We performed TCD examinations using Transpect (Medasonics) in 744 cases (cerebral infarct or TIA: 482, control: 112, other diseases: 150) . In order to establish the TCD diagnostic criteria of MCA stenosis (MCAS), the highest mean flow velocity (MFV) in the control group was evaluated. MFV was 110 cm/s in cases aged between 17-29 years, 104 cm/s in cases aged 30-49 years, 94 cm/s in cases aged 50-69 years, and 64 cm/s in cases older than 70 years. For the detection of milder stenosis, an interhemispheric asymmetry index was calculated using the following formula:
Al=MV1-MV2/ (MV1+MV2) /2×100
where MV1 and MV2 represent mean velocities of the middle cerebral arteries. The diagnostic criteria of MCAS were considered to be an MFV higher than the highest MFV of the control group, and an AT more than 30%. The criterion of MCA occlusion (MCAO) was undetectable MCA signals in the presence of PCA, ACA, ICA signals. TCD findings in angiographically diagnosed MCAS (25 cases) and MCAO (12 cases) were assessed for sensitivity and specificity. The sensitivity of TCD diagnosis in MCAS and MCAO was 100%, respectively. The specificity was 98% in MCAS and 95% in MCAO. In conclusion, TCD is a very accurate method of diagnosing MCAS and MCAO.
