Use of CTA in Diagonising Brain Death: Bilateral ICA Nonopacification
Poster #: 204
Session/Time: A
Author:
Vyshnavi Anandan, MD
Mentor:
Suraj Jaisinghani, MD
Research Type: Case Report
Abstract
INTRODUCTION:
Appropriately declaring patient brain death (BD) is crucial for maintaining realistic expectations, limiting unnecessary medical interventions, and facilitating organ donation. The current standard of declaring brain death includes a clinical evaluation and an apnea test. In cases when apnea testing cannot be performed, ancillary testing is required to confirm the diagnosis of BD. The current gold standard ancillary test is digital subtraction angiography (DSA), which uses an arterial catheter to inject contrast into cerebral vessels. Computed tomography angiography (CTA) has been proposed as a less invasive, cheaper, faster alternative to DSA. There is currently no scientific consensus about the reliability of CTA in diagnosing BD. This case demonstrates an example of bilateral ICA nonopacification on CTA, a finding highly suggestive of BD.
CASE INFORMATION:
A 36- year- old female presented to the ED after being found unresponsive at home. EMS resuscitated the patient and achieved return of spontaneous circulation. In the ED, the patient was unresponsive with fixed and dilated pupils. Her Glasgow coma scale score was 3. Initial workup revealed labs consistent with respiratory failure, a pan-positive urine drug screen, and a BAC of 0.16. Head CT showed massive subarachnoid hemorrhage, diffuse cerebral edema with sulci effacement, and intraventricular hemorrhage within the fourth ventricle. CTA head and neck showed bilateral nonopacification of the cerebral ICA and intradural segments of the vertebral arteries, a finding highly suggestive of BD. Apnea testing was performed at bedside the following day, and the patient was pronounced dead by neurologic criteria at this time.
DISCUSSION/CLINICAL FINDINGS:
The patient's clinical workup was consistent with severe respiratory failure and cardiopulmonary arrest in the setting of SAH secondary to polysubstance abuse. Non-opacification of the ICAs was an unanticipated finding on this CTA. This finding is highly suggestive of BD, but is not currently an approved method of diagnosing BD. Instead, DSA or radionuclide perfusion scintigraphy (SPECT) would have typically been ordered to diagnose BD. DSA is reliable but technically challenging and expensive. SPECT is well validated and simpler to perform than DSA, but materials are expensive. CTA is currently investigational and not a validated ancillary test for BD determination. Research evaluating the reliability of CTA in diagnosing BD has yielded mixed results. A recent meta-analysis highlighted that CTA may result in false negatives. False positives are rare but may occur in patients with very low perfusion pressures. All existing studies on this topic have small sample sizes, and further studies with larger sample sizes are needed before a conclusion is drawn about the reliability of CTA as an ancillary test. Our case underscores CTA's potential utility as a minimally invasive and readily available test for BD.
CONCLUSION:
Utilizing CTA as an ancillary test to diagnose BD should be approached with caution, and more robust clinical evidence is needed before using CTA as a reliable indicator of BD. However, the finding of bilateral ICA non-opacification highlighted in this case is an excellent example of how CTA may be a cheaper, easier way to detect BD.
Appropriately declaring patient brain death (BD) is crucial for maintaining realistic expectations, limiting unnecessary medical interventions, and facilitating organ donation. The current standard of declaring brain death includes a clinical evaluation and an apnea test. In cases when apnea testing cannot be performed, ancillary testing is required to confirm the diagnosis of BD. The current gold standard ancillary test is digital subtraction angiography (DSA), which uses an arterial catheter to inject contrast into cerebral vessels. Computed tomography angiography (CTA) has been proposed as a less invasive, cheaper, faster alternative to DSA. There is currently no scientific consensus about the reliability of CTA in diagnosing BD. This case demonstrates an example of bilateral ICA nonopacification on CTA, a finding highly suggestive of BD.
CASE INFORMATION:
A 36- year- old female presented to the ED after being found unresponsive at home. EMS resuscitated the patient and achieved return of spontaneous circulation. In the ED, the patient was unresponsive with fixed and dilated pupils. Her Glasgow coma scale score was 3. Initial workup revealed labs consistent with respiratory failure, a pan-positive urine drug screen, and a BAC of 0.16. Head CT showed massive subarachnoid hemorrhage, diffuse cerebral edema with sulci effacement, and intraventricular hemorrhage within the fourth ventricle. CTA head and neck showed bilateral nonopacification of the cerebral ICA and intradural segments of the vertebral arteries, a finding highly suggestive of BD. Apnea testing was performed at bedside the following day, and the patient was pronounced dead by neurologic criteria at this time.
DISCUSSION/CLINICAL FINDINGS:
The patient's clinical workup was consistent with severe respiratory failure and cardiopulmonary arrest in the setting of SAH secondary to polysubstance abuse. Non-opacification of the ICAs was an unanticipated finding on this CTA. This finding is highly suggestive of BD, but is not currently an approved method of diagnosing BD. Instead, DSA or radionuclide perfusion scintigraphy (SPECT) would have typically been ordered to diagnose BD. DSA is reliable but technically challenging and expensive. SPECT is well validated and simpler to perform than DSA, but materials are expensive. CTA is currently investigational and not a validated ancillary test for BD determination. Research evaluating the reliability of CTA in diagnosing BD has yielded mixed results. A recent meta-analysis highlighted that CTA may result in false negatives. False positives are rare but may occur in patients with very low perfusion pressures. All existing studies on this topic have small sample sizes, and further studies with larger sample sizes are needed before a conclusion is drawn about the reliability of CTA as an ancillary test. Our case underscores CTA's potential utility as a minimally invasive and readily available test for BD.
CONCLUSION:
Utilizing CTA as an ancillary test to diagnose BD should be approached with caution, and more robust clinical evidence is needed before using CTA as a reliable indicator of BD. However, the finding of bilateral ICA non-opacification highlighted in this case is an excellent example of how CTA may be a cheaper, easier way to detect BD.