Diagnosis of Delayed Cerebral Ischemia in Patients with Aneurysmal Subarachnoid Hemorrhage and Triggers for Intervention

Abstract

Introduction Delayed cerebral ischemia (DCI) is a major determinant for poor neurological outcome after aneurysmal subarachnoid hemorrhage (aSAH). Detection and treatment of DCI is a key component in the neurocritical care of patients with aSAH after initial aneurysm repair. Methods Narrative review of the literature. Results Over the past 2 decades, there has been a paradigm shift away from macrovascular (angiographic) vasospasm as a main diagnostic and therapeutic target. Instead, the pathophysiology of DCI is hypothesized to derive from several proischemic pathomechanisms. Clinical examination remains the most reliable means for monitoring and treatment of DCI, but its value is limited in comatose patients. In such patients, monitoring of DCI is usually based on numerous neurophysiological and/or radiological diagnostic modalities. Catheter angiography remains the gold standard for the detection of macrovascular spasm. Computed tomography (CT) angiography is increasingly used instead of catheter angiography because it is less invasive and may be combined with CT perfusion imaging. CT perfusion permits semiquantitative cerebral blood flow measurements, including the evaluation of the microcirculation. It may be used for prediction, early detection, and diagnosis of DCI, with yet-to-prove benefit on clinical outcome when used as a screening modality. Transcranial Doppler may be considered as an additional noninvasive screening tool for flow velocities in the middle cerebral artery, with limited accuracy in other cerebral arteries. Continuous electroencephalography enables detection of early signs of ischemia at a reversible stage prior to clinical manifestation. However, its widespread use is still limited because of the required infrastructure and expertise in data interpretation. Near-infrared spectroscopy, a noninvasive and continuous modality for evaluation of cerebral blood flow dynamics, has shown conflicting results and needs further validation. Monitoring techniques beyond neurological examinations may help in the detection of DCI, especially in comatose patients. However, these techniques are limited because of their invasive nature and/or restriction of measurements to focal brain areas. Conclusion The current literature review underscores the need for incorporating existing modalities and developing new methods to evaluate brain perfusion, brain metabolism, and overall brain function more accurately and more globally.

Association of sepsis and delayed cerebral ischemia in patients with aneurysmal subarachnoid hemorrhage

“…While DCI is defined as cerebral ischemia due to sequelae of SAH 6 , sepsis can cause cerebral ischemia via the multifactorial pathophysiological processes described above 7,8,35 . Hence, both sepsis and DCI are associated with derangements of vascular tone and integrity, microthrombosis formation and neuroinflammation resulting in cerebral ischemia 4,8,11,35 . These pathophysiological effects are concordant with the results of the present study in that both sepsis and DCI were independent risk factors for poor functional outcome in our cohort of aSAH patients.…”

“…Both sepsis and delayed cerebral ischemia (DCI) are severe complications in patients with aneurysmal subarachnoid hemorrhage (aSAH) and are significant determinants for poor outcome [1][2][3][4] . The term DCI presents a pro-ischemic complication in patients who survive the initial aSAH ictus 5,6 .…”

“…Both sepsis and DCI are characterized by a dysregulation in vascular regulation and integrity 9,10 . DCI was mainly thought to be caused by cerebral vasospasm, however, recent studies support the concept of a multifactorial pathophysiology, including microcirculatory disturbances due to microthrombosis and neuroinflammation 4,11 .…”

“…Both sepsis and DCI are characterized by a dysregulation in vascular regulation and integrity 9,10 . DCI was mainly thought to be caused by cerebral vasospasm, however, recent studies support the concept of a multifactorial pathophysiology, including microcirculatory disturbances due to microthrombosis and neuroinflammation 4,11 . Microcirculatory dysfunction is also a key mechanism of septic organ dysfunction caused by direct effects of circulating mediators, capillary leak and microthrombus formation, which can affect any organ including the brain 7,10 .…”

Year in Review: Synopsis of Selected Articles in Neuroanesthesia and Neurocritical Care from 2023

“…Abdulazim et al have published a review on current modalities used for monitoring patients after aSAH, on the diagnosis of delayed cerebral ischemia, and putative triggers for intervention. 41 Adrogue and Madias have published a compressive review (case-based discussion) on the Syndrome of Inappropriate Antidiuresis (SIADH). 42 Mazzoleni et al have published a review that provides an update on the etiological diagnostic workup, acute treatment, and prognosis of ICH.…”