Proximal Internal Carotid Artery Research Articles

Onyx HD-500 embolization of intracranial aneurysms: Modified technique using continuous balloon inflation under conscious sedation

The conventional technique of intracranial aneurysm embolization using Onyx HD-500 (ev3 Neurovascular, Irvine, CA, USA) involves repetitive balloon inflation-deflation cycles under general anesthesia. By limiting parent artery occlusion to 5minutes, this cyclic technique is thought to minimize cerebral ischemia. However, intermittent balloon deflation may lengthen procedure time and allow balloon migration, resulting in intimal injury or Onyx leakage. We report our experience using a modified technique of uninterrupted Onyx injection with continuous balloon occlusion under conscious sedation. All Onyx embolization procedures for unruptured aneurysms performed by the senior author (A.J.R.) between September 2008 and April 2010 were retrospectively reviewed. Demographic, clinical, angiographic, and procedural data were recorded. Twenty-four embolization procedures were performed in 21 patients with 23 aneurysms, including four recurrences. Twenty aneurysms (87%) involved the paraclinoid or proximal supraclinoid internal carotid artery. Size ranged from 2.5 to 24mm and neck diameter from 2 to 8mm. The modified technique was employed in 19 cases. All but one patient (94.4%) tolerated continuous balloon inflation. Complete occlusion was achieved in 20 aneurysms (83.3%) and subtotal occlusion in three (12.5%). Stable angiographic results were seen in 85%, 94%, 94%, and 100% of patients at 6, 12, 24, and 36months, respectively. There were no deaths. Permanent non-disabling neurological morbidity occurred in one patient (4.2%). Minor, transient, and/or angiographic complications were seen in three patients (12.5%), none related to the technique itself. Onyx embolization of unruptured intracranial aneurysms can be safely and effectively performed using continuous balloon inflation under conscious sedation.

Extracranial carotid artery stenting followed by intracranial stent-based thrombectomy for acute tandem occlusive disease

ObjectiveAcute tandem occlusions of the extracranial internal carotid artery (ICA) and a major intracranial artery respond poorly to intravenous tissue plasminogen activator (tPA) and present an endovascular challenge. We describe...

Radiation dose analysis of large and giant internal carotid artery aneurysm treatment with the pipeline embolization device versus traditional coiling techniques

BackgroundFlow diversion is an effective and increasingly accepted method for endovascular treatment of cerebral aneurysms. Additionally, the public has heightened concerns regarding radiation exposure from medical procedures. This study analyzes...

Carotid stent infection: a rare but potentially fatal complication of carotid artery stenting

Infections involving endovascular devices are rare and, to our knowledge, only three cases of infection with an inserted carotid stent have ever been reported. A 68-year-old man underwent carotid artery...

Emergency carotid artery stenting in patients with acute ischemic stroke due to occlusion or stenosis of the proximal internal carotid artery: a single-center experience

BackgroundThe feasibility, safety and effectiveness of emergency carotid artery stenting (eCAS) in patients with acute ischemic stroke (AIS) due to proximal internal carotid artery (ICA) stenosis or occlusion are still...

Abstract 44: Global Hypomethylation and Promoter Hypomethylation of Flt1 Concurrently Occurred Iin Atherosclerotic Tissues

Background and objectives: Epigenetic alterations have been suggested as a pathological mechanism in atherosclerosis development. However, global and gene-specific epigenetic changes have not been well-known in atherosclerotic tissues yet. We evaluated whether the global methylation and promoter methylation of vascular endothelial growth factor (VEGF) and VEGF receptor (VEGFR) genes of atherosclerotic tissues was different from peripheral leukocytes in carotid stenosis patients. Methods: We used carotid endarterectomy (CEA) tissues and peripheral leukocytes (WBC) collected from 27 patients, who received CEA to remove athoerslcerotic plaque from proximal internal carotid artery. To evaluate global methylation status in the CEA tissue and WBC of each patient, pyrosequencing for long-interspersed nuclear element (LINE) sequence was performed. The evaluation of gene-specific promoter methylation status targeted to angiogenesis-related genes including VEGF, VEGFR1 (Flt1), and VEGFR2 (KDR). The methylation status of each gene was evaluated using methylation specific polymerase chain reaction. The differences of global and gene-specific methylation status of each tested gene were compared between CEA and WBC of all patients. Results: On global methylation status evaluation, LINE methylation was lower in CEA than WBC (CEA, 63.7±1.7; WBC, 65.8±3.3%, p=0.002). CEA tissues also showed significantly lower promoter methylations in VEGFR1 (CEA, 5.3±7.1; WBC, 11.9±9.4%, p=0.007). The methylation status of VEGFR2 (CEA, 21.4±11.5; WBC, 25.5±13.5%, p=0.220) and VEGF (CEA, 19.3±11.8; WBC, 18.0±9.9%, p=0.561) was not statistically different between CEA and WBC samples of the patients. Conclusion: The concurrent decrease pattern of LINE and VEGFR1 suggested that the hypomethylation occurred globally and gene-specifically in angiogenesis-related genes of proximal ICA stenosis. In particular, the VEGFR1 promoter hypomethylation in atherosclerotic tissues might be an epigenetic evidence to explain the increase of angiogenesis increasing inside of atherosclerotic plaque.

Abstract T P129: Association of Increased Serum Alkaline Phosphatase with Intracranial Atherosclerosis

Background: Vascular calcification is strongly associated with cardiovascular morbidity and mortality by reducing arterial elastance. Recently alkaline phosphatase (ALP) is identified as the critical factor for vascular calcification, but no clinical studies investigating relevance of ALP and cerebral atherosclerosis have been reported. In this study, we assessed the hypothesis that increased levels of serum ALP may be associated with severity of cerebral atherosclerosis. Methods: From October 2010 to March 2012, we prospectively included total 518 patients (313 men/205 women) aged 25-96 years with acute ischemic stroke. Cardioembolic stroke patients were excluded because of the interference by acute arterial embolic occlusion. The patients were divided by baseline measurements into quantiles of ALP levels (<58, 58-69, 70-89, >90 IU/L). Bilateral middle cerebral arteries, distal internal carotid arteries and basilar artery were selected for the evaluation of intracranial atherosclerosis, bilateral proximal internal carotid arteries and common carotid arteries for the extracranial atherosclerosis. We defined significant arterial stenosis as moderate or more stenosis (50-100%) evaluated by at least one angiographic study using MR angiography, CT angiography or digital subtraction angiography. Statistical analyses were performed using the multivariate logistic regression analysis adjusted for age, gender, hypertension, diabetes, dyslipidemia, smoking, presence of secondary prevention, serum calcium levels. Results: In the multivariate logistic regression analysis, compared with the first ALP quantile, adjusted odds ratio of the third and fourth quantiles for significant intracranial atherosclerosis were 2.30 (95% confidence interval 1.06-5.01) and 3.84 (1.78-8.30). There was no significant correlation between ALP levels and significant extracranial atherosclerosis. Conclusions: In conclusion, our study demonstrated that increased serum levels of ALP are an independent risk factor for significant intracranial atherosclerosis.

Comparison of carotid artery dimensions and lesion length measured by B‐mode ultrasonography and quantitative angiography in patients with severe stenosis undergoing percutaneous revascularization

To evaluate the correlation and agreement of the carotid artery landmarks necessary for carotid artery stenting obtained by B-mode ultrasonography (BMU), and by quantitative angiography (QCA) in patients with severe carotid artery stenosis. In 75 patients undergoing carotid artery stenting, the distal common (CCA), proximal internal (ICA) carotid artery diameter, and lesion length were measured preoperatively by BMU, and intraoperatively by QCA. In 96% of the subjects, BMU imaging was adequate for interpretation. BMU and QCA Pearson correlation and Lin concordance coefficients were 0.75 (p < 0.001) and 0.959 (95% CI: 0.930 - 0.996), respectively, for CCA diameter, 0.88 (p < 0.001) and 0.954 (95% CI: 0.928-0.983), respectively, for ICA diameter, and 0.62 (p < 0.001) and 0.734 (95% CI: 0.719-0.760), respectively, for lesion length, with a 0.765 bias correction factor and a wider data scatter by Bland Altman plots showing shorter lesion length by BMU than by QCA. In patients with carotid artery stenosis, BMU can provide reliable distal CCA and proximal ICA diameters in comparison with QCA, whereas lesion length measured by BMU has an acceptable correlation, but a poor agreement with QCA.

Choroid artery occlusion after treatment of ICA termination aneurysm: was it caused by stent induced vasospasm?

Dear Sirs: Endovascular occlusion has become the main treatment for cerebral aneurysms in the last decade. This development was much facilitated by the ISAT trial [1] for ruptured aneurysms, but coiling, stenting and flow diversion are now also widely used for unruptured cases. While endovascular treatment is usually less invasive than surgical aneurysm clipping, coil occlusion of an aneurysm seems less durable. This has led to the increasing use of stents to reconstruct the vessel wall for the prevention of recurrences. If an elective stent placement is performed under appropriate antiplatelet medication, stentrelated complications such as thrombotic stent occlusion and embolic events are infrequent [2, 3]. We report on a rare complication after placement of a selfexpanding endovascular stent, leading to a disabling stroke in a young patient with an unruptured internal carotid artery (ICA) aneurysm. A 27-year-old female patient, who had delivered a healthy daughter 6 weeks previously, presented to her local hospital with transient left-sided weakness. Vascular risk factors included obesity (BMI=35 kg/m) and smoking. A probable transient ischaemic attack (TIA) was diagnosed, and the patient was investigated accordingly. While no obvious aetiologywas found for the TIA, her brain imaging had shown an incidental lesion, which was suggestive of a left ICA aneurysm with a diameter of around 10 mm. A subsequent CT angiogram (CTA) done at the local neurosciences centre confirmed the presence of a broad-based left ICA termination aneurysm with a maximum diameter of 12 mm, mostly extending on to the left M1 segment, but also slightly affecting the A1. No other aneurysm was seen. Given the size of the aneurysm, the patient was offered endovascular treatment. She was quoted a risk of permanent neurological deficit of 3 % or less. Because of the large neck size, a stent-assisted coil embolisation was planned, and the patient was asked to take 75 mg of aspirin and clopidogrel each starting 5 days before the planned procedure. The patient was admitted on the morning of the intervention and clerked by the clinical team. She confirmed having taken her dual antiplatelet therapy as prescribed. She also stated that she was only smoking occasionally, but her frequent absences from the ward suggested higher nicotine consumption on that morning. The procedure was performed under general anaesthetic (GA). However, bronchospasm and a sudden severe drop in blood saturation levels complicated the induction of the anaesthesia. The patient had no background of respiratory problems, and according to the anaesthetist, heavy smoking prior to the GAwas the most likely explanation. A diagnostic angiogram after intubation confirmed the presence of a large left carotid terminus aneurysm (Fig. 1a). No other abnormalities were seen. The patient received IV heparin under ACT monitoring (>250 s), but platelet function inhibition was not tested. Over an exchange wire, a 6-F 90-cm Terumo Destination sheath was placed into the left proximal ICA, and a Fargomax distal access catheter was advanced into the petrous segment of the ICA. This was complicated by vasospasm at the tip of the long sheath, and therefore, 2 mg of nimodipine was added to the saline flush. W. Kuker (*) Department of Neuroradiology, West Wing, John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK e-mail: wilhelm.kuker@ndcn.ox.ac.uk

Stenotic Transverse Sinus Predisposes to Poststenting Hyperperfusion Syndrome as Evidenced by Quantitative Analysis of Peritherapeutic Cerebral Circulation Time

Hyperperfusion syndrome is a devastating complication of carotid stent placement. The shortening of cerebral circulation time after stent placement is seen as a good indicator of the development of hyperperfusion syndrome. The purpose of our study was to evaluate whether patients with ipsilateral transverse sinus stenosis are prone to having shortened cerebral circulation time after stent placement, subsequently leading to the possible development of hyperperfusion syndrome. Forty-nine patients with >70% unilateral carotid stenosis undergoing stent placement were recruited for analysis. Group A consisted of patients with a stenotic ipsilateral transverse sinus >50% greater than the diameter of the contralateral transverse sinus; the remaining patients were in group B. Quantitative DSA was used to calculate cerebral circulation time. Cerebral circulation time was defined as the time difference between the relative time to maximal intensity of ROIs in the proximal internal carotid artery and the internal jugular vein. ΔCCT was defined as cerebral circulation time before stent placement minus cerebral circulation time after stent placement. ΔCCT, white matter hyperintensity signals, and sulcal effacement in MR imaging were compared between the 2 groups. ΔCCT was significantly shorter in group A (0.65 ± 1.3) than in group B (-0.12 ± 1.4). Three patients had white matter hyperintensity signals in group A, and 1 developed hyperperfusion syndrome. Group B showed no MR imaging signs of hyperperfusion syndrome. Ipsilateral hypoplastic transverse sinus was associated with prolonged cerebral circulation time before stent placement and greatly shortened cerebral circulation time after stent placement. Inadequate venous drainage might play a role in impaired cerebral autoregulation and might influence the development of poststenting hyperperfusion syndrome.

Prolonged hypotension following elective stenting of an internal carotid artery stenosis

We report a case of a 72-year-old man who had undergone elective stenting of an asymptomatic high grade stenosis of the proximal left internal carotid artery. The indication was progression...

MR Angiography at 3 Tesla to Assess Proximal Internal Carotid Artery Stenoses: Contrast-Enhanced or 3D Time-of-Flight MR Angiography?

The aim of this study was to compare the diagnostic accuracy of 3D time-of-flight (TOF-MRA) and contrast-enhanced (CE-MRA) magnetic resonance angiography at 3T for detection and quantification of proximal high-grade stenosis using multidetector computed tomography angiography (MDCTA) as reference standard. The institutional ethics committee approved this prospective study. A total of 41 patients suspected of having internal carotid artery (ICA) stenosis underwent both MDCTA and MRA. CE-MRA and TOF-MRA were performed using a 3.0-T imager with a dedicated eight-element cervical coil. ICA stenoses were measured according to the North American Symptomatic Carotid Endarterectomy Trial criteria and categorized as 0-25 % (minimal), 25-50 % (mild), 50-69 % (moderate), 70-99 % (high grade), and 100 % (occlusion). Sensitivity and specificity for the detection of high-grade ICA stenoses (70-99 %) and ICA occlusions were determined. In addition, intermodality agreement was assessed with κ-statistics for detection of high-grade ICA stenoses (70-99 %) and ICA occlusions. A total of 80 carotid arteries of 41 patients were reviewed. Two previously stented ICAs were excluded from analysis. On MDCTA, 7 ICAs were occluded, 12 ICAs presented with and 63 without a high-grade ICA stenosis (70-99 %). For detecting 70-99 % stenosis, both 3D TOF-MRA and CE-MRA were 91.7 % sensitive and 98.5 % specific, respectively. Both MRA techniques were highly sensitive (100 %), and specific (CE-MRA, 100 %; TOF-MRA, 98.7 %) for the detection of ICA occlusion. However, TOF-MRA misclassified one high-grade stenosis as occlusion. Intermodality agreement for detection of 70-99 % ICA stenoses was excellent between TOF-MRA and CE-MRA [κ = 0.902, 95 % confidence interval (CI) = 0.769-1.000], TOF-MRA and MDCTA (κ = 0.902, 95 % CI = 0.769-1.000), and CE-MRA and MDCTA (κ = 0.902, 95 % CI = 0.769-1.000). Both 3D TOF-MRA and CE-MRA at 3T are reliable tools for detecting high-grade proximal ICA stenoses (70-99 %). 3D TOF-MRA might misclassify pseudo-occlusions as complete occlusions. If there are no contraindications for CE-MRA, CE-MRA is recommended as primary MR imaging modality.

Double Steal Syndrome: Two Case Presentations

Double steal syndrome is a phenomenon that has been minimally described in the literature and here we present two cases. The first case presented with symptoms and early evidence of reversal of flow on carotid duplex in the right proximal internal carotid artery with significant innominate stenosis. The second case was an asymptomatic patient with clear retrograde flow observed in the right proximal internal carotid artery with innominate stenosis. Both patients were also found to have reversal of flow in the vertebral artery of the ipsilateral side. Intervention consisted of stent placement at the proximal origin of the innominate artery. Both patients remained on clopidogrel according to post-procedure instructionsand returned to the clinic within the first week for follow up carotid duplex demonstrating decreased innominate velocity with antegrade right internal carotid and vertebral artery flow.

Iatrogenic rupture of undiagnosed blood blister-like aneurysm during aneurysmal neck clipping.

Iatrogenic rupture of undiagnosed blood blister-like aneurysm during aneurysmal neck clipping.

Effect of the Interaction between Recanalization and Collateral Circulation on Functional Outcome in Acute Ischaemic Stroke.

Identification of patients with acute ischaemic stroke who could most benefit from arterial recanalization after endovascular treatment remains an unsettled issue. Although several classifications of collateral circulation have been proposed, the clinical role of collaterals is still debated. We evaluated the effect of the collateral circulation in relation to recanalization as a predictor of clinical outcome. Data were prospectively collected from 103 patients consecutively treated for proximal middle cerebral or internal carotid artery occlusion. The collateral circulation was evaluated with a novel semiquantitative-qualitative score, the Careggi collateral score (CCS), in six grades. Both CCS and recanalization grades (TICI) were analysed in relation to clinical outcome. A statistical analysis was performed to evaluate the effect of interaction between recanalization and collateral circulation on clinical outcome. Out of the 103 patients, 37 (36.3%) had poor collaterals, and 65 (63.7%) had good collaterals. Patients with good collaterals had lower basal National Institute of Health Stroke Scale (NIHSS), more distal occlusion, smaller lesions at 24h CT scan and better functional outcome. After multivariate analysis, the interaction between recanalization and collateral grades was significantly stronger as a predictor of good outcome (OR 6.87, 95% CI 2.11-22.31) or death (OR 4.66, 95%CI 1.48-14.73) compared to the effect of the single variables. Collaterals showed an effect of interaction with the recanalization grade in determining a favourable clinical outcome. Assessment of the collateral circulation might help predict clinical results after recanalization in patients undergoing endovascular treatment for acute ischaemic stroke.

Endovascular Treatment of Aneurysmal Subarachnoid Hemorrhage in Japanese Registry of Neuroendovascular Therapy (JR-NET) 1 and 2

To distinguish the characteristics of ruptured cerebral aneurysm that are suitable for endovascular treatment from those that are not, we evaluated factors that influenced the results of aneurysm embolization in patients with ruptured cerebral aneurysm, based on data from the Japanese Registry of Neuroendovascular Therapy (JR-NET) 1 and 2. The multivariate analysis revealed that young patients, patients with low modified Rankin Scale (mRS) scores before onset, and patients with low World Federation of Neurosurgical Societies (WFNS) grades had good outcome. Compared to proximal internal carotid artery (ICA) aneurysms, the odds ratio of middle cerebral artery (MCA) aneurysms was 1.67, indicating poorer outcome for MCA aneurysms, and patients with small, wide-neck cerebral aneurysms had poor outcome. Patients treated after 15 days had better outcome than during other periods. The timing of treatment, however, did not influence the outcome in patients treated within 14 days. The outcome was poorer when the responsible doctor for the treatment was a specialist or a non-specialist than a supervisory doctor. The outcome of patients treated with bare platinum coils, and three dimensional (3D) rotational angiography was better, and the outcome of patients who completed treatment with body filling was poorer than in patients with complete occlusion. Perioperative hemorrhagic complications, all ischemic complications, and rebleeding occurred in 4.5%, 6.4%, and 1.4% of patients, respectively. All these complications had poor outcome factors on day 30, with odds ratios of 2.72, 2.96, and 25.49, respectively. We must be fully aware of these risk factors and determine indications for the treatment when endovascular treatment is performed as the treatment of choice for ruptured cerebral aneurysm.

Objective duplex ultrasound evaluation of the extracranial circulation in multiple sclerosis patients undergoing venoplasty of internal jugular vein stenoses: A pilot study

Chronic cerebrospinal venous insufficiency (CCSVI) is a condition associated with multiple sclerosis (MS) and manifested by stenoses in the extracranial venous circulation. There is a need for an objective non-invasive assessment of CCSVI that is able to accurately identify the location of stenoses and quantify physiological changes in blood flows following treatment. A duplex ultrasound method, extracranial duplex ultrasound (ECDU), is described where the internal jugular veins (IJVs) and vertebral veins (VVs) were examined in the supine and sitting position before and after venoplasty in eight patients with clinically diagnosed MS. High-resolution B-mode imaging was used to detect obvious stenoses, intra-luminal membranes, valve abnormalities and vein wall thickening. ECDU was then used to assess blood flow including reflux. To assess obstruction, venous blood volume flows (BVFs) were taken bilaterally from the proximal (J1), mid (J2) and distal (J3) segments of the IJVs and the mid cervical VVs. To assess cerebral perfusion, bilateral BVF measurements were taken, in the supine position only, from the proximal internal carotid arteries (ICA) and mid cervical vertebral arteries (VA). The global arterial cerebral blood flow (GACBF) was then calculated as the sum of the ICA and VA measurements. Pre-venography ECDU detected IJV stenoses or obstruction in all patients. Venography findings were consistent with those of the pre-treatment ECDU with the exception of the detection of bilateral IJV stenoses in two patients diagnosed with unilateral IJV stenosis by ECDU. A significant improvement in GACBF was evident following venoplasty (p < 0.05). A trend to improvement in the post-treatment BVFs of both the IJVs and the mid cervical VVs was also observed. This improvement was most marked in the left VVs (p = 0.052) and the J2 segment of right IJVs (p < 0.05). The ECDU examination described provides a reliable objective assessment of IJV and VV stenoses and, with the use of BVFs, can quantify the degree of obstruction. These results support the use of ECDU as a non-invasive post-operative assessment of the success of venoplasty. The ability of ECDU to measure GACBF provides an additional parameter to monitor vascular pathophysiology in MS patients. The current findings support the view that the early symptomatic benefits observed after venoplasty for stenoses in the extracranial venous circulation may be the result of increased cerebral perfusion.

Is a Constant Doppler Angle of Insonation Worthwhile during Carotid Duplex Ultrasound?

Background/Aims. —Velocity ratio is a good indication to determine the degree of vessel stenosis. This study was done to determine the effect of Doppler angle in carotid artery velocity ratio measurements. Methods. —Thirty-eight patients who underwent routine carotid duplex ultrasound were asked to participate in this study. Peak systolic velocity (PSV) and end-diastolic velocity (EDV) at distal common carotid artery (CCA) and proximal internal carotid artery (ICA) with constant and different Doppler angles were recorded. The ICA/CCA PSV ratio was calculated. Results. —There were 12 female and 26 male patients; their mean age (year, ±SD) was 50.53 ± 16.4 and their mean body mass index (kg/m2, ±SD) was 29.6 ± 9.53. The mean ± SD. ICA PSV, CCA PSV, and the ICA/CCA PSV ratio with a 60° Doppler angle were 80.40 ± 16.6, 87.90 ± 16.96, and 0.93 ± 0.18, respectively. However, the mean ± SD. ICA PSV, CCA PSV, and the ICA/CCA PSV ratio with a 45° Doppler angle were 63.84 ± 16.18, 70.67 ± 16.19, and 0.91 ± 0.17, respectively. Moreover, the ICA60°/CCA45° PSV ratio was 1.17 ± 0.25 and the ICA45°/CCA60° PSV ratio was 0.73 ± 0.16. Paired Student's t-test showed a statistical significance for different Doppler angle of insonation ( p = 0.001) but was not statistically significant when the Doppler angle was constant ( p = 0.389). Conclusion. —Constant Doppler angle is preferred during carotid ultrasound for a consistent result.

Computed tomography angiography intraluminal filling defect is predictive of internal carotid artery free-floating thrombus

Filling defects at the internal carotid artery (ICA) origin in the work-up of stroke or transient ischemic attack may be an ulcerated plaque or free-floating thrombus (FFT). This may be challenging to distinguish, as they can appear morphologically similar. This is an important distinction as FFT can potentially embolize distally, and its management differs. We describe a series of patients with suspected FFT and evaluate its imaging appearance, clinical features, and evolution with therapy. Between 2008 and 2013, we prospectively collected consecutive patients with proximal ICA filling defects in the axial plane surrounded by contrast on CT/MR angiography. We defined FFT as a filling defect that resolved on follow-up imaging. We assessed the cranial-caudal dimension of the filling defect and receiver operating characteristics to identify clinical and radiological variables that distinguished FFT from complex ulcerated plaque. Intraluminal filling defects were identified in 32 patients. Filling defects and resolved or decreased in 25 patients (78%) and felt to be FFT; there was no change in 7 (22%). Resolved defects and those that decreased in size extended more cranially than those that remained unchanged: 7.3mm (4.2-15.9) versus 3.1mm (2.7-3.7; p = 0.0038). Receiver operating characteristic analysis established a threshold of 3.8mm (filling defect length), sensitivity of 88%, specificity of 86%, and area under the curve of 0.86 (p < 0.0001) for distinguishing FFT from plaque. Filling defects in the proximal ICA extending cranially >3.8mm were more likely to be FFT than complex ulcerated plaque. Further studies evaluating filling defect length as a predictor for FFT are warranted.

Ultrasound-guided subcutaneous cervical plexus block for carotid endarterectomy in a patient with chronic obstructive pulmonary disease

To the Editor: Carotid endarterectomy (CEA) can be performed under regional anesthesia with superficial or deep cervical plexus block (CPB). An advantage of superficial CPB compared with deep CPB is reduced hemi-diaphragmatic paresis due to phrenic nerve block [1]. A subcutaneous block (superficial to the investing cervical fascia) is clinically effective in CEA because the investing cervical fascia is permeable [2, 3]. This is the first report of ultrasound (US)-guided subcutaneous CPB. A 65-year-old man with severe stenosis of the right proximal internal carotid artery was scheduled for CEA. He had a history of severe chronic obstructive pulmonary disease. Pulmonary function test revealed a forced expiratory volume in 1 s of 0.69 L (%FEV1: 24 %, grade V in the Hugh–Jones classification). The patient received 1 mg midazolam in the operating room and was placed in the supine position with the head turned toward the nonoperative side. The carotid artery, internal jugular vein, sympathetic trunk, vagus nerve, and phrenic nerve were visualized in the coronal plane by use of a US machine (SonoSite M-Turbo ; SonoSite Bothell, USA) with a 6 to 13-MHz linear probe. For the subcutaneous block, a 50-mm long insulated needle (Stimuplex A; B. Braun, Germany) connected to a nerve stimulator (0.5 mA) was inserted subcutaneously adjacent to the posterior border of the sternocleidomastoid muscle, without penetrating the investing cervical fascia, by use of real-time US. We used the nerve stimulator to detect whether the needle had been positioned inadvertently in the deep cervical space; contractions of the neck muscles were not provoked by the 0.5mA current. After negative aspiration, 5 mL 0.5 % ropivacaine with 5 lg/mL epinephrine was injected subcutaneously in a cephalad direction. Another 5 mL was injected in a caudad direction [4] (Fig. 1). Fifteen minutes after local anesthetic (LA) injection, the patient showed negative results on pinprick test of the mastoid process, ear lobe, and cricoid cartilage. The duration of surgery was 100 min. Except for mild pain during supraclavicular drain-tube insertion before wound closure, the patient did not complain of pain during the operation. Side effects, for example hoarseness, Horner’s syndrome, and acute respiratory distress did not occur, and elevation of the hemi-diaphragm was not visible on postoperative radiography. After the surgery, the patient did not suffer any cardiopulmonary complications. In a cadaveric study, Pandit et al. [5] demonstrated that the deep cervical fascia was permeable. Anatomical dissection revealed that dye injected below the investing fascia spread to the deep cervical space, coating the scalene muscles, phrenic nerve, and cervical nerve roots. On the basis of this fact, we considered that LA injected below the investing fascia can enter the deep cervical space and affect the phrenic nerve. LA is administered blind in the conventional technique, and this procedure may result in serious puncture-related complications. In our case, realtime US was important in preventing inadvertent deep block. In conclusion, we suggest that US-guided subcutaneous CPB is potentially safe and clinically effective regional H. J. Shin (&) H. N. Yu S. Z. Yoon Department of Anesthesiology and Pain Medicine, College of Medicine, Korea University, #5 Anam-dong Sungbuk-gu, Seoul 136-705, Korea e-mail: may335@naver.com