Cerebral Autoregulation Dynamics in Acute Ischemic Stroke after rtPA Thrombolysis

BACKGROUND: To investigate whether there is: (1) a specific temporal course of cerebral dysautoregulation in acute ischemic stroke, and (2) a separate detrimental effect of recombinant tissue plasminogen activator (rtPA) on autoregulation dynamics in this situation. METHODS: We studied 16 patients with acute middle cerebral artery (MCA) occlusion and rtPA thrombolysis (intra-arterial or intravenous application, or both). Controls were 71 healthy adults and 11 patients with minor stroke not receiving rtPA. Dynamic autoregulation was recorded from spontaneous fluctuations of blood pressure and MCA flow velocity (transcranial Doppler) using two well-described approaches (index Mx, phase shift). Three measurements were performed (study 1: 20 +/- 9 h of ictus; study 2: 64 +/- 10 h; study 3: 112 +/- 7 h). RESULTS: Two groups of clinical outcome were identified: good (modified Rankin scale 2, n = 7, MCA infarct volume = 62 +/- 21%). In the good outcome group, no relevant changes in Mx and phase were observed on both MCA sides compared with controls. In the poor outcome group, the index Mx deteriorated over studies 1-3 on affected sides, with worse values compared to the controls (p < 0.05). Phase was already impaired on affected sides of poor outcome patients in study 1 (p < 0.01 vs. controls) and tended to decrease further until study 3. Phase also decreased moderately on contralateral sides in poor outcome patients from studies 1 to 3 (p < 0.05, nonsignificant compared with controls). CONCLUSIONS: Cerebral autoregulation is increasingly impaired, mainly on the affected side, over the first 5 days of major ischemic stroke after unsuccessful rtPA thrombolysis. It is bilaterally preserved in minor stroke after successful rtPA thrombolysis, indicating no separate detrimental effect of rtPA on the cerebral autoregulatory mechanism.