A 78-year-old woman is admitted to the hospital after losing consciousness at home. She reports that she was walking from the kitchen to the bedroom and began to feel “light-headed.” Within a few seconds, symptoms progressed to the point of unconsciousness and she fell to the floor. Her daughter, who witnessed the event, reports that she regained consciousness almost immediately after falling to the floor. She had one prior similar episode the week before. The patient has no significant past medical history except for hypertension, for which she takes hydrochlorothiazide and metoprolol. Blood pressure is 138/64 standing and 140/70 supine. Physical examination is otherwise unrevealing. ECG shows a sinus rhythm. An echocardiogram reveals no structural heart abnormality. What is the best next test to evaluate her sudden loss of consciousness?A) Carotid ultrasound
Syncope is usually caused by decreased blood flow to the brain. Although occasionally seizures or hypoglycemia can cause transient loss of consciousness, this patient’s rapid onset of symptoms and rapid recovery once recumbent suggest decreased cerebral perfusion. She has no evidence of aortic stenosis or other structural heart disease on echocardiogram. It would be reasonable to monitor the patient’s heart rhythm initially in the hospital. Carotid artery disease almost never causes transient syncope, although vertebral-basilar disease may. Therefore, carotid Doppler imaging is not recommended as part of the routine evaluation of syncope. Structural imaging of the brain and EEG are not part of the routine evaluation of syncope unless history or physical examination suggests seizure or a focal CNS lesion.