A comprehensive review of the vertebral artery anatomy.

BACKGROUND: The vertebral arteries (VA) play a critical role by supplying nearly one-third of the brain's blood flow, predominantly contributing to the posterior circulation. These arteries may need to be exposed in a various cranial and cervical procedures and offers access to investigate or treat vascular lesions by endovascular means related to the posterior circulation. Given its complex anatomy, which is subject to numerous variations, and its role in supplying vital brain regions, a thorough understanding of the VA's anatomy is paramount for any related procedure. OBJECTIVE: To provide a comprehensive overview of vertebral artery anatomy and its relevance in contemporary clinical practice. METHODS: Dissection of the entire vertebral artery length using cadaveric specimen, combined with a comprehensive literature review. RESULTS: The vertebral artery can be subdivided into four segments. Each of these segments has its own unique topographic anatomy with its variations, anastomoses, and significance in surgery. CONCLUSION: As surgical and endovascular techniques continue to evolve with technological improvements, we are now more equipped than ever to manage complex lesions involving the VA. However, with its increasingly complexity comes the necessity for a deeper and more comprehensive understanding of the VA. Possessing the detailed knowledge of the VA is vital for the successful execution of any procedure involving it.

Spontaneous intracranial vertebral artery dissections presenting with subarachnoid hemorrhage.

BACKGROUND: Vertebral artery dissection (VAD) is an infrequent source of subarachnoid hemorrhage (SAH), with a high mortality rate, primarily due to the risk of rebleeding both before and after medical intervention. This paper provides a comprehensive analysis of the anatomy, pathophysiology, clinical presentation, treatment strategies, and outcomes of intracranial vertebral artery dissections that result in subarachnoid hemorrhage. METHODS: Comprehensive five-year literature review (2018-2022) and a retrospective analysis of patient records from our institution between 2016 and 2022. We included studies with a minimum of 5 patients. RESULTS: The study incorporated ten series from the literature and 22 cases from CHUM. Key anatomical factors increasing the risk of VAD include the vertebral artery's origin from the aortic arch, asymmetry of the vertebral artery, and its tortuosity. Patients may display specific collagen and genetic abnormalities. The occurrence of VAD appears to be more prevalent in men. Those with a ruptured intracranial VAD typically show prodromal symptoms and present with severe SAH. Rebleeding within the first 24 h is frequent. While standard imaging methods are usually adequate for VAD diagnosis, they may not provide detailed information about the perforator anatomy. Treatment approaches include both deconstructive and reconstructive methods. CONCLUSION: Ruptured VAD is a critical, life-threatening condition. Many patients have a poor neurological status at presentation, and rebleeding prior to treatment is a significant concern. Deconstructive techniques are most effective in preventing rebleeding, whereas the efficacy of reconstructive techniques needs more investigation.

Hemodynamic factors of spontaneous vertebral artery dissecting aneurysms assessed with numerical and deep learning algorithms: Role of blood pressure and asymmetry.

BACKGROUND AND OBJECTIVES: The pathophysiology of spontaneous vertebral artery dissecting aneurysms (SVADA) is poorly understood. Our goal is to investigate the hemodynamic factors contributing to their formation using computational fluid dynamics (CFD) and deep learning algorithms. METHODS: We have developed software that can use patient imagery as input to recreate the vertebrobasilar arterial system, both with and without SVADA, which we used in a series of three patients. To obtain the kinematic blood flow data before and after the aneurysm forms, we utilized numerical methods to solve the complex Navier-Stokes partial differential equations. This was accomplished through the application of a finite volume solver (OpenFoam/Helyx OS). Additionally, we trained a neural ordinary differential equation (NODE) to learn and replicate the dynamical streamlines obtained from the computational fluid dynamics (CFD) simulations. RESULTS: In all three cases, we observed that the equilibrium of blood pressure distributions across the VAs, at a specific vertical level, accurately predicted the future SVADA location. In the two cases where there was a dominant VA, the dissection occurred on the dominant artery where blood pressure was lower compared to the contralateral side. The SVADA sac was characterized by reduced wall shear stress (WSS) and decreased velocity magnitude related to increased turbulence. The presence of a high WSS gradient at the boundary of the SVADA may explain its extension. Streamlines generated by CFD were learned with a neural ordinary differential equation (NODE) capable of capturing the system's dynamics to output meaningful predictions of the flow vector field upon aneurysm formation. CONCLUSION: In our series, asymmetry in the vertebrobasilar blood pressure distributions at and proximal to the site of the future SVADA accurately predicted its location in all patients. Deep learning algorithms can be trained to model blood flow patterns within biological systems, offering an alternative to the computationally intensive CFD. This technology has the potential to find practical applications in clinical settings.

Using artificial intelligence to quantify dynamic retraction of brain tissue and the manipulation of instruments in neurosurgery.

PURPOSE: There is no objective way to measure the amount of manipulation and retraction of neural tissue by the surgeon. Our goal is to develop metrics quantifying dynamic retraction and manipulation by instruments during neurosurgery. METHODS: We trained a convolutional neural network (CNN) to analyze microscopic footage of neurosurgical procedures and thereby generate metrics evaluating the surgeon's dynamic retraction of brain tissue and, using an object tracking process, evaluate the surgeon's manipulation of the instruments themselves. U-Net image segmentation is used to output bounding polygons around cerebral parenchyma of interest, as well as the vascular structures and cranial nerves. A channel and spatial reliability tracker framework is used in conjunction with our CNN to track desired surgical instruments. RESULTS: Our network achieved a state-of-the-art intersection over union ([Formula: see text]) for biological tissue segmentation. Multivariate statistical analysis was used to evaluate dynamic retraction, tissue handling, and instrument manipulation. CONCLUSION: Our model enables to evaluate dynamic retraction of soft tissue and manipulation of instruments during a surgical procedure, while accounting for movement of the operative microscope. This model can potentially provide the surgeon with objective feedback about the movement of instruments and its effect on brain tissue.

Palinacousis: an eloquent symptom of temporal lobe lesion.

A 24-year-old woman was referred to us for an intracranial haemorrhage in the left temporal lobe caused by a ruptured cavernous malformation; the bleeding extended over the left Heschl's gyrus and Wernicke area. On admission, the patient had global aphasia. A few days later, she spontaneously improved but remained with mild residual comprehensive dysphasia. She reported hearing, in her right ear, recently heard words, which is consistent with palinacousis. Auditory acuity testing was normal. EEG showed focal slowing in the left temporal region with no epileptiform activity. During awake surgery for resection of the cavernous malformation, stimulation of the superior temporal gyrus did not provoke palinacousis. The patient made good recovery with complete resolution of the aphasia and no recurrence of palinacousis. We aimed to review this phenomenon and to provide a systematic review of the current literature.

Persistent Trigeminal Artery as Collateral Circulation in Ischemic Stroke.

The persistent trigeminal artery is the most frequent of the persistent embryonic carotid-basilar artery anastomoses. In the literature, it has most often been described in relation to cerebrovascular pathologies such as aneurysms, vascular nerve compression, trigeminal cavernous fistulas, and thromboembolic ischemia. Its role as collateral circulation, thus supplying brain perfusion during main arterial trunk occlusion, has seldom been described. We describe the case of a patient who presented with a stroke due to a traumatic dissection of the internal carotid artery at the neck, in which the infarction may have been limited by a persistent trigeminal artery.

How I do it: lateral supra-cerebellar infra-tentorial approach for P2-P3 junction cerebral aneurysms.

BACKGROUND: P2-P3 junction aneurysms are challenging to treat surgically because of their frequent complex morphology and their location deep in close proximity to the midbrain. The sub-temporal route requires significant retraction of the temporal lobe in addition to potential injury to the vein of Labbe. We describe the technique for treating such aneurysms via a lateral supra-cerebellar infra-tentorial (LSCIT) approach, which eliminates manipulation of the temporal lobe. METHOD: Cadaveric dissection provided comprehensive understanding of relevant anatomy. Intraoperative video shows clipping of the aneurysm using a LSCIT approach. CONCLUSION: LSCIT approach allows safe clipping of P2-P3 aneurysms with minimal brain manipulation.

Atypical Presentation of Parietal Convexity Dural-Based Cavernous Hemangioma: A Case Report and Review of Literature.

BACKGROUND: Dural presentation of a cavernous hemangioma is a rare occurrence. Classically an intraparenchymal lesion with varying symptomatology including mostly headaches, seizures, and neurologic deficits depending on its location, a few cases have been reported along the convexity of the brain, even less eroding the calvaria, with none occasioning abnormal movements as the initial presentation. CASE DESCRIPTION: This is a case of a 67-year-old male who presented to the clinic for atypical progressive choreiform movements of the right side of his body and a soft subgaleal mass. Radiographic imaging showed a parietal tumor with intradural and extradural invasion mimicking a meningioma, which does not provide, given its location, a clear explanation of the symptoms. A craniotomy was performed on 29 January, 2018, during which the tumor was resected along with the invaded dura mater and calvaria. CONCLUSIONS: A pathology report was positive for cavernous hemangioma, an unexpected diagnosis based on the tumor's characteristics. After surgery, the patient recovered completely without residual symptoms, suggesting a compressive mass effect causing the atypical movement disorders.

Posterolateral route for a midbrain cavernous malformation reaching the anterior surface of the brainstem.

Cavernous malformations in the midbrain can be accessed via several safe entry zones. The accepted rule of thumb is to enter at the point where the lesion is visible at the surface of the brainstem to pass through as little normal brain tissue as possible. However, in some cases, in order to avoid critical neural structures, this rule may not apply. A different safe entry zone can be chosen. Our video presents a case of a ruptured cavernous malformation in the midbrain reaching its anterior surface which was successfully resected via a posterolateral route using the supracerebellar infratentorial approach. The video can be found here: https://youtu.be/7kt-OQuBmz0.

Surgical treatment of ruptured anterior circulation aneurysms: comparison of pterional and supraorbital keyhole approaches.

BACKGROUND: Recent advancements in microsurgical techniques and instrumentation have allowed the development of the keyhole approach in aneurysm surgery. OBJECTIVE: To compare the safety, efficacy, and 1-year clinical outcome of supraorbital keyhole and standard pterional approaches for ruptured anterior circulation aneurysms. METHODS: A total of 87 patients underwent surgical clipping, 40 through the pterional and 47 through the supraorbital keyhole approach. Baseline demographics, operative time, procedural complications, and 1-year patient outcome were retrospectively compared. RESULTS: The 2 groups were comparable with respect to baseline characteristics, with the exception of a higher proportion of small aneurysms (<7 mm) in the supraorbital group (70.2% vs. 37.5%, P = .002). Total operative time was significantly shorter in the supraorbital group (205 minutes, P < .001) compared with the pterional group (256 minutes). The rate of procedural complications was lower in patients treated through the pterional (17.5%) vs the supraorbital approach (23.4%, P = .4). Intraoperative aneurysm ruptures occurred more frequently in the supraorbital group (10.6% vs. 2.5%). No patient experienced early or late rebleeding in either group. One year after treatment, 75% (30/40) of patients achieved a favorable outcome (Glasgow outcome scale IV or V) in the pterional group vs 76.6% (36/47) in the supraorbital group (P = .8). CONCLUSION: The rate of procedural complications may be higher with the supraorbital keyhole approach, but overall patient outcomes appear to be comparable. The pterional approach is a simple, reliable, and efficient procedure. The keyhole approach may be an acceptable alternative for neurosurgeons who have gained sufficient experience with the technique, especially for small noncomplex aneurysms.