scholarly journals Advantages of petrosectomy for superficial temporal artery to superior cerebellar artery bypass based on three-dimensional distance measurements using cadaver heads

2021 ◽  
Author(s):  
Kenji Uda ◽  
Kuniaki Tanahashi ◽  
Takashi Mamiya ◽  
Fumiaki Kanamori ◽  
Kinya Yokoyama ◽  
...  
Keyword(s):  
Superficial Temporal Artery ◽  
Three Dimensional ◽  
Major Axis ◽  
Temporal Artery ◽  
Minor Axis ◽  
Field Size ◽  
Superior Cerebellar Artery ◽  
Operative Field ◽  
Axis Length ◽  
Optimal Approach

AbstractSuperficial temporal artery (STA) to superior cerebellar artery (SCA) bypass is usually performed via the subtemporal approach (StA), anterior transpetrosal approach (ApA), or combined petrosal approach (CpA), but no study has yet reported a quantitative comparison of the operative field size provided by each approach, and the optimal approach is unclear. The objective of this study is to establish evidence for selecting the approach by using cadaver heads to measure the three-dimensional distances that represent the operative field size for STA–SCA bypass. Ten sides of 10 cadaver heads were used to perform the four approaches: StA, ApA with and without zygomatic arch osteotomy (ApA-ZO− and ApA-ZO+), and CpA. For each approach, the major-axis length and the minor-axis length at the anastomosis site (La-A and Li-A), the major-axis length and the minor-axis length at the brain surface (La-B and Li-B), the depth from the brain surface to the anastomosis site (Dp), and the operating angles of the major axis and the minor axis (OAa and OAi) were measured. Shallower Dp and wider operating angle were obtained in the order CpA, ApA-ZO+, ApA-ZO−, and StA. In all parameters, ApA-ZO− extended the operative field more than StA. ApA-ZO+ extended La-B and OAa more than ApA-ZO−, whereas it did not contribute to Dp and OAi. CpA significantly decreased Dp, and widened OAa and OAi more than ApA-ZO+. ApA and CpA greatly expanded the operative field compared with StA. These results provide criteria for selecting the optimal approach for STA-SCA bypass in light of an individual surgeon’s anastomosis skill level.

Intracranial Vertebral Endarterectomy

Neurosurgery ◽  
1990 ◽  
Vol 26 (3) ◽  
pp. 465-471 ◽  
Author(s):  
James I. Ausman ◽  
Fernando G. Diaz ◽  
Balaji Sadasivan ◽  
Manuel Dujovny
Keyword(s):  
Vertebral Artery ◽  
Medical Therapy ◽  
Superficial Temporal Artery ◽  
Posterior Inferior Cerebellar Artery ◽  
Temporal Artery ◽  
Superior Cerebellar Artery ◽  
Focal Lesion ◽  
Cerebellar Infarction ◽  
Vertebrobasilar Insufficiency ◽  
Cerebellar Artery

Abstract Intracranial vertebral endarterectomy was performed on six patients with vertebrobasilar insufficiency in whom medical therapy failed. The patients underwent operations for stenotic plaque in the intracranial vertebral artery with the opposite vertebral artery being occluded, hypoplastic, or severely stenosed. In four of the patients, the stenosis was mainly proximal to the posterior inferior cerebellar artery (PICA). In this group, after endarterectomy, the vertebral artery was patent in two patients, and their symptoms resolved: in one patient the endarterectomy occluded, but the patient's symptoms improved; and in one patient the endarterectomy was unsuccessful, and he continued to have symptoms. In one patient, the plaque was at the origin of the PICA. The operation appeared technically to be successful, but the patient developed a cerebellar infarction and died. In one patient the stenosis was distal to the PICA. During endarterectomy, the plaque was found to invade the posterior wall of the vertebral artery. The vertebral artery was ligated, and the patient developed a Wallenburg syndrome. The results of superficial temporal artery to superior cerebellar artery anastomosis are better than those for intracranial vertebral endarterectomy for patients with symptomatic intracranial vertebral artery stenosis. The use of intracranial vertebral endarterectomy should be limited to patients who have disabling symptoms despite medical therapy, a focal lesion proximal to the PICA, and a patent posterior circulation collateral or bypass.

Deep Bypasses to the Distal Posterior Circulation

Neurosurgery ◽  
2010 ◽  
Vol 66 (1) ◽  
pp. 92-101 ◽  
Author(s):  
Zsolt Zador ◽  
Daniel C. Lu ◽  
Christine M. Arnold ◽  
Michael T. Lawton
Keyword(s):  
Temporal Lobe ◽  
Artery Bypass ◽  
Superficial Temporal Artery ◽  
Temporal Artery ◽  
Posterior Circulation ◽  
Superior Cerebellar Artery ◽  
Brain Shift ◽  
Morphometric Measurements ◽  
Subtemporal Approach ◽  
Cerebellar Artery

Abstract OBJECTIVE The subtemporal approach for a superficial temporal artery–to–superior cerebellar artery bypass requires significant superior retraction that can injure the temporal lobe, compromise veins, and cause edema postoperatively. In contrast, the pretemporal approach requires posterolateral retraction that seems to be less injurious to the temporal lobe and better tolerated clinically. We hypothesized that the pretemporal approach provides ample exposure, more gentle retraction, and better clinical results than the subtemporal approach. METHODS Standard orbitozygomatic-pterional and subtemporal approaches were performed on both sides of 4 formalin-fixed cadaver heads for morphometric measurements. Temporal lobe retraction was quantified for each approach in terms of brain shift and retraction pressure by using both sides of 3 fresh, unfixed cadaver heads. Similar morphometric measurements were made in 14 patients in whom bypasses to the distal posterior circulation were performed. The effect of temporal lobe retraction was assessed with edema volumes on postoperative computed tomography scans. RESULTS In cadaver heads and in patients, the pretemporal approach optimized exposure of the P2A segment of the posterior cerebral artery (PCA) and the subtemporal approach optimized exposure of the lateral pontomesencephalic segment of the superior cerebellar artery (SCA). Working depths and lengths of exposed artery were similar with these 2 approaches, but the PCA was a larger recipient than the SCA. Brain shift was 42% less with pretemporal than with subtemporal retraction, and retraction pressure was 43% less with pretemporal than with subtemporal retraction. The volume of temporal lobe edema was 56% less in patients with bypasses performed with the pretemporal approach as compared with the subtemporal approach. CONCLUSION Pretemporal exposure of the PCA is equivalent to subtemporal exposure of the SCA, but the pretemporal approach is facilitated by a larger recipient artery. Posterolateral temporal lobe retraction associated with the pretemporal approach is gentler than superior retraction with the subtemporal approach. These results validate our preference for the pretemporal approach over the subtemporal approach when performing deep bypasses to the posterior circulation.

Effect of Nozzle Geometry on the Near-Field Flow Characteristics of High-Pressure Gas Leak Jets

2018 ◽  
Author(s):  
Xiaopeng Li ◽  
Fakun Zhuang ◽  
Rui Zhou ◽  
Yian Wang ◽  
Libo Wang ◽  
...  
Keyword(s):  
High Pressure ◽  
Nozzle Exit ◽  
Flow Behavior ◽  
Near Field ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Major Axis ◽  
Minor Axis ◽  
Nozzle Geometry ◽  
Square Jets

Three-dimensional large eddy simulations of high-pressure jets at the same nozzle pressure ratio of 5.60 but issuing from different nozzles are conducted. Four different nozzle geometries, i.e., the circular, elliptic, square, and rectangular nozzles, are used to investigate the effect of the nozzle geometry on the near-field jet flow behavior. A high-resolution, hexahedral, and block-structured grid containing about 31.8 million computational cells is applied. The compressible flow solver, astroFoam, which is developed based on the OpenFOAM C++ library, is used to perform the simulations. The time-averaged near-field shock structures and the mean axial density are compared with the experiment data to validate the fidelity of the LES results, and the reasonable agreement is observed. The results indicate that the remarkable differences exist in the near-field flow structures of the jets. In particular, the circular and square jets correspond to a three-dimensional helical instability mode, while the elliptic and rectangular jets have a two-dimensional lateral instability in their minor axis planes. A subsonic flow zone exists after the Mach disk in the circular and square jets, but is lacking in the elliptic and rectangular jets. The intercepting shocks in the circular jet originate near the nozzle exit, and appear to be circular in cross-section. The intercepting shocks in the square jet originate at the four corners of the nozzle exit at first, and then are observed along the major axis plane some distance downstream of the nozzle exit. However, the formation of the intercepting shock is observed in the major axis planes but is lacking in the minor axis planes for the elliptic and rectangular jets. In addition, the real mass flow rates and discharge coefficients for different jets are computed based on the LES modeling, and their differences are explored.

scholarly journals Electric field bridging pattern of pre-breakdown and breakdown condition in transformer oil

2020 ◽  
Vol 19 (3) ◽  
pp. 1210
Author(s):  
Nur Badariah Ahmad Mustafa ◽  
N H Nik Ali ◽  
H. Zainuddin ◽  
Marizuana Mat Daud ◽  
Farah Hani Nordin
Keyword(s):  
Electric Field ◽  
Electrical Power ◽  
Major Axis ◽  
Dielectric Strength ◽  
Minor Axis ◽  
Transformer Oil ◽  
Support Vector ◽  
Electrical Power System ◽  
Feature Descriptors ◽  
Axis Length

Transformer is considered as one of the most important equipment in electrical power system networks. However, most problems occurred in transformer were related to the defects and weakness of the insulation systems. The oils used in transformer act as coolant and insulation purposes hence maintaining the dielectric strength of the transformer. In this work, electric field bridging pattern is observed from pre-breakdown and breakdown condition. The electric field bridging formation was recorded in the experimental setup and images were captured per frame. 193 images were randomly chosen from the whole video frames where 102 images were the pre-breakdown images and 91 images were the breakdown images. This system comprises of four stages: (i) a preprocessing stage to mark the electrodes tips and background subtraction; (ii) a segmentation stage to extract the electric field bridging formation in region of interest; (iii) a feature extraction stage to extract electric field bridging using feature descriptors, <em>area</em>, <em>minor-axis </em>and <em>major-axis length  </em> (iv) a classification stage to identify the pre-breakdown and breakdown condition. System performance was evaluated using support vector machine (SVM), <em>k</em>-nearest neighbour (<em>k</em>-NN) and random forest (RF) and SVM provided the most promising accuracy that was 99%. The results show that the combination of three feature descriptors, <em>area</em>, <em>minor-axis </em>and <em>major-axis length </em>are the best features combination in identifying the transformer oil condition. In future work, further studies will be conducted to investigate the pattern of pre- and post-breakdown due to some similarity found in image pattern. Due to that, more feature descriptors will be identified to find a unique pattern between pre- and post-breakdown condition

scholarly journals Automatic Tajweed Rules Recognition using K-Nearest Neighbour (K-NN)

2019 ◽  
Vol 8 (2S11) ◽  
pp. 552-557
Keyword(s):  
Classification Accuracy ◽  
Major Axis ◽  
Shape Descriptor ◽  
Processing Technique ◽  
Input Image ◽  
Minor Axis ◽  
Image Processing Technique ◽  
Nearest Neighbour ◽  
The People ◽  
Axis Length

Tajweed refers to a pronunciation rule for Al-Quran recitation in Islam. It acts as guidance for Muslims in reciting the Al-Quran in a correct manner. Yet, Tajweed rules could be complicated as it consists of various types of laws. It could also be confusing, and difficult to remember particularly for the people who have less knowledge in Tajweed rules. Thus, a study on automatic tajweed rules recognition using image processing technique is proposed. The scope of this study is limited to Idgham laws only. Initially, the input image went through the pre-processing process which includes four sub-processes which are greyscale conversion, binary conversion, thinning and flip, and word segmentation. Next, six attributes of shape descriptor which are major axis length, minor axis length, eccentricity, filled area, solidity, and perimeter were extracted from each input image. A technique of k-Nearest Neighbour (k-NN) is employed to recognize the two types of Idgham Laws which are Idgham Maal Ghunnah and Idgham Bila Ghunnah. The performance of the proposed study is evaluated to 180 testing images which returned 84.44% of classification accuracy. The outcome of this study is expected to recognize the Tajweed rules automatically and may assist the user on a proper recitation of Al-Quran.

Resolving Occlusive Lesions of the Basilar Artery

Neurosurgery ◽  
1985 ◽  
Vol 17 (5) ◽  
pp. 811-814 ◽  
Author(s):  
John R. Little ◽  
Anthony J. Furlan
Keyword(s):  
Basilar Artery ◽  
Artery Bypass ◽  
Superficial Temporal Artery ◽  
Temporal Artery ◽  
Posterior Circulation ◽  
The Other ◽  
Superior Cerebellar Artery ◽  
Cerebellar Artery ◽  
Basilar Artery Stenosis ◽  
Occlusive Lesion

Abstract Progression of severe basilar artery stenosis to occlusion is a well-recognized phenomenon, but regression of a severe basilar artery atherothrombotic lesion has not been described previously. In this report, two patients with a symptomatic severe basilar artery occlusive lesion showed substantial angiographic improvement after 3 months of anticoagulation in one case and 4 months after superficial temporal artery to superior cerebellar artery bypass in the other case. The findings in these cases indicate that clinical improvement in similar cases may reflect recanalization of a basilar artery occlusive lesion. The uncertain natural history and potential for regression of symptomatic basilar artery atherothormbosis make us hesitant to recommend posterior circulation revascularization immediately after such lesions are first demonstrated angiographically.

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