Evaluation of controlled digital carotid artery compression in cerebrovascular insufficiency

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Abstract
Unilateral digital compression of the carotid was performed on 166 patients with clinical evidence of cerebrovascular insufficiency (CVI) and 280 patients without clinical evidence of CVI in order to evaluate the presence of a "cardioinhibitory" carotid sinus response (vagal response) as a diagnostic sign in patients with CVL The following conclusions can be drawn Increased carotid sinus sensitivity occurs significantly more often in patients with CVI than in patients without CVI only if the patients are under the age. of 60; therefore, a sensitive carotid sinus may be of value in the clinical diagnosis of CVI in patients under the age of 60 but not in older patients. A unilateral sensitive carotid sinus usually but by no means invariably is present on the side opposite to unilateral carotid "tree" insufficiency. In patients under 60, the presence of both a vagal response due to carotid sinus stimulation and an ischemic response (using the eeg as an end point) due to occlusion of the carotid artery is better evidence of CVI than the presence of only one or the other of these responses. A sensitive carotid sinus found in a patient with CVI may be independent of any evidence of atherosclerosis elsewhere in the body. However, if a patient has coronary artery insufficiency, finding a sensitive carotid sinus decreases the value of this sign in making a diagnosis of CVL This works in reverse, too, that is, if the patient has CVI, finding a sensitive carotid sinus decreases the use of this sign in making a diagnosis of coronary artery disease. No evidence was obtained from this study that a hypersensitive carotid sinus plays an important role in the transient episodes seen in some patients with CVL Digital carotid compression is not without risk. The following suggestions are offered: (1) A sensitive carotid sinus in a patient without cerebrovascular disease may be evidence of "subclinical" CVI, that is, some degree of cerebrovascular disease but not enough disease to produce the signs and symptoms, of cerebrovascular insufficiency. (2) The apparent increase in carotid sinus sensitivity found in patients with CVI may not represent an actual increase in the sensitivity of this organ, but, rather, it may only be that it is easier to elicit this reflex by digital compression because of atheromatous changes in the carotid artery. It would follow then that the 2 possible types of responses that can be elicited by digital compression of the carotid are due to 2 different factors: the vagal response of the carotid sinus may be a manifestation of atheromatous changes at the carotid bifurcation, while the ischemic response is a measure of cerebral collateral circulation.