Embolization Of Cerebral Arteriovenous Malformations Research Articles

Arm-only combined transarterial and transvenous access for neurointerventional procedures: a double-center retrospective study.

This study aims to share our experience with the arm-only combined transarterial and transvenous access approach for neurointerventional procedures and evaluate its efficacy and safety. The arm-only combined transarterial and transvenous access approach was performed using the right/bilateral proximal radial arteries and the right forearm superficial vein system, guided by ultrasonic guidance. Arterial access closure was achieved using a transradial band radial compression device, while manual compression was utilized for venous approach closure. Thirteen procedures were successfully performed using the arm-only combined transarterial and transvenous access approach, yielding favorable outcomes. The procedures included dural arteriovenous fistula embolization (seven cases), cerebral arteriovenous malformation embolization (four cases), venous sinus thrombosis catheter-directed thrombolysis and intravenous thrombectomy (one case), and cerebral venous sinus stenosis manometry (one case). All procedures were uneventful, allowing patients to ambulate on the same day. At discharge, all patients exhibited modified Rankin scores of 0-2, without any access site or perioperative complications. This double-center study preliminarily demonstrates the feasibility and safety of arm-only combined transarterial and transvenous access applied in neurointerventional procedures for complicated cerebrovascular diseases. The proximal radial artery and forearm superficial vein are recommended as the primary access sites. Unobstructed compression is strongly recommended for radial approach closure. This study aimed to add evidence and experience on the arm-only combined transarterial and transvenous access, as a new approach, for neurointerventional treatment that required arteriovenous approaches.

Partial Onyx embolization triggers spontaneous regression of cerebral AVM: A case report

Spontaneous regression of a cerebral arteriovenous malformations (AVMs) is a rare and poorly understood phenomenon. We present a case of unruptured cerebral AVM in a patient presenting with intermittent headache. In order to reduce hemorrhagic risk, the patient underwent partial embolization of the AVM with Onyx glue. Follow-up digital subtraction angiography (DSA) showed complete obliteration of the residual AVM three months after the treatment. In conclusion, partial Onyx embolization of cerebral AVM may be an etiological factor of spontaneous regression. In order to reduce hemorrhagic risk, targeted partial embolization of the AVM may be an alternative treatment for some cases.

Association between general anesthesia and contrast-induced encephalopathy after endovascular treatment on neurovascular diseases.

Contrast-induced encephalopathy (CIE) is a rare neurological complication that can occur in the context of various endovascular procedures. Although many potential risk factors for CIE have been reported, it is still unclear whether anesthesia is a risk factor for the occurrence of CIE. The goal of this study was to investigate the incidence of CIE in patients who underwent endovascular treatment under different anesthesia methods and anesthetics administration and to explore whether general anesthesia was a potential risk factor for CIE. We retrospectively reviewed available clinical data from 1,043 patients with neurovascular diseases undergoing endovascular treatment between June 2018 and June 2021 in our hospital. A propensity score-based matching strategy and logistic regression were used to analyze the association between anesthesia and the occurrence of CIE. In this study, we implemented the embolization of intracranial aneurysm in 412 patients, stent implantation of extracranial artery stenosis in 346, stent implantation of intracranial artery stenosis in 187, embolization of cerebral arteriovenous malformation or dural arteriovenous fistula in 54, endovascular thrombectomy in 20, and other endovascular treatments in 24. A total of 370 patients (35.5%) received treatment under local anesthesia, while the remaining 673 (64.5%) underwent treatment under general anesthesia. In total, 14 patients were identified as CIE, resulting in a total incidence rate of 1.34%. After propensity score-based matching of anesthesia methods, the occurrence of CIE was significantly different between the general anesthesia and local anesthesia group (P = 0.007). After propensity score-based matching of CIE, the anesthesia methods were significantly different between the two groups. Pearson contingency coefficients and logistic regression showed a significant correlation between general anesthesia and the risk of CIE. General anesthesia might be a risk factor for CIE, and propofol might be associated with the increased occurrence of CIE.

Efficacy and safety of endovascular embolization of cerebral AVM

Background; Endovascular embolization of cerebral arteriovenous malformations (AVM) has several benifits including AVM occlusion and flow reduction in preparation for other treatment techniques. Aim and objectives; To assess the efficacy and safety of endovascular embolization of cerebral AVM with different techniques and materials. Patients and methods; In a prospective and retrospective study, 22 patients diagnosed as AVM or arteriovenous fistula (AVF) and underwent endovascular embolization at Neurosurgical intervention Unit at Al Hussein University Hospital were recruited in the period from beginning of Jan, 2020 to the end of May, 2022. We included patients aged above one month, diagnosed to have cerebral AVM or AVF. Recent cerebral hemorrhage patients were delayed for at least two weeks. We excluded patients with vein of Galen malformation, neonatal AVM, patients underwent surgical excision, patients with contraindication to radiation or dye injection, and inaccessible endovascular techniques such as severely tortuous vessels. Results: In the current study, the mean age was 24.5 ± 14.7 years. Most cases were male (68.2%). Most cases (86.4% ) manifested headache, 40.9% had hemorrhage, 31.8% had side weakness and 27.3% had fits. Spetzler and Martin grade (SMG) of the cerebral AVMs was significantly improved after embolization compared to the initial grading score (P=0.002). Eight patients showed complete occlusion of nidus and 14 had partial occlusion according to SMG . After 3 months follow up, Modified Rankin scale, epilepsy, and headache were improved. No patient had procedure-related complications.

PHIL and Squid Embolization of Cerebral Arteriovenous Malformation: A Retrospective Case Series of 23 Patients.

Precipitating hydrophobic injectable liquid (PHIL; MicroVention, Aliso Viejo, CA, USA) and Squid (Balt, Irvine, CA, USA) are 2 newer liquid embolic agents used in endovascular embolization of cerebral arteriovenous malformation (AVM). This study aims to investigate and compare the effectiveness and safety profile of the 2 newer liquid embolic agents in the embolization of cerebral AVM. This is a retrospective study on all patients diagnosed with cerebral AVM undergoing endovascular embolization with liquid embolic agents PHIL and Squid admitted to the Division of Neurosurgery, Department of Surgery in Prince of Wales Hospital from January 2014 to June 2021. Twenty-three patients with cerebral AVM were treated with 34 sessions of endovascular embolization with either PHIL or Squid (17 sessions each) liquid embolic agents with a male to female ratio of 2.3:1 (male 16; female 7) and mean age of 44.6 (range, 12 to 67). The mean total nidus obliteration rate per session was 57% (range, 5% to 100%). Twenty-one patients (91.3%) received further embolization, stereotactic radiosurgery, or surgical excision after initial endovascular embolization. There were 2 morbidities (1 neurological and 1 non-neurological, 6%) and no mortalities (0%). All patients had static or improvement in modified Rankin Scale at 3 to 6 months at discharge. PHIL and Squid are effective and safe liquid embolic agents for endovascular embolization of cerebral AVM, achieving satisfactory nidal obliteration rates and patient functional outcomes.

A Case of Occlusion of the Contralateral Posterior Cerebral Artery Caused by the Migration of Onyx during Embolization of Cerebral Arteriovenous Malformation and Successful Recanalization Therapy Using a Stent Retriever

A Case of Occlusion of the Contralateral Posterior Cerebral Artery Caused by the Migration of Onyx during Embolization of Cerebral Arteriovenous Malformation and Successful Recanalization Therapy Using a Stent Retriever

Adenosine-induced transient circulatory arrest in transvenous embolization of cerebral arteriovenous malformations.

Due to advances in interventional techniques, the transvenous approach may present an effective treatment option for embolization of brain arteriovenous malformations (AVMs). Contrary to the transarterial method, the transvenous approach can only be utilized in a specific subset of patients and is not suitable as a standard procedure for all AVM lesions. While this technique can be helpful in certain patients, careful patient selection to ensure patient safety and favorable clinical outcomes is important. However, especially in high-flow AVMs, targeted deposition of embolic materials through a transvenous access can be challenging. Therefore, a temporary flow arrest may prove helpful. Transient cardiac arrest by use of adenosine has been applied in cerebrovascular surgery but is not common for endovascular embolization. Adenosine-induced arrest and systemic hypotension may be a feasible, safe method to reduce flow and help endovascular transvenous embolization of certain AVMs. Our study evaluated the efficiency and safety of adenosine-induced circulatory arrest for transvenous embolization of cerebral AVMs.

Morbidity and mortality associated with sequential flow reduction embolization technique of cerebral arteriovenous malformations using n-butyl cyanoacrylate

BackgroundEndovascular embolization of cerebral arteriovenous malformations (AVM) with liquid n-butyl cyanoacrylate (n-BCA) serves multiple purposes including AVM occlusion and flow reduction in preparation for other treatment modalities. The objective was...

The Comaneci Device for Entering an Acute-Angled Small Feeder during Cerebral Arteriovenous Malformation Embolization: A Novel Technique to Support Microcatheterization.

In this report, we describe the use of the Comaneci device to support microcatheterization in a small branch arising from a parent artery during embolization. In 2 cases, arteriovenous malformations presented with intracranial hemorrhage. A microcatheter was navigated into a small feeder while the Comaneci device was deployed just distal to the feeder with an acute angle from the parent artery. Our technical note represents an alternative option of catheterization in cases with difficult access to small feeders originating from higher flow arteries at a sharp angle while maintaining continuous flow in the parent artery.

Endovascular embolization of high-flow arteriovenous fistulae with non-adhesive agents in the structure of cerebral arteriovenous malformations on the background of adenosine-induced cardioplegia

To analyze the initial results of endovascular embolization of cerebral arteriovenous malformations involving high-flow arteriovenous fistulae with non-adhesive agents on the background of cardioplegia. There were 13 patients who underwent surgery in 2018. Embolization of AVM with non-adhesive agents (ONYX, SQUID) was performed on the background of temporary cardiac arrest achieved by bolus intravenous administration of adenosine triphosphate. Adenosine administration in endovascular treatment of AVM with non-adhesive agents is able to improve the safety of surgical intervention and ensure more qualitative embolization.

Periprocedural intracranial hemorrhage after embolization of cerebral arteriovenous malformations: a meta-analysis.

The primary goal of the treatment of cerebral arteriovenous malformations (AVMs) is angiographic occlusion to eliminate future hemorrhage risk. Although multimodal treatment is increasingly used for AVMs, periprocedural hemorrhage after transarterial embolization is a potential endovascular complication that is only partially understood and merits quantification. Searching the period between 1990 and 2019, the authors of this meta-analysis queried the PubMed and Embase databases for studies reporting periprocedural hemorrhage (within 30 days) after liquid embolization (using cyanoacrylate or ethylene vinyl alcohol copolymer) of AVMs. Random effects meta-analysis was used to evaluate the pooled rate of flow-related hemorrhage (those attributed to alterations in AVM dynamics), technical hemorrhage (those related to procedural complications), and total hemorrhage. Meta-regression was used to analyze the study-level predictors of hemorrhage, including patient age, Spetzler-Martin grade, hemorrhagic presentation, embolysate used, intent of treatment (adjuvant vs curative), associated aneurysms, endovascular angiographic obliteration, year of study publication, and years the procedures were performed. A total of 98 studies with 8009 patients were included in this analysis, and the mean number of embolization sessions per patient was 1.9. The pooled flow-related and total periprocedural hemorrhage rates were 2.0% (95% CI 1.5%-2.4%) and 2.6% (95% CI 2.1%-3.0%) per procedure and 3.4% (95% CI 2.6%-4.2%) and 4.8% (95% CI 4.0%-5.6%) per patient, respectively. The mortality and morbidity rates associated with hemorrhage were 14.6% and 45.1%, respectively. Subgroup analyses revealed a pooled total hemorrhage rate per procedure of 1.8% (95% CI 1.0%-2.5%) for adjuvant (surgery or radiosurgery) and 4.6% (95% CI 2.8%-6.4%) for curative intent. The treatment of aneurysms (p = 0.04) and larger patient populations (p < 0.001) were significant predictors of a lower hemorrhage rate, whereas curative intent (p = 0.04), angiographic obliteration achieved endovascularly (p = 0.003), and a greater number of embolization sessions (p = 0.03) were significant predictors of a higher hemorrhage rate. There were no significant differences in periprocedural hemorrhage rates according to the years evaluated or the embolysate utilized. In this study-level meta-analysis, periprocedural hemorrhage was seen after 2.6% of transarterial embolization procedures for cerebral AVMs. The adjuvant use of endovascular embolization, including in the treatment of associated aneurysms and in the presurgical or preradiosurgical setting, was a study-level predictor of significantly lower hemorrhage rates, whereas more aggressive embolization involving curative intent and endovascular angiographic obliteration was a predictor of a significantly higher total hemorrhage rate.

Gamma knife surgery with and without embolization for cerebral arteriovenous malformations: A systematic review and meta-analysis

The benefit and risk of gamma knife surgery (GKS) in the treatment of residual cerebral arteriovenous malformations (AVMs) after endovascular embolization remain controversial. The aim of this meta-analysis was to assess current evidence regarding the efficiency and safety of GKS for AVMs with and without prior embolization. To compare GKS in patients with and without embolization, the authors conducted a meta-analysis of studies by searching the literature via PubMed and EMBASE databases for the period between January 2006 and December 2017. Six retrospective studies were finally identified. Outcomes were the rate of AVM obliteration on a 3-year follow-up angiogram, hemorrhage at 3 years after GKS and permanent neurological deficits. Six studies eligible for analysis included 2069 patients: 637 had undergone embolization followed by GKS, and 1432 had undergone GKS alone. The obliteration rate was significantly lower in patients who had undergone embolization followed by GKS than in those who had undergone GKS alone (49.5% vs 70.4%, OR 2.29, 95% CI 1.55–3.38, p < 0.00001). Subgroup analysis also indicated high obliteration rates in ‘similar mean nidus volume’, ‘high quality’ and ‘sample size over 100 patients’ subgroups. However, the rates of rehemorrhage (8.9% vs 4.2%, OR 0.59, 95% CI 0.23–1.57, p = 0.29) and permanent neurological deficits rate (3.6% vs 4.6%, OR 0.51, 95% CI 0.57–3.12, p = 0.51) were not significantly different between the two groups and subgroups. Embolization prior to GKS significantly decreases the AVM obliteration rate and didn’t reduce the risk of hemorrhage and permanent neurological deficits. Further evaluation by well-designed prospective or randomized cohort studies is highly needed.

Endovascular treatment of small cerebral arteriovenous malformations as a primary therapy.

PurposeThe patient population that would benefit most from endovascular curative treatment of intracranial arteriovenous malformations is not clearly established. The aim of the study was to determine the effect of curative embolization of cerebral arteriovenous malformations with special regard to radiographic and clinical outcomes and procedure-related complications.Material and methodsBetween January 2009 and December 2014, 18 patients with intracranial arteriovenous malformations were embolized with Onyx with intent to cure. There were 4 women and 14 men with a mean age of 40 years (range 10-62 years). Inclusion criteria were: maximal diameter of the lesions ≤ 3 cm and arterial supply consisting of no more than 2 major arteries. There were 5 (27.8 %) patients with ruptured and 13 (72.2%) with unruptured lesions. Mean arteriovenous malformations size was 2.3 cm (range 1.5-2.9 cm).ResultsThirty-three procedures were performed in 18 patients. Total obliteration was achieved in 5 patients (27.8%). The most common reason for initial incomplete angiographic occlusion were unfavorable angioarchitectural features of arteriovenous malformations with the rate of 44.4%. The mean follow-up of patients with complete occlusion was 35.2 months (range 18-60 months). Complication rate was 12.1%. One patient had permanent neurological deficit with resulting morbidity of 5.6%. There were no deaths.ConclusionsEmbolization of intracranial arteriovenous malformations plays a limited role as a sole therapeutic modality even in terms of small lesions with two or less arterial feeders, although larger prospective series are necessary to confirm your findings. Associated complications are not trivial and should be considered when choosing this form of treatment.

Curative and adjunctive AVM Onyx embolization of AVMs through the choroidal arteries.

Objective The anterior or posterior choroidal artery is often recruited to supply deep location arteriovenous malformations (AVMs). This study is to report curative and adjunctive AVM Onyx embolization through these arteries. Methods This study retrospectively reviewed six patients with cerebral AVMs who underwent endovascular embolization through the choroidal arteries between October 2015 and October 2016. Embolization was performed as a curative procedure in five patients and adjunctive procedure in one patient. Results Four patients underwent embolization through the anterior choroidal artery (AchA), and two patients underwent embolization through the lateral posterior choroidal artery (LPchA). One of the four patients in whom embolization was from the AchA (distal to the plexal point) developed transient hemiparesis. Complete obliteration was confirmed by angiography at the last follow-up in five patients. Conclusions Onyx embolization of cerebral AVMs through the choroidal arteries is possible as a curative or adjunctive procedure.

Successful Endovascular Neurosurgical Practice in Resource-poor Exclusive Rural Neuro-hospital Setup.

Aim:The aim of this study to evaluate the feasibility of establishing endovascular neurosurgery in remote resource-poor neuro-hospital setup and evaluate its outcome.Materials and Methods:Retrospective analysis of diagnostic and therapeutic endovascular neurosurgical procedures performed during September 2013–June 2016.Results:A total of 174 diagnostic cerebral and spinal digital subtraction angiograms and 70 major endovascular neurosurgeries were performed during the period. The endovascular neurosurgical procedures included 54 aneurysms coiled, 4 cerebral arteriovenous malformation embolization, 2 dural arteriovenous fistulas embolization, 2 cerebral tumor embolizations, 2 intracranial stentings, 5 extracranial carotid stentings, 1 transverse sinus stenting. No complications were seen during diagnostic procedures. Operation related morbidity of 1.4% and mortality of 1.4% seen, with a procedural success rate of 97.2%.Conclusion:Endovascular neurosurgery is feasible in resource-poor remote rural exclusive neuro-hospital setup with procedural success rate and outcomes comparable to existing literature.

Validity assessment of grading scales predicting complications from embolization of cerebral arteriovenous malformations

ObjectiveEndovascular embolization, though initially approved as an adjunctive therapy for surgical excision of cerebral arteriovenous malformations (AVMs), has found extensive use in the management of these lesions. A number of systems have been proposed to stratify AVMs by the procedural risk of embolization, including the Buffalo score and AVM Neuroendovascular grade. An external validity assessment of these systems has not been performed. Patients and methodsA retrospective review of all patients who underwent embolization of cerebral AVMs at a single institution, between 2010 and 2016, was performed. Data including patient demographics, AVM characteristics, procedural details, complications, and outcomes were collected. ResultsFifty-five embolization procedures in 39 patients (median age 53.1 years) were identified. Ten (25.6%) patients underwent more than 1 embolization procedure. A triaxial catheter system for support was used in 48 (87.3%) of the embolization procedures and a detachable tip microcatheter was used in 28 (50.9%). Complete obliteration of the AVM was achieved in 10.9% of the cases. There was one (2.6%) mortality unrelated to the procedure. Three minor (5.5%) and 2 major (3.6%) clinical complications occurred. Neither Spetzler-Martin grade, Buffalo score, or AVM Neuroendovascular grade correlated with complications. ConclusionNeither Buffalo score nor AVM Neuroendovascular grade predicted complications from embolization in the present study. Given the relative infrequency of complications, the number of factors that may influence AVM treatment, recent advancements in endovascular technologies, and the subjectivity inherent in these grading systems, the relative utility of risk stratification scales in the embolization of AVMs remains largely unknown.

Embolization of the choroidal artery in the treatment of cerebral arteriovenous malformations.

OBJECTIVE The anterior and posterior choroidal arteries are often recruited to supply arteriovenous malformations (AVMs) involving important paraventricular structures, such as the basal ganglia, internal capsule, optic radiation, lateral geniculate body, and medial temporal lobe. Endovascular embolization through these arteries is theoretically dangerous because they supply eloquent territories, are of small caliber, and lack collaterals. This study aimed to investigate the safety and efficacy of embolization through these arteries. METHODS This study retrospectively reviewed 13 patients with cerebral AVMs who underwent endovascular embolization through the choroidal arteries between 2006 and 2014. Embolization was performed as a palliative procedure before open surgery or Gamma Knife radiosurgery. Computed tomography and MRI were performed the day after embolization to assess any surgical complications. The incidence and type of complications and their association with clinical outcomes were analyzed. RESULTS Decreased blood flow was achieved in all patients after embolization. Postoperative CT detected no hemorrhagic complications. In contrast, postoperative MRI detected that 4 of the 13 patients (30.7%) developed infarctions: 3 patients after embolization through the anterior choroidal artery, and 1 patient after embolization through the lateral posterior choroidal artery. Two of the 4 patients in whom embolization was from the cisternal segment of the anterior choroidal artery (proximal to the plexal point) developed symptomatic infarction of the posterior limb of the internal capsule, 1 of whom developed morbidity (7.7%). The treatment-related mortality rate was 0%. Additional treatment was performed in 12 patients: open surgery in 9 and Gamma Knife radiosurgery in 3 patients. Complete obliteration was confirmed by angiography at the last follow-up in 10 patients. Recurrent bleeding from the AVMs did not occur in any of the cases during the follow-up period. CONCLUSIONS Ischemic complications are possible following the embolization of cerebral AVMs through the choroidal artery, even with modern neurointerventional devices and techniques. Although further study is needed, embolization through the choroidal artery may be an appropriate treatment option when the risk of surgery or radiosurgery is considered to outweigh the risk of embolization.

Preoperative Embolization of Cerebral Arteriovenous Malformations with Silk Suture and Particles: Technical Considerations and Outcomes.

ObjectiveEmbolization of cerebral arteriovenous malformations (AVMs) is commonly performed prior to surgical resection in order to reduce intraoperative bleeding and improve the safety of resection. Although most modern embolization procedures utilize permanent embolic agents, silk suture and polyvinyl alcohol (PVA) particles may offer unique advantages for preoperative devascularization. The aims of this retrospective cohort study are to describe the technical considerations and determine the outcomes for preoperative silk suture and PVA particle embolization (SPE) of AVMs.Materials and MethodsWe performed a retrospective review of our AVM embolization database. AVM patients who underwent preoperative SPE and subsequent surgical resection were included for analysis. Baseline patient demographics, AVM characteristics, embolization and operative records, and post-treatment outcomes were reviewed.ResultsA total of 11 patients who underwent 12 preoperative SPE procedures were included for analysis. Five AVMs were ruptured (45%), and the median nidus volume was 3.0 cm3 (range: 1.3-42.9 cm3). The Spetzler-Martin grade was I-II in seven patients (64%) and III-IV in four patients (36%). The degree of nidal obliteration was less than 25% in two procedures (17%), 25-50% in one procedure (8%), 50-75% in eight procedures (67%), and greater than 75% in one procedure (8%). The rates of post-embolization AVM hemorrhage and mortality were 8% and 0%, respectively. The postoperative angiographic obliteration rate was 100%, and the modified Rankin Scale score improved or stable in 91% of patients (median follow-up duration 2 months).ConclusionPreoperative AVM SPE affords a reasonable risk to benefit profile for appropriately selected patients.

New software to standardize the assessment of embolization of cerebral arteriovenous malformations

Staged embolization of high-grade Spetzler-Martin AVMs gains popularity. The assessment of AVM devascularization degree depends on a specialist's personal experience and is very subjective. The goal of our study was to develop software for accurate and objective calculation of AVM devascularization percentage. 34 patients underwent a partial AVM embolization procedure using both adhesive and non-adhesive embolic material. Their pre- and postoperative DICOM angiographic images were assessed by both 4 skilled interventional radiologists and by our new software. We compared the evaluations of AVM devascularization degree made by the software and the specialists. 54 tests were performed. The software was based on a LabVIEW tm platform. The degree of AVM devascularization was estimated in percent values. Mean difference of values was 14,8% 1,6 (range 0%-40%) between human estimations and 3,4% 0,4 (range 0,7-9,2%) between computer calculations. Reliability of the samples was estimated by Kolmogorov-Smirnov criterion. Critical value of the criterion was 2 = 4,89, which corresponds to p value &lt; 0,01. The new software demonstrated adequate efficiency and accuracy to be used for standardization of AVM devascularization degree evaluation.

Dexmedetomidine may impair cognitive testing during endovascular embolization of cerebral arteriovenous malformations: a retrospective case report series.

After the reported successful use of dexmedetomidine to sedate patients in the intensive care unit without respiratory depression, we began to use dexmedetomidine for interventional neuroradiologic procedures. We report on five patients who had dexmedetomidine administered for sedation during embolization of cerebral arteriovenous malformations. All patients were comfortably sedated and breathing spontaneously. However, although patients were awake and following simple commands 10 minutes after the discontinuation of the infusion of dexmedetomidine, they were nevertheless unable to undergo cognitive testing. They were still unable to undergo cognitive testing 45 minutes after the infusion was stopped. In contrast, 10 minutes after the discontinuation of the infusion of propofol, all patients were awake, alert, cooperative, and able to undergo cognitive testing without difficulty. In conclusion, on examination of five non-randomly selected case records, we found that dexmedetomidine significantly prevented neurologic and cognitive testing.