Approaches to classification of microembolic signals in patients recovering from ischemic stroke

Introduction. Microembolus detection by transcranial Doppler (TCD) is the only non-invasive modality for visualization of cerebral embolism. Currently, there is no unified classification of recorded microembolic signals (MES) that could be used in clinical practice. The aim of the study is to investigate biophysical MES parameters in patients with ischemic stroke, as well as to assess approaches to microemboli differentiation by structure and origin to improve the diagnostic accuracy of the method and to reduce the risk of recurrent ischemic events. Materials and methods. The inclusion criterion was TCD-detected signs of MES. We analyzed the data of 28 patients with ischemic stroke (9 women and 19 men; mean age was 58 years 13). We recorded power, duration, and frequency for each MES, and calculated an energy index. Results. A total of 938 MES were reported. In patients with cardioembolic stroke and all other pathogenetic stroke subtypes, biophysical parameter limits were as follows: 14.65 dB for the average power, 9.45 ms for the average duration, and 0.16 J for the average energy index. For patients with atrial fibrillation, characteristic MES power was found to be 13 dB. The MES frequency limit was determined to be 650 Hz for microemboli differentiation by acoustic density. Conclusion. The data obtained can be used to further search for optimal limit ranges for biophysical parameters of various MES in order to establish a single MES classification, which will increase the diagnostic value of microembolus detection by TCD in stroke treatment practice.