Symptomatic Cerebral Air Embolism During Stent-assisted Coiling of an Unruptured Middle Cerebral Artery Aneurysm: Intraoperative Diagnosis and Management of a Rare Complication

Investigation of air bubble behaviour after gas embolism events induced in a microfluidic network mimicking microvasculature

Gas embolism is a medical condition that occurs when gas bubbles are present in veins or arteries, decreasing blood flow and potentially reducing oxygen delivery to vital organs, such as the brain. Although usually reported as rare, gas embolism can lead to severe neurological damage or death. However, presently, only limited understanding exists regarding the microscale processes leading to the formation, persistence, movement, and resolution of gas emboli, as modulated by microvasculature geometrical features and blood properties. Because gas embolism is initially a physico-chemical-only process, with biological responses starting later, the opportunity exists to fully study the genesis and evolution of gas emboli using in vitro microfluidic networks mimicking small regions of microvasculature. The microfluidics networks used in this study, which aim to mimic microvasculature geometry, comprise linear channels with T-, or Y-junction air inlets, with 20, 40, and 60 μm widths (arterial or venous), and a 30 μm width honeycombed network (arterial) with three bifurcation angles (30°, 60°, and 90°). Synthetic blood, equivalent to 46% haematocrit concentrations, and water were used to study the modulation of gas embolism-like events by liquid viscosity. Our study shows that (i) longer bubbles with lower velocity occur in narrower channels, e.g., with 20 μm width; (ii) the resistance of air bubbles to the flow increases with the higher haematocrit concentration; and lastly (iii) the propensity of gas embolism-like events in honeycomb architectures increases for more acute, e.g., 30°, bifurcation angles. A dimensionless analysis using Euler, Weber, and capillary numbers demarcated the conditions conducive to gas embolism. This work suggests that in vitro experimentation using microfluidic devices with microvascular tissue-like structures could assist medical guidelines and management in preventing and mitigating the effects of gas embolism.

Diagnostic Accuracy of Somatosensory Evoked Potentials and Electroencephalography During Endovascular Treatment of Unruptured Cerebral Aneurysms

OBJECTIVE

Endovascular treatment (EVT) of unruptured cerebral aneurysms (UCA) offers a safer alternative to clipping. However, it is still associated with an increased risk for Postprocedural Neurological deficit (PPND). Prompt recognition using intraoperative neurophysiologic monitoring (IONM) and intervention can reduce the incidence and impact of new postoperative neurological complications. We aim to evaluate the diagnostic accuracy of IONM in predicting PPND after EVT of UCA.

METHODS

We included 414 patients who underwent EVT for UCA from 2014 to 2019. The sensitivities, specificities, and diagnostic odds ratio of somatosensory evoked potentials and electroencephalography monitoring methods were calculated. We also determined their diagnostic accuracy using receiver operating characteristic plots.

RESULTS

The highest sensitivity of 67.7% (95% confidence interval {CI}, 34.9%-90.1%) was obtained when either modality had a change. Simultaneous changes in both modalities have the highest specificity of 97.8% (95% CI, 95.8%-99.0%). The area under the receiver operating characteristic curve was 0.795 (95% CI, 0.655-0.935) for changes in either modality.

CONCLUSIONS

IONM with somatosensory evoked potentials alone or in combination with electroencephalography has high diagnostic accuracy in detecting periprocedural complications and resultant PPND during EVT of UCA.

Cone-beam computed tomography for trauma

Radiographic imaging is critical in helping guide treatment of critically injured patients. Cone-beam computed tomography is an axial imaging technique available from fixed imaging systems found in hybrid operating rooms. It can be used to provide focused studies of specific anatomical regions, where patients cannot undergo conventional multidetector computed tomography. This includes non-contrast-enhanced evaluation of the intracranial contents and vascular imaging throughout the body. There are a number of advantages and disadvantages to cone-beam computed tomography, but these are not widely discussed within the trauma literature. This narrative review article presents the initial practical experience of this novel imaging modality. LEVEL OF EVIDENCE: Review article, level III.

Multiple small hemorrhagic infarcts in cerebral air embolism: a case report

Background

Cerebral air embolism is a rare cause of cerebral infarction. In cerebral air embolism, T2 star-weighted imaging shows numerous spotty hypointense signals. Previous reports have suggested that these signals represent air in the brain and are gradually diminished and absorbed. We experienced two cases of cerebral air embolism, and in one of them, we conducted an autopsy.

Case presentation

Case 1 was a 76-year-old Japanese man with lung cancer and emphysema. A spasmodic cough induced massive cerebral and cardiac air embolisms and the patient died because of cerebral herniation. T2 star-weighted imaging of brain magnetic resonance imaging showed multiple spotty low signals. Brain autopsy showed numerous spotty hemorrhagic infarcts in the area of T2 star-weighted imaging signals. Case 2 was an 85-year-old Japanese man with emphysema who suffered from acute stroke. Similar spotty T2 star-weighted imaging signals were observed and remained unchanged 2 months after the onset.

Conclusions

These findings indicate that T2 star-weighted imaging in cerebral air embolism partially represents micro-hemorrhagic infarction caused by air bubbles that have migrated into the brain.

Spontaneous Absorption of Cerebral Air Embolus Developed Accidentally during an Intra-arterial Procedure

Cerebral arterial air embolism (CAAE), although infrequent, is a complication that can occur at any time during an invasive medical procedure. We experienced two cases of CAAE during cerebral angiography accidentally. The author reports the two cases of CAAE wherein air emboli dissolved spontaneously and immediately under normal atmospheric pressure, not under therapeutic hyperbaric environment. One of the cases shows entire dissolution of the air embolus on the moving image. This report shows that arterial air embolus can be absorbed spontaneously, and air embolus size is one of the factors that influence air embolus dissolution besides hyperbaric oxygen condition.

Republished: Paradoxical cerebral air embolism causing large vessel occlusion treated with endovascular aspiration

Cerebral air embolism is a dreaded complication of invasive medical procedures. The mainstay of therapy for patients with cerebral air embolism has been hyperbaric oxygen therapy, high flow oxygen therapy, and anticonvulsants. We present a novel therapeutic approach for treatment of cerebral air embolism causing large vessel occlusion, using endovascular aspiration. Our patient developed a cerebral air embolism following sclerotherapy for varicose veins. This caused near total occlusion of the superior division of the M2 segment of the right middle cerebral artery. Symptoms included unilateral paralysis, unintelligible speech, and hemianopia; National Institutes of Health Stroke Scale (NIHSS) on presentation was 16. The air embolism was treated using a distal aspiration technique. Angiography following aspiration showed Thrombolysis in Cerebral Infarction 2B reperfusion. Following aspiration, the patient was re-examined; NIHSS at that time was 4. At 1 month follow-up, the modified Rankin Scale score was 1 and NIHSS was 1. Treatment of cerebral air embolism is discussed.

Paradoxical cerebral air embolism causing large vessel occlusion treated with endovascular aspiration

Cerebral air embolism is a dreaded complication of invasive medical procedures. The mainstay of therapy for patients with cerebral air embolism has been hyperbaric oxygen therapy, high flow oxygen therapy, and anticonvulsants. We present a novel therapeutic approach for treatment of cerebral air embolism causing large vessel occlusion, using endovascular aspiration. Our patient developed a cerebral air embolism following sclerotherapy for varicose veins. This caused near total occlusion of the superior division of the M2 segment of the right middle cerebral artery. Symptoms included unilateral paralysis, unintelligible speech, and hemianopia; National Institutes of Health Stroke Scale (NIHSS) on presentation was 16. The air embolism was treated using a distal aspiration technique. Angiography following aspiration showed Thrombolysis in Cerebral Infarction 2B reperfusion. Following aspiration, the patient was re-examined; NIHSS at that time was 4. At 1 month follow-up, the modified Rankin Scale score was 1 and NIHSS was 1. Treatment of cerebral air embolism is discussed.