Transient Occlusion of the Middle Cerebral Artery by Macroembolism During Carotid Stenting for Traumatic Dissection of the Common Carotid Artery
Carotid stenting has been used more frequently not only for atherosclerotic carotid stenosis but also for dissection of the carotid artery.1 Transcranial Doppler ultrasound (TCD) has been reported to be able to detect circulating cerebral microembolic signals in patients with ischemic stroke.2 TCD can provide useful online information about hemodynamic change and cerebral embolism during carotid endarterectomy.3 We present our findings during carotid stenting in a patient to illustrate an obstruction of the middle cerebral artery (MCA) main trunk by a macroembolus resulting in ischemic stroke. A 27-year-old man with traumatic dissection of the left common carotid artery with the intimal flap underwent carotid stenting without the use of a distal protection device. We used a TCD machine (Multi-Dop X4, DWL) with two 2-MHz probes mounted on a head frame to insonate the bilateral MCA through the transtemporal window. The dissection was stented with a self-expanding, 8×27-mm Wallstent. An 8×40-mm balloon was introduced to dilate the stent further, but was removed later without inflation because of the mismatch between the length of the balloon and that of the stent. During this manipulation, we detected 3 embolic signals from the left MCA having unique chirping sounds. Thereafter, the left MCA mean velocity suddenly decreased from 68 cm/s to 16 cm/s (Figure 1). The patient developed aphasia and right hemiparesis. Within 5 minutes of this episode, the MCA velocity returned to the previous value with no additional embolic signals. The cerebral angiogram obtained after the normalization of the MCA velocity showed left MCA branch occlusion (Figure 2). A microcatheter system was advanced and located near the occluded artery. Although intra-arterial infusion of 300 000 U urokinase was administered, recanalization was not obtained. Diffusion-weighted images performed 3 days later revealed a fresh cortical infarct in the left MCA territory (Figure 3). One month later, the patient had almost completely recovered from aphasia and right hemiparesis.
This case demonstrates an obstruction of the MCA main trunk by a macroembolus probably being dislodged from the carotid dissection, followed by spontaneous recanalization and distal embolism. The macroembolism was supported by the findings of both the cerebral angiography and the diffusion-weighted images. This is the first report that describes a macroembolism detected as embolic signals and the sudden decline of MCA velocity during carotid stenting. TCD can noninvasively detect both microembolism and macroembolism during carotid stenting.
This work was supported by the Research Grant for Cardiovascular Diseases (14C-1) from the Ministry of Health, Labor and Welfare.
Liu AY, Paulsen RD, Marcellus ML, Steinberg GK, Marks MP. Long-term outcomes after carotid stent placement treatment of carotid artery dissection. Neurosurgery. 1999; 45: 1373–1374.
Georgiadis D, Lindner A, Manz M, Sonntag M, Zunker P, Zerkowski HR, Borggrefe M. Intracranial microembolic signals in 500 patients with potential cardiac or carotid embolic source and in normal controls. Stroke. 1997; 28: 1203–1207.
Ackerstaff RG, Moons KG, van de Vlasakker CJ, Moll FL, Vermeulen FE, Algra A, Spencer MP. Association of intraoperative transcranial Doppler monitoring variables with stroke from carotid endarterectomy. Stroke. 2000; 31: 1817–1823.