Preoperative risk assessment for carotid occlusion by transcranial Doppler ultrasound

ASNM and ASN joint guidelines for transcranial Doppler ultrasonic monitoring: An update

Today, it seems prudent to reconsider how ultrasound technology can be used for providing intraoperative neurophysiologic monitoring that will result in better patient outcomes and decreased length and cost of hospitalization. An extensive and rapidly growing literature suggests that the essential hemodynamic information provided by transcranial Doppler (TCD) ultrasonography neuromonitoring (TCDNM) would provide effective monitoring modality for improving outcomes after different types of vascular, neurosurgical, orthopedic, cardiovascular, and cardiothoracic surgeries and some endovascular interventional or diagnostic procedures, like cardiac catheterization or cerebral angiography. Understanding, avoiding, and preventing peri- or postoperative complications, including neurological deficits following abovementioned surgeries, endovascular intervention, or diagnostic procedures, represents an area of great public and economic benefit for society, especially considering the aging population. The American Society of Neurophysiologic Monitoring and American Society of Neuroimaging Guidelines Committees formed a joint task force and developed updated guidelines to assist in the use of TCDNM in the surgical and intensive care settings. Specifically, these guidelines define (1) the objectives of TCD monitoring; (2) the responsibilities and behaviors of the neurosonographer during monitoring; (3) instrumentation and acquisition parameters; (4) safety considerations; (5) contemporary rationale for TCDNM; (6) TCDNM perspectives; and (7) major recommendations.

The Rate of Symptomatic Ischemic Events after Passing Balloon Test Occlusion of the Major Intracranial Arteries: Meta-Analysis

BACKGROUND

Balloon test occlusion is a widely used method for predicting tolerance of vessel occlusion in the treatment of aneurysms, fistulae, and head and neck neoplasms. However, the false-negative rate is variably reported due in part to the diversity of perfusion monitoring methods.

OBJECTIVE

To evaluate the rate of symptomatic ischemic events after a negative balloon test occlusion and determine whether perfusion monitoring methods contribute to differences in these rates.

METHODS

PubMed was systematically searched for studies between 1990 and 2020 that reported rates of ischemic outcomes of parental vessel occlusion in patients who passed balloon test occlusion. A generalized linear mixed model meta-analysis was performed. Results were expressed as the rate of symptomatic ischemic events after parental vessel occlusion without vessel bypass in patients who passed balloon test occlusion.

RESULTS

Thirty-two studies met the inclusion criteria. The overall pooled rate of ischemic events after passing balloon test occlusion was 3.7% (95% confidence interval [CI]: 1.7-7.8). This rate was 3.8% (95% CI: 1.1-12.8) when monitored with angiography, 2.2% (95% CI: 0.4-10.2) when monitored by a form of computed tomography, and 5.3% (95% CI: 1.2-20.4) when monitored by 2 or more methods of perfusion assessment. The complication rate of balloon test occlusion was 0.8% (95% CI: 0.2-2.7).

CONCLUSIONS

Balloon test occlusion results in a low rate of subsequent ischemic events, without conclusive evidence of variation between methods of perfusion assessment. The choice of method should focus on reduction of complication risk, experience of the interventional team, and avoidance of prolonged test occlusion times.

Internal Carotid Artery Test Balloon Occlusion Using Single Photon Emission Computed Tomography Scan in the Management of Complex Cerebral Aneurysms and Skull Base Tumors: A 20-Year Review

BACKGROUND

Test balloon occlusion (TBO) is important in the management of complex cerebrovascular and skull base lesions when permanent occlusion (PO) of a parent artery may be indicated. Several adjuncts may be used to increase the sensitivity of TBO to predict whether PO will be tolerated. This is an observational study to evaluate the utility of internal carotid artery (ICA) TBO using single photon emission computed tomography (SPECT) scan in the management of complex vascular pathology and skull base tumors.

METHODS

All TBO procedures performed over a 20-year period were analyzed. Clinical assessment and angiographic collateral flow were combined with semi-quantitative cerebral blood flow analysis using ^99mTc hexamethylpropylene-amine oxime SPECT scan during ICA TBO. Evaluation of collateral circulation after TBO, and the complications of TBO and the safety of PO after successful TBO were evaluated.

RESULTS

Eighty-three patients underwent TBO without complication. Of 45 patients with satisfactory TBO, 28 proceeded to PO. Three patients developed transient ischemic symptoms thought to be embolic in origin. Thirty-eight patients had unsatisfactory TBO, of whom 15 required PO accompanied by a bypass procedure. Forty patients in the series did not undergo permanent vessel occlusion.

CONCLUSIONS

SPECT scan-enhanced TBO is an important component of the management of complex vascular pathology and skull base tumors, permitting safe PO of the parent vessel and definitive treatment of the main pathology.

Prediction of Borderzone Infarction by CTA in Patients Undergoing Carotid Embolization for Carotid Blowout

BACKGROUND AND PURPOSE

Permanent common carotid artery and/or ICA occlusion is an effective treatment for carotid blowout syndrome. Besides postoperative thromboembolic infarction, permanent common carotid artery and/or ICA occlusion may cause borderzone infarction when the collateral flow to the deprived brain territory is inadequate. In this study, we aimed to test the predictive value of CTA for post-permanent common carotid artery and/or ICA occlusion borderzone infarction in patients with carotid blowout syndrome.

MATERIALS AND METHODS

In this retrospective study, we included 31 patients undergoing unilateral permanent common carotid artery and/or ICA occlusion for carotid blowout syndrome between May 2009 and December 2016. The vascular diameter of the circle of Willis was evaluated using preprocedural CTA, and the risk of borderzone infarction was graded as very high risk, high risk, intermediate risk, low risk, and very low risk.

RESULTS

The performance of readers' consensus on CTA for predicting borderzone infarction was excellent, with an area under receiver operating characteristic curve of 0.938 (95% confidence interval, 0.85-1.00). We defined very high risk, high risk, and intermediate risk as positive for borderzone infarction, the sensitivity, specificity, positive predictive value, and negative predictive value of CTA for borderzone infarction were 100% (7/7), 62.5% (15/24), 43.8% (7/16), and 100% (15/15), respectively. The interobserver reliability was excellent (κ = 0.807). No significant difference in the receiver operating characteristic curves was found between the 2 readers (P = .114).

CONCLUSIONS

CTA can be used to predict borderzone infarction after permanent common carotid artery and/or ICA occlusion by measuring the collateral vessels of the circle of Willis.

Perfusion Study for Internal Carotid Artery Trapping of a Traumatic Pseudoaneurysm in an Unconscious Patient

Perfusion study should be preoperatively required for the trapping of an internal carotid artery (ICA) in the traumatic pseudoaneurysm in the petrous ICA. A 23-year-old man was admitted with a semicomatose consciousness after a passenger traffic accident. A fracture on the right petrous apex and a pseudoaneurysm in the right petrous ICA was found in the brain computed tomography (CT) angiogram. The size of aneurysm grew in the catheter angiogram at the 3rd day of trauma. One-day protocol of brain single photon emission CT (SPECT), which the first scan with 20 mCi of technetium-99m-ethyl cysteinate diethylester (^99mTc-ECD) and the second scan with 40 mCi in double dose at 15 minutes during the balloon test occlusion (BTO) at the same day, was done for the perfusion evaluation before trapping the right ICA. Perfusion asymmetry was aggravated of 21% at the post-occlusion scan in the right frontal cortex. So, he got a superficial temporal artery-middle cerebral artery anastomosis and then ICA trapping. After the surgery, he recovered consciousness and went back to his normal life. He has not developed new neurologic symptom for 8 years. Brain SPECT with double-dose injection of ^99mTc-ECD may be a useful tool to be performed with BTO.

Monitoring balloon test occlusion of the internal carotid artery with transcranial Doppler. A case report and literature review

Angiographic balloon test occlusion (BTO) allows preoperative risk evaluation of patients undergoing permanent therapeutic occlusion of the internal carotid artery (ICA). The sensitivity of the BTO can be increased using different complementary techniques. Transcranial Doppler (TCD) stands out as a non-invasive, bedside method providing real-time monitoring of cerebral haemodynamics, therefore accurately identifying patients at risk of stroke. A case of a 30-year-old woman with a giant intracavernous aneurysm of the left ICA presenting with subacute left VI nerve palsy is described. A pre-operative TCD- and EEG-monitored BTO of the left ICA was performed. The 16.7% drop found in the middle cerebral artery's peak systolic velocity (PSVMCA) predicts clinical and haemodynamic tolerance to the permanent loss of that vessel. This case illustrates the potential of TCD monitoring during temporary BTO of the ICA. It highlights its ability to provide a complete preclinical evaluation of collateralization and autoregulatory adaptation to unilateral ICA occlusion. TCD may also decrease the time of occlusion required for the BTO.

Monitoring cerebral oxygenation during balloon occlusion with multichannel NIRS

We report on oxygenation changes noninvasively recorded by multichannel continuous-wave near infrared spectroscopy (CW-NIRS) during endovascular neuroradiologic interventions requiring temporary balloon occlusion of arteries supplying the cerebral circulation. Digital subtraction angiography (DSA) provides reference data on the site, timing, and effectiveness of the flow stagnation as well as on the amount and direction of collateral circulation. This setting allows us to relate CW-NIRS findings to brain specific perfusion changes. We focused our analysis on the transition from normal perfusion to vessel occlusion, i.e., before hypoxia becomes clinically apparent. The localization of the maximal response correlated either with the core (occlusion of the middle cerebral artery) or with the watershed areas (occlusion of the internal carotid artery) of the respective vascular territories. In one patient with clinically and angiographically confirmed insufficient collateral flow during carotid artery occlusion, the total hemoglobin concentration became significantly asymmetric, with decreased values in the ipsilateral watershed area and contralaterally increased values. Multichannel CW-NIRS monitoring might serve as an objective and early predictive marker of critical perfusion changes during interventions-to prevent hypoxic damage of the brain. It also might provide valuable human reference data on oxygenation changes as they typically occur during acute stroke.

Carotid and vertebral artery sacrifice with a combination of Onyx and coils: technical note and case series

INTRODUCTION

Permanent vessel sacrifice has become a routine for the management of aneurysms, pseudoaneurysms, tumors, and carotid blowouts. The purpose of this study is to describe a new technique for carotid and vertebral artery sacrifice using a combination of Onyx and coils and to assess its feasibility, safety, and efficacy.

METHODS

The technique consists of deploying a few coils in the parent vessel under proximal flow arrest followed by Onyx embolization directly into the coil mass. A total of 41 patients underwent carotid/vertebral artery sacrifice using this technique in our institution.

RESULTS

A total of 26 internal carotid arteries and 15 vertebral arteries were treated. In all but one patient, a balloon test occlusion was performed prior to permanent arterial sacrifice. The mean number of coils used was 6.8 (range, 2-19). The total volume of Onyx used was 1.3 ml on average (range, 0.2-5.2 ml). All 41 (100%) parent arteries were successfully occluded. No distal migration of Onyx or coils was noted. Periprocedural complications occurred in 14.6% (6/41) of cases causing permanent morbidity in 7.3% (3/41). No patient developed a recurrence during the follow-up period (mean, 14 months).

CONCLUSION

Parent vessel sacrifice with a combination of Onyx and coils appears to be feasible, safe, and effective and may be an alternative to the traditional deconstruction technique with coils alone. The risk of thromboembolism exists with this technique, but there were no instances of Onyx migration.

Diagnosis of Intracranial Arterial Stenosis Using Transcranial Doppler Flowmetry

In this case report we describe the use of transcranial Doppler flowmetry during induction of anesthesia in a patient with a large pituitary tumor. In this patient, both IV anesthesia induction and onset hyperventilation were followed by severe decreases of flow velocity in the middle cerebral artery of the affected side. Transcranial Doppler detected critical blood flow reduction in response to anesthesia induction and onset of hyperventilation in a brain tumor patient.

Symptomatic cavernous sinus aneurysms: management and outcome after carotid occlusion and selective cerebral revascularization

BACKGROUND AND PURPOSE

Therapeutic internal carotid artery (ICA) occlusion for symptomatic intracavernous artery aneurysms can result in ischemic infarction despite normal clinical balloon test occlusion (BTO). We evaluated outcomes in patients with symptomatic cavernous sinus aneurysms in whom clinical BTO was normal, who underwent carotid occlusion with selective bypass surgery guided by physiologic BTO using quantitative cerebral blood flow (CBF) analysis by means of stable xenon-enhanced CT.

METHODS

After a normal clinical BTO, 26 consecutive patients with symptomatic cavernous sinus aneurysms underwent a baseline xenon-enhanced CT CBF analysis followed by a second CBF analysis, during which repeat BTO was performed. Patients with a decrease in cortical CBF to below 30 mL/100 g/min were considered moderate risk and those with greater than 30 mL/100 g/min were low risk for developing postocclusion ischemic infarction. Moderate-risk patients underwent cerebral revascularization followed by proximal carotid occlusion. Low-risk patients underwent carotid occlusion alone. Patients were clinically followed up for at least 3 months after carotid occlusion. All patients underwent head CT at least 1 month after carotid occlusion.

RESULTS

Eight patients were moderate risk and 18 low risk. Mean follow-up was 15.3 months. Mean CT follow-up was 10.2 months. No low-risk patient developed a postocclusion ischemic deficit by examination or infarct by CT. One patient in the moderate-risk group developed right hemiparesis and a left posterior middle cerebral artery infarction by CT 2 months after carotid occlusion.

CONCLUSION

In this series, BTO combined with quantitative CBF analysis was a safe and reliable technique for identification of patients at risk for ischemic infarction after carotid occlusion, despite a normal clinical BTO.

Evaluating brain tolerability to carotid artery occlusion

An objective and practicable method to evaluate the brain tolerance to unilateral carotid artery occlusion was attempted. Ten consecutive cases were studied. Endovascular trial balloon occlusion of the unilateral carotid artery in conjunction with single-photon emission computed tomography (SPECT) as well as digital subtraction angiography (DSA) and clinical neurological evaluation was routinely performed for those patients who might undergo permanent occlusion of the internal (ICA) and/or common carotid artery (CCA). The result of SPECT was analyzed semi-quantitatively and compared with the baseline data as well as the data from contralateral side. The relative symmetry index (rS) of side-to-side radioactivity counts relevant to the baseline was calculated. One subject failed the balloon occlusion test (BOT), even though an angiographically adequate collateral circulation was observed. The rS of the patient was 74.5%. The remaining patients passed the 45-min BOT without any neurological deficiency induced. Their value of rS was 97.8% +/- 4.4%. Based the BOT results, the left ICA, CCA and external carotid artery were excised in one patient, CCA-ICA reconstructions after carotid occlusions were performed in three. The carotid arteries were saved in five. For one patient, the ICA was occluded spontaneously during the BOT. There were no neurological impairments developed after the surgery. With this BOT technique, clinically silent areas of decreased perfusion might be detected. We suggest it be a routine preparatory to carotid manipulations.

Operative management of skull base malignancies: choosing the appropriate approach

Malignant tumors of the skull base are complex lesions. Identifying the indications and contraindications for resection is essential for the successful treatment of these lesions. This requires an understanding of the pathology, principles of resection, and nonsurgical therapeutic modalities. Choosing the appropriate surgical approach requires an understanding of the tumor and its association with the anatomy of the skull base. Preoperative assessment and preparation of the patient for the postoperative course, including functional and cosmetic deficits, are reviewed in the context of the specific approach. Anatomical variations encountered in the preoperative planning are discussed. A review of reconstructive alternatives is presented that is specific to the approach and anatomical violation. Finally, the use of a multidisciplinary team both in and out of the operating room is recommended, emphasizing a team approach during the resection itself.

Perfusion MR neuroimaging in patients undergoing balloon test occlusion of the internal carotid artery

BACKGROUND AND PURPOSE

We sought to investigate whether the combination of conventional, diffusion-weighted, and perfusion-weighted MR imaging increases the diagnostic accuracy of balloon test occlusion of the internal carotid artery. We describe perfusion anomalies and patterns of enhancement seen in areas of altered brain perfusion during MR-monitored temporary balloon occlusion of the internal carotid artery.

METHODS

Nine patients underwent balloon occlusion testing under standard angiographic conditions with continuous clinical and EEG monitoring. One patient who failed the test by clinical criteria underwent an external carotid to internal carotid bypass operation, followed by a repeat balloon test occlusion, thereby bringing the total number of procedures to 10. Patients were further imaged at 1.5 T with perfusion- and diffusion-weighted imaging as well as with conventional noncontrast and contrast-enhanced turbo fluid-attenuated inversion recovery (FLAIR) and T1-weighted sequences.

RESULTS

Seven of 10 patients who tolerated unilateral carotid test occlusion without adverse clinical neurologic or EEG changes exhibited delayed first-pass transit of contrast material through the affected cerebral hemisphere, indicative of altered perfusion without significant concurrent cerebral blood flow or blood volume changes. Four of these patients and both symptomatic patients showed pial or subarachnoid contrast staining in areas of altered perfusion without abnormalities on diffusion-weighted images.

CONCLUSION

Our findings indicate that MR perfusion-weighted imaging is safe and easily accomplished in a high-field-strength magnet and that contrast-enhanced turboFLAIR imaging may provide clinically useful MR imaging evidence of abnormal cerebral blood flow and subclinical ischemia.

Transcranial Doppler ultrasonography-guided management of internal carotid artery closure

OBJECTIVE

To emphasize the integrated use of transcranial Doppler ultrasonography (TCD) in the management of internal carotid artery (ICA) closure.

METHODS

Thirty-three patients being considered for ICA closure underwent TCD assessment, vasomotor reserve testing/estimation, and carotid artery test occlusion with concomitant middle cerebral artery (MCA) blood velocity (V(MCA)) monitoring, including calculation of the MCA pulsatility index. Twelve of these patients proceeded to undergo ICA sacrifice. Sequential TCD sonograms guided their postoperative treatment.

RESULTS

ICA aneurysms and neck neoplasms affected the TCD results and vasomotor reserve insignificantly, whereas carotid-cavernous fistulae induced characteristic circulatory alterations. The 10 subjects who tolerated ICA sacrifice hemodynamically all showed an initial decrease in the ipsilateral V(MCA) to > or =60% of the preocclusion value and a progressively decreasing MCA pulsatility index during carotid artery test occlusion. The two patients who developed hemodynamic cerebral infarctions exhibited a decrease in V(MCA) to <60% and a MCA pulsatility index that remained stable after a vast initial reduction. Postoperative hypervolemic and hypertensive support was safely titrated in all patients who received postoperative TCD surveillance, providing an ipsilateral V(MCA) of > or =80% of the preocclusion value. ICA closure permanently altered the cerebral circulatory pattern.

CONCLUSION

The hemodynamic outcome of ICA sacrifice can be correctly predicted by using the TCD occlusion test. TCD provides the means to titrate the extent of postoperative hypervolemic/hypertensive support.