[Topographic study of the parietal region for the elaboration of revascularized cranium vault autograft]. / Izuchenie topografo-anatomicheskikh osobennostei temennoi oblasti pri razrabotke revaskulyariziruemogo kostno-fastsial'nogo temennogo autotransplantata.

OBJECTIVE: Topographic and blood vessel architecture study of the parietal area and distal regional pool of the superficial temporal artery (STA) to assess the possibility of revascularized cranium vault bone autograft formation. MATERIAL AND METHODS: For the topographic and anatomical study, 30 non-fixed corpses (17 male and 13 female) were selected, the average age of which was 59±5 years. In the anamnesis and catamnesis, there were no indications of trauma or other pathology of the head and neck, including vascular. STA was contrasted with a non-radiocontrast dye (brilliant green) with the introduction of the dye into the STA with preliminary ligation of the frontal branch of the STA. The area of blood supply to soft tissue and bone structures was studied. The angioarchitectonics of the parietal region was studied, the feeding vessel of the studied flap was identified. RESULTS: The obtained anatomical landmarks for the collection of CPFP flap make it possible to form a flap with high accuracy and minimize the morbidity of the donor area.

Middle Cerebral Artery-to-Middle Cerebral Artery Bypass with Superficial Temporal Artery Interposition Graft for the Treatment of Recurrent Thrombosed Middle Cerebral Artery Aneurysm.

Microsurgical treatment of thrombosed middle cerebral artery (MCA) aneurysm is very complicated, especially in recurrent cases. A 48-year-old man presented with a recurrent thrombosed right MCA aneurysm. We performed MCA-to-MCA bypass using a superficial temporal artery (STA) interposition graft and proximal trapping. Initially, an STA-to-MCA bypass with aneurysm trapping was planned because 1 MCA branch of the superior trunk of the M2 segment needed flow replacement after aneurysm trapping. However, the blood flow from the proximal STA was insufficient because of the previous surgical trauma and redo clipping was not feasible. As the backflow from the distal STA segment was good, we used it as an interposition graft for the MCA-to-MCA bypass. The patient recovered well without any neurologic deficits. In this case, the recurrent aneurysm was a fusiform MCA-M2 segment aneurysm with clip slippage. Our initial surgical plan could not be executed. We changed our surgical plan to an MCA-interposition graft-MCA bypass considering the mobility of the M3 arteries. The options for interposition grafts included radial artery, saphenous vein, or ipsilateral or contralateral STA. The caliber discrepancy in the radial artery or saphenous vein grafts makes them less suitable. Further, harvesting the contralateral STA is time-consuming and tedious. Thus the ipsilateral STA interposition graft was used and showed promising results. We recommend this surgical technique in cases in which good STA backflow is guaranteed. In conclusion, revision surgery performed for a recurrent thrombosed MCA aneurysm with an MCA-STA interposition graft-MCA bypass with proximal trapping was successful. This technique is safe and effective for complex aneurysms with suboptimal condition of the STA, which could be due to reduced blood flow, previous surgery, or trauma.

Supermicrosurgical reconstruction of nasal tip defects using the preauricular reversed superficial temporal artery flap.

BACKGROUND: Microsurgical reconstruction of nasal tip defects is difficult to achieve. The free composite auricular flap allows for repair in a one-stage procedure. However, anastomosis to the recipient facial artery is often complicated because of its variable anatomy and the need for a vessel graft. In this study, we describe our experience using the alar artery and angular vein as recipient vessels for direct super microsurgical anastomosis. METHOD: From February 2004 to December 2015, thirty-two patients with different degrees of full-thickness multi-subunit nasal tip defects were included in this study. The superficial temporal vessels, alar artery, and angular vein were marked preoperatively by ultrasound detection. The preauricular reversed superficial temporal artery flap was harvested and transferred to the nasal tip defect region as a free flap using a supermicrosurgical technique. Patient pictures were taken before surgery and at 1, 3, and 6 months of follow-up. Outcomes and complications were recorded and analyzed. Moreover, a postoperative patient satisfaction survey was performed. RESULTS: The reversed superficial temporal artery flap was used in a total of 32 patients for the reconstruction of nasal tip defects in a one-stage procedure. In all cases, the alar artery and angular vein showed no anatomical variations and were used as recipient vessels. The size of the harvested preauricular flap size was 2.5 × 2.0 to 4.0 × 3.6 cm2, and the average flap size was 3.6 × 2.7 cm2. The length of the arterial pedicle was 4.0 to 6.7 cm, 5.58 cm on average. The length of the venous pedicle was 5.0 to 6.8 cm, 6.21 cm on average. Direct anastomosis was achieved in all patients, and in none of the cases, a vascular graft was needed. Donor sites were all closed primarily. Flap survival was complete, except for one case of vascular thrombosis, resulting in a 10% flap necrosis. Temporary hematoma was noted in one patient. The postoperative outcome showed excellent functional coverage and improved esthetic appearance. The average follow-up period was 12 months. The majority of patients (98.5%) rated their postoperative outcome as highly improved and improved. No late recurrence or other complications were seen in any of the patients. Twenty-two patients underwent a secondary debulking procedure of the flap for fine adjustment. CONCLUSION: Our results demonstrate that the alar artery and angular vein are suitable recipient vessels for the super microsurgical reconstruction of nasal tip defects. Surgical planning and procedure are facilitated by their reliable anatomy without the need for a vessel graft. This technique may offer wider applications by extension to other facial cutaneous defects.

Utilization of Intraparotid Segments of Superficial Temporal Vessels for Head and Scalp Free Flap Microanastomosis: A Clinical, Histological, and Cadaveric Study.

BACKGROUND: The superficial temporal vessels (STV) are an underutilized target for head and neck microvascular reconstruction. Most surgeons regard the dissection as difficult, unreliable, and the anastomosis prone to vasospasm. The intraparotid course of the STV may provide more reliable flow without accompanying morbidity. METHODS: A retrospective review of patients who underwent head and scalp free flap reconstruction utilizing STV intraparotid segment was performed. Demographic factors such as intraoperative and postoperative complications are reported. Five bilateral cadaver heads were dissected to describe the relationship to the facial nerve. STV histology was performed on four of the cadavers, noting intraluminal diameter and vessel wall thickness. RESULTS: Thirty-nine patients underwent free flap reconstruction with anastomosis to intraparotid STVs. Defect etiology included tumor resection (71.8%), traumatic brain injury (10.3%), intracranial bleed (12.8%), and acute trauma (5.1%). Flaps transferred included anterolateral thigh (51.3%), latissimus (33.3%), thoracodorsal artery perforator (7.7%), radial forearm (2.8%), and vastus lateralis (5.1%). Two flaps (5.1%) required takeback for arterial thrombosis, with one incidence of total flap loss (2.8%). There were no instances of transient or permanent facial nerve damage nor sialocele. On cadaver dissection, three distinct vessel segments were identified. Segments 1 and 2 represented the STVs superior to the upper tragal border. Segment 3 (intraparotid segment) began at the upper tragal border and STVs enlarged with a targeted anastomosis point at an average of 16.3 mm medial and 4.5 mm inferior to the upper border of the tragus. The frontal branch coursed 11.7 mm inferior and 11.5 mm anterior to this point. On histology, the intraluminal diameter of segment 3 was significantly larger than segment 2 (1.2 vs. 0.9 mm, p = 0.007). CONCLUSION: Head and neck free flap reconstruction with microanastomosis to the intraparotid segment of STVs can be safely and reliably performed.

Superficial temporal vessels, both anterograde and retrograde limbs, are viable recipient vessels for recurrent head and neck reconstruction in patients with frozen neck.

BACKGROUND: Reconstruction of recurrent head and neck malignancy especially in the presence of a frozen neck is challenging. The superficial temporal vessels would be ideal as recipient vessels because they lie out of the previous surgical and radiation field. METHODS: We conducted a retrospective case-control study based on our database between January 2013 and June 2016. A total of 581 primary cases were selected as controls. The 60 test group patients had (a) recurrent head and neck reconstruction, (b) previous surgery and irradiation, (c) frozen neck, and (d) superficial temporal vessels as recipients. RESULTS: There was no significant difference between vascular compromise rates of superficial temporal vessels (anterograde and retrograde limbs) and controls (P > .05). Flap success rate of the test and control group is comparable, 95% vs 98% respectively. CONCLUSION: Superficial temporal vessels, both anterograde and retrograde, should be the first consideration for recurrent intraoral, facial, and scalp reconstruction with frozen necks.

Intracranial-Intracranial Bypass with a Graft Vessel: A Comprehensive Review of Technical Characteristics and Surgical Experience.

OBJECTIVE: Intracranial-intracranial (IC-IC) bypass with a graft vessel (IBGV) is a straightforward arterial reconstruction technique used for the treatment of complex aneurysms and skull base tumors. We have described the technical characteristics and summarized the clinical results of IBGV in complex cerebrovascular disorders. METHODS: We performed a search of the PubMed and Google Scholar online databases. The terms "intracranial-intracranial bypass," "jump graft bypass," "interposition graft bypass," "radial artery graft bypass," "saphenous vein graft bypass," and "superficial temporal artery graft bypass" were searched. Studies involving IBGV combined with other bypass methods were excluded. Illustrations of the technique have been provided to enhance comprehension. RESULTS: We identified 59 cases involving 6 types of graft vessels were identified from 1978 to July 2018. The IBGV technique was divided into the following 4 subtypes: type IA, in situ interposition graft bypass; type IB, Y-shaped double-barrel interposition graft bypass; type IIA, long jump graft bypass; and type IIB, Y-shaped double-barrel jump graft bypass. Grafts from the radial (44.1%; 26 of 59) and superficial temporal (39.3%; 22 of 59) arteries were used most frequently, and the middle cerebral artery territory was the most commonly involved region for IBGV. Of the cases with the specified postoperative characteristics, the graft patency and overall uneventful rates were 96.3% (52 of 54) and 82.2% (37 of 45), respectively. A higher patency rate (100% vs. 90.5%) and a lower complication rate (<20% vs. 60%) were observed with the type II group with an arterial graft. CONCLUSIONS: The IBGV method is a technically feasible option for vascular disease or complex cerebral tumors and should be considered by neurosurgeons. Long jump bypass with arterial grafts should be preferred when IC-IC bypass has been considered owing to the high rates of graft patency and favorable clinical outcomes.

Venous Congestion in Pedicled Frontal Branch Superficial Temporal Artery Flaps Reconstructions for Head and Neck Defects: A Review.

The superficial temporal artery (STA) flap is a versatile flap for head and neck defect reconstruction. It can be based on the frontal branch of the STA and an islanded 360-degree rotation arc for various defects on the scalp, cheek, and auricular region. It provides a nonmicrosurgical option for reconstructing such defects, which is itself relatively easy to perform. However, venous congestion is a problem than often can cause worry to the clinician and hence preclude its use. In this review, we revisit this flap in head and neck reconstruction, with case examples used for reconstruction of defects on the scalp, maxilla, lip, ear, and retroauricular area. The STA flap in our review can be used either as a fasciocutaneous flap or with its fascia alone. The main issue with the STA flap is that it is generally a high-inflow flap with variable outflow. Venous congestion is frequently encountered in our practice, and adequate management of the venous drainage in the postoperative period is crucial in ensuring its success as a versatile and viable option for head and neck reconstruction.

Analysis of In Vivo Serpin Functions in Models of Inflammatory Vascular Disease.

Serpins have a wide range of functions in regulation of serine proteases in the thrombotic cascade and in immune responses, representing up to 2-10% of circulating proteins in the blood. Selected serpins also have cross-class inhibitory actions for cysteine proteases in inflammasome and apoptosis pathways. The arterial and venous systems transport blood throughout the mammalian body representing a central site for interactions between coagulation proteases and circulating blood cells (immune cells) and target tissues, a very extensive and complex interaction. While analysis of serpin functions in vitro in kinetics or gel shift assays or in tissue culture provides very necessary information on molecular mechanisms, the penultimate assessment of biological or physiological functions and efficacy for serpins as therapeutics requires study in vivo in whole animal models (some also consider cell culture to be an in vivo approach).Mouse models of arterial transplant with immune rejection as well as models of inflammatory vasculitis induced by infection have been used to study the interplay between the coagulation and immune response pathways. We describe here three in vivo vasculitis models that are used to study the roles of serpins in disease and as therapeutics. The models described include (1) mouse aortic allograft transplantation, (2) human temporal artery (TA) xenograft into immunodeficient mouse aorta, and (3) mouse herpes virus (MHV68)-induced inflammatory vasculitis in interferon-gamma receptor (IFNγR) knockout mice.

Internal Maxillary Artery to Anterior Circulation Bypass with Local Interposition Grafts Using a Minimally Invasive Approach: Surgical Anatomy and Technical Feasibility.

BACKGROUND: The internal maxillary artery (IMA) is a reliable donor for extracranial-intracranial high-flow bypasses. However, previously described landmarks and techniques to harvest the IMA are complex and confusing and require extensive bone drilling, carrying significant neurovascular risk. The objective of our study was to describe a minimally invasive technique for exposing the IMA and to assess the feasibility of using the IMA as a donor for anterior-circulation recipient vessels using 2 different local interposition vessels. METHODS: Via a minimally invasive technique, the IMA was harvested in 10 cadaveric specimens and a pterional craniotomy was performed. Two interposition grafts-the superficial temporal artery (STA) and middle temporal artery-were evaluated individually. Transsylvian exposure of the second segment of middle cerebral artery (M2), the supraclinoid internal carotid artery, and the proximal postcommunicating anterior cerebral artery segment was completed. Relevant vessel calibers and graft lengths were measured for each bypass model. RESULTS: The mean caliber of the IMA was 2.7 ± 0.5 mm. Of all 3 recipients, the shortest graft length was seen in the IMA-STA-M2 bypass, measuring 42.0 ± 8.4 mm. There was a good caliber match between the M2 (2.4 ± 0.4 mm) and STA (2.3 ± 0.4 mm) at the anastomotic site. The harvested middle temporal artery was sufficient in length in only 30% cases, with a mean distal caliber of 2.0 ± 0.7 mm. CONCLUSIONS: This study confirmed the technical feasibility of IMA as a donor for an extracranial-intracranial bypass to the second segment of the anterior cerebral artery, M2, and the supraclinoid internal carotid artery. However, IMA-STA-M2 was observed to be the most suitable bypass model.

Inhibition of JAK-STAT Signaling Suppresses Pathogenic Immune Responses in Medium and Large Vessel Vasculitis.

BACKGROUND: Giant cell arteritis, a chronic autoimmune disease of the aorta and its large branches, is complicated by aneurysm formation, dissection, and arterial occlusions. Arterial wall dendritic cells attract CD4+ T cells and macrophages to form prototypic granulomatous infiltrates. Vasculitic lesions contain a diverse array of effector T cells that persist despite corticosteroid therapy and sustain chronic, smoldering vasculitis. Transmural inflammation induces microvascular neoangiogenesis and results in lumen-occlusive intimal hyperplasia. We have examined whether persistent vessel wall inflammation is maintained by lesional T cells, including the newly identified tissue-resident memory T cells, and whether such T cells are sensitive to the cytokine-signaling inhibitor tofacitinib, a Janus kinase (JAK) inhibitor targeting JAK3 and JAK1. METHODS: Vascular inflammation was induced in human arteries engrafted into immunodeficient mice that were reconstituted with T cells and monocytes from patients with giant cell arteritis. Mice carrying inflamed human arteries were treated with tofacitinib or vehicle. Vasculitic arteries were examined for gene expression (reverse transcription polymerase chain reaction), protein expression (immunohistochemistry), and infiltrating cell populations (flow cytometry). RESULTS: Tofacitinib effectively suppressed innate and adaptive immunity in the vessel wall. Lesional T cells responded to tofacitinib with reduced proliferation rates (<10%) and minimal production of the effector molecules interferon-γ, interleukin-17, and interleukin-21. Tofacitinib disrupted adventitial microvascular angiogenesis, reduced outgrowth of hyperplastic intima, and minimized CD4+CD103+ tissue-resident memory T cells. CONCLUSIONS: Cytokine signaling dependent on JAK3 and JAK1 is critically important in chronic inflammation of medium and large arteries. The JAK inhibitor tofacitinib effectively suppresses tissue-resident memory T cells and inhibits core vasculitogenic effector pathways.

Revascularization of the anterior cerebral artery by Y-shaped superficial temporal artery interposition graft for the treatment of a de novo aneurysm arising at the site of A3-A3 bypass: technical case report.

The most frequently used option to reconstruct the anterior cerebral artery (ACA) is an ACA-ACA side-to-side anastomosis. The long-term outcome and complications of this technique are unclear. The authors report a case of a de novo aneurysm arising at the site of A3-A3 anastomosis. A 53-year-old woman underwent A3-A3 side-to-side anastomosis for the treatment of a ruptured right A2 dissecting aneurysm. At 44 months after surgery, a de novo aneurysm developed at the site of anastomosis. The aneurysm developed in the front wall of the anastomosis site, and projected to the anterosuperior direction. A computational fluid dynamics (CFD) study showed the localized region with high wall shear stress coincident with the pulsation in the front wall of the anastomosis site, where the aneurysm developed. A Y-shaped superficial temporal artery (STA) interposition graft was used successfully to reconstruct both ACAs, and then the aneurysm was trapped. To the authors' knowledge, this is the first case of a de novo aneurysm that developed at the site of an ACA-ACA side-to-side anastomosis. A CFD study showed that hemodynamic stress might be an underlying cause of the aneurysm formation. A Y-shaped STA interposition graft is a useful option to treat this aneurysm. Long-term follow-up is necessary to detect this rare complication after ACA-ACA anastomosis.

Assessment of the Temporopolar Artery as a Donor Artery for Intracranial-Intracranial Bypass to the Middle Cerebral Artery: Anatomic Feasibility Study.

BACKGROUND: Intracranial-intracranial bypass is a valuable cerebral revascularization option. Despite several advantages, one of the main shortcomings of the intracranial-intracranial bypass is the possibility of ischemic complications of the donor artery. However, when sacrificed, the temporopolar artery (TPA) is not associated with major neurologic deficits. We sought to define the role of TPA as a donor for revascularization of the middle cerebral artery (MCA). METHODS: Pterional craniotomy was performed on 14 specimens. The TPA was released from arachnoid trabecula, and the small twigs to the temporal lobe were cut. The feasibility of side-to-side and end-to-side bypass to the farthest arterial targets on insular, opercular, and cortical MCA branches was assessed. The distance of the bypass point was measured in reference to limen insulae. RESULTS: A total of 15 TPAs were assessed (1 specimen had 2 TPAs). The average cisternal length of the TPA was 37.3 mm. For side-to-side bypass, the TPA was a poor candidate as an intracranial donor, except for the cortical orbitofrontal artery, which was reached in 87% of cases. However, the end-to-side bypass was successfully completed for most arteries (87%-100%) on the anterior frontal operculum and more than 50% of the cortical or opercular middle and posterior temporal arteries. There was no correlation between the TPA's cisternal length and maximum bypass reach. CONCLUSIONS: When of favorable diameter, the TPA is a competent donor for intracranial-intracranial bypass to MCA branches at the anterior insula, and anterior frontal and middle temporal opercula (arteries anterior to the precentral gyrus coronal plane).

Aesthetic Eyebrow Reconstruction with an Expanded Scalp Island Flap Pedicled by the Superficial Temporal Artery.

PURPOSE: This case study demonstrates a new operative method of eyebrow reconstruction, in which the hair density of the reconstructed eyebrow is controlled by the surgeon and is more similar to that of the uninjured side, resulting in a more natural facial expression and greater aesthetic value for our patients. MATERIALS AND METHODS: The operation was divided into two stages: Stage 1: Implantation of a soft tissue expander into the corresponding subgaleal position of the parietal branch of the superficial temporal artery on the injured side, followed by dilation of the expander until the density of the hair on the expanded scalp reached a suitable value and was lower than that of the uninjured eyebrow. Stage 2: Harvesting of the scalp island flap pedicled by the superficial temporal artery, the end of which was attached to the expanded scalp, followed by the downward movement of the flap to the defect site of the eyebrow via a subcutaneous tunnel, resulting in new eyebrow formation. RESULTS: In eight cases who were monitored for 4-16 months of follow-up, almost all of the reconstructed eyebrows successfully assumed a desirable shape and exhibited a natural appearance, which was consistent with preoperative expectations; the transplanted hairs were highly similar to those of the original eyebrows. All participants remained healthy after the operation, which was indicated by sufficient blood supply to the expanded flap and normal growth of a new eyebrow without postoperative complications. CONCLUSION: Our study demonstrated the excellent performance of an innovative procedure in which a expanded scalp island flap pedicled by the superficial temporal artery was used in the construction of a new eyebrow. It can be performed very safely and reliably to ensure expected results. LEVEL OF EVIDENCE V: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Free temporal artery posterior auricular skin (TAPAS) flap: A new option in facial and intra-oral reconstruction.

BACKGROUND: There is a limited availability of suitable microvascular free flap options for the reconstruction of small to medium-sized facial and intraoral defects. The purpose of this report is to present a new free temporal artery based posterior auricular skin (TAPAS) flap in facial and intraoral reconstruction. PATIENTS AND METHODS: Four patients were deemed suitable for TAPAS flap reconstruction and consisted of two males and two females with a mean age of 43 years (range 22-66). Defect aetiology and location comprised of post-traumatic lower eyelid scarring, late lower lip scarring post tumour resection, and floor of mouth and tongue defects following tumour resection. The dimensions of the resultant defects ranged from 25 × 50 mm (smallest) to 40 × 70 mm (largest). All patients underwent microvascular reconstruction using a free fasciocutaneous TAPAS flap raised from the retroauricular region based on the superficial temporal vessels. RESULTS: The maximal pedicle length was 60 mm and the maximum flap size measured 40 mm by 70 mm. The latter patient required skin grafting of the postauricular donor site. Postoperatively, there was one case of mild transient venous congestion that spontaneously resolved after 2 days and one case of minor partial flap dehiscence that required re-suturing. Follow-up time ranged from 6 to 14 months. Overall, all flaps survived with good aesthetic and functional outcome. CONCLUSION: The TAPAS flap is a small flap with exceptional qualities and may be a useful addition to the armamentarium of free flaps in facial and oral reconstructions. © 2016 Wiley Periodicals, Inc. Microsurgery 37:525-530, 2017.

The anterior temporal artery: an underutilized but robust donor for revascularization of the distal middle cerebral artery.

OBJECTIVE The anterior temporal artery (ATA) supplies an area of the brain that, if sacrificed, does not cause a noticeable loss of function. Therefore, the ATA may be used as a donor in intracranial-intracranial (IC-IC) bypass procedures. The capacities of the ATA as a donor have not been studied previously. In this study, the authors assessed the feasibility of using the ATA as a donor for revascularization of different segments of the distal middle cerebral artery (MCA). METHODS The ATA was studied in 15 cadaveric specimens (8 heads, excluding 1 side). First, the cisternal segment of the artery was untethered from arachnoid adhesions and small branches feeding the anterior temporal lobe and insular cortex, to evaluate its capacity for a side-to-side bypass to insular, opercular, and cortical segments of the MCA. Any branch entering the anterior perforated substance was preserved. Then, the ATA was cut at the opercular-cortical junction and the capacity for an end-to-side bypass was assessed. RESULTS From a total of 17 ATAs, 4 (23.5%) arose as an early MCA branch. The anterior insular zone and the frontal parasylvian cortical arteries were the best targets (in terms of mobility and caliber match) for a side-to-side bypass. Most of the insula was accessible for end-to-side bypass, but anterior zones of the insula were more accessible than posterior zones. End-to-side bypass was feasible for most recipient cortical arteries along the opercula, except for posterior temporal and parietal regions. Early ATAs reached significantly farther on the insular MCA recipients than non-early ATAs for both side-to-side and end-to-side bypasses. CONCLUSIONS The ATA is a robust arterial donor for IC-IC bypass procedures, including side-to-side and end-to-side techniques. The evidence provided in this work supports the use of the ATA as a donor for distal MCA revascularization in well-selected patients.

Topographic Surgical Anatomy of the Parasylvian Anterior Temporal Artery for Intracranial-Intracranial Bypass.

BACKGROUND: The anterior temporal artery (ATA) is an appealing donor artery for intracranial-intracranial bypass procedures. However, its identification may be difficult. Current literature lacks useful landmarks to help identify the ATA at the surface of the sylvian fissure. The objective of this study was to define the topographic anatomy of the cortical segment of the ATA relative to constant landmarks exposed during the pterional approach. METHODS: The temporopolar artery (TPA), ATA, and middle temporal artery (MTA) were examined in 16 cadaveric specimens. The topographic anatomy and key landmarks of the arteries at the sylvian fissure were recorded. The distance between the point of emergence from the sylvian fissure to the lesser sphenoid wing and anterior tip of the temporal lobe was measured. The features of the inferior frontal gyrus relative to each of the arteries at the sylvian fissure were also recorded. RESULTS: The average distances from the lesser sphenoid wing to the TPA, ATA, and MTA were 3.7 mm, 21.2 mm, and 37 mm. The mean distances from the temporal pole were TPA, 14.7 mm; ATA, 32.0 mm; and MTA, 45.4 mm. The differences between the average distances were statistically significant (P < 0.0001). The ATA most frequently faced pars triangularis, whereas the TPA always faced pars orbitalis. The MTA was always found posterior to the junction of pars triangularis and pars opercularis. CONCLUSIONS: This article provides topographic evidence for efficient identification of the ATA in the parasylvian space. The key relationship and landmarks identified in this study may increase efficiency and safety when harvesting the ATA for intracranial-intracranial bypass.

4D flow MRI assessment of extracranial-intracranial bypass: qualitative and quantitative evaluation of the hemodynamics.

INTRODUCTION: Our aim was to assess the feasibility of using time-resolved 3D phase-contrast (4D flow) MRI to characterize extracranial-intracranial (EC-IC) bypass. METHODS: We enrolled 32 patients who underwent EC-IC bypass (15 men, 17 women; mean age 66.4 years). In all, 16 underwent radial artery graft (RAG) bypass and 16 underwent superficial temporal artery (STA) bypass. 4D flow MRI, time-of-flight (TOF) magnetic resonance angiography (MRA), and computed tomography angiography (CTA) were performed. Bypass patency, flow direction, and blood flow volume (BFV) of each artery were determined by 4D flow MRI. Arterial diameters were measured by TOF-MRA and CTA. We compared RAG and STA bypasses by evaluating the flow direction and BFV of each artery. We evaluated the correlation between arterial diameters (measured by CTA or MRA) and the BFV and the detectability of flow direction (measured by 4D flow MRI) of each artery. RESULTS: 4D flow MRI confirmed the patency of each bypass artery. Flow direction of the M1 segment of the middle cerebral artery and BFV in the bypass artery differed between RAG and STA groups (p < 0.01). BFV in the bypass slightly correlated with the diameters on CTA (p < 0.05, R (2) = 0.287). Of the 29 arteries in the circle of Willis, nine were not depicted on 4D flow MRI. Cutoff values for arterial diameters on CTA and TOF-MRA for detecting the artery on 4D flow MRI were 2.4 and 1.8 mm, respectively. CONCLUSION: 4D flow MRI provided unique information for characterizing EC-IC bypasses, although this detectability is limited when addressing small arteries with slow flow.