Microsurgical anatomy of the superficial veins of the cerebrum

Cerebral transmantle vein on magnetic resonance imaging: an embryological pattern persisting up to the adulthood

PURPOSE

The intracranial venous system is characterized by a great variability both in anatomic and functional issues. In particular, the supratentorial venous system is distinguished in the adult configuration in a deep and superficial pathway. The communication between these two compartments is provided by the so-called transcerebral veins, tiny venous channels connecting the deep medullary veins with the superficial medullary veins. No further connection between the two systems has been described in the literature.

METHODS

We are presenting an incidental finding in a patient undergoing brain Magnetic Resonance Imaging (MRI) in the diagnostic work-up of headache of migraine type. In fact, a hyperintense linear signal change in the white matter of the right hemisphere was identified, connecting the subependymal periventricular region with the pial surface and associated with a Susceptibility Weighted Imaging (SWI) appearance of a long venous channel continuing the course of the lateral thalamostriate vein. No further changes were identified and neuronal migration anomalies were absent.

CONCLUSIONS

We described a new type of connection between deep and superficial venous system, different from the transcerebral veins, and we called it transmantle vein, detailing anatomic and embryologic remarks.

Sensory Aphasia After Cerebral Venous Sinus Thrombosis: Quantitative Evaluation of the Recovery Process of Language Function Using Tractography

Cerebral venous sinus thrombosis (CVST) is a rare condition with high mortality that requires careful imaging evaluation. While arterial spin labeling (ASL) proves valuable for CVST assessment and diffusion tensor imaging (DTI) effectively evaluates language function in stroke, no studies have combined these techniques to assess the progression of higher brain dysfunction in CVST. A 59-year-old man presented with severe sensory aphasia. Magnetic resonance venography (MRV) showed left sigmoid sinus disruption with decreased proximal signal intensity, while conventional MRI showed no ischemic findings. The patient underwent sequential imaging with ASL and DTI using a 1.5 Tesla MRI system (SIGNA Explorer 1.5T, GE Healthcare Japan, Tokyo, Japan). The sensory aphasia was resolved by day two, coinciding with improvement in MRV and normalization of ASL findings. DTI tractography, analyzed using XTRACT auto-segmentation, showed changes in fractional anisotropy (FA) values of language-related white matter tracts that paralleled symptom improvement. Recovery of Chinese character reading and writing corresponded with changes in FA values in the inferior fronto-occipital and inferior longitudinal bundles, reflecting the resolution of venous congestion. This case demonstrates the complementary value of ASL and DTI in monitoring recovery from CVST. While ASL showed increased cerebral blood flow during the acute phase, DTI provided objective measures of functional recovery through changes in FA values in language-related white matter tracts. This combined imaging approach offers a promising method to assess both perfusion changes and functional recovery in CVST with associated higher brain dysfunction.

Superior cortical venous anatomy for endovascular device implantation: a systematic review

Endovascular electrode arrays provide a minimally invasive approach to access intracranial structures for neural recording and stimulation. These arrays are currently used as brain-computer interfaces (BCIs) and are deployed within the superior sagittal sinus (SSS), although cortical vein implantation could improve the quality and quantity of recorded signals. However, the anatomy of the superior cortical veins is heterogenous and poorly characterised. MEDLINE and Embase databases were systematically searched from inception to December 15, 2023 for studies describing the anatomy of the superior cortical veins. A total of 28 studies were included: 19 cross-sectional imaging studies, six cadaveric studies, one intraoperative anatomical study and one review. There was substantial variability in cortical vein diameter, length, confluence angle, and location relative to the underlying cortex. The mean number of SSS branches ranged from 11 to 45. The vein of Trolard was most often reported as the largest superior cortical vein, with a mean diameter ranging from 2.1 mm to 3.3 mm. The mean vein of Trolard was identified posterior to the central sulcus. One study found a significant age-related variability in cortical vein diameter and another identified myoendothelial sphincters at the base of the cortical veins. Cortical vein anatomical data are limited and inconsistent. The vein of Trolard is the largest tributary vein of the SSS; however, its relation to the underlying cortex is variable. Variability in cortical vein anatomy may necessitate individualized pre-procedural planning of training and neural decoding in endovascular BCI. Future focus on the relation to the underlying cortex, sulcal vessels, and vessel wall anatomy is required.

Challenging Resection of Bilateral Parasagittal and Falcine Meningioma Involving Both Anterior Third and Middle Third of the Superior Sagittal Sinus: A Case Report and Literature Review

Meningiomas typically manifest as benign, slow-growing, and well-defined tumors on a macroscopic level and are usually asymptomatic. However, the mass effect caused by large meningiomas may lead to various neurological symptoms, commonly headaches and visual problems. Radiological imaging can establish the diagnosis, and a biopsy can provide a definitive diagnosis. Our case report describes the surgical intervention for bilateral parasagittal-falcine meningioma in a 57-year-old male who presented to the emergency department with a tonic-clonic seizure. On examination, he had a bifrontal longitudinal mass. Magnetic resonance imaging (MRI) revealed a large anterior superior falcine extra-axial mass, measuring about 5.7 x 5.3 x 3.1 cm, with surrounding vasogenic edema and superior sagittal sinus invasion. He underwent surgery for tumor resection involving the anterior third and middle third of the superior sagittal sinus without radiotherapy. He did not develop any intraoperative complications, and during the post-operative evaluation, he was symptom-free. A follow-up MRI with contrast performed three months later showed no neurological complications or recurrent tumor. To achieve better outcomes, surgical intervention for parasagittal and falcine meningiomas involving the superior sagittal sinus should aim to eliminate clinical signs, control tumor growth, and prevent neurological deterioration post-operatively.

The neurosurgeon's familiarity with the vein of Rolando

The vein of Rolando, also known as the central sulcal vein, is a critical superficial cerebral vein located in the central sulcus, playing a pivotal role in the venous drainage of the motor and sensory cortices. Named after the Italian anatomist Luigi Rolando, this vein serves as a crucial anatomical landmark in neurosurgery, guiding surgeons to approach critical brain structures with minimal damage. This article explores the anatomy and clinical significance of the vein of Rolando, emphasizing its role in neurosurgery and neuroimaging. Advanced imaging techniques such as functional MRI (fMRI), Magnetic Resonance Venography (MRV), and CT Angiography have enhanced the ability to diagnose and preserve this vein, reducing surgical risks. The article also discusses the interconnectedness of the vein of Rolando with other cerebral veins like the vein of Trolard and underscores the importance of understanding venous variations and drainage patterns for successful surgical outcomes. Preventive measures to protect the vein during neurosurgery are essential to prevent complications such as venous congestion and intracranial pressure. This overview highlights the necessity for precise anatomical knowledge and advanced diagnostic tools in optimizing neurosurgical procedures and patient care.

The cavernous sinus: An anatomic study with clinical implication

Objective

The management of lesions involving the cavernous sinus remains a formidable challenge. To optimize care for patients with tumors extending into this skull base region a detailed understanding of the surrounding osteology as well as neural and vascular relationships is requisite. This thesis examines the gross anatomy of the region and highlights important surgical implications drawn from these as well as previously published studies.

Methods

A review of the historical scientific, anatomic, clinical, and surgical literature extending to the present (1992) relating to the cavernous sinus has been performed and discussed. Additionally, the author has performed and described cadaveric dissections revealing novel details about the macroscopic (dural and neurovascular anatomic relationships) and microscopic structure of the cavernous sinus. A series of cases of cavernous sinus pathologies that were addressed in an interdisciplinary surgical approach at the author's institution is also reported.

Results

Included in this report is a comprehensive review of the embryology of the cavernous sinus and its associated neurovascular structures. Cadaveric dissections have also revealed novel details about dural/meningeal compartments of the cavernous sinus as well as well as associated arterial, venous, and neural relationships. Microscopic observations also reveal novel fundamental insights into the components and structure of the cavernous sinus. Clinical examples from 20 patients illustrate the critical importance for clinical application of cavernous sinus anatomic knowledge to the surgical treatment of pathologies in this region.

Conclusion

The cavernous sinus is a tripartite venous osteomeningeal compartment intimately neighboring vital structures including the optic tracts, pituitary gland, cranial nerves III, IV, V, V, VI, and the internal carotid artery. Surgical management of cavernous sinus lesions has and continues to evolve with increasing anatomic and clinical study as well as advancements in diagnostic and surgical methodologies.

Level of Evidence

NA.

The Significance of Cross-Sectional Shape Accuracy and Non-Linear Elasticity on the Numerical Modelling of Cerebral Veins under Tensile Loading

Traumatic brain injury (TBI) is a serious global health issue, leading to serious disabilities. One type of TBI is acute subdural haematoma (ASDH), which occurs when a bridging vein ruptures. Many numerical models of these structures, mainly based on the finite element method, have been developed. However, most rely on linear elasticity (without validation) and others on simplifications at the geometrical level. An example of the latter is the assumption of a regular cylinder with a constant radius, or the geometry of the vein acquired from medical images. Unfortunately, these do not replicate the real conditions of a mechanical tensile test. In this work, the main goal is to evaluate the influence of the vein's geometry in its mechanical behaviour under tensile loading, simulating the real conditions of experimental tests. The second goal is to implement a hyperelastic model of the bridging veins where it would be possible to observe its non-linear elastic behaviour. The results of the developed finite element models were compared to experimental data available in the literature and other models. It was possible to conclude that the geometry of the vein structure influences the tensile stress-strain curve, which means that flattened specimens should be modelled when validating constitutive models for bridging veins. Additionally, the implementation of hyperelastic material models has been verified, highlighting the potential application of the Marlow and reduced polynomial (of fourth and sixth orders) constitutive models.

Significant Slowed Cortical Venous Blood Flow in Patients with Acute Ischemic Stroke with Large Vessel Occlusion Suggests Poor Collateral Circulation and Prognosis

RATIONALE AND OBJECTIVES

To investigate the change of cortical venous flow in acute ischemic stroke patients with large vessel occlusion (LVO-AIS) and its clinical value.

MATERIALS AND METHODS

Baseline whole-brain 4D-CTA/CTP and clinical data of LVO-AIS and a control group were collected from June 2020 to October 2021. Venous inflow time (VIT), venous peak time (VPT), and venous outflow time (VOT) were analyzed on both sides of patients and normal controls. The VIT/VPT/VOT were statistically described and compared between the patient group and normal controls, then, in patients with different collateral circulation and prognoses. Next, the correlation between cortical venous drainage time and collateral circulation grading was analyzed. Finally, logistic regression analysis was used to explore the relationship between the three venous times and prognosis, and receiver operating characteristic (ROC) curves were plotted to assess the value of delayed cortical venous imaging in predicting prognosis.

RESULTS

149 LVO-AIS and 73 normal controls were collected. VIT, VPT, and VOT were significantly delayed on the affected side in the patient group compared with the healthy side (p<0.05) and the controls (p<0.05); VIT and VPT were also significantly delayed on the healthy side of patients compared with the controls (p<0.05). Delayed VIT and VPT on the affected side in the patient group were more significant in patients with poor collateral circulation (p<0.05), and VIT and VPT on the affected side in the patient group were negatively correlated with arterial collateral scores. VIT and VPT were significantly delayed in both sides of patients in the poor prognosis group compared with the good prognosis group (p<0.05). logistic regression showed that patients' affected VPT, arterial collateral scores, and NIHSS were independent predictors of poor prognosis, with an accuracy of 79.6% in predicting poor prognosis. The affected VPT and NIHSS were independent predictors of poor prognosis for patients presenting within 24 hours, with an accuracy of 79.6% in predicting poor prognosis.

CONCLUSION

Cortical venous flow was significantly slowed in both sides of LVO-AIS patients. delayed ipsilateral VPT in LVO-AIS patients can be used as an imaging indicator to determine poor collateral circulation and predict poor prognosis.

A Case of Cavernous Sinus Dural Arteriovenous Fistula Draining Solely to the Superior Ophthalmic Vein with Normal Cerebral Venous Flow from the Superficial Middle Cerebral Vein to the Inferior Petrosal Sinus due to a Septum in the Cavernous Sinus

Objective

We report here an atypical case of cavernous sinus dural arteriovenous fistula (CSDAVF) with a septation that separates the cavernous sinus (CS) into two components, namely, normal cerebral venous drainage and shunted blood drainage into the superior ophthalmic vein (SOV) alone. The CSDAVF was successfully treated by selective transvenous embolization (TVE) through the septum with the trans-inferior petrosal sinus (IPS) approach.

Case Presentation

A 74-year-old woman presented with right exophthalmos and tinnitus on the right side. Neuroradiological examination showed CSDAVF mainly supplied by multiple feeders from the bilateral ascending pharyngeal artery and meningohypophyseal trunk with a shunted pouch located medial-dorsally to the right CS. Blood from the CSDAVF drained via the anterior component of the CS to the right SOV only. Normal cerebral venous blood from the right superficial middle cerebral vein drained through the dorsolateral component of the right CS into the right IPS. These findings suggest that a septal barrier exists between the outflow tract of the dural arteriovenous fistula and the normal cerebral venous outflow tract within the CS. The CSDAVF was successfully treated by selective TVE through the septum with the trans-IPS approach after detailed evaluation of 3D rotational angiography (3DRA) and MRA/MR venography (MRV) cross-sectional images. The patient's symptoms improved, and she was discharged uneventfully.

Conclusion

Septation within the CS can completely separate the drainage route of the CSDAVF from the normal cerebral drainage route. Successful catheterization to the shunted pouch through the septum with the IPS approach and selective embolization were possible with detailed evaluation of anatomy on MRA/MRV cross-sectional images and 3DRA images.

Revisiting the Tentorial Venous Sinuses: Anatomical and Histological Study

BACKGROUND

Anatomical studies of the tentorial sinuses (TS) are scant, and to our knowledge, histological studies of this structure have not been reported. Therefore, we aim to better elucidate this anatomy.

METHODS

In 15 fresh frozen, latex injected, adult cadaveric specimens, the TS were evaluated with microsurgical dissection and histology.

RESULTS

The superior layer had a mean thickness of 0.22 mm, and the inferior layer had a mean thickness of 0.26 mm. Two types of TS were identified. Type 1 was a small intrinsic plexiform sinus with no obvious connections to the draining veins with gross examination. Type 2 was a larger tentorial sinus with direct connections to the bridging veins from the cerebral and cerebellar hemispheres. In general, type 1 sinuses were located more medially than type 2 sinuses. The inferior tentorial bridging veins drained directly into the TS along with connections to the straight and transverse sinuses. In 53.3% of specimens, superficial and deep sinuses were seen, with superior and inferior groups draining the cerebrum and cerebellum, respectively.

CONCLUSIONS

We identified novel findings for the TS which can be considered surgically and when diagnosing pathology involves these venous sinuses.

Anatomy of Intracranial Veins

The cerebral venous system is complex and sophisticated and serves various major functions toward maintaining brain homeostasis. Cerebral veins contain about 70% of cerebral blood volume, have thin walls, are valveless, and cross seamlessly white matter, ependymal, cisternal, arachnoid, and dural boundaries to eventually drain cerebral blood either into dural sinuses or deep cerebral veins. Although numerous variations in the cerebral venous anatomic arrangement may be encountered, the overall configuration is relatively predictable and landmarks relatively well defined. A reasonable understanding of cerebral vascular embryology is helpful to appreciate normal anatomy and variations that have clinical relevance. Increasing interest in transvascular therapy, particularly transvenous endovascular intervention provides justification for practitioners in the neurosciences to acquire at least a basic understanding of the cerebral venous system.

Occipital Interhemispheric Transtentorial Approach for Tumors of Posterior Third Ventricular Region: Review of Surgical Results

Background

Controversies exist regarding the ideal surgical approach for tumors in posterior third ventricular region (PTV).

Objective

To evaluate the results of occipital interhemispheric transtentorial (OITT) approach for tumors in PTV.

Materials And Methods

Thirty-three patients underwent surgery via OITT approach for PTV tumors at Sri Sathya Sai Institute of Higher Medical Sciences during the study period of 5 years (June 2011-May 2016). Ideal trajectory for OITT approach was determined by neuronavigation. Endoscope was used for removing any residual lesion at the blind spots.

Results

Postoperative magnetic resonance imaging (MRI) performed in all the patients revealed gross total or near-total (>95%) excision of tumor in 31 patients (93.9%). Preoperative neurological deficits improved either completely or significantly following excision of the tumor in 73.3% (11/15) of the patients. Outcome was good (modified Rankin scale ≤2) at discharge in 93.9% (31/33) and at a final follow-up of 3 months or more in 96.8% (30/31) of the patients. None of the patients died during the postoperative period. Complications included upgaze palsy (transient- 6.1% [2/33], persisting- 3% [1/33]), visual field defects (transient- 3% [1/33], persisting- 3% [1/33]), transient third nerve paresis (1/33-3%), transient hemiparesis (1/33-3%), operative site hematoma (1/33-3%), small posterior cerebral artery (PCA) territory infarct (1/33-3%), and small venous infarct (1/33-3%). At least one follow-up MRI could be performed in 23 patients. Final follow-up MRI revealed no recurrence or increase in the size of the residual lesion compared to postoperative images in 20 patients (20/23-87%) and large recurrence in 3 patients (3/23-13%) with high-grade lesions.

Conclusion

Gross total/near-total excision can be performed in majority of the PTV tumors through OITT approach with minimal morbidity and mortality.

Cranial defect and pneumocephalus are associated with significant postneurosurgical positional brain shift: evaluation using upright computed tomography

Only few studies have assessed brain shift caused by positional change. This study aimed to identify factors correlated with a large postneurosurgical positional brain shift (PBS). Sixty-seven patients who underwent neurosurgical procedures had upright computed tomography (CT) scan using settings similar to those of conventional supine CT. The presence of a clinically significant PBS, defined as a brain shift of ≥ 5 mm caused by positional change, was evaluated. The clinical and radiological findings were investigated to identify factors associated with a larger PBS. As a result, twenty-one patients had a clinically significant PBS. The univariate analysis showed that supratentorial lesion location, intra-axial lesion type, craniectomy procedure, and residual intracranial air were the predictors of PBS. Based on the multivariate analysis, craniectomy procedure (p < 0.001) and residual intracranial air volume (p = 0.004) were the predictors of PBS. In a sub-analysis of post-craniectomy patients, PBS was larger in patients with supratentorial craniectomy site and parenchymal brain injury. A large craniectomy area and long interval from craniectomy were correlated with the extent of PBS. In conclusion, patients who undergo craniectomy and those with residual intracranial air can present with a large PBS. In post-craniectomy patients, the predisposing factors of a large PBS are supratentorial craniectomy, presence of parenchymal injury, large skull defect area, and long interval from craniectomy. These findings can contribute to safe mobilization among postneurosurgical patients and the risk assessment of sinking skin flap syndrome.

Imaging of the venous plexus of Rektorzik using CT-digital subtraction venography: a retrospective study

PURPOSE

The venous plexus of Rektorzik (VPR), first described by Rektorzik in 1858, is a venous plexus around the internal carotid artery in the carotid canal. However, the VPR has never been investigated using the recently developed imaging modalities. In this study, we analyzed the VPR using computed tomography-digital subtraction venography (CT-DSV).

METHODS

This study included 253 patients who had undergone head CT-DSV. The presence or absence of the right and left VPRs and their connecting veins were visually examined by two researchers.

RESULTS

The VPR was observed in 60 patients (24%), 39 of which showed VPR only on the right side, 10 only on the left side, and 11 on both sides. VPR was significantly more common on the right side (p = 0.0002) and was observed more frequently around the horizontal segment of the internal carotid artery than around the vertical segment. The most common veins identified as distal and proximal VPR connections were the cavernous sinus (63/71, 89%) and the anterior condylar confluence (27/71, 38%), respectively. The mean age was significantly lower in patients with the VPR than in those without (53 vs. 57 years, p = 0.02).

CONCLUSION

The VPR was significantly more frequent on the right side and in younger patients but was not a radiographically constant structure. In most cases, the VPR connected the cavernous sinus and anterior condylar confluence. Preoperative evaluation of VPR may lead to refined surgical procedures.

Anatomical Variations of Superior Sagittal Sinus and Tributary Bridging Veins: A Cadaveric Study

Background and objective

Injuries to the parasagittal cerebrovenous structures may lead to devastating complications. Being aware of the inherent anatomical heterogeneity in the region might lower the rate of undesirable outcomes. In this study, our goal was to characterize the superior sagittal sinus (SSS) positioning in relation to the midline and depict tributary bridging veins (BVs) distribution over the lateral surface of the cerebral hemispheres.

Methods

We performed anatomical dissections of the brain in 10 cadaveric specimens (five females and five males; median age: 52 years, range: 44-74 years). Measurements (in mm) of the SSS width and deviation of its lateral margin from the midline were obtained along the entire length of the structure at six craniometric points [at mid-distance between Nasion and Bregma (½ N-B); at Bregma (B); in the middle of the Bregma-Lambda segment (½ B-L); at Lambda (L); halfway between Lambda and Inion (½ L-I); and at Inion (I)]. The count, diameter, and lateral insertion points of the draining BVs were also documented in three segments [Nasion-Bregma (N-B), Bregma-Lambda (B-L), and Lambda-Inion (L-I)].

Results

The width of the SSS increased progressively along the direction of the blood flow (p<0.01). There was an SSS lateral deviation bias to the right, but the comparison failed to reach the significance level (p=0.12). The maximal lateralization of the SSS in the pre-Lambdal interval was 13.1 mm on the right side and 11.7 mm on the left side. These values increased up to 19.8 mm and 15.1 mm in the torcular area on the right and left sides, respectively. A total of 191 BVs were identified (a mean of 19.1 ± 2.5 per individual). The L-I segment showed a lower number of BVs as compared to its N-B and B-L counterparts (mean: 0.9 ± 0.6 vs. 8 ± 1.8 and 10.2 ± 2, respectively, p<0.01). Along the entire span of the SSS, the average diameter of the BVs was larger on the right side (mean: 1.4 ± 0.9 mm vs. 1.1 ± 0.8 mm on the left, p<0.01). The average lateralization of BVs dural entry points was lower on the left side in the B-L segment (mean: 5.6 ± 6.4 mm vs. 8.8 ± 6.7 mm on the right, p<0.01). There was a statistically significant trend of decreasing BVs lateralization with each consecutive SSS segment (mean: 10.9 ± 7.4 mm in the N-B segment, 7.3 ± 6.7 mm in B-L, and 1.6 ± 1.2 mm in L-I, p<0.01). The maximal lateral deviation of BVs insertion points was 33.6 mm in N-B, 30 mm in B-L, and 4.1 mm in L-I portions of the SSS.

Conclusions

In most cases, the SSS deviated laterally from the midline, up to 13 mm in the pre-Lambdal segment and up to 20 mm in the torcular area. Right-sided BVs were of larger average diameters. The lateral insertion points of BVs decreased along the rostrocaudal span of the SSS.

Tentorial venous anatomy of mice and humans

We recently described a transtentorial venous system (TTVS), which to our knowledge was previously unknown, connecting venous drainage throughout the brain in humans. Prior to this finding, it was believed that the embryologic tentorial plexus regresses, resulting in a largely avascular tentorium. Our finding contradicted this understanding and necessitated further investigation into the development of the TTVS. Herein, we sought to investigate mice as a model to study the development of this system. First, using vascular casting and ex vivo micro-CT, we demonstrated that this TTVS is conserved in adult mice. Next, using high-resolution MRI, we identified the primitive tentorial venous plexus in the murine embryo at day 14.5. We also found that, at this embryologic stage, the tentorial plexus drains the choroid plexus. Finally, using vascular casting and micro-CT, we found that the TTVS is the dominant venous drainage in the early postnatal period (P8). Herein, we demonstrated that the TTVS is conserved between mice and humans, and we present a longitudinal study of its development. In addition, our findings establish mice as a translational model for further study of this system and its relationship to intracranial physiology.

Dissection of the Sylvian Fissure in the Trans-sylvian Approach Based on the Morphological Classification of the Superficial Middle Cerebral Vein

The superficial middle cerebral vein (SMCV) is one of the main factors that can impede a wide opening of the sylvian fissure. To reveal the most efficient SMCV dissection for a wide operative field while preserving the veins in the trans-sylvian approach, we retrospectively investigated the SMCVs through intraoperative video images. We characterized the SMCV as composed of the frontosylvian trunk (FST; receiving frontosylvian veins [FSVs] or parietosylvian veins [PSVs]), the temporosylvian trunk (TST; receiving temporosylvian veins [TSVs]), and the superficial middle cerebral common trunk (SMCCT; receiving both FSV/PSV and TSV), and classified the SMCVs of the 116 patients into 5 types based on the morphological classification of the SMCV. Type A SMCV (60.4%) with the SMCCT anastomosed to the frontal side had few bridging veins (BVs) between the SMCCT and the temporal side during dissection. Type B (7.8%) had the SMCCT with no anastomoses to the frontal side. In Type C (17.2%) consisting of the FST and TST and Type D (12.9%) with a merging of the vein of Trolard and Labbé posteriorly and the SMCVs dividing into the FST and the TST again proximally, there were few BVs between the FST and the TST during dissection. Finally, in Type E (1.7%) showing an undeveloped SMCV, there were no BVs between the frontal and the temporal lobes. Postoperative venous infarction occurred in 2.6%. Morphological classification of the SMCV can inform appropriate dissection line to create a wide operative field while preserving the veins in the trans-sylvian approach.

Interhemispheric Precuneus Retrosplenial Transfalcine Approach for Falcotentorial Meningiomas: Anatomic Study and Clinical Series

BACKGROUND

Falcotentorial meningiomas are surgically challenging. Currently accepted approaches include occipital interhemispheric and supracerebellar infratentorial approaches, which have documented drawbacks.

OBJECTIVE

To propose an alternative approach to the posterior tentorial incisural space, the interhemispheric precuneus retrosplenial transfalcine approach (IPRTA).

METHODS

A total of 6 colored-silicone-injected adult cadaveric heads were dissected. We measured the interval between bridging veins and studied computed tomography venography scans of 20 subjects to confirm the feasibility of the IPRTA. Bony landmarks, the region's bridging veins, and the anterior and posterior borders of the approach were identified. The surgical corridor widths (veins' interval) and lengths were compared between alternative midline approaches. We also reviewed 4 consecutive clinical cases using this approach.

RESULTS

The IPRTA provides the shortest distance to the anterior and posterior limits of the posterior tentorial incisura. Moreover, it is the only approach that provides direct visualization of the anterior and posterior limits of falcotentorial junction meningiomas. In all specimens and patients, a minimum 30-mm interval between the anterior and posterior parietal veins was found in at least one of the hemispheres. Tumor removal was successful in all 4 patients but resulted in mild paresthesia in the lower extremities of 2 patients and temporary foot drop in 1 patient.

CONCLUSION

The IPRTA offers the shortest and most direct corridor for falcotentorial meningiomas and provides excellent visualization of most of the critical structures in the region. Detailed preoperative evaluation of the deep and superficial venous structures is recommended.

Eponyms in Vascular Neurosurgery: Comprehensive Review of 18 Veins

This review is the first comprehensive anatomic report of all venous eponyms used in vascular neurosurgery and provides the historical context of their authors as well as the surgical relevance of every structure. A PubMed literature review identified 13 individuals for whom 18 eponymous venous structures of the brain were named. These structures are the Batson plexus, veins of Breschet, Breschet sinus, vein of Dandy, vein of Galen, prosencephalic vein of Markowski, torcular Herophili, vein of Labbé, venous plexus of Rektorzik, vein of Rolando, basal vein of Rosenthal, sylvian veins, lateral lakes of Trolard, vein of Trolard, hypoglossal plexus of Trolard, petro-occipital vein of Trolard, venous circle of Trolard, and the vein of Vesalius. Eponyms provide a valuable shorthand that encompasses anatomic nuances, variabilities, and surgical relevance. In addition, they elucidate the historical context in which these structures were described and are an academic honor to our predecessors.

Interhemispheric transcallosal approach: going further based on the vascular anatomy

Preserving cortical frontal bridging veins draining into the superior sagittal sinus is a factor of good neurological outcome in anterior interhemispheric transcallosal approaches, classically performed to reach intraventricular tumors. Challenging the idea that veins are utterly variable, we propose a statistical analysis of 100 selective cerebral angiographies to determine where to place the craniotomy in order to expose the most probable vein-free area. The mean distance to the first pre-coronal vein was 6.66 cm (± 1.73, 1.80 to 13.00) and to the first post-coronal vein 0.94 cm (± 0.92, 0 to 3.00) (p < 0.001). The probability of absence of bridging veins was 92.0% at 4 cm anterior to the coronal suture versus 37.5% at 1 cm and 12.5% at 2 cm posteriorly. The length of the surgical corridor (distance between the first pre-coronal and post-coronal vein) was 7.60 cm (± 1.72, 3.00 to 14.10). Overall, the ideal centering point of the craniotomy was 2.86 cm (± 1.08, - 0.65 to 6.50) ahead of the coronal suture. The mean number of veins within 6 cm behind the coronal suture was 8.47 (± 2.11, from 3 to 15) versus 0.530 (± 0.82, from 0 to 3) ahead of the coronal suture (p < 0.001). These findings support a purely pre-coronal 5 cm craniotomy for interhemispheric approaches.

Tentorial Venous Anatomy: Variation in the Healthy Population

BACKGROUND AND PURPOSE

A new transtentorial venous system consisting of medial, intermediate, and lateral tentorial veins, connecting infra- and supratentorial compartments, was recently shown in 2 cadaver dissections and 2 patient scans. We sought to characterize the venous patterns within the tentorium and their relation to measures of skull development in a cohort of healthy adults.

MATERIALS AND METHODS

We retrospectively reviewed tentorial venous anatomy of the head using CTA/CTV performed for routine care or research purposes in 238 patients. Included studies had adequate contrast opacification of venous structures and a section thickness of ≤2 mm; we excluded cases with space-occupying lesions and vascular pathologies. Tentorial angle, dural sinus configurations, and measures of skull base development were assessed as predictors of tentorial venous anatomy variation via Cramér V association, the binary encoded Pearson correlation, and nearest-point algorithm with the Euclidean distance metric for clustering.

RESULTS

Tentorial vein development was related to the ringed configuration of the tentorial sinuses (P < .005). There were 3 configurations. Groups 1A and 1B (n = 50/238) had ringed configuration, while group 2 did not (n = 188/238). Group 1A (n = 38/50) had a medialized ringed configuration, and group 1B had a lateralized ringed configuration (n = 12/50). Measurements of skull base development were predictive of these groups. The ringed configuration of group 1 was related to the presence of a split confluens, which correlated with a decreased internal auditory canal-petroclival fissure angle. Configuration 1A was related to the degree of petrous apex pneumatization (P value = .010).

CONCLUSIONS

Variations in the transtentorial venous system directly correlate with cranial development.

Collagen fibre orientation in human bridging veins

Bridging veins (BVs) drain the blood from the cerebral cortex into dural sinuses. BVs have one end attached to the brain and the other to the superior sagittal sinus (SSS), which is attached to the skull. Relative movement between these two structures can cause BV to rupture producing acute subdural haematoma, a head injury with a mortality rate between 30 and 90%. A clear understanding of the BVs microstructure is required to increase the biofidelity of BV models when simulating head impacts. Twelve fresh BV samples draining in the superior sagittal sinus (SSS) from a single human cadaver were cut open along their length and placed on an inverted multiphoton microscope. To ensure that the BVs were aligned with the axial direction an in-house built, uniaxial tension set-up was used. Two scans were performed per sample. Before the first scan, a minor displacement was applied to align the tissue; then, a second scan was taken applying 50% strain. Each BV was scanned for a length of 5 mm starting from the drainage site into the SSS. Imaging was performed on a Zeiss LSM780 microscope with an 25[Formula: see text] water immersion objective (NA 0.8), coupled to a tunable MaiTai DS (Spectraphysics) pulsed laser with the wavelength set at 850 nm. Second harmonic and fluorescence signals were captured in forward and backward direction on binary GaAsP (BiG) detectors and stored as four colour Z-stacks. Prior to the calculation of the local orientations, acquired Z-stacks were denoised and enhanced to highlight fibrillar structures from the background. Then, for each Z-plane of the stack, the ImageJ plugin OrientationJ was used to extract the local 2D orientations of the fibres based on structure tensors. Two kinds of collagen architectures were seen. The most common (8[Formula: see text]12 samples) was single layered and had a uniform distribution of collagen. The less common (4[Formula: see text]12 samples) had 2 layers and 7 to 34 times thicker collagen bundles on the outer layer. Fibre angle analysis showed that collagen was oriented mainly along the axial direction of the vessel. The von Mises fittings showed that in order to describe the fibre distribution 3 components were needed with mean angles [Formula: see text] at [Formula: see text] 0.35, 0.21, [Formula: see text] 0.02 rad or [Formula: see text] 20.2[Formula: see text], 12.1[Formula: see text], [Formula: see text] 1.2[Formula: see text] relative to the vessel's axial direction which was also the horizontal scan direction.

Anatomical Variations in the Location of Veins Draining Into the Anterior Superior Sagittal Sinus: Implications for the Transbasal Approach

BACKGROUND

Many approaches are used for midline anterior cranial fossa meningioma resection. In the subfrontal approach, the anterior superior sagittal sinus (SSS) is commonly ligated to release the anterior falx. The transbasal approach allows access to the origin of the anterior SSS, allowing for maximum venous preservation.

OBJECTIVE

To investigate variations in the first and second veins draining into the SSS.

METHODS

We performed stepwise dissections for a transbasal level 1 approach on 8 anatomic specimens. We visualized the first and second veins draining into the sinus and measured the distance from the foramen cecum to these veins. We also measured the orbital bar height to determine the length of sagittal sinus that could be preserved with orbital bar removal.

RESULTS

The distance between the foramen cecum and the first vein ranged from 4 to 36 mm while the distance to the second vein ranged from 6 to 48 mm. The mean orbital bar height was 26.4 mm. Based on these measurements, with a traditional bicoronal craniotomy without orbital bar removal, 81% of first veins and 58% of second veins would be sacrificed.

CONCLUSION

A supraorbital bar or nasofrontal osteotomy, part of the transbasal skull base approach, is helpful to preserve the first and second veins when ligating the anterior SSS. Based on this study, it may be difficult to preserve these veins without orbital bar removal. Preservation of these veins may be of clinical importance when approaching midline anterior fossa pathologies.

Venous anatomy of the supratentorial compartment

The cerebral venous drainage system in humans has several unique characteristics that set it apart from its arterial counterpart. The intracranial drainage system can be broadly divided into supra- and infratentorial components. The supratentorial venous drainage is further subclassified into superficial and deep systems, each with a unique set of features. A thorough knowledge of the normal and variant venous drainage pathways is important to understand the different pathologic processes involving the venous vasculature, to identify and anticipate the different venous channels encountered during surgery and also to predict the possible sequelae of intentional or inadvertent venous sacrifice during surgery. This chapter summarizes the anatomic and radiologic characteristics of the venous supply of the supratentorial compartment of the brain, reviews its general characteristics, sheds light on the different classifications and nomenclature used for its descriptions, and briefly discusses its embryologic development.

Three-Dimensional Angles of Confluence of Cortical Bridging Veins and the Superior Sagittal Sinus on MR Venography: Does Drainage of Adjacent Brain Arteriovenous Malformations Alter this Spatial Configuration?

Few neuroimaging anatomic studies to date have investigated in detail the point of entry of cortical bridging veins (CBVs) into the superior sagittal sinus (SSS). Although we know that most CBVs join the SSS at an acute angle opposite to the direction of SSS blood flow, the three-dimensional (3-D) spatial configuration of these venous confluences has not been studied previously. This anatomical information would be pertinent to several clinically applicable scenarios, such as in planning intracranial surgical approaches that preserve bridging veins; studying anatomical factors in the pathophysiology of SSS thrombosis; and when planning endovascular microcatheterization of pial veins to retrogradely embolize brain arteriovenous malformations (AVMs). We used the concept of Euclidean planes in 3-D space to calculate the arccosine of these CBV-SSS angles of confluence. To test the hypothesis that pial AVM draining veins may not be any more acutely angled or difficult to microcatheterize at the SSS than for normal CBVs, we measured 70 angles of confluence on magnetic resonance venography images of 11 normal, and nine AVM patients. There was no statistical difference between normal and AVM patients in the CBV-SSS angles projected in 3-D space (56.2° [SD = 22.4°], and 46.2° [SD = 22.3°], respectively; P > 0.05). Hence, participation of CBVs in drainage of pial AVMs should not confer any added difficulty to their microcatheterization across the SSS, when compared to the acute angles found in normal individuals. This has useful implications for potential choices of strategies requiring endovascular transvenous retrograde approaches to treat AVMs. Clin. Anat. 33:293-299, 2020. © 2019 Wiley Periodicals, Inc.

Planning of Endocranial Supratentorial Basal Cistern and Skull Base Approaches Depending on Venous Patterns Using a Topogram

BACKGROUND

Because damage or sacrifice of venous drainage during supratentorial basal cistern and skull base approaches may have severe and harmful consequences, methods to identify preoperatively veins at risk are of paramount importance. Among methods, a codified assessment with a venous topogram is helpful, with practical implications.

METHODS

This technical note describes how to construct an easy-to-use topogram. Three regions of interest are defined as triangles. The anterior triangle corresponds to the anterior frontal veins draining to the superior sagittal sinus at risk during anterior cerebral fossa surgery, the middle triangle corresponds to the anterior sylvian veins draining to the cavernous sinus at risk during pterional approaches, and the inferior triangle corresponds to the inferior cerebral veins draining to the transverse sinus at risk in subtemporal approaches and temporal lobe surgery.

RESULTS

Depending on predominance of the drainage, 4 situations were defined: an anterior, an inferior, and a middle predominance or equilibrium between the 3 triangles. These anatomic features have important practical implications in skull base and basal cistern approaches.

CONCLUSIONS

This is, to our knowledge, the only topogram described in the scientific literature. Any well-defined approach should be adapted to the individual patient according not only to location and type of lesion but also to the venous drainage to be encountered along the way.

Analysis of Temporobasal Vein with Short Subdural Segment for Anterior Transpetrosal Approach

BACKGROUND

The anterior transpetrosal approach (ATPA) is applied to petroclival and brainstem lesions. Although neurosurgeons need to minimize the risk of neurologic complications, brain retraction is necessary for procedures of ATPA. Bridging veins (BVs) limit mobility of the temporal lobe. In the present study, BVs around the petrous bone were analyzed, focusing on the dural entrance and termination points.

METHODS

The relationship between subdural and meningeal segments of temporobasal veins (TBVs) was analyzed by preoperative computed tomography venography in 102 patients who underwent ATPA. TBVs were classified by the dural entrance and termination points.

RESULTS

TBVs mainly entered the transverse sinus and rarely entered transverse-sigmoid sinus (T-S) junction and superior petrosal sinus (SPS). TBVs entered a dural sinus either directly or indirectly through a meningeal vein. The changes in vascular diameter of the lumen, shape, and course were identified between the subdural and meningeal segments. Generally, BVs with long subdural segment do not limit mobility of the temporal lobe. TBVs draining into the T-S junction and SPS tended to be shorter than those draining into the transverse sinus. Furthermore, a few TBVs indirectly entered the dural sinuses through the meningeal vein (early dural entrance). The subdural segment of these TBVs was much shorter.

CONCLUSIONS

TBVs entering the T-S junction or SPS with short subdural segment may limit the mobility of the temporal lobe. Changes in vascular diameter, shape, and course were detected by computed tomography venography, which was helpful to detect the subdural-meningeal transition.

Early detection of cerebral ischemic events on intraoperative magnetic resonance imaging during surgical procedures for deep brain stimulation

BACKGROUND

Although intracerebral hemorrhage is the most feared complication of deep brain stimulation (DBS) surgery, cerebral ischemic events in association with DBS surgery have only rarely been described. We therefore evaluated the role of intraoperative MRI (iMRI) for early identification of cerebral ischemic events during DBS procedures and determined how ischemic infarctions affect patients over acute and long-term periods.

METHODS

Between January 2010 and December 2017, 1160 DBS electrodes were implanted in 595 patients at Chinese People's Liberation Army General Hospital, with the help of iMRI. The iMRI was performed in all patients after implantation, to define the accuracy of lead placement and detect complications. A CT scan was performed on postoperative days 1 to 7.

RESULTS

The iMRI showed that cerebral ischemic changes happened in nine (1.51% of patients, 0.78% of leads) patients. Only two (0.34%) of nine patients had an ischemic infarction in the basal ganglia, while seven (1.18%) had cortical ischemia. Six (67%) of the nine patients had long-term complications, two with mild hemiparesis, two with seizures, one with language dysfunction, and one with memory loss. Of those with a cortical ischemic infarction, only three (42.86%) of seven patients had no long-term complications. Long-term follow-up imaging showed that not all the patients recovered normal morphological structure in the area of ischemic foci. The factors of sex, age, target, and anesthesia were not related to ischemic events. In six (66.7%) cases, the entry point on the cortex or the path was not ideal.

CONCLUSIONS

Intraoperative ischemic events are not uncommon in DBS surgery. Ischemia can cause serious permanent complications, and regions subject to severe ischemia cannot be restored; it is therefore necessary to pay careful attention to any signs of ischemia. iMRI objectively provides the basis for early diagnosis of intraoperative ischemic infarction, providing guidance for follow-up treatment. The deviation in the entry point on the cortex or in the path resulted in vascular injury; it may be the key cause of ischemic events during DBS procedures.

Morphological Pattern and Classification of the Superficial Middle Cerebral Vein by Cadaver Dissections: An Embryological Viewpoint

In this study, we used 45 adult cadaveric cerebral hemispheres to investigate the anatomical classification of the superficial middle cerebral vein (SMCV) based on the number of stems, course, and anastomosis at the distal portion. We classified the SMCVs into five types based on embryological concept. Type A (18 cases, 40.0%) is that the frontosylvian veins (FSVs) merge with the vein of Trolard (VT) and the vein of Labbé (VL) at the distal portion of the sylvian fissure. Type B (5 cases, 11.1%) is that the temporosylvian veins (TSVs) merge with the VT and the VL at the distal portion. Type C (13 cases, 28.9%) is that no vein merge with the VT and the VL at the distal portion. The VT merges with the SMCV from the FSV and the VL merges with the SMCV from the TSV. They course along the sylvian fissure and merge at the proximal portion. In Type D (eight cases: 17.8%), the VT and the VL merge at the distal portion, and the SMCV from the FSV and the SMCV from the TSV join their confluence without merging. Type E (one case, 2.2%) show an undeveloped SMCV. Formation rate of intravenous anastomoses or bridging veins(BVs) at the distal portion between the frontosylvian trunk (FST) and the temporosylvian trunk (TST), between the FST and the temporal lobe, and between the TST and the frontal lobe was very low, because these formation may be difficult to occur during the embryological process in which the SMCV is formed from the telencephalic vein.

Tentorial Venous Anatomy: Cadaveric and Radiographic Study with Discussion of Origin and Surgical Significance

BACKGROUND

Described variations of tentorial venous anatomy impact surgical sectioning of the tentorium in skull base approaches; however, described configurations do not consistently explain postoperative complications. To understand the outcomes of 2 clinical cases we studied the tentorial venous anatomy of 2 cadavers.

METHODS

The venous anatomy of the tentorium isolated in 2 uninjected fresh cadaver head specimens with preserved bridging veins was observed by transillumination before and after methylene blue injection of the dural sinuses and tentorial veins. Our findings in cadavers were applied to explain the clinical and radiologic (magnetic resonance imaging and computed tomographic venography) findings in the 2 cases presented.

RESULTS

A consistent transtentorial venous system, arising from transverse and straight sinuses, communicating with supra- and infratentorial bridging veins was seen in the cadaver and patient radiography (magnetic resonance imaging and computed tomographic venography). Our first patient had a cerebellar venous infarct from compromise of the venous drainage from the adjacent brain after ligation of a temporal lobe bridging vein to the tentorium. Our second patient suffered no clinical effects from bilateral transverse sinus occlusion due to drainage through the accessory venous system within the tentorium.

CONCLUSIONS

Herein, we elaborate on transtentorial venous anatomy. These veins, previously reported to obliterate in completed development of the tentorium, remain patent with consistent observed configuration. The same transtentorial venous system was observed in both cases and provided insight to their outcomes. These findings emphasize the importance of the transtentorial venous system physiologically and in surgical approaches.

Modelling of intracranial behaviour on occiput impact in judo

Acute subdural hematoma (ASDH) sometimes occurred in judo because of the bridging veins' failure by rotation of the brain in the skull. However, the relationship between intracranial behaviour and the motion of the body on occiput impact has not yet been clarified. In this study, we developed an intracranial mechanical model based on multibody dynamics and compared it with experimental results. The results show the importance of modelling bridging veins and cerebral spinal fluid to the relative displacement between brain and skull. The proposed model will contribute to accident analyses or the optimum design of supporting devices.

Cerebral blood vessel damage in traumatic brain injury

Traumatic brain injury is a devastating cause of death and disability. Although injury of brain tissue is of primary interest in head trauma, nearly all significant cases include damage of the cerebral blood vessels. Because vessels are critical to the maintenance of the healthy brain, any injury or dysfunction of the vasculature puts neural tissue at risk. It is well known that these vessels commonly tear and bleed as an immediate consequence of traumatic brain injury. It follows that other vessels experience deformations that are significant though not severe enough to produce bleeding. Recent data show that such subfailure deformations damage the microstructure of the cerebral vessels, altering both their structure and function. Little is known about the prognosis of these injured vessels and their potential contribution to disease development. The objective of this review is to describe the current state of knowledge on the mechanics of cerebral vessels during head trauma and how they respond to the applied loads. Further research on these topics will clarify the role of blood vessels in the progression of traumatic brain injury and is expected to provide insight into improved strategies for treatment of the disease.

Bridging vein and tentorial sinus in the subtemporal corridor during the anterior transpetrosal approach

BACKGROUND

The bridging vein (BV) and the tentorial sinus (TenS) are important venous structures in neurological surgery. These venous structures during the anterior transpetrosal approach (ATPA) have not been reported. The objective of this study is to examine the BV and the TenS in the subtemporal corridor during the ATPA and propose a technique to identify the BV preoperatively.

METHODS

This study included 126 patients treated via the ATPA. The BV and the TenS located in the operative fields were analyzed. Furthermore, in the preoperative evaluation, the cross-sectional shapes of the intradural vein and the interdural sinus were analyzed by curved planar reconstruction (CPR), and the flattening rate was calculated. Flattening rate = (a-b)/a = 1-b/a (a: long radius, b: short radius).

RESULTS

Seventeen BVs and 18 TenS were identified. The bridging site was divided into two groups: tentorial and middle fossa. The middle fossa group was divided into three subgroups: cavernous sinus, middle fossa dural sinus, and middle fossa dural adherence. Five isolated TenS were sacrificed and no venous complications were observed. The mean flattening rate was 0.13 in the intradural vein and 0.51 in the interdural sinus, respectively (P = 0.0003).

CONCLUSIONS

We showed classification of the BV, and preservation of the BV and TenS during the ATPA. Furthermore, we found that the interdural sinus was significantly flatter than the intradural veins. Measuring the flattening rate by CPR may be useful to identify BVs preoperatively.

Detection of bridging veins rupture and subdural haematoma onset using a finite element head model

BACKGROUND

One of the most severe traumatic brain injuries, the subdural haematoma, is related to damage and rupture of the bridging veins, generating an abnormal collection of blood between the dura mater and arachnoid mater. Current numerical models of these vessels rely on very simple geometries and material laws, limiting its accuracy and bio-fidelity.

METHODS

In this work, departing from an existing human head numerical model, a realistic geometry for the bridging veins was developed, devoting special attention to the finite elements type employed. A novel and adequate constitutive model including damage behavior was also successfully implemented.

FINDINGS

Results attest that vessel tearing onset was correctly captured, after comparison against experiments on cadavers.

INTERPRETATION

Doing so, the model allow to precisely predict the individual influence of kinematic parameters such as the pulse duration, linear and rotational accelerations in promoting vessel tearing.

Material and Structural Modeling Aspects of Brain Tissue Deformation under Dynamic Loads

The aim of this work was to assess the numerous approaches to structural and material modeling of brain tissue under dynamic loading conditions. The current technological improvements in material modeling have led to various approaches described in the literature. However, the methods used for the determination of the brain’s characteristics have not always been stated or clearly defined and material data are even more scattered. Thus, the research described in this paper explicitly underlines directions for the development of numerical brain models. An important element of this research is the development of a numerical model of the brain based on medical imaging methods. This approach allowed the authors to assess the changes in the mechanical and geometrical parameters of brain tissue caused by the impact of mechanical loads. The developed model was verified through comparison with experimental studies on post-mortem human subjects described in the literature, as well as through numerical tests. Based on the current research, the authors identified important aspects of the modeling of brain tissue that influence the assessment of the actual biomechanical response of the brain for dynamic analyses.

The microneurosurgical anatomy legacy of Albert L. Rhoton Jr., MD: an analysis of transition and evolution over 50 years

The authors chronologically categorized the 160 original articles written by Dr. Rhoton and his fellows to show why they selected their themes and how they carried out their projects. The authors note that as neurosurgery progresses and new techniques and approaches are developed, accurate and safe treatment will depend upon continued clarification of microsurgical anatomy.

Contralateral Transfalcine Versus Ipsilateral Anterior Interhemispheric Approach for Midline Arteriovenous Malformations: Surgical and Anatomical Assessment

BACKGROUND

The contralateral anterior interhemispheric approach (CAIA) is considered to provide surgical advantages to access deep midline lesions: wider working angle, gravity enhanced dissection and retraction, more efficient lighting, and ergonomics. Our team has previously published on the merits of using a contralateral trajectory for medial frontoparietal arteriovenous malformations (AVMs) compared with the conventional anterior interhemispheric approach (IAIA). In this article, we compare the IAIA and CAIA for the resection of medial frontoparietal AVMs using quantitative surgical and anatomical analysis.

METHODS

Two models were designed mimicking the most common features of midline AVMs. The CAIA and IAIA were performed bilaterally in 10 specimens. Variables to compare technical feasibility (surgical window [SW] and surgical freedom [SF], target exposure, and angle of attack) were independently assessed using stereotactic navigation. The average SW, SF, and angle of attack were compared with the Student t test. Significance threshold was set at 0.05.

RESULTS

The CITA and IAIA were similar in terms of SW, target exposure, and SF in the superior aspect of the AVM. In the depth of the interhemispheric fissure, the CAIA was significantly superior to IAIA in both AVM models: 77% wider AA for the inferior aspect of the AVM (P < 0.01) and greater SF for the draining vein (54%, P = 0.01), ipsilateral (98%, P = 0.02), and contralateral ACA (117%, P < 0.01).

CONCLUSIONS

This study suggests technical superiority of the CAIA for the resection of deep midline AVMs. No objective difference was noted in the superficial areas of our models, denoting that IAIA is a safer choice for superficial AVMs. Our results set the foundation for further clinical analysis comparing both approaches.

Cerebral venous thrombosis: state of the art diagnosis and management

PURPOSE

This review article aims to discuss the pathophysiology, clinical presentation, and neuroimaging of cerebral venous thrombosis (CVT). Different approaches for diagnosis of CVT, including CT/CTV, MRI/MRV, and US will be discussed and the reader will become acquainted with imaging findings as well as limitations of each modality. Lastly, this exhibit will review the standard of care for CVT treatment and emerging endovascular options.

METHODS

A literature search using PubMed and the MEDLINE subengine was completed using the terms "cerebral venous thrombosis," "stroke," and "imaging." Studies reporting on the workup, imaging characteristics, clinical history, and management of patients with CVT were included.

RESULTS

The presentation of CVT is often non-specific and requires a high index of clinical suspicion. Signs of CVT on NECT can be divided into indirect signs (edema, parenchymal hemorrhage, subarachnoid hemorrhage, and rarely subdural hematomas) and less commonly direct signs (visualization of dense thrombus within a vein or within the cerebral venous sinuses). Confirmation is performed with CTV, directly demonstrating the thrombus as a filling defect, or MRI/MRV, which also provides superior characterization of parenchymal abnormalities. General pitfalls and anatomic variants will also be discussed. Lastly, endovascular management options including thrombolysis and mechanical thrombectomy are discussed.

CONCLUSIONS

CVT is a relatively uncommon phenomenon and frequently overlooked at initial presentation. Familiarity with imaging features and diagnostic work-up of CVT will help in providing timely diagnosis and therapy which can significantly improve outcome and diminish the risk of acute and long-term complications, optimizing patient care.

Post Mortem Validation of MRI-Identified Veins on the Surface of the Cerebral Cortex as Potential Landmarks for Neurosurgery

Background and Objective: Image-guided neurosurgery uses information from a wide spectrum of methods to inform the neurosurgeon's judgement about which tissue to resect and which to spare. Imaging data are registered to the patient's skull so that they correspond to the intraoperative macro- and microscopic view. The correspondence between imaging and optical systems breaks down during surgery, however, as a result of cerebro-spinal fluid drain age, tissue resection, and gravity-based brain shift. In this work we investigate whether a map of surface veins, automatically segmented from MRI, could serve as additional reference system.

Methods: Gradient-echo based T2*-weighted imaging was performed on two human cadavers heads using a 7 Tesla MRI scanner. Automatic vessel segmentation was performed using the Frangi vesselness filter, and surface renderings of vessels compared with photographs of the surface of the brain following craniotomy.

Results: A high level of correspondence was established between vessel maps and the post autopsy photographs. Corresponding veins, including the prominent superior anastomotic veins, could be identified in all brain lobes.

Conclusion: Automatic surface vessel segmentation is feasible and the high correspondence to post autopsy photographs indicates that they could be used as an additional reference system for image-guided neurosurgery in order to maintain the correspondence between imaging and optical systems.This has the advantage over a skull-based reference system that veins are clearly visible to the surgeon and move and deform with the underlying tissue, potentially making this surface net of landmarks robust to brain shift.

Supratentorial acute subdural haematoma during microvascular decompression surgery: report of three cases

Supratentoiral haemorrhage during posterior fossa surgery is very rare. Authors report three cases of acute subdural haematoma occurred during microvascular decompression (MVD). Bleeding was observed in the suboccipital surgical area during operation but the origin of the bleeding was not confirmed intraoperatively in all cases. Decompression procedure was completed and immediate postoperative computed tomography revealed supratentorial subdural haematoma. This complication was observed during MVD in healthy young patients with hemifacial spasm in our cases. Flexion of the head with reduction of cerebrospinal fluid may have induced rotational movement of the cerebrum resulting in rupture of bridging veins, but no definitive mechanism that fulfils the clinical characteristics was clearly determined.

Anterior interhemispheric transsplenial approach to pineal region tumors: anatomical study and illustrative case

Pineal region tumors are challenging to access because they are centrally located within the calvaria and surrounded by critical neurovascular structures. The goal of this work is to describe a new surgical trajectory, the anterior interhemispheric transsplenial approach, to the pineal region and falcotentorial junction area. To demonstrate this approach, the authors examined 7 adult formalin-fixed silicone-injected cadaveric heads and 2 fresh human brain specimens. One representative case of falcotentorial meningioma treated through an anterior interhemispheric transsplenial approach is also described. Among the interhemispheric approaches to the pineal region, the anterior interhemispheric transsplenial approach has several advantages. 1) There are few or no bridging veins at the level of the pericoronal suture. 2) The parietal and occipital lobes are not retracted, which reduces the chances of approach-related morbidity, especially in the dominant hemisphere. 3) The risk of damage to the deep venous structures is low because the tumor surface reached first is relatively vein free. 4) The internal cerebral veins can be manipulated and dissected away laterally through the anterior interhemispheric route but not via the posterior interhemispheric route. 5) Early control of medial posterior choroidal arteries is obtained. The anterior interhemispheric transsplenial approach provides a safe and effective surgical corridor for patients with supratentorial pineal region tumors that 1) extend superiorly, involve the splenium of the corpus callosum, and push the deep venous system in a posterosuperior or an anteroinferior direction; 2) are tentorial and displace the deep venous system inferiorly; or 3) originate from the splenium of the corpus callosum.

Use of a contoured bioresorbable plate with a hemostatic plug to control life-threatening bleeding from the superior sagittal sinus during hemispherotomy: technical note

Profuse bleeding originating from an injured cerebral sinus can be a harrowing experience for any surgeon, particularly during an operation on a young child. Common surgical remedies include sinus ligation, primary repair, placement of a hemostatic plug, and patch or venous grafting that may require temporary stenting. In this paper the authors describe the use of a contoured bioresorbable plate to hold a hemostatic plug in place along a tear in the inferomedial portion of a relatively inaccessible part of the posterior segment of the superior sagittal sinus in an 11-kg infant undergoing hemispherotomy for epilepsy. This variation on previously described hemostatic techniques proved to be easy, effective, and ultimately lifesaving. Surgeons may find this technique useful in similar dire circumstances when previously described techniques are ineffective or impractical.