[Short loss of consciousness: etiology and diagnostic approach. Results of a prospective study]

Transient loss of consciousness is a frequent reason for hospitalization, but very few prospective studies have been devoted to this topic. Our study involved 150 patients who were admitted for sudden and total loss of consciousness (syncope) with spontaneous return to normality. All patients underwent thorough physical examination, standard laboratory tests, electrocardiography (ECG) and radiography of the chest. Depending on the results of this first evaluation, the patients were investigated for postural hypotension and had carotid sinus massage, electroencephalography (EEG), computerized tomography of the brain, cardiac Holter recording, electrophysiological exploration and, if necessary, other special examinations. The cause of the syncope was found in 93 cases (62 per cent); it was cardiac in 39 cases (bradycardia 25, tachycardia 14), vascular in 20 cases (vagal 14, postural hypotension 6), epileptic "grand mal" type in 32 cases and "miscellaneous" in 2 cases. The syncope occurred in a state of acute drunkenness in 14 cases and was unquestionably due to the absorption of medicines in 6 cases. Clinical findings and ECG or EEG provided the aetiological diagnosis in 82.7 per cent of the patients and the other, sophisticated examinations in 17.3 per cent. These results are similar to those of other prospective studies found in the literature. It may be concluded that the causes of the syncope are only found in about 2 out of 3 cases, that clinical data are all-important in the diagnostic approach and that complementary examinations are either unnecessary or yield little that is not already suggested by clinical examination.