DETECTION OF MICROEMBOLIC SIGNALS IN PATIENTS WITH MIDDLE CEREBRAL-ARTERY STENOSIS BY MEANS OF A BIGATE PROBE - A PILOT-STUDY

Background and Purpose Middle cerebral artery (MCA) stenosis is a rela tively rare occlusive disease with an annual stroke risk of approximat ely 7% to 8%. However, the frequent coincidence of cardiac or ipsilate ral carotid artery disease may lead to difficulties in identifying the relevant embolizing source in symptomatic patients. We undertook this study to evaluate the prevalence of microembolic signals (MES) as wel l as the potential and limitations of bigate monitoring in patients wi th MCA stenosis. Methods Fourteen patients aged 33 to 87 years with an giographically demonstrated symptomatic (acute, n=2; chronic, n=8) or asymptomatic (n=4) MCA stenosis were examined. Six patients (43%) had additional cardiac (n=3) or carotid artery (n=3) disease. By means of a bigate probe, simultaneous insonation of prestenotic and poststenoti c vessel segments was attempted. Results In 10 patients (71%), MES det ection could be performed sufficiently at target vessel sites. In the remaining patients, either prestenotic (n=3) or poststenotic (n=1) mon itoring was not satisfactory due to insufficient transtemporal bone wi ndow or the great length or extent of MCA stenosis. Poststenotic MES w ere detectable in 2 acutely symptomatic and 1 asymptomatic patient (pr evalence, 21%). In the latter case, the sequential appearance of MES i n both prestenotic and poststenotic channels excluded MCA stenosis but strongly favored coexisting carotid artery stenosis as the active emb olic source. Conclusions MES are detectable in patients with MCA steno sis. Bigate monitoring in this setting is feasible and allows identifi cation of the active source among ''competing'' embolizing conditions.