Clinically Silent Circulating Microemboli in 20 Patients with Carotid or Vertebral Artery Dissection

Abstract

Background and Purpose: Carotid and vertebral artery dissections are frequently complicated by cerebral embolism. Detection of clinically silent circulating microemboli by transcranial Doppler sonography (TCD) is now widely investigated in patients with carotid artery disease in the hope to identify patients at increased risk for stroke. Methods: In 20 patients with carotid (n = 17) or vertebral (n = 2) artery dissection, or both (n = 1), we performed a 1-hour microembolus detection downstream to the dissection in the middle or in the posterior cerebral artery, respectively. Results: Five patients with a carotid artery stenosis of ≧90% or with carotid artery occlusion showed microembolic signals at a rate of up to 15 events/h. In all these patients, the onset of the dissection was within the last 58 days. Patients with lower degrees of stenosis or onset of symptoms beyond 58 days did not show microembolic signals at all. Three patients who had presented with recurrent ischaemic events prior to TCD monitoring unexceptionally had microembolic signals. Conclusion: Microembolic signals occur in patients with high-grade stenosis or occlusion due to acute cervical artery dissection. Patients with microemboli seem to be at increased macroembolic risk, i.e. stroke recurrence, and may require close-meshed clinical follow-up and possibly stronger antithrombotic treatment.

Antiplatelets Versus Anticoagulation in Cervical Artery Dissection

“…20 -24 Similarly, in eVAD, HITS were shown in the posterior cerebral artery. 20 The frequency of HITS in CAD patients is reported within the range of 25% to 60%. 20 -24 However, sample sizes of 6 to 28 patients limit the significance of these numbers.…”

“…However, HITS occur also despite antithrombotic therapy. 20,24 Furthermore, no association was recorded between the presence or number of HITS and the type of antithrombotic treatment (ie, anticoagulants or antiplatelets). 24 Among a population of 20 CAD patients, all 5 HITS-positive ones had some form of antithrombotic therapy during transcranial doppler monitoring.…”

Mechanism of Ischemic Infarct in Spontaneous Cervical Artery Dissection

“…An autopsy case has provided the only direct demonstration of secondary intracranial emboli. 46 Three studies described indirect signs of emboli on transcranial Doppler monitoring studies, [47][48][49] but the sample sizes of these studies limit the significance of these results. According to current concepts relating mechanism and stroke pattern, strokes in pial or perforating artery territories are more likely to be embolic, 50 whereas border-zone infarcts are more likely to be hemodynamic.…”

Microemboli Monitoring in Ischemic Stroke

“…Presence of microemboli seems to be a predictor of stroke recurrence (Molina, Alvarez-Sabin et al 2000). Microemboli are seen both in dissection of carotid and vertebral arteries, and possibly predict thromboembolic events (Droste, Junker et al 2001). Presence of microemboli may be a determining factor in choosing the right medication, favoring anticoagulation over antiplatelet agents (Engelter, Brandt et al 2007).…”