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Published on: June 18, 2021
Early identification of brain tissue at risk for delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage
Leodante da Costa1, Joseph Fisher, David J Mikulis
1Division of Neurosurgery, Department of Surgery, Sunnybrook Hospital, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Room A1-37, Toronto, ON, Canada, leo.dacosta@sunnybrook.ca.
Insights
Functional MRI can detect early changes in cerebrovascular reactivity, predicting the risk of delayed cerebral ischemia (DCI) in aneurysmal subarachnoid hemorrhage (aSAH) patients. This noninvasive method may help identify at-risk brain tissue before symptoms appear.
Area of Science:
- Neuroimaging
- Cerebrovascular Physiology
- Medical Diagnostics
Background:
- Delayed cerebral ischemia (DCI) is a significant cause of death and disability in aneurysmal subarachnoid hemorrhage (aSAH) patients.
- Current DCI diagnosis occurs after symptom onset, leading to worse outcomes and increased healthcare costs.
- Early identification of at-risk brain tissue is crucial for improving patient prognosis.
Observation:
- Functional MRI (fMRI) with CO2 challenge was used to measure cerebrovascular reactivity (CVR).
- fMRI exams were performed shortly after aneurysm treatment in five aSAH patients.
- The study assessed the blood oxygenation level-dependent (BOLD) response to CO2 to evaluate CVR.
Findings:
- Two of three patients who developed DCI had abnormal fMRI CVR results.
- The two patients who did not develop DCI had normal fMRI CVR.
- Impaired CVR on fMRI spatially corresponded with the areas where DCI later occurred.
Implications:
- fMRI measurement of CVR shows promise as an early, noninvasive marker for DCI risk in aSAH.
- This technique could enable timely interventions to prevent or mitigate DCI.
- Further research is warranted to validate these findings in larger patient cohorts.
Background:
Delayed cerebral ischemia (DCI) continues to be a major cause of morbidity and mortality in patients with aneurysmal subarachnoid hemorrhage (aSAH) because it can only be diagnosed after the onset of clinical symptoms, contributing to poor clinical outcomes and huge use of clinical resources. We hypothesized that early disturbances in cerebrovascular reactivity, noninvasively measured with functional MRI + CO₂, can be a sensitive marker of brain tissue at risk for DCI.
Methods:
Functional MRI exam as soon as possible after the initial bleed and after surgical treatment of the aneurysm was performed in five patients. The functional MRI exam consisted of spatial cerebrovascular reactivity measurements by the blood oxygenation level-dependent (BOLD) response to a standardized carbon dioxide challenge.
Results:
Of the three patients who later developed DCI, two had abnormal functional MRI study results. The two patients without DCI had normal MRI results. Brain areas with impaired cerebrovascular reactivity on the functional MRI examination demonstrated a spatial correspondence between impaired cerebrovascular reactivity and the onset of DCI.
Conclusions:
In this feasibility study, functional MRI measurements of cerebrovascular reactivity showed a spatial correspondence between impaired cerebrovascular reactivity and the onset of DCI in patients with aSAH.
