differential diagnosis of coma

Differential diagnosis: === normal brainstem reflexes, no lateralizing signs === 1) CT or MRI normal a) drug or toxin ingestion b) endogenous metabolic encephalopathy c) shock d) hypertensive encephalopathy e) meningitis f) viral encephalitis (non herpetic) g) epilepsy, nonconvulsive status epilepticus h) Reye's syndrome i) fat embolism j) subarachnoid hemorrhage k) Creutzfeldt-Jacob disease l) catatonia 2) hemispheric lesions found by CT or MRI a) hydrocephalus b) bilateral subdural hematoma c) bilateral contusions, edema or axonal shearing of hemispheres due to closed head trauma d) subarachnoid hemorrhage e) acute disseminated encephalomyelitis === normal brainstem reflexes, lateralizing motor signs (CT or MRI abnormal) === 1) unilateral mass lesion a) cerebral hemorrhage (basal ganglia, thalamus) b) large infarction with surrounding brain edema c) herpes viral encephalitis (temporal lobe lesion) d) subdural or epidural hematoma e) tumor with edema f) brain abscess with edema g) vasculitis with multiple infarctions h) metabolic encephalopathy superimposed on pre-existing focal lesions (i.e. stroke with hyperglycemia or hyponatremia, etc) i) pituitary apoplexy 2) asymmetric signs accompanied by diffuse hemispheric dysfunction a) metabolic encephalopathies with asymmetric signs b) isodense subdural hematoma c) thrombotic thrombocytopenic purpura (TTP) d) epilepsy with focal seizure/postictal state e) nonconvulsive status epilepticus === multiple brainstem reflex abnormalities === 1) anatomic lesions in brainstem a) pontine or midbrain hemorrhage b) cerebellar hemorrhage, tumor, abscess c) cerebellar infarction with brainstem compression d) mass in hemisphere causing advanced upper brainstem compression e) primary brainstem tumor, demyelination or abscess f) traumatic brainstem contusion-hemorrhage 2) brainstem dysfunction without mass lesion a) basilar artery thrombosis causing brainstem infarction b) severe drug overdose c) brainstem encephalitis d) basilar artery migraine

References

Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 133