Dynamic cerebral autoregulation is compromised in ischaemic stroke of undetermined aetiology only in the non-affected hemisphere.

To assess dynamic cerebral autoregulation (CA) in patients with acute ischaemic stroke of undetermined aetiology, within 72h of stroke onset.In 6 patients with ischaemic stroke of undetermined aetiology (aged 66±9 years, National Institutes of Health Stroke Scale [NIHSS] score on admission: 4.0, range: 4-11), selected based on screening of 118 consecutive ischaemic stroke patients and in 14 volunteers (aged 62±10 years), we continuously monitored RR intervals (RRI), mean arterial pressure (MAP) by means of photoplethysmography, mean cerebral blood flow velocity (CBFV) using transcranial Doppler ultrasonography, end-tidal CO2 (ETCO2) and respiration during 2-min deep breathing paced at 6min(-1) (0.1Hz). To assess CA, we evaluated the impact of breathing-induced MAP oscillations on fluctuations of CBFV in the hemispheres with stroke, the non-involved hemispheres and randomly selected hemispheres of controls by applying cross-spectral analysis and calculating coherence, transfer function gain (CBFV-MAP gain) and phase shift angle between the two oscillating signals.Phase shift angle between MAP and CBFV oscillations showed values >0 and was significantly reduced in the hemispheres without stroke as compared to controls (0.39±0.95 vs. -1.59±0.33rad, p=0.015), whereas in the hemispheres with stroke, phase shift angle did not differ significantly from that observed in the control hemispheres. Clinical status of stroke patients significantly improved at discharge from the hospital (NIHSS: 2.0, range: 1-8, p=0.028).During the first days of ischaemic stroke of undetermined aetiology, dynamic cerebral autoregulation is compromised in the non-affected hemisphere, but not in the hemisphere with ischaemic lesion.