Difficulties exist in distinguishing patients with currently recanaliz
ed mainstem occlusion of the middle cerebral artery (MCA) from branch
occlusion. Thirty-five patients, 8 women and 27 men, at a mean age of
64 +/- 15 (standard deviation) years, with clinical signs of infarctio
n in the MCA territory confirmed by computed tomography (CT), were eva
luated by repeated clinical and transcranial Doppler sonography within
2 days of the event, 2 to 5 days later, and at 2 weeks after admissio
n. The quotient MCA I/MCA C, derived to evaluate side differences, is
defined as mean velocity (MV) in the MCA on the infarcted (I) side div
ided by MV in the MCA on the contralateral (C) side. Occlusion of the
MCA was found in 13 of 35 patients at the first examination. A very hi
gh MV of 94 +/- 6 cm/sec with an abnormal turbulent flow pattern was f
ound in 3 patients at the first examination, consistent with pseudoste
nosis after recanalization. The remaining 19 patients with a patent MC
A had a lower MV in the affected side compared to the healthy side (37
+/- 15 and 54 +/- 20 cm/sec, p < 0.001). Five (38%) of 13 patients wi
th acute MCA mainstem occlusions demonstrated recanalization at the se
cond examination, within 1 week after the onset of stroke, with a MV o
f 82 +/- 44 cm/sec and pulsatility index (PI) of 0.68 +/- 0.38, which
differed (p < 0.05) from the MV of 46 +/- 19 cm/sec and PI of 0.99 +/-
0.20 in the remainder. The MCA I/MCA C quotient revealed a difference
(p < 0.01) between primarily patent vessels and recanalization at the
second examination. A tendency to a better prognosis was found in ori
ginally patent or later recanalized vessels. Progression of neurologic
al signs was noted in 3 (23%) of 13 patients with MCA occlusion and in
1 (4%) of 22 with nonoccluded MCAs.