Location Of Internal Carotid Artery Research Articles

Abstract 208: Optimal Catheter Position and Aspiration Technique Improves Safety and Efficacy Using Next Generation Funnel Catheter

Introduction The Advanced Neurovascular Access (ANA5, Anaconda Biomed) is a novel stroke thrombectomy catheter comprising a distal self‐expanding covered funnel designed to locally restrict blood flow in the Internal Carotid Artery (ICA) and, when used in conjuction with available stent retreiver, reduce clot fragmentation during clot ingestion. The ANAIS study aimed to investigate the safety and efficacy of the ANA5 device (‘Funnel’) in different deployment locations and aspiration conditions. Methods Prospective, single‐arm, multi‐center study to assess the safety and performance of ANA5 in combination with a stent retriever in patients with Acute Ischemic Stroke (ANAIS). An independent imaging corelab and Clinical Events Committee assessed the different predefined outcomes. Patients with anterior circulation vessel occlusion admitted within 24 hours from symptom onset were eligible. The primary efficacy endpoint was successful recanalization, defined as mTICI ≥2b in the target vessel within three passes of the Funnel device. The primary safety endpoint was a composite of symptomatic Intracranial Hemorrhage within 24 hours and any device related severe adverse event. The impact of the funnel deployment location in the different ICA segments (C1 to C4 or above) and the condition of the aspiration on angiographical outcome was also evaluated. Results A total of 39 subjects who complied with all inclusion/exlusion criteria were treated by 10 different physicians in 3 stroke centers. Mean age was 69.9 ±13.2 years, 52.5% women, and the median National Institutes of Health Stroke Scale on admission was 16.0 [12.5‐19.5]. Initial occlusion location was: TICA 25.0%, M1‐MCA 52.5% and M2‐MCA 22.5%. The rate of succesful reperfusion within 3 passes was 74.4% (29/39) (primary efficacy endpoint). First pass effect (FPE) mTICI 2b‐3 and 2c‐3 was 56.4% (22/39) and 48.7% (19/39), respectively. Zero sICHs at 24h or SADE at 5 days were reported (primary safety endpoint). At 90 days, the rate of modified Rankin Scale score 0‐2 was: 57.9% (22/38). The efficacy of the thrombectomy procedure using the Funnel increases when: 1. The funnel was deployed in the higher ICA segments (below ophtalmic artery) with diameter between 3.5‐5.0mm, ensuring full apposition of the funnel to the vessel wall: C1(n=10): 40.0% vs. C2 or higher (n=29): 86.2% (p < 0.002). 2. Continuous aspiration was applied during the full retrieval of the stentriever in the Funnel (89.3% (n=28) vs. 36.4% (n=11), p < 0.0005). 3. When both continuous aspiration and appropriate ICA location were achieved, the Clinical efficacy endpoint improved to 95.5% (n=22), and FPE mTICI 2b‐3 and 2c‐3 were 72.7% and 59.1% respectively. Conclusion The use of the next generation Funnel Device in the ANAIS study results in a high rate of successful recanalization with an optimal safety profile and favorable 90 days clinical outcomes. The performance improved when the Funnel was deployed above the C1 cervical segment of the ICA, and continuous aspiration was applied during the full stent retrieval.

Strategies to avoid internal carotid artery injury in "sandwich" atlantoaxial dislocation patients during surgery.

To elucidate the anatomic relationship between the internal carotid artery (ICA) and the bony structures of the craniovertebral junction among "sandwich" atlantoaxial dislocation (AAD) patients, and to analyze the risks of injury during surgical procedures. The distance from the medial wall of ICA to the midsagittal plane (D1), the shortest distance between the ICA wall and the anterior cortex of the lateral mass of atlas (LMA) (D2) on the most caudal and cranial levels of LMA and the angle (A) between the sagittal plane passing through the screw entry point of C1 lateral mass(C1LM) screw and the medial tangent line of the vessel passing through the entry point were measured. Besides, the location of ICA in front of the atlantoaxial vertebra was divided into 4 categories (Z1-Z4). There was a statistically difference between the male and female patients regarding D1, and the difference between D2 at level a and level b as well as angle A between the left and right sides were statistically different (p < 0.05). Ninety-two ICAs (57.5%) were anteriorly located in Z3, 50 (31.3%) were located in Z4, 17 were located in Z2, and only one ICA was located in Z1 in all 80 patients. In "sandwich" AAD patients, particular attention should be paid to excessively medialized ICA to avoid ICA injury during trans-oral procedures, and the risk of injuring the ICA with more cranially and medially angulated C1LM screw placement was relatively less during posterior fixation procedures. A novel classification of ICA location was used to describe the relationship between ICA and LMA.

Machine learning to predict in-stent stenosis after Pipeline embolization device placement.

BackgroundThe Pipeline embolization device (PED) is a flow diverter used to treat intracranial aneurysms. In-stent stenosis (ISS) is a common complication of PED placement that can affect long-term outcome. This study aimed to establish a feasible, effective, and reliable model to predict ISS using machine learning methodology.MethodsWe retrospectively examined clinical, laboratory, and imaging data obtained from 435 patients with intracranial aneurysms who underwent PED placement in our center. Aneurysm morphological measurements were manually measured on pre- and posttreatment imaging studies by three experienced neurointerventionalists. ISS was defined as stenosis rate >50% within the PED. We compared the performance of five machine learning algorithms (elastic net (ENT), support vector machine, Xgboost, Gaussian Naïve Bayes, and random forest) in predicting ISS. Shapley additive explanation was applied to provide an explanation for the predictions.ResultsA total of 69 ISS cases (15.2%) were identified. Six predictors of ISS (age, obesity, balloon angioplasty, internal carotid artery location, neck ratio, and coefficient of variation of red cell volume distribution width) were identified. The ENT model had the best predictive performance with a mean area under the receiver operating characteristic curve of 0.709 (95% confidence interval [CI], 0.697–0.721), mean sensitivity of 77.9% (95% CI, 75.1–80.6%), and mean specificity of 63.4% (95% CI, 60.8–65.9%) in Monte Carlo cross-validation. Shapley additive explanation analysis showed that internal carotid artery location was the most important predictor of ISS.ConclusionOur machine learning model can predict ISS after PED placement for treatment of intracranial aneurysms and has the potential to improve patient outcomes.

Determinants of intracranial aneurysm retreatment following embolization with a single flow-diverting stent.

Flow diverting stents have revolutionized the treatment of intracranial aneurysms through endoluminal reconstruction of the parent vessel. Despite this, certain aneurysms require retreatment. The purpose of this study was to identify clinical and radiologic determinants of aneurysm retreatment following flow diversion. A multicenter flow diversion database was evaluated to identify patients presenting with an unruptured, previously untreated aneurysm with a minimum of 12 months' clinical and angiographic follow-up. Univariate and multivariate logistic regression modeling was performed to identify determinants of retreatment. We identified 189 aneurysms treated in 189 patients with a single flow-diverting stent. Mean age was 54 years, and 89% were female. Complete occlusion was achieved in 70.3% and 83.6% of patients at six and 12 months, respectively. Aneurysm retreatment with additional flow-diverting stents occurred in 5.8% of cases. Univariate analysis revealed that dome diameter 10 mm (p = 0.012), pre-clinoid internal carotid artery location (p = 0.012), distal > proximal parent vessel diameter (p = 0.042), and later dual antiplatelet therapy (DAPT) discontinuation (p < 0.001) were predictive of retreatment. Multivariate analysis identified discontinuation of DAPT 12 months (p = 0.003) as a strong determinant of retreatment with dome diameter 10 mm trending toward statistical significance (p = 0.064). Large aneurysm neck diameter, presence of aneurysm branch vessels, patient age, smoking history, and hypertension were not determinant of retreatment on multivariate analysis. Prolonged DAPT is the most important determinant of aneurysm retreatment following single-device flow diversion. Abbreviating DAPT duration to only six months should be a consideration in this population, especially for patients with a large aneurysm dome diameter.

Impact of aneurysm morphology on aneurysmal subarachnoid hemorrhage severity, cerebral infarction and functional outcome

ObjectiveAneurysmal subarachnoid hemorrhage (aSAH) is associated with high morbidity. The objective was to evaluate, whether specific morphological aneurysm characteristics could serve as predictive values for aSAH severity, disease-related complications and clinical outcome. MethodsA total of 453 aSAH patients (mean age: 54.9 ± 13.8 years, mean aneurysm size: 7.5 ± 3.6 mm) treated at a single center were retrospectively included. A morphometric analysis was performed based on angiographic image sets, determining aneurysm location, aneurysm size, neck width, aneurysm size ratios, aneurysm morphology and vessel size. The following outcome measures were defined: World Federation of Neurosurgical Societies (WFNS) grade 4 and 5, Fisher grade 4, vasospasm, cerebral infarction and unfavorable functional outcome. ResultsRegarding morphology parameters, aneurysm neck width was an independent predictor for Fisher 4 hemorrhage (OR: 1.1, 95%CI: 1.0–1.3, p = 0.048), while dome width (OR: 0.92, 95%CI: 0.86–0.97, p = 0.005) and internal carotid artery location (OR: 2.1, 95%CI: 1.1–4.2, p = 0.028) predicted vasospasm. None of the analyzed morphological characteristics prognosticated functional outcome. Patient age (OR: 0.95, 95%CI: 0.93–0.96, p < 0.001), WFNS score (OR: 4.8, 95%CI: 2.9–8.0, p < 0.001), Fisher score (OR: 2.3, 95%CI: 1.4–3.7, p < 0.001) and cerebral infarction (OR: 4.5, 95%CI: 2.7–7.8, p < 0.001) were independently associated with unfavorable outcome. ConclusionsThe findings indicate a correlation between aneurysm morphology, Fisher grade and vasospasm. Further studies will be required to reveal an independent association of aneurysm morphology with cerebral infarction and functional outcome.

Irregular pulsation of intracranial unruptured aneurysm detected by four-dimensional CT angiography is associated with increased estimated rupture risk and conventional risk factors

BackgroundIntracranial aneurysms (IAs) are common in the population and current imaging-based rupture risk assessment needs to be refined. We aimed to use four-dimensional CT angiography (4D-CTA) to investigate the associations...

Identifying Predictors for Aneurysm Remnants After Clipping by Morphometric Analysis and Proposal of a Novel Risk Score

Although the risk of aneurysm remnants after microsurgical clipping is generally low, complete aneurysm occlusion is not always guaranteed. We performed a morphometric analysis of intracranial aneurysms to identify predictors for aneurysm remnants and to propose a novel risk score. This is a retrospective, single-center analysis of consecutive patients with ruptured and unruptured aneurysms that underwent microsurgical clipping and postoperative digital subtraction angiography between 2010 and 2018. Based on preoperative rotational angiography, distinct morphological aneurysm characteristics were determined and correlated with postoperative angiographic results. Factors predictive in the univariate and multivariate analyses were determined to establish a risk score for postoperative remnants after aneurysm clipping. Among 140 patients with 166 clipped aneurysms, aneurysm remnants were present in 19.9%. In the multivariate analysis, ruptured aneurysm status (OR: 7.8, 95% CI: 1.7 - 36; p<0.01) and increased aspect ratio (OR: 1.9, 95% CI: 1.0 - 4.0; p=0.07) were associated with postoperative aneurysm remnants. Anterior communicating artery location (p=0.02), internal carotid artery location (p=0.06), increased aneurysm inclination angle (p<0.01) and irregular aneurysm shape (p=0.07) were further predictors for aneurysm remnants in the univariate analysis. These factors were weighted and included into a risk sum score for postoperative aneurysm remnants (range: 0 - 8 points), which performed with good accuracy (AUC = 0.807). After external validation of the proposed risk score, it could help identify cases requiring angiographic control after aneurysm surgery.

Treatment Risk for Elderly Patients with Unruptured Cerebral Aneurysm from a Nationwide Database in Japan

This study aimed to clarify the risk factors of treatment for unruptured cerebral aneurysms (UCAs) in elderly patients by comparing the morbidity at discharge between surgical clipping and endovascular coiling in nonelderly (<65 years) and elderly (≥65 years) patients based on a national database in Japan. A total of 36,017, including 15,671 patients with UCA after exclusion of unknown location, were registered in the Diagnosis Procedure Combination, the nationwide database, from 2010 to 2015 in Japan. Outcome of Barthel Index at discharge was investigated and multivariate logistic regression analysis identified risk factors for morbidity of Barthel Index <90 at discharge in nonelderly and elderly patient groups. Risk factors for morbidity at discharge were basilar artery aneurysm compared with internal carotid artery (ICA), diabetes mellitus (odds ratio [OR], 2.0-2.5; 95% confidence interval [CI], 1.6-3.7), antiplatelet drug, and anticoagulation drug; however, highest hospital volume compared with lowest was an inverse risk factor in both age groups. Endovascular coiling (OR, 0.4; 95% CI, 0.3-0.5) was a significantly inverse risk in the elderly group. Anterior communicating artery aneurysm compared with ICA was a significant risk (OR, 1.6; 95% CI, 1.0-2.6) in the nonelderly group; on the other hand, anterior communicating artery aneurysm (OR, 0.7; 95% CI, 0.5-0.95) and middle cerebral artery aneurysm (OR, 0.6; 95% CI, 0.5-0.8) compared with ICA were significantly inverse risks in the elderly group. Endovascular coiling after control of diabetes mellitus was recommended for the treatment of UCA in elderly patients. The ICA location of aneurysm in the elderly should be paid attention as the treatment risk.

Mechanical Thrombectomy in Acute Stroke Due to Carotid Occlusion: A Series of 153 Consecutive Patients

Background: Strokes due to carotid artery occlusion (CAO) are associated with bad clinical prognosis and poor response to intravenous thrombolysis. Several studies in the past have shown the benefits of mechanical thrombectomy (MT) and compared bridging therapy (BT) and primary MT (PMT) in large vessel occlusions, but only a few studies have focused on the specific population of CAO and their response to endovascular treatment. Methods: Retrospective review of patients treated at our center between January 2010 and June 2017 that (1) presented with acute ischemic stroke caused by CAO in the first 4.5 h since symptom onset, and (2) were treated with MT (BT or PMT). Baseline characteristics of the population, comparison between BT and PMT, intrahospital mortality, symptomatic intracranial hemorrhage, and functional outcome were investigated. Results: A total of 153 patients were included. Baseline characteristics: 51.6% were male, and the median age was 71 years. The most frequent risk factor was hypertension (71.9%). The main stroke etiology was atherothrombotic (40.5%). The mean admission National Institute of Health Severity Score (NIHSS) was 19, mean discharge NIHSS was 7. Isolated occlusion of the Extracranial or Intracranial Internal Carotid Artery was the most frequent occlusion location (52.3%). TICI 2b-3 was achieved in 87.6%, intrahospital mortality was 26.8%, symptomatic hemorrhage was 8.5%, and 3 months-modified Rankin Score (mRS) 0–2 was 26.8%. Definitive carotid stenting was needed in 33.3% of the cases. BT versus PMT: Patients treated with PMT presented a higher incidence of atrial fibrillation, anticoagulation, and cardioembolic stroke compared to those treated with BT. No differences in TICI 2b-3, 3 months-mRS or symptomatic hemorrhage were found between both groups. Intrahospital mortality: Poor perfusion-CT mismatch (p = 0.005), isolated Internal carotid artery location (p = 0.024), and symptomatic hemorrhage (p < 0.001) were independent predictors. Symptomatic intracranial hemorrhage: Patients with post-treatment symptomatic hemorrhage had higher intrahospital mortality (p < 0.001) and worse 3 months-mRS (p = 0.033). Functional outcome: Admission NIHSS (p = 0.012) independently predicted 3 months-mRS. Conclusions: In our population, patients with CAO clinically present with severe strokes. Isolated occlusions of the extra- or intracranial segments of the carotid are more frequent than tandem occlusions. Successful recanalization after thrombectomy is achieved in most of the patients, but association with favorable functional outcome is poor. Clinical evolution is similar in patients treated with PMT and BT. Intracranial symptomatic hemorrhage after treatment is associated with higher intrahospital mortality and worse 3 months-mRS. Poor perfusion-CT mismatch, symptomatic hemorrhage, and isolated CAO are independent predictors of intrahospital mortality. Admission NIHSS is an independent predictor of 3 months-mRS.

Characteristics of Unruptured Compared to Ruptured Intracranial Aneurysms: A Multicenter Case-Control Study.

Only a minority of intracranial aneurysms rupture to cause subarachnoid hemorrhage. To test the hypothesis that unruptured aneurysms have different characteristics and risk factor profiles compared to ruptured aneurysms. We recruited patients with unruptured aneurysms or aneurysmal subarachnoid hemorrhages at 22 UK hospitals between 2011 and 2014. Demographic, clinical, and imaging data were collected using standardized case report forms. We compared risk factors using multivariable logistic regression. A total of 2334 patients (1729 with aneurysmal subarachnoid hemorrhage, 605 with unruptured aneurysms) were included (mean age 54.22 yr). In multivariable analyses, the following variables were independently associated with rupture status: black ethnicity (odds ratio [OR] 2.42; 95% confidence interval [CI] 1.29-4.56, compared to white) and aneurysm location (anterior cerebral artery/anterior communicating artery [OR 3.21; 95% CI 2.34-4.40], posterior communicating artery [OR 3.92; 95% CI 2.67-5.74], or posterior circulation [OR 3.12; 95% CI 2.08-4.70], compared to middle cerebral artery). The following variables were inversely associated with rupture status: antihypertensive medication (OR 0.65; 95% CI 0.49-0.84), hypercholesterolemia (0.64 OR; 95% CI 0.48-0.85), aspirin use (OR 0.28; 95% CI 0.20-0.40), internal carotid artery location (OR 0.53; 95% CI 0.38-0.75), and aneurysm size (per mm increase; OR 0.76; 95% CI 0.69-0.84). We show substantial differences in patient and aneurysm characteristics between ruptured and unruptured aneurysms. These findings support the hypothesis that different pathological mechanisms are involved in the formation of ruptured aneurysms and incidentally detected unruptured aneurysms. The potential protective effect of aspirin might justify randomized prevention trials in patients with unruptured aneurysms.

Microvascular doppler associated with neuronavigation to intraoperative identification and location of internal carotid artery in transsphenoidal endoscopic pituitary macroadenomas surgery

Context: Enhancements in pulsed doppler techniques have made easier to apply those techniques not only to diagnose brain vascular diseases but also in brain surgery, especially to disclose arteries close to tumors and avoid their manipulation. The aim of this paper is to describe the technique of microvascular doppler associated with neuronavigation in transsphenoidal endoscopic surgery to remove pituitary macroadenomas in three patients. Material And Methods: A sterile 2mm 16-MHz probe was used inside a long curved canula of 17 cm length, attached with a neuronavigation reference. The neuronavigation mapping was done with MRI and angiotomography, which took place 24 hours before the procedure. Results: Intraoperatively, the doppler identified arterial flow compatible with the anatomical localization of the cavernous portion of internal carotid artery, as shown by the neuronavigation system, and this place was avoided during surgery, allowing manipulation of the tumor without risk of damage to the internal carotid artery. The results after surgery were total removal of the tumor in all three cases. No postoperative vascular complications were present. Conclusion: The method with microvascular doppler associated with neuronavigation was essential to the intraoperative vascular diagnosis allowing radical tumoral resections while preventing damage to the internal carotid artery.

Is C1 lateral mass screw placement safe for the Chinese, Indians, and Malays? An analysis of 180 computed tomography scans.

C1 lateral mass (C1LM) screw is a common procedure in spine surgery. However, related studies are lacking in Asia. We aim to determine the safety of C1LM screw for the Chinese, Indians, and Malays. Three-dimensional computed tomographies of 180 subjects (60 from each ethnic) were analyzed. The length and angulations of C1LM screw and the location of internal carotid artery (ICA) in relation to C1LM were assessed and classified according to the classification by Murakami et al. The incidence of ponticulus posticus (PP) was determined and the differences among the population of these three ethnics were recorded. The average base length was 8.5 ± 1.4 mm. The lengths within the lateral mass were between 14.7 ± 1.6 mm and 21.7 ± 2.3 mm. The prevalence of PP was 8.3%. 55.3% (199) of ICA were located in zone 0, 38.3% (138) in zone 1-1, 6.4% (23) in zone 1-2, and none in zone 1-3 and zone 2. The average angulation from the entry point to the ICA was 8.5° ± 6.4° laterally. The mean distance of ICA from C1 anterior cortex was 3.7 ± 1.7 mm (range: 0.6∼11.3). There was no difference in distribution of ICA in zone 1 among the three population (Chinese-47%, Indians-61%, and Malays-53%; p > 0.05). No ICA is located medial to the entry point of C1LM screw. If bicortical purchase of C1LM screw is needed, screw protrusion of less than 3 mm or medially angulated is safe for ICA. The incidence of PP is 8.3% with higher prevalence among the Indian population.

Blister-like Aneurysms in Atypical Locations: A Single-Center Experience and Comprehensive Literature Review

Blister-like aneurysms (BLAs) were originally described to arise typically along the nonbranching segment of the dorsal wall of the internal carotid artery (ICA); however, BLAs located in areas other than the dorsal ICA have been described more recently. We present a case series of "atypical" BLAs and a systematic review of the literature on this subject. We conducted a literature search using the key word "blister-like aneurysm." Studies reporting BLAs in locations other than the dorsal ICA wall were selected. Clinical presentation, treatment modality, complications, and outcomes (modified Rankin Scale for neurologic outcomes and Roy scale for radiologic outcomes) were extracted from each study. We also reviewed our single-institution experience with atypical BLAs and analyzed the topography and outcomes of all the atypical BLAs according to each specific treatment modality. Atypical BLAs were observed in the anterior communicating, middle cerebral, basilar, posterior cerebral, anterior cerebral, and posterior inferior cerebellar arteries. Surgery was the treatment in 65% of patients, an endovascular approach was used in 30%, and a combined approach was used in 5%. A good outcome (modified Rankin Scale 0-1-2) was experienced by 88% and 55% of the patients in the endovascular and surgical groups, respectively. There were 4 deaths, 2 in the endovascular group and 2 in the surgical group. Endovascular treatment of BLAs seems to be associated with reduced morbidity and mortality andto provide a better outcome compared with surgical approaches. Further prospective studies are needed to confirm these results. It is important for clinicians to remember that BLAs may also occur in sites other than the typical ICA location.

Risk of internal carotid artery injury during C1 screw placement: analysis of 160 computed tomography angiograms

Background contextInjury to the internal carotid artery (ICA) is a potentially catastrophic complication of C1-lateral mass (C1-LM) or C1–C2 transarticular screw insertion. PurposeThis study was designed to determine the risk of injury to the ICA during placement of these screws using computed tomography angiography (CTA). Study designRadiographic analysis using CTA. Patient sampleOne hundred sixty CTAs were examined, for a total of 320 ICAs. Outcome measuresNot applicable. MethodsFine-cut intravenous CTAs with multiplanar and three-dimensional reconstruction were reviewed. The position of the ICA in relation to the anterior cortex (AC) of C1, anterior end of the anterior tubercle (AT), and medial margin of the transverse foramen (TF) was measured bilaterally in three ascending and equidistant levels of the C1-AT. ResultsThe position of the ICA in relation to C1 was variable. The average distance between the ICA and the AC of C1 was only 3.7 mm. Furthermore, 96% of the time the posterior margin of the ICA was located posterior to the anteriormost aspect of the anterior C1 tubercle (average distance, 5.4 mm), making the ICA vulnerable to damage if a drill, tap, or screw was inserted to the depth of the anteriormost portion of the AT as seen on a lateral fluoroscopic or radiographic view. The medial margin of the ICA was located medial to the TF (a location potentially vulnerable to injury with bicortical screw placement) less often at the caudal aspect of the C1-AT (54%) than at its middle or cranial aspect (74% and 75%, respectively). No ICAs were located anterior to the medial 30% of the C1-LM or more medially. ConclusionsBicortical C1-LM or C1–C2 transarticular screw placement carries a potential risk of ICA injury. Given the wide variation in ICA location relative to C1, if bicortical C1 fixation is required, preoperative CTA should be considered to determine the optimal screw trajectory. In general, inferomedially angulated C1-LM screws appear to be safer with respect to the ICA injury than other potential trajectories.

The effect of patient age on the internal carotid artery location around the atlas

The aim of this study was to analyze the exact location of the internal carotid artery (ICA) relative to the C-1 lateral mass and describe the effect of age on the tortuosity of the ICA. The authors analyzed 641 patients who had undergone CT angiography to evaluate the location of the ICA in relation to the C-1 lateral mass. Each patient was assigned to 1 of 3 age groups (< 41 years, 41-60 years, and > 60 years of age). The degree of lateral positioning of the ICA was classified into 4 groups: Group 1 (lateral to the C-1 lateral mass), Group 2 (lateral half of the lateral mass), Group 3 (medial half of the lateral mass), or Group 4 (medial to the lateral mass). The anteroposterior relationship of the ICA was classified into Group A (posterior to the anterior tubercle) or Group B (anterior to the anterior tubercle). Distances from the ICA to the midline, anterior tubercle, and anterior cortex of the lateral mass were measured. Distances between the lateral margin of the lateral mass and the longus capitis muscle were also evaluated. The prevalence of the ICA located in front of the lateral mass (Groups 2 and 3) was 47.4% overall. The position of the ICA changes with age due to vessel tortuosity. Only 18.3% of patients in the youngest age group (< 41 years of age) had an ICA in front of the lateral mass (Group 2 or 3 area). However, this percentage increased in the older 2 groups (43.5% in the 41-60 year old group, and 57% in the > 60-year-old age group). The mean distance from the midline to the ICA was 22.6 mm, and the mean distance from the ICA to the C-1 anterior tubercle and the ventral cortex of the lateral mass was 4.7 and 4.5 mm, respectively. Moreover, the ICA is more prone to injury during bicortical C-1 screw placement when the longus capitis muscle is hypotrophic and does not cover the entire ventral surface of the lateral mass. Elderly patients have a higher incidence of a medially located ICA that may contribute to the risk of injury to the ICA during bicortical C-1 screw or C1-2 transarticular screw placement. Although the small number of reported cases of ICA injury does not allow for determination of a direct relationship with specific anatomical characteristics, the presence of unfavorable anatomy does warrant serious consideration during evaluation for C-1 screw placement in elderly patients.

Imaging of the Internal Carotid Artery and Adjacent Skull Base with Three-Dimensional CT Angiography for Preoperative Planning and Intraoperative Surgical Navigation

Introduction: Three-dimensional computed tomographic angiography (3D-CTA) demonstrates the spatial relationships of the internal carotid artery (ICA) and adjacent skull base. This imaging modality may be incorporated into intraoperative surgical navigation. Methods: The charts of all patients who had undergone 3D-CTA imaging between July 2002 and June 2004 were reviewed. For 3D-CTA, 1-mm axial CT scan images were obtained with simultaneous intravenous contrast bolus on a multidetector CT scanner. The CBYON Suite version 2.6–2.8 (Med-Surgical Services, Inc., Mountain View, CA) was used to create CTA images through its volume-rendering protocols. Results: A total of 20 patients had 21 3D-CTA studies performed for diagnostic evaluation and/or preoperative planning and in 16 instances, the 3D-CTA images were used during intraoperative surgical navigation. The diagnoses included neoplasm (7 malignant and 4 benign), fibro-osseous lesion (2), fungal sphenoiditis (2), CSF leak (2), mucocele (1), and other (2). Images generated by 3D-CTA helped easily define the anatomic relationships between the ICA and skull base lesion. During intraoperative surgical navigation, the 3D-CTA provided critical information about the ICA location and adjacent skull base anatomy in the operative field. Conclusion: 3D-CTA is a useful means for assessing the ICA and its relationship to skull base lesions. Incorporation of 3D-CTA into intraoperative surgical navigation facilitates the comprehension of operative field anatomy in the ICA region. As a result, this imaging technique, especially when combined with intraoperative surgical navigation, may enhance surgical outcomes. This strategy extends the applications of minimally invasive endoscopic approaches to the skull base.

Three‐Dimensional Computed Tomography Angiography of the Internal Carotid Artery for Preoperative Evaluation of Sinonasal Lesions and Intraoperative Surgical Navigation

Three-dimensional computed tomographic angiography (3DCTA) demonstrates the spatial relationships of the internal carotid artery (ICA) and adjacent skull base. This imaging modality may be incorporated into intraoperative surgical navigation during endoscopic skull base surgery. The charts of patients who had undergone 3DCTA imaging between July 2002 and February 2005 were reviewed. For 3DCTA, 1 mm axial computed tomography (CT) scan images were obtained with simultaneous intravenous contrast bolus on a multidetector CT scanner (Somatom Sensation 16, Siemens, Munich, Germany). The CBYON Suite version 2.6 to 2.8 (Med-Surgical Services, Mountain View, CA) was also used for creating CTA images through its volume-rendering protocols. A total of 22 3DCTA studies were performed for diagnostic evaluation or preoperative planning. In 18 instances, the 3DCTA images were used during intraoperative surgical navigation. The specific indications for obtaining the 3DCTA study included neoplasm (11 cases), cerebrospinal fluid leak (3 cases), fibro-osseous lesion (2 cases), mucocele (2 cases), and other (4 cases). Images generated by 3DCTA facilitated the definition of the anatomic relationships between the ICA and skull base lesion. During intraoperative surgical navigation, the 3DCTA provided critical information about the ICA location and adjacent skull base anatomy in the operative field. 3DCTA is a useful means for assessing the ICA and its relationship to skull base lesions. Incorporation of 3DCTA into intraoperative surgical navigation facilitates the comprehension of operative field anatomy in the ICA region. As a result, this imaging technique, especially when combined with intraoperative surgical navigation, may extend the applications of minimally invasive endoscopic approaches to the skull base.

Ascertainment of Internal Carotid Artery Location Using Frontal Digital Subtraction Angiography and Lateral Cephalography in Velocardiofacial Syndrome

Ascertainment of Internal Carotid Artery Location Using Frontal Digital Subtraction Angiography and Lateral Cephalography in Velocardiofacial Syndrome