Cerebral microembolus detection in an unselected acute ischemic stroke population

The aims of this study were firstly to determine prevalence, frequency, and clinical significance of cerebral microemboli in an unselected acute ischemic stroke population and secondly to examine how this information may improve ischemic stroke subtype classification.

We intended to perform transcranial Doppler (TCD) microembolus monitorings of the middle cerebral artery (MCA) in the symptomatic hemisphere for 45 min in 120 consecutive patients with internal carotid artery territory ischemia. The first examination was performed within 72 h from start of symptoms and the second 5 +/- 1 days later. Platelet and coagulation system activation were measured following TCD monitoring in 38 patients. The strokes were subtyped using the TOAST classification criteria, and the patients' clinical status was assessed at discharge using the Scandinavian Stroke Scale and the Barthel Index.

Microembolus monitoring was technically possible in 83 (69.2%) of the 120 patients. Thirty-two (26.6%) patients had an inadequate temporal bone acoustic window or were too restless to allow long-time monitoring. In 5 (4.2%) patients the relevant MCA was occluded. Twenty-two (26.5%) of the 83 patients had microemboli despite the fact that over 90% were receiving an antiplatelet or an anticoagulant treatment. The mean frequency of microemboli was 6.7 +/- 13.6 per 45 min. Microemboli were more prevalent in assumed cardioembolic stroke than in other subtypes of ischemic stroke (p = 0.047). We found no association between the presence of cerebral microemboli and the clinical outcome or the parameters for platelet or coagulation system activation. The presence of microemboli was not associated with in-hospital deaths (p = 0.17), whereas MCA occlusion was (p = 0.01).

Cerebral microemboli are frequent in unselected acute ischemic stroke patients despite antiplatelet or anticoagulant treatment. TCD detection of microemboli provides valuable pathophysiological information and may, therefore, improve current ischemic stroke subtype classification.