neurologic disorders
Overview of Coma and Impaired Consciousness
Key Points
Coma and impaired consciousness require dysfunction of both cerebral hemispheres or dysfunction of the reticular activating system. Manifestations include abnormalities of the eyes (eg, abnormal conjugate gaze, pupillary responses, and/or oculocephalic or oculovestibular reflexes), vital signs (eg, abnormal respirations), and motor function (eg, flaccidity, hemiparesis, asterixis, multifocal myoclonus, decorticate or decerebrate posturing). Taking a complete history of prior events is critical; ask witnesses and relatives about the time course for the change in mental status and about possible causes (eg, recent travel, ingestion of unusual meals, exposure to possible infections, drug or alcohol use, possible trauma). Do a general physical examination, including thorough examination of the head and face, skin, and extremities and a complete neurologic examination (focusing on level of consciousness, the eyes, motor function, and deep tendon reflexes), followed by appropriate blood and urine tests, toxicology screening, and fingerstick plasma glucose measurements. As soon as the patient has been stabilized, do noncontrast CT or, if immediately available, MRI to check for masses, hemorrhage, edema, hydrocephalus, or evidence of bone trauma (particularly on a CT scan); overall, MRI provides greater detail for diagnostic purposes when it is done 72 hours or more after symptom onset. Ensure adequate airway, breathing, and circulation. Give IV or IM thiamin and IV glucose if plasma glucose is low and IVnaloxoneif opioid overdose is suspected. Control ICP using various strategies, which may include sedatives (as needed) to control agitation, temporary hyperventilation, fluids and diuretics to maintain euvolemia, and antihypertensives to control BP. Treat the cause. 