The most benign causes of syncope include syncope brought on by fear or pain, orthostatic hypotension, prolonged standing, or seizure. Dangerous causes of syncope that should concern you include syncope with exertion, because this suggests cardiac outflow obstruction, syncope without warning, suggesting an arrhythmia, syncope while recumbent, which also suggests an arrhythmia, or syncope associated with significant injury.
LOSS OF CONSCIOUSNESS OR COMA A true coma is a level of unresponsiveness in which the patient cannot be awakened or aroused. This is an extreme form of impaired consciousness, in which there are varying degrees of mentation that do not represent full arousal or full coma. In order to have a coma, the disturbance must be in both cerebral hemispheres or must involve damage to the reticular activating system, which controls arousal. The reticular activating system is located in the pons, midbrain, and posterior diencephalon of the brain. Causes of coma can be focal ischemia of the reticular activating system, hemorrhage of the same area, hypoxia, hypoglycemia, drug overdose, or uremia. Increased intracranial pressure for any reason can lead to coma plus a secondary risk of brain herniation. Psychiatric causes can look like coma but can be relatively distinguished from a genuine coma by the neurological examination. Your examination should include an eye examination. The pupils can be mid-position and fixed, unequal, dilated, or pinpoint with a dysconjugate or paralyzed gaze. Examine the blink reflex as well as the oculocephalic reflex, which is the “doll’s eyes” examination, looking for movement in response to head rotation. Breathing and heart rate patterns can be abnormal. Cheyne-Stokes breathing, hypertension, and bradycardia can be present. The motor exam is variable, with completely flaccid muscles, muscle spasticity, myoclonus, decorticate posturing, or decerebrate posturing. Your diagnostic process includes a neurological examination, urgent imaging of the brain, pulse oximetry, blood glucose measurement, electrolytes, CBC, and a urine drug screen. If there is evidence of increased intracranial pressure, this may have to be
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