Clinical and Sonographic Patterns of Tandem ICA / MCA Occlusion in TPA Treated Patients
Background: The National Institutes of Health Stroke Scale (NIHSS) has limited ability to identify clot location in the anterior circulation. We describe clinical and sonographic patterns that are associated with tandem ICA and MCA occlusions. Subjects and Methods: Consecutive patients receiving intravenous tissue plasminogen activator (TPA) were studied. Pre-treatment NIHSS scores and bedside transcranial Doppler (TCD) were obtained in all patients. Results: A total of 95 patients treated with iv TPA at 132±60 minutes from stroke onset were studied: 48 had isolated MCA occlusion (mean NIHSS 16.8±5.8, median 17 points, range 5–28); and 16 had tandem ICA/MCA occlusion (mean NIHSS 18.8±5.8, median 22 points, range 8–29, ns). Patients with tandem occlusions had NIHSS scores similar to isolated MCA occlusion. In both groups, respectively, 19% and 11% had NIHSS scores less than 12 points. Lower NIHSS scores were attributable to partial arm and/or leg paresis, higher number of collateral channels and low resistance flow at the M1 origin suggesting perfusion of perforating arteries on TCD. Although TCD can not differentiate between high grade ICA stenosis or occlusion, collateral flow patterns and stenotic signals at the terminal ICA identified tandem lesions from isolated MCA occlusion (p<0.01) with no false positive results at subsequent angiography (n=12). Conclusions: Tandem ICA/MCA occlusion was found in 17% of all iv TPA treated patients. NIHSS scores were similar in patients with isolated MCA and tandem occlusions. TCD can be used to accurately identify patients with tandem lesions. Collateral flow and patent perforators are associated with lower NIHSS scores.