gms | German Medical Science

Objective: Cortical spreading depolarizations (CSDs) influence cortical oxygen availability (O₂) by changes in local blood flow in the cortical microcirculation and augmented metabolism. Intraoperative laser speckle data of cortical cerebral blood flow in patients suffering malignant hemispheric stroke (MHS) revealed that multiple CSDs coincidence with either hyperemic or hypoemic flow responses. However, data of O₂-availability during CSDs occurring in patients with MHS is still missing. We designed this study to evaluate the effect of CSDs on O₂-availability in patients with MHS during a 7 day monitoring period after ictus.

Method: In 11 patients with MHS and clinical decision for hemicraniectomy a 6-contact platinum subdural electocoticographic (ECOG) recording strip (Ad-Tech Medical, Racine, WI, USA) was positioned over the ipsilateral frontal cortex and a Clark-type probe (Licox CC1-SB, IntegraNeuroscience, Andover, UK) was placed next to the ECoG-strip electrode in an oblique fashion to assess cortical tissue partial pressure of oxygen (ptiO₂). PtiO₂ values were continuously recorded and analyzed. ptiO₂ alterations were referred to as monophasic decrease (MD), monophasic increase (MI) and biphasic (BI) when they occurred in spatial and temporal association with CSDs. Delayed infarct progression was determined from serial MRI on the day after surgery and after the monitoring period.

Results: We found a total of 336 CSDs in 1463 h of recording time in 11 patients. In 60% of CSDs ptiO₂ changes occurred in spatial and temporal association to ECOG events. 67% of CSDs occurred recurrently. Monophasic decrease (MD) (48.1%) and biphasic (BI) (47.5%) ptiO₂ responses were mainly associated with SD. Monophasic increase (MI) was only rarely detected (1.3%). No significant association of type of ptiO₂ responses with SD Cluster occurence as well as clinical outcome was detected. Patients with delayed infarct progression showed significantly more monophasic ptiO₂ decrease in association with CSDs.

Conclusions: Clear spatial and temporal associations of ptiO₂ responses with EcoG events were found in 60% of CSDs in patients suffering MHS. Predominantly, MD and BI ptiO₂ changes were detected and occurrence of MD was significantly higher in patients with delayed infarct progression. We conclude that hyperemic changes in cerebral blood flow may not be sufficient to anticipate augmented metabolism during CSD in MHS leading to decreased oxygen availability.