Dynamic Cerebral Autoregulation in Acute Ischemic Stroke Assessed From Spontaneous Blood Pressure Fluctuations

Abstract

Background and Purpose-This study investigates dynamic cerebral autoregulation assessed from spontaneous blood pressure (ABP) and cerebral blood flow velocity (CBFV) fluctuations and its time course in acute ischemic stroke. Methods-Forty patients admitted with acute ischemic stroke in the territory of the middle cerebral artery (MCA) were enrolled. Admission National Institutes of Health Stroke score was 6Ϯ4. Study 1 was performed within 22 (Ϯ11) hours and study 2 was performed within 134 (Ϯ25) hours of ictus. The final analysis comprised 33 and 29 patients for study 1 and study 2, respectively. Twenty-five age-and sex-matched controls were studied. ABP (Finapres method) and CBFV in both MCAs (transcranial Doppler) were recorded over 10 minutes. Correlations between diastolic and mean ABP and CBFV fluctuations were averaged, yielding the correlation coefficient indices (Dx, Mx). Transfer function analysis was applied to obtain phase shift and gain between ABP and CBFV oscillations. Results-No disturbance of autoregulation was indicated by all parameters at study 1. Separate analyses for clinical severity, stroke side, and size did not reveal significant differences for the various autoregulatory indices at study 1 and 2. At study 2, MCA flow velocity was significantly increased on both sides, the autoregulation index Mx was slightly but significantly (PϽ0.05) worse on both sides in comparison to study 1, and phase showed a trend toward poorer values on affected sides. No significant differences to controls occurred. Clinical outcome in patients completing both studies was good in all but one patient. Conclusions-Dynamic

Near-Infrared Spectroscopy can Monitor Dynamic Cerebral Autoregulation in Adults

“…Moreover, a comparison of volunteers to medicated, ventilated patients may be misleading. This has been partially discussed previously [29]. Both Tox and Mx show rapid variations which may be caused by changes in the intensity of useful components for the assessment of autoregulation (slow waves) or fast changes in the strength of dynamic regulation (see example in Fig.…”

Cerebral Autoregulation in Stroke

“…In 9 studies, the initial stroke severity was not reported, [25][26][27][28][29][30][31][32][33] and 8 studies failed to provide information about other clinical conditions (such as arrhythmias, diabetes mellitus, and carotid pathology) associated with impaired cerebral autoregulation. 25,30,[32][33][34][35][36][37] All studies allowed hypertensive patients to be included. In 2 studies, only information about the nonaffected hemisphere was presented because of permanent occlusion of contralateral middle cerebral artery.…”

“…stroke, 30,41-44,46,47 particularly when stroke is moderate to severe, [41][42][43][44] or after follow-up. 36,41 In 5 studies, impaired autoregulation also could be demonstrated in the nonaffected hemisphere, [41][42][43][44] which was particularly the case for first-ever lacunar stroke. 46 Eames et al 42 showed that these bilateral changes are unrelated to previous antihypertensive treatment, baseline BP levels, or BP changes after stroke, age, and stroke subtype or stroke severity.…”

“…In 3 studies, dynamic cerebral autoregulation was recorded from spontaneous fluctuations of BP using the approaches of frequency domain (transfer function analysis [TFA]) and time domain analysis. 36,41,46 In sum, TFA is a complex linear analysis to estimate the magnitude and the phase relationship between spontaneous or induced changes in BP and CBFV. 5,48 In the time domain analysis, either the delay of CBFV counter-regulation during changes in BP or the degree of correlation between averaged CBFV and BP over time is used.…”

Prominence of Medullary Veins on Susceptibility-Weighted Images Provides Prognostic Information in Patients with Subacute Stroke

“…9 Prominence of the MV is also seen in the subacute stage of ischemic stroke. 10 In clinical practice, we have noted that prominent MV may be seen ipsilateral or contralateral to infarction. Such imaging signs may provide important prognostic information to guide clinicians toward the application of tissue-rescue therapies (such as recanalization or vasodilation) to prevent stroke progression during the subacute phase.…”