Limitations of noninvasive evaluation of carotid occlusive disease

A series of 32 patients examined by two different noninvasive techniques in two different laboratories and by cerebral angiography were retrospectively studied. Significant differences in ophthalmic artery pressures as measured by oculopneumoplethysmography (OPPG), and significant delays in ocular pulse arrival time combined with characteristic recorded bruits as determined by oculoplethysmography/carotid phonoangiography (OPG/CPA) were considered as an index of carotid stenosis. Cerebral angiography was performed on all 32 patients to confirm or refute the diagnosis suggested by noninvasive testing. In this selected group of patients with difficult diagnostic problems, only 67% of significant (greater than 50% diameter) stenoses were detected by OPPG, and only 58% by OPG/CPA. Combining OPPG and OPG/CPA increased the probability of detecting a greater than 50% diameter stenosis to 92%.