Ultrasound and Clinical Predictors of Recurrent Ischemia in Symptomatic Internal Carotid Artery Occlusion

Abstract

Background and Purpose-Occlusion of the internal carotid artery puts patients at risk of recurrent ischemic events because of hemodynamic compromise. Our goal was to characterize clinical and duplex parameters indicating patients at risk of recurrent ischemia. Methods-We retrospectively identified patients with symptomatic internal carotid artery occlusion. Clinical characteristics and ultrasound parameters, including collateral networks, were analyzed. Predictors for recurrent ipsilateral ischemia were investigated by Cox regression analysis. Results-Of 68 patients, at least 1 recurrent ischemic event within the same vascular territory was observed in 14 patients (20.6%) within 2 to 92 days (median, 29.5 days). The median follow-up period was 6 months. Diabetes mellitus and previous transient ischemic attack were associated with recurrence, as was activation of the maximum number of collateral pathways on transcranial ultrasound (28.6% versus 5.6%; P=0.03). Furthermore, flow in the posterior cerebral arteries was higher in patients with recurrence in ipsilateral and contralateral posterior cerebral artery P2 segments (76 IQR 37.5 versus 59, IQR 22.5 cm/s and 68, IQR 35.6 versus 52, IQR 21 cm/s; P<0.01 and 0.02). Conclusions-Flow increases in both posterior cerebral artery P2 segments suggest intensified compensatory efforts when other collaterals are insufficient. Together with the presence of diabetes mellitus and a history of transient ischemic attack, this duplex parameter indicates that patients with internal carotid artery are at particular risk of recurrent ischemia.

Symptomatic Carotid Occlusion Is Frequently Associated With Microembolization

“…5, 6, 36 However, unlike some prior studies, we did not see a difference in clinical outcome between MES+ and MES− patients. 23–25 Currently, there are no surgical and few targeted therapeutic options for those with symptomatic carotid occlusion in contrast to carotid stenosis.…”

Leptomeningeal collateral activation indicates severely impaired cerebrovascular reserve capacity in patients with symptomatic unilateral carotid artery occlusion

“…The identification of the four main collateral pathways that can be assessed with TCD, was done as follows. 6,20,21 Here, for the number of possible collaterals we used the data for ACOM and PCOM from TOF MRA images, for ophthalmic artery the measured flow in Doppler TCD verified for presence of possible collateral since the ophthalmic artery identification in TOF MRA is due to anatomical conditions limited. 22 If no ophthalmic artery flow was measurable in TCD and no ophthalmic artery identifiable in TOF MRA, we counted as no anatomical possibility for ophthalmic collateral.…”

“…Previous studies showed conflicting results regarding impact of secondary collaterals: while some studies linked the activation of secondary collaterals to impaired cerebral vasoreactivity, 11,21 others suggested that not the type but the number of activated collateral pathways indicates a higher risk of stroke recurrence in patients with carotid artery occlusion. 6,38,40 Connolly et al 41 assessed the activation of primary and secondary collaterals in patients with symptomatic ICA occlusion using TCD, and showed that ACOM collateral was most frequently activated, followed by ophthalmic, the PCOM and the leptomeningeal collaterals. In our cohort, likewise, ACOM collateral was most frequently activated followed by ophthalmic.…”

“…The activation of secondary collaterals in addition to primary collaterals was already in previous studies related to compromisedexhausted -hemodynamic status. 6,11,14 A negative flow reactivity is significantly associated with a dependence on leptomeningeal collaterals and implies a state of maximal hemodynamic compromise. In 1994, Smith et al 42 in patients with symptomatic cerebrovascular disease who underwent angiography and xenon-enhanced computed tomographic cerebral blood flow studies before and after acetazolamide found a significant association between negative flow reactivity and a dependence on leptomeningeal collaterals indicating a state of maximal hemodynamic compromise.…”

Carotid endarterectomy in patients with symptomatic occlusions of the contralateral internal carotid artery

“…По данным эпидемиологических исследований [2], симптоматические окклюзии ВСА ежегодно развиваются более чем у 6 на 100 000 населения, без учета пациентов, не обратившихся за специализированной помощью. Ультразвуковые исследования у больных с симптомами хронической церебральной ишемии выявляют каротидные окклюзии в 4% случаев [4].…”