Timing of recanalization after tissue plasminogen activator therapy determined by transcranial doppler correlates with clinical recovery from ischemic stroke.
BACKGROUND
The duration of cerebral blood flow impairment correlates with irreversibility of brain damage in animal models of cerebral ischemia. Our aim was to correlate clinical recovery from stroke with the timing of arterial recanalization after therapy with intravenous tissue plasminogen activator (tPA).


METHODS
Patients with symptoms of cerebral ischemia were treated with 0.9 mg/kg tPA IV within 3 hours after stroke onset (standard protocol) or with 0.6 mg/kg at 3 to 6 hours (an experimental institutional review board-approved protocol). National Institutes of Health Stroke Scale (NIHSS) scores were obtained before treatment, at the end of tPA infusion, and at 24 hours; Rankin Scores were obtained at long-term follow-up. Transcranial Doppler (TCD) was used to locate arterial occlusion before tPA and to monitor recanalization (Marc head frame, Spencer Technologies; Multigon 500M, DWL MultiDop-T). Recanalization on TCD was determined according to previously developed criteria.


RESULTS
Forty patients were studied (age 70+/-16 years, baseline NIHSS score 18.6+/-6.2). A tPA bolus was administered at 132+/-54 minutes from symptom onset. Recanalization on TCD was found at the mean time of 251+/-171 minutes after stroke onset: complete recanalization occurred in 12 (30%) patients and partial recanalization occurred in 16 (40%) patients (maximum observation time 360 minutes). Recanalization occurred within 60 minutes of tPA bolus in 75% of patients who recanalized. The timing of recanalization inversely correlated with early improvement in the NIHSS scores within the next hour (polynomial curve, third order r(2)=0.429, P<0.01) as well as at 24 hours. Complete recanalization was common in patients who had follow-up Rankin Scores if 0 to 1 (P=0.006). No patients had early complete recovery if an occlusion persisted for >300 minutes.


CONCLUSIONS
The timing of arterial recanalization after tPA therapy as determined with TCD correlates with clinical recovery from stroke and demonstrates a 300-minute window to achieve early complete recovery. These data parallel findings in animal models of cerebral ischemia and confirm the relevance of these models in the prediction of response to reperfusion therapy.
Center for Noninvasive Brain Perfusion Studies, Stroke Treatment Team, University of Texas-Houston Medical School, USA.
I
I
Christou
A V
AV
Alexandrov
W S
WS
Burgin
A W
AW
Wojner
R A
RA
Felberg
M
M
Malkoff
J C
JC
Grotta
D000368:Aged; D001783:Blood Flow Velocity / Q000187:drug effects; D002545:Brain Ischemia / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000503:physiopathology*; D002536:Cerebral Arteries / Q000000981:diagnostic imaging*; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008991:Monitoring, Physiologic / Q000379:methods; D010960:Plasminogen Activators / Q000008:administration & dosage*; D011446:Prospective Studies; D020127:Recovery of Function / Q000187:drug effects; D015203:Reproducibility of Results; D013997:Time Factors; D010959:Tissue Plasminogen Activator / Q000008:administration & dosage*; D017585:Ultrasonography, Doppler, Transcranial
D010960:Plasminogen Activators; D010959:Tissue Plasminogen Activator