodehydrogenase deficiency, Isovaleric Acidemia, Late onset Argininosuccinase lyase deficiency, Long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency, Medium-Chain Acyl-CoA Dehydrogenase Deficiency, Neonatal Argininosuccinase lyase deficiency, Ornithine transcarbamylase (OTC) Deficiency, Fatal familial insomnia, Inborn urea cycle disorder, Methylmalonic acidemia, Methylmalonic aciduria with homocystinuria and cobalamin F, Mitochondrial acetoacetyl-CoA thiolase deficiency, N-acetyl glutamate synthetase deficiency
Hematologic	Antiphospholipid Syndrome, Hemolytic uremic syndrome, Thrombotic thrombocytopenic purpura, Waterhouse-Friderichsen syndrome
Iatrogenic	No underlying causes
Infectious Disease	Bacterial: Ehrlichiosis, Epidemic typhus, Melioidosis, Rocky Mountain spotted fever, Septicemia, Streptococcal Group B invasive disease, Typhoid fever, Vancomycin resistant enterococcal bacteremia, Brain abscess, Cerebellar abscess, Cerebral abscess, Meningitis, Postoperative septicaemia Virus: Herpes simplex encephalitis, Meningitis, Arbovirosis, Hendra Virus, HIV/AIDS, Kyasanur-Forrest disease, Lyssavirus, Rabies, Rift Valley Fever, Simian B virus infection, Togaviridae disease, Viral Hemorrhagic Fever, West nile encephalitis, Western equine encephalitis, Yellow fever, HHV-6 encephalitis, Venezuelan equine encephalitis, Western/Eastern/California encephalitis Fungus: Cryptococcal Meningitis Parasites: Chagas disease, Katayama fever, Malaria, Sleeping sickness (East African), Sleeping sickness (West African), Toxoplasmosis
Musculoskeletal / Ortho	No underlying causes
Neurologic	Acute Disseminated Encephalomyelitis, ADANE, African Sleeping sickness, Alzheimer's disease, Basedow's coma, Bing-Neel syndrome, Brain abscess, Brain cancer, Brain compression, Brain cyst, Brain death, Bristowe's syndrome, Brown-Symmers disease, Cataplexy, Cerebellar abscess, Cerebral abscess, Cerebral hemorrhage, Cerebral metastases, Concussion, Creutzfeldt-Jakob Disease, Cryptococcal Meningitis, Encephalitis, Encephalomyelitis, Epidural haemorrhage, Epilepsy, Fatal familial insomnia, Hashimoto's encephalitis, Familial type 1 hemiplegic migraine, Hemorrhagic shock and encephalopathy syndrome, Hepatic encephalopathy, HHV-6 encephalitis, High altitude cerebral edema, , Hypoxic encephalopathy, Intracerebral hematoma, Jamaican vomiting sickness, Japanese encephalitis, Marchiafava-Bignami disease, Meningoencephalitis, Narcolepsy, Persistent vegetative state, Pituitary apoplexy, Raised intracranial pressure, Acute Spinal cord injury, Stroke, Subarachnoid hemorrhage, Subdural haemorrhage, Traumatic Brain Injury, Vanishing white matter leukodystrophy, Venezuelan equine encephalitis, Western/Eastern/California encephalitis, Westphal-Leyden ataxia, Chagas disease, Herpes simplex encephalitis, Carcinomatosis meningitis, Catatonia, Hydrocephalus
Nutritional / Metabolic	Biotinidase deficiency, Hyperglycerolemia-juvenile form, Hyperornithinemia-hyperammonemia-homocitrullinuria syndrome, Inborn amino acid metabolism disorder, Inborn Urea cycle disorder, Leucinosis, Maple syrup urine disease, Methylmalonic Acidemia, Methylmalonic aciduria with homocystinuria, cobalamin F, Vitamin B12 unresponsive methylmalonicaciduria, Mitochondrial acetoacetyl-CoA thiolase deficiency, Mitochondrial trifunctional protein deficiency, N-acetyl glutamate synthetase deficiency, Periodic hyperlysinemia, Porphyria, Pyruvate carboxylase deficiency, Group B, Thiamine (Vitamin B1) deficiency, Uremia, Wernicke-Korsakoff syndrome, 2-methylbutyryl-coenzyme A dehydrogenase deficiency, 3 alpha methylcrotonyl-Coa carboxylase 1 deficiency, 3 alpha methylcrotonyl-coa carboxylase 2 deficiency, 3-methylcrotonyl-CoA carboxylase deficiency, Arginosuccinic aciduria, Carbamoyl-phosphate synthase 1 deficiency, Carnitine deficiency (systemic), Carnitine transporter deficiency, Citrullinemia I, Citrullinemia II, Flavoprotein deficiency, Fructose-1,6-bisphosphatase deficiency, hereditary, Fructose-1-phosphate aldolase deficiency, hereditary, Fumarase deficiency, Glycine synthase deficiency, HMG-CoA lyase deficiency, Holocarboxylase synthetase deficiency, Isovaleric acidemia, Late onset Argininosuccinase lyase deficiency, Long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency, Medium-chain Acyl-CoA dehydrogenase deficiency, Neonatal Argininosuccinase lyase deficiency, Ornithine transcarbamylase (OTC) Deficiency
Obstetric/Gynecologic	Eclampsia, Pregnancy toxemia
Oncologic	Brain cancer, Cerebral metastases, Functioning pancreatic endocrine tumor, Insulinoma, Metastatic insulinoma
Opthalmologic	No underlying causes
Overdose / Toxicity	Acetylsalicylic Acid, Amitriptyline, Amlodipine, Antipsychotic drugs, Lorazepam overdose, Atropine, Baclofen, Barbiturates, Benzodiazepine, Bromazepam, Bupivacaine, Buprenorphine, Buspirone, Chlorpheniramine, Chlorpromazine, Cinnarizine, Clonazepam, Clonidine, Clotiapine, Codeine, Colchicine, Tricyclic antidepressant, Cyclobenzaprine, Cycloserine, Dantrolene, Meperidine (patient information), Deserpidine, Desipramine, Diamorphine, Diazepam, Diphenhydramine, Diphenidol, Disulfiram, Dothiepin, Efavirenz, Eszopiclone, Ether, Ethinamate, Felodipine, Flurazepam, Flunitrazepam, Gabapentin, Ganaxolone, General anaesthesia, Glutethimide, Haloperidol, Heroin, Hydroxyzine, Inhalational anaesthetics, Isoniazid, Isradipine, Acetaminophen, Aminoglycosides, Aminosalicylic acid, Amphotericin B, Aspirin, Bacitracin, Bismuth, Cefaloridine, Chloroform, Chlortetracycline, Cisplatin, Contrast agents, Cyclophosphamide, Cyclosporin, Ibuprofen, Lithium, Methicillin, Neomycin, Nonsteroidal anti-inflammatory drugs, Oxytetracycline, Polymyxin, Prostaglandin synthetase inhibitors, Rifampin, Sulphonamides, Trimethoprim, Levetiracetam, Levomepromazine, Lidocaine, Lofexidine, Lorazepam, Malathion, Medazepam, Meprobamate, Methadone, Methamphetamine, Methyldopa, Metoclopramide, Mianserin, Midazolam, Mirtazapine, Morphine, Nimodipine, Nitrates, Nitrazepam, Nitroglycerin, Nitrous oxide, Nortriptyline, Olanzapine, Opioid, Oxazepam, Oxycontin, Perazine, Percocet, Phencyclidine, Phenelzine, Phenobarbital, Phenothiazine, Pipothiazine, Pizotifen, Pramipexole, Prazepam, Pregabalin, Primidone, Prochlorperazine, Propanol, Propiomazine, Propofol, Quetiapine, Quinidine, Reserpine, Temazepam, Thiopentone, Tizanidine, Tolterodine, Topiramate, Tramadol, Triazolam, Trifluperidol, Vicodin, Vigabatrin, Xanax, Dilaudid,
Psychiatric	Hysteria
Pulmonary	Anoxemia, Asphyxia, Lung disease, Pulmonary embolism, Respiratory acidosis, Respiratory failure
Renal / Electrolyte	Acid-Base Imbalance, Chronic kidney disease, End-stage renal disease, Hyperthermia, Hypocalcemia, Hypoglycemia, Hypokalemia, Hypomagnesemia, Hypoosmolality, Hypercalcemia, Hyperkalemia, Hypermagnesemia, Hypernatremia, Hyperosmolality, Hyperphosphatemia, Hypophosphatemia
Rheum / Immune / Allergy	Anaphylaxis
Sexual	No underlying causes
Trauma	Head trauma, Skull fracture
Urologic	No underlying causes
Dental	No underlying causes
Miscellaneous	Alcohol withdrawal syndrome, Amyloidosis, Anticholinergic syndrome, Electrocution, Fat embolism, Graft-versus-host disease, Malignant Buotonneuse fever, Neuroleptic Malignant Syndrome, Oculoleptomeningeal Amyloidosis,postoperative Hemorrhage, Postoperative septicaemia, Reye's syndrome, Self-induced water intoxication and schizophrenic disorders syndrome, Serotoninergic syndrome, Shaken Baby Syndrome, Streptococcal toxic shock syndrome, Ureterosigmoidostomy, Venomous snake bites, Venomous spider bites

In alphabetical order

1,1-Dimethylhydrazine poisoning 1,2-Dichloromethane 2-Methyl-4-Chlorophenoxyacetic Acid poisoning 2-methylbutyryl-coenzyme A dehydrogenase deficiency 3 alpha methylcrotonyl-Coa carboxylase 1 deficiency 3 alpha methylcrotonyl-coa carboxylase 2 deficiency 3-methylcrotonyl-CoA carboxylase deficiency Acetaminophen Acetone Acetylene poisoning Acetylsalicylic acid Acid-Base Imbalance Ackee Fruit Food poisoning Acrolein poisoning ACTH resistance Acute Chemical poisoning -- Varnish makers' and painters' Naptha Acute Disseminated Encephalomyelitis Acute hemorrhagic leukoencephalitis Acute xylene poisoning ADANE Addison's Disease African Sleeping sickness Aftershave poisoning Alcohol intoxication Alcohol withdrawal syndrome Aldrin poisoning Alicyclic hydrocarbons poisoning Allethrin poisoning Acute altitude sickness Alzheimer's disease Amanita polypyramis poisoning Amidithion poisoning Aminoglycosides Aminosalicylic acid Amiton poisoning Amitriptyline Amlodipine Ammonium Bifluoride Ammonium Sulfamate poisoning Amphotericin B Amyl Alcohol Amyloidosis Anaphylaxis Anchovy (clupeotoxin) poisoning Aniline poisoning Anoxemia Anticholinergic syndrome Antifreeze poisoning Antiphospholipid Syndrome Antipsychotic drugs Apallic syndrome Apricot seed poisoning Arbovirosis Arginosuccinic aciduria Aristolochic acid Arsenic Asphyxia Aspirin Atropine Azinfos-methyl poisoning Azinphos-ethyl poisoning Azinphosmetile poisoning Azothoate poisoning Bacitracin Baclofen Barbiturates Basedow's coma Benoxafos poisoning Bentazon poisoning Benzene toxicity Benzodiazepine Beta ketothiolase deficiency Bing-Neel syndrome Biotinidase deficiency Bird cherry seed poisoning Bismuth Bitter almond seed poisoning Black henbane poisoning Black jetbead poisoning Blue-ringed octopus poisoning Boric Acid Box Jellyfish poisoning Brain abscess Brain cancer Brain compression Brain cyst Brain death Bristowe's syndrome Bromazepam Bromide toxicity Bromoform poisoning Brown Recluse spider poisoning Brown-Symmers disease Bupivacaine Buprenorphine Buspirone Butyl Alcohol poisoning Cadmium Camphor Cannabinoids Carbamate insecticide poisoning Carbamoyl-phosphate synthase 1 deficiency Carbaryl Carbinoxamine Carbon monoxide poisoning Carbon Tetrachloride Carbophenothion Carcinomatosis meningitis Cardiac arrest Carnitine deficiency (systemic) Carnitine transporter deficiency Cataplexy Catatonia Celandine poisoning Cephaloridine Cerebellar abscess Cerebral abscess Cerebral hemorrhage Cerebral metastases Chagas disease Cherry laurel seed poisoning Cherry seed poisoning Chlophedianol toxicity Chloral hydrate poisoning Chlorate salts poisoning Chlorfenvinphos poisoning Chloroform Chloromethane poisoning Chloropyrifos poisoning Chlorpheniramine Chlorpromazine Chlortetracycline Chokecherry seed poisoning Christmas Cherry poisoning Chromium Chromium poisoning Chronic kidney disease Cinnarizine Cisplatin Citrullinemia I Citrullinemia II Clonazepam Clonidine Clotiapine Clupeotoxism Cobra poisoning Cocaine Codeine Colchicine Comly syndrome Common poppy poisoning Concussion Cone shell poisoning Congenital Hyperinsulinism Contrast agents Copper toxicity Coumaphos poisoning Cresols poisoning Cresylic acid poisoning Creutzfeldt-Jakob Disease Cryptococcal Meningitis Cyanide poisoning Tricyclic antidepressant Cyclobenzaprine Cyclophosphamide Cycloserine Cyclosporin Dantrolene Daphne poisoning Darvocet Hyperthermia Hypocalcemia Hypoglycemia Hypokalemia Hyponatremia Death Angel poisoning Death Camas poisoning Degreasing solvents Dehydration Demethyldiazepam Demeton-O-methyl poisoning Demeton-S-methyl poisoning Deserpidine Desipramine Devil's trumpet poisoning Diabetes Insipidus Diabetic coma Diabetic ketoacidosis Dialifos poisoning Diamorphine Diazepam Diazinon Dichloralphenazone poisoning Dichloroacetylene Dichloronaphthoquinone poisoning Dichlorvos poisoning Dicrotophos poisoning

Dieldrin poisoning Diethylene glycol Diethylene Glycol poisoning Dilaudid Dimethoate poisoning Dimethyl Phthalate poisoning Dinitrocresol poisoning Dinitrophenol poisoning Di-n-Octyl phathalate poisoning Dioxathion poisoning Diphenhydramine Diphenidol Disulfiram Disulfoton poisoning Dothiepin Eclampsia Efavirenz Ehrlichiosis Electrocution Encephalitis Encephalomyelitis End Stage Liver Failure Endocarditis Endothion poisoning End-stage renal disease English Ivy poisoning English Laurel poisoning Epidemic typhus Epidural haemorrhage Epilepsy Eszopiclone poisoning Ethchlorvynol poisoning Ether poisoning Ethinamate poisoning Ethion poisoning Ethoate-methyl poisoning Ethoprophos poisoning Ethylene glycol ethers Ethylene Glycol poisoning Ethyl-guthion poisoning Etrimfos poisoning Eucalyptus Oil poisoning Fat embolism Fatal familial insomnia Felodipine Fenchlorphos poisoning Fenitrothion Fensulfothion Fentanyl Fenthion poisoning Fire cherry poisoning Flavoprotein deficiency Flurazepam Flunitrazepam Fonophos poisoning Formaldehyde poisoning Formothion poisoning Fructose-1,6-bisphosphatase deficiency, hereditary Fructose-1-phosphate aldolase deficiency, hereditary Fumarase deficiency Functioning pancreatic endocrine tumor Funnel Web spider poisoning Gabapentin Ganaxolone Gasoline General anaesthesia Germanium Glue solvent vapors Glutethimide Glycine synthase deficiency Graft-versus-host disease Hair Bleach Hair Dye Hairdressing sprays Haloperidol Hashimoto's encephalitis Head trauma Heart attack Heart failure Heat stroke Heavy metals Hemiplegic migraine, familial type 1 Hemolytic uremic syndrome Hemorrhagic shock and encephalopathy syndrome Hendra Virus Hepatic encephalopathy syndrome Hepatitis Heptenophos poisoning Herbicide Heroin Herpes simplex encephalitis Hexachloro-1,3-butadiene Hexachlorobutadiene poisoning HHV-6 encephalitis High altitude cerebral edema HIV/AIDS HMG-CoA lyase deficiency Holocarboxylase synthetase deficiency Hyacinth bean poisoning Hydrocarbons Hydrocephalus Hydroxyzine Hyperbaric sickness Juvenile form hyperglycerolemia Hyperinsulinism due to glucokinase deficiency Hyperinsulinism due to glutamodehydrogenase deficiency Hypermagnesaemia Hypernatremia Hyperornithinemia-hyperammonemia-homocitrullinuria syndrome Hyperosmolality Hyperosmolar non-ketotic diabetic coma Hyperparathyroidism Hyperphosphatemia Hypoglycemia Hypomagnesemia Hyponatremia Hypoosmolality Hypophosphatemia Hypothermia Hypothyroidism Hypoxic encephalopathy Hysteria Ibuprofen Imazapyr poisoning Inborn amino acid metabolism disorder Inborn urea cycle disorder Inhalational anaesthetics Insulinoma Intracerebral hematoma Iodofenphos poisoning Isoniazid Isovaleric Acidemia Isradipine Jamaican vomiting sickness Japanese encephalitis Japanese pagoda tree poisoning Jessamine poisoning Jimsonweed poisoning Katayama fever Kyasanur-Forrest disease Lantana poisoning Late onset Argininosuccinase lyase deficiency Lead poisoning Leucinosis Levetiracetam Levomepromazine Lidocaine Lithium Lobelia poisoning Lofexidine Long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency Loquat poisoning Lorazepam Lung disease Lupine poisoning Lyssavirus Malaria Malathion Malignant Buotonneuse fever Malignant hypertension Maple syrup urine disease Marchiafava-Bignami disease Mayapple poisoning Mecarbam Medazepam Medium-Chain Acyl-CoA Dehydrogenase Deficiency Melioidosis Meningitis Meningoencephalitis Mephenoxalone Meperidine Meprobamate Mercury Metaldehyde Metastatic insulinoma Methacrifos Methadone Methamidophos Methamphetamine Methanol Methaqualone Methemoglobin-producing agents Methicillin Methidathion Methiocarb Methyl Bromide Methyldopa Methylmalonic acidemia Methylmalonic aciduria with homocystinuria, cobalamin F Methylmalonic aciduria, vitamin B12 unresponsive Methyprylon Metoclopramide Mexican tea poisoning Mianserin Midazolam

Mirtazapine Mitochondrial acetoacetyl-CoA thiolase deficiency Mitochondrial trifunctional protein deficiency Morphine Mountain sickness Multiple endocrine neoplasia type 1 Multiple endocrine neoplasia type 2 Multiple endocrine neoplasia type 3 Nabilone N-acetyl glutamate synthetase deficiency Naked brimcap poisoning Narcolepsy Near-drowning Neomycin Neonatal Argininosuccinase lyase deficiency Neuroleptic Malignant Syndrome Nimodipine Nitrates Nitrazepam Nitroglycerin Nitrous oxide Nonsteroidal anti-inflammatory drugs Nortriptyline Oculoleptomeningeal Amyloidosis Olanzapine Omethoate poisoning Opioid Organophosphate insecticide poisoning Ornithine transcarbamylase (OTC) Deficiency Oxazepam Oxycontin Oxydeprofos poisoning Oxydisulfoton poisoning Oxytetracycline Paint thinners Paints Paraquat ochratoxin A Parathion poisoning Pentachlorophenol poisoning Perazine Perchloroethylene Percocet Periodic hyperlysinemia Persistent vegetative state Pesticide solvents Phencyclidine Phenelzine Phenobarbital Phenothiazine poisoning Pheochromocytoma crisis Phorate poisoning Phosalone poisoning Phosdrin poisoning Phosmet poisoning Phosphamidon poisoning Phoxim poisoning Phthalthrin poisoning Pipothiazine Pirimiphos-methyl Pituitary apoplexy Pizotifen Platinum Poison hemlock poisoning Polyethylene Glycol -- Low Molecular Weight Polymyxin Porphyria Postoperative hemorrhage Postoperative septicemia Pramipexole Prazepam Pregabalin Pregnancy toxemia Primidone Primiphos methyl Prochlorperazine Profenofos Progressive familial intrahepatic Cholestasis 2 progressive familial intrahepatic Cholestasis 3 Progressive Multifocal Leukoencephalopathy Propanol Propiomazine Propofol Propoxur Prostaglandin synthetase inhibitors Prothidathion poisoning Prothoate poisoning Pulmonary embolism Pyrimidifen poisoning Pyrimitate poisoning Pyruvate carboxylase deficiency, Group B Quetiapine Quinalphos poisoning Quinidine Quintiofos poisoning Rabies Raised intracranial pressure Ramelteon poisoning Reserpine Respiratory acidosis Respiratory failure Reye's syndrome Rheumatic Fever Rifampin Rift Valley Fever Rocky Mountain spotted fever Sardine poisoning (clupeotoxin) Selenious Acid Self-induced water intoxication and schizophrenic disorders syndrome Septicemia Serotoninergic syndrome Shaken Baby Syndrome Shock Silicon compounds Silver Simian B virus infection Skull fracture Sleeping sickness (East African) Sleeping sickness (West African) Slickhead poisoning (clupeotoxin) Sodium Monofluoroacetate Solvents Sophamide Spinal cord injury, acute Streptococcal Group B invasive disease Streptococcal toxic shock syndrome Stroke Styrene Subarachnoid hemorrhage Subdural haemorrhage Suffocation Sulfotep poisoning Sulphonamides Systemic monochloroacetate poisoning Tapioca poisoning Temazepam Terbufos poisoning Tetraethyl Pyrophosphate poisoning Tetrahydrocannabinol Tetramethrin poisoning Tetramethylenedisulfotetramine poisoning Thallium sulfate Thiamine (Vitamin B1) deficiency Thiometon Thiopentone Thornapple poisoning Thrombotic thrombocytopenic purpura Thyroid gland failure Tizanidine Togaviridae disease Tolclofos methyl poisoning Tolterodine Toluene Topiramate Toxoplasmosis Tramadol Traumatic Brain Injury Triazolam Triazophos poisoning Triazotion poisoning Trichloroethane Trichloroethylene Triclofos Tricyclic antidepressants Triethylene Glycol Trifenfos Trifluperidol Trimethoprim Typhoid fever Uranium Urea Cycle Disorder Uremia Ureterosigmoidostomy Vancomycin resistant enterococcal bacteremia Vanishing white matter leukodystrophy Venezuelan equine encephalitis Snakebite Spider bite Ventricular fibrillation Very low blood pressure Vicodin Vigabatrin Viral Hemorrhagic fevers Waterhouse-Friderichsen syndrome Wernicke-Korsakoff syndrome West nile encephalitis Western equine encephalitis Western/Eastern/California encephalitis Westphal-Leyden ataxia White snakeroot poisoning Wild cherry seed poisoning Wild Lima bean poisoning Xanax overdose [[X-linked adrenoleukodystrophy -- Addison disease only Yellow fever Zaleplon Ziconotide Zolpidem Zopiclone

Severity

The severity of coma impairment is categorized into several levels. Patients may or may not progress through these levels. In the first level, the brain responsiveness lessens, normal reflexes are lost, the patient no longer responds to pain and cannot hear.

Contrary to popular belief, a patient in a coma does not always lie still and quiet. They may move, talk, and perform other functions that may sometimes appear to be conscious acts but are not.

Two scales of measurement often used in TBI diagnosis to determine the level of coma are the Glasgow Coma Scale (GCS) and the Ranchos Los Amigos Scale (RLAS). The GCS is a simple 3 to 15-point scale (3 being the worst and 15 being that of a normal person) used by medical professionals to assess severity of neurologic trauma, and establish a prognosis. The RLAS is a more complex scale that has eight separate levels, and is often used in the first few weeks or months of coma while the patient is under closer observation, and when shifts between levels are more frequent.

Outcome

Outcomes range from recovery to death. Comas generally last a few days to a few weeks. They rarely last more than 2 to 5 weeks but some have lasted as long as several years. After this time, some patients gradually come out of the coma, some progress to a vegetative state, and others die. Some patients who have entered a vegetative state go on to regain a degree of awareness. Others remain in a vegetative state for years or even decades (the longest recorded period being 37 years).

The outcome for coma and vegetative state depends on the cause, location, severity and extent of neurological damage. A deeper coma alone does not necessarily mean a slimmer chance of recovery, because some people in deep coma recover well while others in a so-called milder coma sometimes fail to improve.

People may emerge from a coma with a combination of physical, intellectual and psychological difficulties that need special attention. Recovery usually occurs gradually — patients acquire more and more ability to respond. Some patients never progress beyond very basic responses, but many recover full awareness. Regaining consciousness is not instant: in the first days, patients are only awake for a few minutes, and duration of time awake gradually increases.

Predicted chances of recovery are variable owing to different techniques used to measure the extent of neurological damage. All the predictions are based on statistical rates with some level of chance for recovery present: a person with a low chance of recovery may still awaken. Time is the best general predictor of a chance of recovery: after 4 months of coma caused by brain damage, the chance of partial recovery is less than 15%, and the chance of full recovery is very low.

The most common cause of death for a person in a vegetative state is secondary infection such as pneumonia which can occur in patients who lie still for extended periods.

Occasionally people come out of coma after long periods of time. After 19 years in a minimally conscious state, Terry Wallis spontaneously began speaking and regained awareness of his surroundings.

A brain-damaged man, trapped in a coma-like state for six years, was brought back to consciousness in 2003 by doctors who planted electrodes deep inside his brain. The method, called deep-brain electrical stimulation (DBS) successfully roused communication, complex movement and eating ability in the 38-year-old American man who suffered a traumatic brain injury. His injuries left him in a minimally conscious state (MCS), a condition akin to a coma but characterized by occasional, but brief, evidence of environmental and self-awareness that coma patients lack.

See also

• Persistent vegetative state (vegetative coma), deep coma without detectable awareness
• Brain death (irreversible coma), irreversible end of all brain activity
• Process Oriented Coma Work, for an approach to working with residual consciousness in comatose patients

Additional Resources

• BIAUSA (Brain Injury Association of America), Types of Brain Injury.
• NINDS (National Institute of Neurological Diseases and Stroke), public domain information on TBI
• NINDS (National Institute of Neurological Diseases and Stroke), public domain information on coma