Case Report of Ruptured Large Fusiform Distal Anterior Cerebral Artery Aneurysm Treated With A3-A3 In Situ Bypass, Reimplantation, and Trapping With Aneurysmectomy: 2-Dimensional Operative Video.

Large fusiform aneurysms in the distal anterior cerebral territory are infrequent and pose considerable treatment challenges, as they necessitate comprehensive aneurysm resolution without compromising physiological flow dynamics.1-3 We present the case of a 52-year-old man with a ruptured distal anterior cerebral artery fusiform aneurysm. The patient consented to the procedure; this complex condition was successfully managed through an A3-A3 in situ bypass, branch reconstruction, and trapping accompanied by aneurysmectomy. The multifaceted nature of fusiform lesions precludes the feasibility of endovascular interventions as a sole remedy. In addition, reconstructive and deconstructive approaches exhibit elevated mortality rates in patients experiencing high-grade subarachnoid hemorrhage.1,4 Given the intricacies intrinsic to this clinical context and the exigent nature of fusiform aneurysms, the surgical therapeutic arsenal embraces a diverse array of surgical methodologies, each offering a bespoke spectrum of techniques meticulously tailored to attain predefined objectives.3,5-7 These approaches are attuned to promptly abrogate imminent threats, while concurrently mitigating latent complications linked to subarachnoid hemorrhage ensuing from aneurysmal rupture, encompassing the specters of rebleeding, ischemic stroke, and edematous sequelae.8,9 Crucially, the selection of the most appropriate surgical approach hinges on a comprehensive understanding of available options, patient-specific anatomic considerations, and the preferences of the neurosurgeon. Such a nuanced decision-making process ensures an individualized treatment strategy tailored to optimize patient outcomes.3,6.

Microsurgical thrombectomy: where the ancient art meets the new era.

Mechanical thrombectomy (MT) is the leading treatment for acute large vessel occlusion (LVO). However, surgical thrombectomy (ST) may have a role in well selected LVO patients where MT failed to re-establish flow, the endovascular route is inaccessible, or where MT is a financially prohibitive or absent option (developing and poor countries). We compared the efficacy and efficiency between ST and MT, and described our operative experience and its potential application in the developing world. Clinical outcomes, procedural times, and efficacy of treatment were compared between the MT and ST of acute LVO between 2012 and 2022. Propensity score-matched analysis was also conducted to compare MT and ST. One-hundred nine patients fulfilled the study criteria (77 MTs vs 32 STs). Factors driving outcome were age (aOR: 0.95, 95%CI, 0.91-0.98), hemisphere side (aOR: 0.38, 95%CI, 0.15-0.96), and DWI-ASPECT (aOR: 1.39, 95%CI, 1.09-1.77) at presentation by the multivariate analysis. Times from door-start of procedure (P = 0.45) and start of procedure-recanalization (P = 0.13) were similar between treatment options. Propensity score-matched analysis found no significant difference for 2 treatment methods about time of door to recanalization (P = 0.155) and outcome (P = 0.221). The prognosticators of thrombectomy for acute LVO in patients with successful recanalization were age, affected hemisphere side, and DWI-ASPECT score. Our evidence shows that the efficacy of ST is similar to that of MT. There should be a place of ST for cases of mechanical failure or tandem cervical ICA and MCA occlusion. ST may be a temporizing LVO treatment option in healthcare systems where MT is inexistent or financially prohibitive to patients.

Basal vein of Rosenthal classification: the key to venous outflow of the deep sylvian fissure.

OBJECTIVE: Mastery of sylvian fissure dissection is essential to access lesions within the deep basal cisterns. The deep sylvian vein and its tributaries play a major role during access to and beyond the carotid cistern through the sylvian fissure and determine the complexity of microdissection. Preserving the venous outflow during sylvian fissure dissection is the best reliable strategy to prevent postoperative venous strokes or venous hypertension. The authors report the role of the basal vein of Rosenthal (BVR) in the venous outflow pattern of the deep sylvian cistern. METHODS: The authors analyzed 262 consecutive surgical cases involving sylvian fissure dissection from 2015 to 2017. Inclusion criteria were complete sylvian fissure dissection for the treatment of intracranial aneurysms. Exclusion criteria were giant size (aneurysm diameter > 24 mm), meningitis, subarachnoid hemorrhage within the sylvian cistern, absence of 4D CT angiography, and previous surgery. Retrospective radiological and operative video reviews were carried out to assess the association between the superficial sylvian vein and the BVR. The authors analyzed the course of the BVR and the patterns of venous drainage of the sylvian cistern. The surgical difficulty of sylvian fissure dissection was rated by the authors to study the operative significance of the venous patterns encountered. Two clinical cases are described to illustrate the proposed BVR classification. RESULTS: A total of 97 patients met the selection criteria. The most frequent type of BVR was immature (diameter < 0.5 mm, 68%). When the BVR was incompletely developed or absent (immature type), the deep sylvian veins drained through a middle sylvian vein in 70% of cases, requiring advanced sylvian fissure dissection techniques. However, when the BVR was completely developed (32%), the middle sylvian vein was found in a minority of cases (6%), which allowed for an unobstructed transsylvian corridor. Interrater and test-retest reliability of the surgical difficulty was greater than 0.9. CONCLUSIONS: Preoperative assessment of the BVR anatomy is key to predict the deep sylvian venous pattern. The authors provide objective evidence supporting the reciprocal relationship between the type of BVR and the presence of a middle sylvian vein and the deep sylvian venous outflow. An immature BVR should alert the neurosurgeon of the high likelihood of finding a complex deep venous pattern, which may drive surgical planning.

Current Mouse Models of Intracranial Aneurysms: Analysis of Pharmacological Agents Used to Induce Aneurysms and Their Impact on Translational Research.

Intracranial aneurysms (IAs) are rare vascular lesions that are more frequently found in women. The pathophysiology behind the formation and growth of IAs is complex. Hence, to date, no single pharmacological option exists to treat them. Animal models, especially mouse models, represent a valuable tool to explore such complex scientific questions. Genetic modification in a mouse model of IAs, including deletion or overexpression of a particular gene, provides an excellent means for examining basic mechanisms behind disease pathophysiology and developing novel pharmacological approaches. All existing animal models need some pharmacological treatments, surgical interventions, or both to develop IAs, which is different from the spontaneous and natural development of aneurysms under the influence of the classical risk factors. The benefit of such animal models is the development of IAs in a limited time. However, clinical translation of the results is often challenging because of the artificial course of IA development and growth. Here, we summarize the continuous improvement in mouse models of IAs. Moreover, we discuss the pros and cons of existing mouse models of IAs and highlight the main translational roadblocks and how to improve them to increase the success of translational IA research.

Optimizing the Approach to STA-MCA Bypass Surgery and Reducing Wound Complications.

BACKGROUND AND OBJECTIVES: The treatment of complex intracranial aneurysms with bypass surgery using 2 branches of the superficial temporal artery (STA) proves to be an effective surgical option. However, the harvest of these 2 STA branches, combined with a pterional craniotomy, carries the potential risk of delayed wound healing of the skin flap. This study undertook a retrospective analysis to examine and identify the factors associated with this delayed wound healing. METHODS: A total of 56 consecutive cases, including both ruptured and unruptured complex intracranial aneurysms, that underwent bypass surgery with 2 branches of the STA, were analyzed retrospectively. RESULTS: Major delayed wound healing was observed in 6 (10.7%) cases. Univariate analysis demonstrated significant associations with the following factors: rupture (P = 0.023), presence of diabetes mellitus (P = 0.028), large craniotomy size (P = 0.012), and the type of skin incision (P ≤ 0.001). Age (P = 0.283), sex (P = 0.558), body mass index (P = 0.221), and other blood test parameters did not demonstrate any statistical significance. Similarly, the presence of a dominant frontal branch (P = 0.515) or a low-positioned frontal branch (P = 0.622) did not reveal statistically significant results. CONCLUSIONS: In the treatment of complex intracranial aneurysms, where harvesting of the 2 STA branches is involved with a pterional craniotomy, producing a smaller skin flap (L- or T-shaped incision) is effective in minimizing the risk of delayed wound healing. The process of harvesting the STA and closing the wound demands meticulous care, taking into consideration the normal anatomical structures and the subdermal vascular plexus of the scalp.

Bypass Surgery for Vertebral Artery and Posterior Inferior Cerebellar Artery Fusiform Aneurysms: Surgical Technique and Key Lessons.

Fusiform vertebral artery (VA) aneurysms are challenging to treat due to their pathophysiology, morphology, and anatomic location.1,2 Endovascular treatments are considered to be a widely adopted safe option for this pathology.1 Open microsurgical treatment is considered for complex anatomy, important branch involvement, poor collateral flow, or failed endovascular therapy.3-7 This report aims to show the flow-replacement strategy and bypass technique for a VA aneurysm with complex anatomy and branch involvement. A 24-year-old man presented to our clinic with a bilateral fusiform VA aneurysm discovered during workup of progressive headaches. Further investigation revealed that the left-side aneurysm was mostly thrombosed and the posterior inferior cerebellar artery arose from the aneurysm dome with a fusiform enlargement within a few millimeters from the branching point. After evaluating all management options, the patient decided on surgical treatment of the left VA aneurysm. We performed an occipital artery to posterior inferior cerebellar artery end-to-side anastomosis distal to the fusiform enlargement, followed by trapping of the aneurysm and dome resection (Video 1). Antegrade flow to the distal VA was reestablished using a radial artery interposition graft, thus preventing any flow alterations that may cause growth or rupture of the contralateral aneurysm caused by increased hemodynamic stress if the ipsilateral VA flow is not preserved.8 After in-hospital physical rehabilitation, the patient was discharged with a modified Rankin Scale score of 1. The contralateral aneurysm is managed with serial imaging and treatment will ensue if there is clinical-radiologic evolution. The patient consented to the procedure and publication of his image.

Dome Resection and End-to-End Reanastomosis for a Middle Cerebral Artery Fusiform Aneurysm of the M1 Segment: 2-Dimensional Operative Video.

Fusiform aneurysms of the middle cerebral artery (MCA) are both relatively uncommon and challenging to treat given their pathophysiology, morphology, and anatomy (e.g., perforating arteries involvement).1,2 Endovascular treatment of fusiform MCA aneurysms can achieve good outcomes in well-selected cases.3,4 Open microsurgical strategies are effective in a case of fusiform MCA aneurysms with complex anatomy or perforator involvement.2,5,6 We demonstrate the bypass strategy for resection of a fusiform M1 MCA aneurysm (Video 1). A 48-year-old female was referred for the treatment of a growing incidental right M1 MCA fusiform aneurysm. Imaging showed a tortuous M1 segment with no apparent perforator involvement, which we considered a candidate for resection and reanastomosis. A modified minipterional transsylvian approach was performed as described earlier.7,8 A double superficial temporal artery to middle cerebral artery bypass was performed to maintain flow to MCA territory and distal perforators in anticipation of a long temporary flow arrest due to complex aneurysmal dissection and reanastomosis and also to serve as long-term protective insurance. Resection and end-to-end reanastomosis will preserve the antegrade flow and prevent the risk stump thrombosis carried by a simple trapping.9,10 We cover the nuances of this technique including key steps to an efficient aneurysmal resection and complication avoidance. The patient tolerated the procedure well, and postoperative imaging showed no aneurysmal remnant and flow restoration with no evidence of stroke. We discharged the patient home with a modified Rankin scale of 0. The patient consented to the procedure and publication of his or her image.

Increased PDGFRB and NF-κB signaling caused by highly prevalent somatic mutations in intracranial aneurysms.

Intracranial aneurysms (IAs) are a high-risk factor for life-threatening subarachnoid hemorrhage. Their etiology, however, remains mostly unknown at present. We conducted screening for sporadic somatic mutations in 65 IA tissues (54 saccular and 11 fusiform aneurysms) and paired blood samples by whole-exome and targeted deep sequencing. We identified sporadic mutations in multiple signaling genes and examined their impact on downstream signaling pathways and gene expression in vitro and an arterial dilatation model in mice in vivo. We identified 16 genes that were mutated in at least one IA case and found that these mutations were highly prevalent (92%: 60 of 65 IAs) among all IA cases examined. In particular, mutations in six genes (PDGFRB, AHNAK, OBSCN, RBM10, CACNA1E, and OR5P3), many of which are linked to NF-κB signaling, were found in both fusiform and saccular IAs at a high prevalence (43% of all IA cases examined). We found that mutant PDGFRBs constitutively activated ERK and NF-κB signaling, enhanced cell motility, and induced inflammation-related gene expression in vitro. Spatial transcriptomics also detected similar changes in vessels from patients with IA. Furthermore, virus-mediated overexpression of a mutant PDGFRB induced a fusiform-like dilatation of the basilar artery in mice, which was blocked by systemic administration of the tyrosine kinase inhibitor sunitinib. Collectively, this study reveals a high prevalence of somatic mutations in NF-κB signaling pathway-related genes in both fusiform and saccular IAs and opens a new avenue of research for developing pharmacological interventions.

High-Flow Bypass and Trapping of a Ruptured Internal Carotid Artery Blister Aneurysm: Operative Principles and Key Lessons.

Blood blister-like aneurysms (BBAs) are infrequent but challenging small aneurysms with fragile domes consisting of a thin adventitia layer.1 Flow diversion and microsurgical trapping are acceptable treatment options. While endovascular treatment is becoming the first choice in developed countries, it is prohibitive in most developing countries, where microsurgical treatment is the only feasible option. Microsurgical treatment offers superior obliteration rates at similar neurologic outcomes than endovascular treatment.1-3 Mastering high-flow revascularization and pressure monitoring is necessary to improve outcomes of BBA, especially in the developing world. We present our operative principles, which involve pressure monitoring and a high-flow bypass to ensure sufficient post-trapping cerebral pressure.4 A 53-year-old lady was found to have a modified Fisher 4 subarachnoid hemorrhage after the worst headache of her life. Endovascular flow diversion and trapping and bypass were discussed with the patient and family. A right internal carotid artery BBA was trapped (Video 1). A right superficial temporal artery to M4 middle cerebral artery (MCA) bypass was used to both maintain perfusion during a high-flow bypass and to measure cerebral blood pressure. An external carotid artery to MCA bypass using a saphenous vein graft provided >80% of baseline MCA arterial pressure, which prevents delayed ischemic strokes.4 The patient tolerated the procedure well and was discharged home without deficits on postoperative day 15 after vasospasm watch. The patient consented to the procedure and provided consent to the publication of her images.

The Microcisternal Drainage Technique.

BACKGROUND: Microsurgical dissection of arachnoid cisterns requires a combination of anatomic knowledge and microsurgical skill. The latter relies on experience and microsurgical dexterity, which depend on visual identification of cisternal microvasculature. We describe a novel standardized operative sequence to allow for bloodless arachnoid dissection when cisternal anatomy is challenging. METHODS: We used the reported technique in 1928 cases over the past 5 years (2018-2022). The outer arachnoid was incised to enter the cisternal space. A cotton pledget was placed in contact with an inner membrane and gently pushed laterally and superficially with the suction cannula at medium suction power. When the arachnoid membranes dried, arachnoid trabeculae were cut and microvasculature were released at the convexity of their loops and gently transposed off the dissection trajectory. The same principle was used to release parent and perforating arteries from the aneurysm dome. RESULTS: The microcisternal drainage technique enabled safe and efficient access through adhered arachnoid in all cases. A complex anterior communicating artery aneurysm in a 52-year-old lady demonstrated the use of the microcisternal drainage technique during access through the pericallosal cistern. This technique was used in all cases where cisternal dissection was needed. CONCLUSIONS: The microcisternal drainage technique uses deliberate and strategic suction, dynamic retraction, and nuanced scissor cuts to enable precise and bloodless microdissection of adherent arachnoid cisterns. This technique combines common neurosurgical maneuvers in a novel standardized sequence to improve efficiency and safety during arachnoid dissection.

Reverse Suction Decompression Using the Superior Thyroid Artery During Clipping of a Complex Anterior Choroidal Artery Aneurysm.

Direct aneurysmal suction decompression was first described by Dr. Flamm in 1981 to improve safety and ease clipping of complex aneurysms by deflating their dome.1 This technique evolved over the following decade, from direct aneurysmal puncture to indirect-reverse-suction decompression (RSD).2,3 The conventional technique for RSD involves a cannulation of the internal (ICA) or common (CCA) carotid arteries.2-9 Direct puncture of either the CCA or ICA carry risk of arterial wall damage (e.g., dissection), which may result in significant morbidity.10,11 We routinely cannulate the superior thyroidal artery (SThA) as the vascular access to perform RSD. This subtle technical nuance prevents dissection of either the CCA or ICA while providing a reliable source for RSD.12 In this operative video, the SThA was cannulated to apply reverse suction decompression, which allowed releasing perforating arteries from the dome of an anterior choroidal artery aneurysm in a 68-year-old lady. The patient tolerated the procedure well, was discharged without neurologic deficits, and resumed normal life with no aneurysm remnant. The patient consented to the procedure and video/photography publication. RSD is an optimal technique to enhance efficiency and safety when dissecting around the dome of a complex intradural ICA aneurysm. The use of the SThA avoids the risk of ICA or CCA wall damage due to access, which defeats the protective purpose of RSD itself. Video 1 provides an educational example of the SThA cannulation technique for RSD during dissection and clipping of a complex anterior choroidal artery aneurysm.

A case of facial nerve palsy caused by severe head injury treated by translabyrinthine approach.

Background: Several treatments for traumatic facial paralysis have been reported, but the role of surgery is still controversial. Case Description: A 57-year-old man was admitted to our hospital with head trauma due to a fall injury. A total body computed tomography (CT) scan showed a left frontal acute epidural hematoma associated with a left optic canal and petrous bone fractures with the disappearance of the light reflex. Hematoma removal and optic nerve decompression were performed immediately. The initial treatment was successful with complete recovery of consciousness and vision. The facial nerve paralysis (House and Brackmann scale grade 6) did not improve after medical therapy, and thus, surgical reconstruction was performed 3 months after the injury. The left hearing was lost entirely, and the facial nerve was surgically exposed from the internal auditory canal to the stylomastoid foramen through the translabyrinthine approach. The facial nerve's fracture line and damaged portion were recognized intraoperatively near the geniculate ganglion. The facial nerve was reconstructed using a greater auricular nerve graft. Functional recovery was observed at the 6-months follow-up (House and Brackmann grade 4), with significant recovery in the orbicularis oris muscle. Conclusion: Interventions tend to be delayed, but it is possible to select a treatment method of the translabyrinthine approach.

A case of anterior choroidal artery occlusion test under MEP monitoring for a recurrent internal carotid artery-anterior choroidal artery bifurcation aneurysm clipping.

A 59-year-old female with recurrent Anterior Choroidal Artery (AchA) aneurysm was elected for surgery at our institution through a standard pterional approach. Two thin perforating branches were found to origin from the dome of the aneurysm during operation, and therefore complete aneurysm clipping preserving these branches was not feasible. These perforating branches were temporarily occluded under motor-evoked potential (MEP) monitoring. The MEPs remained stable during 10 min of temporary clipping, and we concluded that these branches could be sacrificed, and therefore neck clipping was performed occluding these tiny AchA perforators. Although postoperative magnetic resonance imaging with diffusion-weighted images showed ischemic signs in left AchA territory after the operation, the patient remained asymptomatic and was discharged home with mRS 0.

"Microcisternal Drainage" Technique for Clipping a Middle Cerebral Artery Aneurysm.

Arachnoid dissection is often challenging because of tight corridors, microvasculature crossing the membranes, and a narrow operative field.1-4 It is often said that "splitting" the sylvian fissure measures the talent of a cerebrovascular neurosurgeon, and there are as many styles of sylvian fissure dissection as neurosurgical schools.4-8 Our principle is to dissect the subarachnoid space sharply and with minimal trauma to neither the microvasculature nor the pia matter.4,7-10 We have developed a technique that allows efficient and safe sharp dissection through the subarachnoid space: the "microcisternal drainage" technique. This technique (Video 1) consists of applying a pledget to a narrow cistern and suctioning the cerebrospinal fluid while maintaining uplifting retraction with the suction shaft. Clear trabeculae are dissected sharply to release microvessels at the convexity of their turns. This technique is especially advantageous when cisterns are narrow (e.g., pia-to-pia) or highly eloquent structures are at risk. The main advantages over conventional cisternal dissection are avoidance of refractive effect, enhanced identification of the microvasculature from the trabeculae, and preservation of pia matter. Using the microcisternal drainage technique, the microvasculature, arachnoid membranes, and pia reveal themselves, and we avoid the cerebrospinal fluid-related refractive effect, therefore maximizing depth perception. We report an example of the "microcisternal drainage" technique to split the sylvian fissure during treatment of an irregular middle cerebral artery bifurcation aneurysm on a 56-year-old woman. The patient tolerated the procedure well, was discharged without neurologic deficits, and resumed normal life with no aneurysm remnant. The patient consented to the procedure and video and photography publication.

From textbook to patient: a practical guide to train the end-to-side microvascular anastomosis.

Microvascular anastomosis is one of the most challenging neurosurgical techniques. Mastering this technique allows to perform intracranial bypass with arteries of small caliber usually placed in deep narrow surgical fields. The aim of this paper is to describe step by step end-to-side microanastomosis training method by using polyvinyl alcohol (PVA) hydrogel tubing as it is easily reproducible. The tubing comes in sizes from 0.3 mm to 5 mm and has a texture and consistency similar to real vessels. This is based on the Teishinkai Hospital anastomosis technique. Continuous practice in microvascular anastomosis is of great importance in training vascular neurosurgeon. The PVA hydrogel tubing described in this article are useful and cost-effective material in the training of microvascular anastomosis. This practical guide model is easy to set up for repeated practice, and will contribute to facilitate 'off-the-job' training by young neurosurgeons and the development and maintenance of microsurgical skills in both resident neurosurgeons and experts who wish to master the various levels of anastomosis technique. There is no shortcut to master this technique, only hard work and perseverance.

Slow-Closing Clip for the Treatment of Nonsaccular Vertebrobasilar Aneurysms: A Retrospective Case Series.

OBJECTIVE: Vertebrobasilar artery nonsaccular aneurysms (VBANSAs) are associated with a 13% annual mortality. Revascularization and flow diversion are life-saving options in select cases; technical failures and rapid hemodynamic changes may contribute to unwanted outcomes. We describe a technique and report clinical outcomes of patients treated with an experimental slow-closing clip (SCC). METHODS: An experimental SCC was created to gradually close the parent artery of aneurysms. Clinical, radiographic, and outcome data from patients with VBANSAs who underwent experimental treatment with the SCC were retrospectively analyzed. RESULTS: Among 10 patients (7 men; mean age, 49.5 years; range, 18-73 years), 6 presented with mass effect symptoms, 1 with ischemic stroke, 2 with subarachnoid hemorrhage, and 1 with hydrocephalus. Five patients underwent revascularization plus SCC application, and 5 were treated with SCC alone. The mean follow-up was 6.7 years. The expected mortality among patients with unruptured VBANSAs with previous treatment options in this period was 52.7%, whereas the observed rate was 20%. Four patients died within 12 months after treatment. Causes of death were brainstem ischemic stroke, poor-grade subarachnoid hemorrhage, poor clinical presentation, and unknown. Six patients were alive at last follow-up, with unchanged or improved modified Rankin Scale scores. Mortality was associated with posterior-projecting aneurysms and late-stage treatment. CONCLUSIONS: In this small case series, use of SCC overcame the natural history of VBANSAs when treatment timing and aneurysm anatomy were suitable. The SCC potentially favors aneurysm thrombosis and collateral reactivation. More studies are necessary to better develop the SCC.