Incomplete circle of Willis as a risk factor for intraoperative ischemic events during carotid endarterectomies performed under regional anesthesia - A prospective case-series.

Background: The role of the willisian collaterals during carotid endarterectomies (CEAs) is a debated issue. The aim of the present work was to test whether an incomplete or non-functional circle of Willis (CoW) is a risk factor for ischemic events during CEA. Patients and methods: CEAs were performed under local anesthesia. Patients were considered symptomatic (SY) if neurological signs appeared after the cross-clamping phase. In SY patients shunt insertion was performed. CoW on CT angiograms (CTa) were analyzed offline and categorized as non-functional (missing or hypoplastic collaterals) or functional collaterals by three neuroradiologists. Near-infrared spectroscopy (NIRS) was performed throughout the procedure. Results: Based on CTa, 67 incomplete circles were found, 54 were asymptomatic (ASY) and 13 were SY. No complete CoW was found among the SY patients. Significant differences could be detected between incomplete and complete circles between ASY and SY groups (Chi-square: 6.08; p = 0.013). The anterior communicating artery was missing or hypoplastic in 5/13 SY cases. There were no cases of the non-functional anterior communicating arteries in the ASY group (Chi-square: 32.9; p = 10-8). A missing or non-functional bilateral posterior communicating artery was observed in 9/13 SY and in 9/81 ASY patients (Chi-square: 24.4; p = 10-7). NIRS had a sensitivity of 76.9% and a specificity of 74.5% in detecting neurological symptoms. Conclusions: Collateral ability of the CoW may be a risk factor for ischemic events during CEAs. Further studies should delineate whether the preoperative assessment of collateral capacity may be useful in decision-making about shunt use during CEA.

The value of transcranial Doppler monitoring of cerebral blood flow changes during carotid endarterectomy performed under regional anesthesia - A case series.

Recent evidence suggests no difference between patient outcomes when carotid endarterectomies (CEAs) are performed under general or regional anesthesia. However, for detecting the need for a shunt, general anesthesia has the drawback of monitoring needs in the intraoperative setting. In the present study, we attempted to perform intraoperative transcranial Doppler (TCD) monitoring for CEAs performed under intermediate plexus block to describe cerebral hemodynamic changes during different phases of the procedure. Patients and methods: Patients with unilateral hemodynamically significant carotid stenosis scheduled for elective CEAs were included. Ultrasound-guided intermediate plexus block was used for regional anesthesia. TCD monitoring of the middle cerebral artery mean blood flow velocity (MCAV) was performed throughout the procedure. MCAVs were offline analyzed during different phases of CEA: (1) resting state, before regional block, (2) after block, before incision, (3) before cross-clamp, (4) after cross-clamp, (5) 5 min after cross-clamp, (6) 10 min after cross-clamp, (7) after declamping, and (8) during the postoperative period (4-6 h). Results: Shunt insertion based on the deterioration of neurological symptoms after cross-clamping was necessary for 11/66 patients (16.6%). In these symptomatic patients, the ipsilateral percent decrease of the MCAV was more than 70% in 8 out of 11 cases (72.7%). In asymptomatic patients, without shunt insertion, the average decrease of MCAV was less than 50%. Conclusions: Neurological symptoms referring to cerebral ischemia may be superior to TCD monitoring of cerebral blood flow for detecting the necessity of a shunt. Regional anesthesia enables reliable, symptom-based monitoring of CEAs.

Assessment of malformations, variations and diameters of vessels forming the circle of Willis - An autopsy study in a non-cerebrovascular cohort.

Background a purpose: The collateral capacity of the circle of Willis (CoW) may play an important role in the development of ischemic strokes. The occurrence of classical polygon shows wide geographical variations and morphological data on diameters of the Willisian collaterals are scarce. We aimed to assess CoW variations and vessel diameters in a Central European cohort. Subjects and methods: CoWs were removed during routine autopsy. The morphological pattern of the circles was recorded. The prepared circles were then put between two glass plates and tightly compressed. The length of the vessels and half of the circumference were measured under a light microscope enabling measurement with an approximation of 0.1 mm. Vessel diameters were calculated from vessel circumference. Results: A total of 110 circles were analysed. Incomplete circles (missing one or two segments of CoW) were found in 25 cases (22.7%). Any forms of anatomical variations were detected in 14 cases (12.7%). When applying the <1 mm diameter threshold for analysis, 36 anterior communicating arteries (32.7%), 53 right posterior communicating arteries (48.2%), 73 left posterior communicating arteries (66.4%) and 18 posterior communicating arteries (16.3%) on both the sides were considered hypoplastic. Conclusions: In patients without stroke in their history, complete CoW may be present in >60% of the cases. Our diameter data may serve as reference values for the Central-European population.

Correlation between calcium, water contents and ultrasonographic appearance of atherosclerotic lesions of carotid artery lesions.

BACKGROUND: We tested the hypothesis whether there is a correlation between the echogenicity and calcium and water contents of carotid plaques. PATIENTS AND METHODS: Ninety carotid befurcations from 45 deceased patients were removed during autopsy. Thirty-four plaques were categorized as homogenous echolucent (HEL), homogenous echogenic (HEG) and heterogenous (HE) plaques based on premortem B-mode image. Water content was expressed in % of wet weight. Ca was determined by proton-induced X-ray emission and expressed in ppm. Relative optical density of the B-mode images was analyzed offline using a computer program. RESULTS: HEL plaques had lower Ca content (medians and IQRs: 6,145 [4,465-6,536 ppm]) compared to HEG (74,100 [15,300-1,44,500-ppm]), P ≤ 0.001). HE plaques showed an intermediate calcium content (7,310 [4,840-9,920 ppm]) that was statistically not different from echolucent plaques. Water content of HEG plaques was statistically not different from HEL and HE (HEG:53.5 [35.5-64%], HEL: 73.5 [69.7-78.5%], HE: 70.6 [67.4-73.9%]). HEG plaques had the highest relative optical densities (196 [188-217%]). HEL and HE had similar relative optical densities (HEL: 176 [164-187%], HE: 164 [144-188%], respectively). A significant positive correlation was found between the Ca content and relative optical density of plaques. CONCLUSIONS: Echogenicity of carotid plaques increases along with their calcium content. Water content may be an important factor in differentiation of different plaques.

Clinical Experiences with the FRONT Formula for Pre-Operative Airway Assessment and Documentation: a Multi-Centre Study.

OBJECTIVE: The prediction of difficult airway is one of the most important challenges before general anaesthesia. This study aimed to assess the clinical usefulness of the FRONT score, a recently developed scoring system to predict and document airway difficulties. METHODS: This multi-centre, inter-observer, prospective and double-blinded study included 976 patients from two university centres. The pre-operative evaluation of the patients was performed by a pre-operative team of anaesthesiologists (team A) who evaluated and scored the expected difficulty of airway management. An intra-operative team of evaluators (team B) working independently of team A, performed the actual instrumentation of the airway and scored the actual findings. Both teams used the FRONT scoring system and worked independently of each other to ensure blinded assessments. The statistical analysis of the pre- and intra-operative FRONT scores was performed in an off-line blinded manner. RESULTS: Our results show a fair and promising association between pre-operative composite FRONT score and that observed at the induction phase (Spearman=0.43). Among the score components, the best correlation was observed for the F and R components (kappa=0.44 and 0.36, respectively), and the worse correlation was observed for the O and T components (kappa=0.25 and 0.24, respectively). CONCLUSION: The FRONT formula for the prediction and documentation of the airway status is a simple and effective method for assessing and defining airway management difficulties. Further prospective studies are required to assess the sensitivity and specificity of the system.

VATS therapy of chylothorax caused by leiomyomatosis complicated with tuberous sclerosis complex.

Lymphangioleiomyomatosis with tuberous sclerosis complex is a rare disease. One of the most frequent complications of lymphangioleiomyomatosis is pleural effusion (chylothorax) wich can be treated with the use of VATS. Authors report a case of pulmonary lymphangioleiomyomatosis in a 56-year-old female patient with tuberous sclerosis complex with an 8-week history of recurrent chylothorax, dyspnea and debilitating weakness. By CT scan a flat tissue proliferation was seen in the site of the thoracic duct and it was supposed to be the reason for the pleural effusion. A VATS resection of this laesion and ligation of the thoracic duct was performed successfully. Chylothorax is often associated with pulmonary lymphangioleiomyomatosis. Lymphangioleiomyomatosis combined with tuberous sclerosis complex is extremely rare. In case of chylothorax VATS treatment is successful and may be the first choice.