disorder of arousal; lack of awareness; impaired consciousness

Classification: 1) lethargy 2) obtundation 3) stupor 4) coma * also see sleep, drowsiness Etiology: 1) bilateral impairment of cerebral hemisphere function 2) failure of the brain stem reticular-activating system 3) structural lesions a) supratentorial lesions 1] encroaching on or compressing diencephalic structures such as the thalamus 2] rapidly exapnding masses a] malignant tumors b] abscesses c] hematomas d] infarction with edema b) infratentorial lesions 1] direct involvement or compression of the reticular activating system by an adjacent lesion (i.e. cerebellar mass) 2] infarction 3] hemorrhage 4] demyelination 5] infection 6] neoplasm 7) central pontine myelinolysis 4) toxic & metabolic abnormalities a) most frequent cause of coma b) more likely to cause coma in a patient with previous brain injury 5) multifocal involvement of the central nervous system a) cerebral vasculitis b) encephalitis c) subarachnoid hemorrhage d) adrenoleukodystrophy 6) status epilepticus, especially non-convulsive 7) sagittal sinus thrombosis Laboratory: 1) basic chemistry panel 2) complete blood count (CBC) 3) lumbar puncture/CSF analysis (after CT of the head) 4) electroencephalography a) non-convulsive status epilepticus b) hepatic encephalopathy c) Herpes simplex encephalitis d) locked-in syndrome e) catatonia f) brain death Radiology: - computed tomography (CT) of the head Differential diagnosis: 1) psychogenic unresponsiveness a) uncommon b) patient may appear unable to respond to environment despite normal function of the reticular activating system & cerebral hemispheres c) conversion disorder d) malingering e) fugue state f) catatonic schizophrenia f) severe depression 2) abulia 3) locked-in syndrome 4) persistent vegetative state Management: (also see coma) 1) reversal of identifiable causes 2) reduction of increased intracranial pressure

Related

abulia altered state of consciousness arousal arousal symptom Glasgow coma scale (GCS) locked-in syndrome; cognitive-motor dissociation sleep

Specific

coma lethargy loss of consciousness (LOC) minimally conscious state obtundation persistent vegetative state stupor

References

Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998