gms | German Medical Science

Objective: Recently, Laser Speckle Contrast Analysis (LASCA) has been introduced as a novel imaging tool for non-invasive intraoperative assessment of cortical cerebral blood flow (CBF). The aim of the present study was to assess, whether next to perfusion, LASCA is also suitable for intraoperative determination of CO₂ reactivity and cerebral autoregulation.

Methods: 31 Patients undergoing standard extracranial-intracranial (EC-IC) bypass surgery (20 patients), decompressive hemicraniectomy (5 patients) or non-related craniotomy (6 patients) were included. The portable LASCA device was centered over the surgical field and continuous recordings of cortical CBF-flux were obtained. For intraoperative assessment of the CO₂ reactivity in patients with hemodynamic compromise, LASCA was performed with simultaneous CO₂ challenge. In a subgroup of patients with Moyamoya disease (MMD), CO₂ challenge was omitted and baseline perfusion was measured before and after completion of the anastomosis. The cerebral autoregulation was tested in patients with malignant hemispheric stroke through artificial alterations in mean arterial pressure (MAP). Validity of the results was determined by comparison to LASCA in patients undergoing craniotomy for either brain tumor surgery (3 patients) or grid-electrode placement due to medication refractory epilepsia (3 patients).

Results: In all cases, we achieved immediate visualization and measurement of relative CBF in addition to flow imaging the cortical vasculature. CO₂ challenge in patients undergoing bypass procedures resulted in a parallel increase in cortical CBF-flux both before (12±10%) and after (12±12%) completion of the anastomosis. However, the rise in CBF-flux during CO₂ increase was significantly lower in hemodynamically compromised patients than in control patients without cerebrovascular disease (20±5%; p<0.05, one-way ANOVA). Baseline CBF measurements in patients with MMD were significantly higher after completion of the bypass anastomosis. Assessment of cerebral autoregulation after malignant hemispheric stroke showed evidence of a disturbed autoregulation with positive correlation of MAP and CBF-flux recordings. In healthy control patients LASCA demonstrated an intact autoregulation with stable CBF-flux recordings during MAP alterations.

Conclusions: LASCA enables reliable, low-cost and non-invasive intraoperative assessment of CO2 reactivity and cerebral autoregulation.