The hemodynamic response of spreading depolarization observed by near infrared spectroscopy after aneurysmal subarachnoid hemorrhage

Background Electrocorticography (ECoG) in brain-injured patients allows to detect spreading depolarization, a potential mechanism of secondary ischemia. Here, we describe the relationship of spreading depolarization with changes in cerebral hemodynamics using a brain tissue probe applying near infrared spectroscopy (NIRS). Methods Simultaneous ECoG and NIRS monitoring was performed in a patient with severe aneurysmal subarachnoid hemorrhage. Changes in cerebral blood oxygenation and regional cerebral blood volume were studied before and after the occurrence of spreading depolarization. Cerebral blood flow measurements were performed daily using an indocyanine green dye dilution mode. Results Single events of spreading depolarizations demonstrated with transient hyperoxic responses and increase in cerebral blood volume. On the other hand, temporal clusters of recurrent spreading depolarizations were associated with prolonged hypoxic responses and decrease in cerebral blood volume. Cerebral blood flow measurements showed higher values before compared to after onset of spreading depolarization (33.7 ± 8.4 vs. 24.2 ± 4.5 ml/100 g/min). Conclusions The findings suggest that NIRS monitoring in the cerebral white matter might reflect the hemodynamic signature of spreading depolarization detected by ECoG recordings. This is of potential interest for the further development of both neuromonitoring methods