Over the last ten years a number of bedside diagnostic tests have been developed to aid in the diagnosis of carotid artery insufficiency. One of these tests is the digital occlusion of first one, then the other carotid artery. This technique was first mentioned by Bonnal et al,1 then first described in this country by Ochs et al.2 Gurdjian and Web-ster3-5 brought this test to the attention of many neurologists and neurosurgeons through their extensive writings. The technique they described is performed as follows:The patient sits during the test. Carotid sinus hypersensitivity is first ruled out by massage of each carotid sinus as the blood pressure and pulse are recorded. Digital pressure is then exerted over the carotid bulb first on one side and then on the other. Pressure is maintained between 10 and 30 seconds.The above authors 3-5 listed syncope, aphasia, extremity weakness, or deepening of coma as indicating the possibility of uni¬ lateral disease of the carotid artery. The digital occlusion would of course cause symp¬ toms when the more patent side was occluded.Webster and Gurdjian5 have reported only two significant complications which oc¬ curred during several hundred compressions. One patient developed increased paralysis 12 hours after the test and another showed ad¬ ditional coronary damage by EKG. This test has been performed thousands of times in the last few years. Silverstein et al 6 reported that almost every patient admitted to the neurology service of the Mt. Sinai Hospital in New York had this test per¬ formed. One of the authors (Bender6) re¬ ported two untoward reactions in several thousand compressions which he personally performed.Before this compression test was devel¬ oped, carotid sinus massage was used for many years, especially to revert supraventricular tachycardias to a regular sinus rhythm. Later, following the extensive writings of Weiss and Baker 7 which de¬ scribed the syndrome of hypersensitivity of the carotid sinus reflex, it became quite com¬ mon to massage, compress, or stimulate the carotid sinus. Three types of pathological responses were listed: hypotension, bradycardia, and cerebral. Several authors 3·8 have questioned the existence of the cerebral form of response to explain some neurological changes following pressure over the carotid sinus. They speculated that neurological symptoms are probably due to a digital oc¬ clusion of one patent carotid artery, the other being occluded by disease. Reese et al 9 have recently shown that a pure cerebral form of response exists since signs of cerebral ische¬ mia were produced by massage in the patient they reported, in spite of an absence of carotid artery disease by arteriography, and in spite of no change in pulse or blood pres¬ sure.Several authors have reported the onset of hemiplegia during or shortly after carotid sinus massage. Askey 10 reported eight such instances. The paralysis in all patients was contralateral, and the cerebral lesion, there¬ fore, was ipsilateral to the carotid sinus which was massaged. Two of the...