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coma. Zhang Yinglan MD, Associate chief physician Emergency Department Longhua Hospital Affiliated Shanghai University of TCM. Definition. the most serious disturbance of consciousness no response to the various external stimuli and cannot be awakened aimless spontaneous activities.
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coma Zhang Yinglan MD, Associate chief physicianEmergency DepartmentLonghua Hospital Affiliated Shanghai University of TCM
Definition • the most serious disturbance of consciousness • no response to the various external stimuli and cannot be awakened • aimless spontaneous activities
an awareness of oneself and surroundings • a quick and accurate response to the pain、touch、seeing、hearingand language A clear consciousness
The important structure to maintain consciousness • reticular activating system in the middle-upper part of the pons • the lesion of the lower part of the pons or medulla will not lead to unawareness • a complete cerebral cortex
Lesion area • focal brainstem lesions or bilateral hemisphere with diffuse lesion • rapidly progressive lesion in one hemisphere cause the midline shift、 extruding the ascending reticular activating system of the brainstem • focal lesions of one hemisphere will not lead to unconsciousness • excessive lesions of bilateral hemisphere but slow progress will not lead to unconsciousness（like Alzheimer‘s Disease）
mechanism reflex arc Specific ascending projection system Nonspecific ascending reticular activiting system General receptor Specific receptor Bilateral cerebral cortex muscle 、 skeleton Pyramidal tracts
Pathogenesis • Intracephalic diseases：the primary lesionof cerebral cortex、 interbrain 、 midbrain and the head-end of the pons • Systemic diseases（secondary brain injury）： poisoning、 infection、 metabolic or endocrine disorders
How systemic diseases cause the coma？ • Obstruction of supply or utilization of oxygen and the substrate • The change of neuronal excitability • The change of cranial capacity
craniocerebral traumais the most common reason to cause coma • internal medicine diseases • cerebrovascular disease 50% • hypoxic-ischemic encephalopathy 20% • the rest are metabolic diseasetoxic encephalopathy
The judgement of coma disturbance of consciousness include • degree of awakening declined • conscious content changed confusion、 delirium
The severity of coma • light coma • Moderate coma • deep coma • brain death
Confusion：loss of concentration、 disorientation、 indifference、 inconsistent language • Delirium：it is an acute advanced nervous disorder and can be seen in hyperpyrexia、 poisoning or metabolic disorders.
Special type • vegetative state VS：in the vegetative state patients can open their eyelids occasionally and demonstrate sleep-wake cycles, but completely lack cognitive function. • minimally conscious state MCS：it is defined as a condition of severely altered consciousness in which minimal but definite behavioral evidence of self or environmental awareness is demonstrated.
Diagnostic criteria of VS • loss of cognitive function， unconscious activities， disable instruction • unable to understand or express language • demonstrate sleep-wake cycles • open the eyes automatically or with stimulus • aimless eyes tracking movement • spontaneous breath or blood pressure • functions of the hypothalamus and brainstem are basically preserved
Classification of VS • Persistent vegetative state(PVS)>1 month • Permanent vegetative state • brain traumatic>1 year • non-traumatic>3 months • transient vegetative state<1 month
Special type • Decorticate syndrome: extensive lesions in bilateral cerebral cortex • Akinetic mutism: damage of brain specific or nonspecific activating system but a complete cortex and efferent pathway
Brain death • in 1968 Harvard Medical School published the first criteria of brain death • in 1981 the United States passed the uniform standards of brain death diagnosis • in 2003 Ministry of Public Health of China worked out a criteria of brain death
Diagnostic criteria of brain death • Brain death is the complete and irreversible loss of brain function (including involuntary activity necessary to sustain life) • Clinical criteria • deep coma • brainstem reflexes disappeared • no spontaneous breathing
Comfirmation test • electrical silence of ECG • non-perfusion of transcranial color doppler（TCD） • short latency somatosensory evoked potentials（SLSEP) disappeared
The Glasgow Coma Scale provides a score in the range 3-15; patients with scores of 3-8 are usually said to be in a coma. • 3’ → poor prognosis • 15’ → better prognosis
Differential diagnosis • hysterical lethargy • syncope • affective stupor • shock • narcolepsy • locked-in syndrome
Diagnostic program • medical history • physical examination and vital signs observation • assistant examination
Key points of inquiry • initial symptoms，the speed of onset？ • medication history， drinking history and toxic exposure？ • brain trauma history？ • HBP、DMor a history of heart、lung、brain、liver、kidney？ • fever ？
intracranial disease location sign types of onset subacute infection subdural or epidural hematoma focal signs angiopathy trauma tumor meningeal irritation subarachnoid hemorrhage meningitis sinus thrombosis acute angiopathy trauma infection chronic tumor
Localization diagnosis from special type of breath type of breathdiseased region apnea after overventilationbilateral frontal lobe Cheyne-Stokes breathinghemisphere conditioned central neurogenic hyperpnea midbrain apneusis upper part of the pons cluster breathing lower part of the pons irregular breathingmedulla oblongata
Odors in the breath • ammonia smell → uremia • apple smell → diabetic ketoacidosis • garlic smell → organophosphorus pesticide poisoning • fetor hepaticus → hepatic encephalopathy • alcohol smell→ alcoholism
Involuntary movement • muscle twitch： uremia、 pulmonary encephalopathy • asterixis： hepatic encephalopathy、 pulmonary encephalopathy • paroxysmal twitch： carbon monoxide intoxication、 atropine intoxicationor some drug poisoning • epilepsy ： hypertensive encephalopathy、 cerebral hemorrhage、 craniocerebral injury • choreic movement： rheumatic encephalopathy
Brainstem reflexes reflexeslocation ciliospinal reflex interbrain frontalis-obicular muscle reflexmidbrain-interbrain oculocephalogyric reflex pupil light reflexmidbrain corneal reflex 、 jaw reflex upper part of pons horizontal oculovestibular reflex lower part of pons oculocardiac reflexmedulla corneomandibular reflex inerbrain or midbrain
Systemic disease • toxic disease • metabolic disease：five visceral organ， five pathogenic factors • endocrine disease：five glands • infectious diseases
Toxic disease • characteristics • acute onset， toxic exposure • group onset • frequently nausea、vomiting、 diarrhea、 excessive sweating、 convulsion • multiple system damaged • special clinical signs：change in skin color、 body odour、temperature、pupils
clinical manifestations • carbon monoxide intoxication → cherry-red lips • organophosphorus pesticide poisoning → breath that smells of garlic • sedative intoxication → low temperature 、low blood pressure • contracted pupil → organophosphorus pesticide 、sedative • dilated pupil → atropine poisoning
Five visceral organs • cardiogenic coma ：severe heart failure、arrhythmia 、 cardiac shock • pulmonary coma ：chronic bronchitis 、 emphysema 、 pulmonary heart disease • hepatic coma ：jaundice 、 cirrhosis、 hepatic dysfunction • renal coma ：oliguria 、 anuria 、anemia、HBP、renal dysfunction • brain-derived coma ：no systemic disease、 focal signs of CNS
Five glands • pituitary crisis：severe bleeding after birth、 postpartumamenorrheaor agalactia • hypothyroidism crisis：myxoedema、obvious low temperature • Addison disease：mucosa pigmentation of the skin、fatigue、 hyponatremia • hyperparathyroidism or hypoparathyroidism crisis：significantly increased or decreased of serum calcium • pancreatic encephalopathy：abdominal pain、 blood amylase ↑、urine amylase↑
Five pathogenic factors • glucose： hypoglycemia or hyperglycemia coma • saline：hyponatremia、 hypernatremia • acid：metabolic acidosis、 respiratory acidosis • toxin：exogenous intoxication • blood pressure：hypertensive encephalopathy、 hypotension and shock
Conclusion of diagnostic thinking differentiate intracranial diseases 、 systemic disease （ initial symptom 、 intracranial hypertension 、 focal signs ） intracranial diseases ： type of onset （acute、subacute、chronic） location sign （ focal lesion 、 meningeal irritation sign ） systemic disease： toxication metabolism ：fivevisceral organs 、five pathogenic factors endocrine disease ：five glands infection
