Macroscopic and histological examination of human bridging veins.

In infantile abusive head injury (AHT), subdural haemorrhage (SDH) is commonly held to result from traumatic damage to bridging veins traversing from the surface of the brain to the dura and dural venous sinuses. However, there are limited published radiological or autopsy demonstrations of ruptured bridging veins and several authors also assert that bridging veins are too large to rupture due to the forces associated with AHT. There have been several studies on the size, locations and numbers of adult bridging veins and there is one small study of infant bridging veins. However, there are no microscopic studies of infant bridging veins and only a select few ultrastructural investigations of adult bridging veins. Hitherto, it has been assumed that bridging veins from infants and younger children will display the same anatomical characteristics as those in adulthood. At 19 neonatal, infant and young child post-mortem examinations, we macroscopically examined and sampled bridging veins for microscopy. We compared the histology of those samples with bridging veins from an older child and two adults. We demonstrate that adult bridging veins are usually surrounded by supportive meningeal tissue that appears to be lacking or minimally present around the bridging veins of younger children. Neonatal, infant and young children's veins had a free 'bridging' section. Neonatal and infant bridging veins had smaller diameter ranges and thinner walls (some only 5-7 µm) than those seen in older children and adults. Bridging vein walls contained both fine strands of elastic fibers and a more pronounced elastic lamina. The presence of an elastic lamina occurred more frequently in the older age groups These anatomical differences between the veins of adults and young children may help to explain apparent increased vulnerability of neonatal/infant bridging veins to the forces associated with a shaking-type traumatic event.

A Modified Anterior Petrosectomy Approach for Resection of Petroclival Meningioma; with Management of Complications.

Due to deep location and for being adjacent to neurovascular structures, petroclival meningiomas (PCMs) are generally considered to be associated with a high rate of recurrence and cranial nerve deficits.1 This video presents a 49-year-old female patient reporting right trigeminal neuralgia for more than 1 year. The incidence of this symptom with PCMs is about 5%.2 According to the classification system proposed by Kawase et al.3 and Ichimura et al.,4 this is a tentorium type PCM. A modified anterior petrosectomy approach was adopted based on the tumor size and its origin. The case presentation, surgical technique, postoperative outcome are reviewed. The treatments to the intraoperative trochlear nerve injury and temporal bridging vein occlusion are displayed (Video 1). The patient gave verbal consent for participating in the procedure and surgical video.

Bridging veins at the craniocervical junction: from anatomy to clinical significance in dural arteriovenous shunts.

PURPOSE: Bridging veins (BVs) serve as a route of pial venous reflux, and its anatomy is essential to understand the pathophysiology of dural arteriovenous shunts (dAVSs) around the craniocervical junction (CCJ) (from the jugular foramen level to the atlantal level). However, the anatomical variations of the BVs and their proximal connections remained poorly elucidated. This study aimed to radiologically investigate the anatomy of the bridging veins around CCJ and discuss the clinical significance of these BVs in the dAVS. METHODS: We investigated normal venous anatomy of the BVs from the jugular foramen level to the atlantal level using preoperative computed tomography digital subtraction venography in patients undergoing elective neurosurgery. BVs affected by the dAVSs in the same region were also evaluated. The three types of dAVS, craniocervical junction, anterior condylar, and proximal sigmoid sinus, were investigated. RESULTS: We identified six BV groups: superolateral, anterolateral, lateral, posterior, inferolateral, and inferoposterior. The superolateral and inferolateral groups, connected with the proximal sigmoid sinus and suboccipital cavernous sinus, respectively, were the largest groups. Each group has a specific downstream venous connection. The association with dVASs was observed only in the inferolateral group, which was typically the sole venous drainage in most dAVSs at the CCJ. CONCLUSION: We reported detailed anatomy of BVs from the jugular level to the atlantal level, which enhanced our understanding of the pathophysiology of dAVSs in the corresponding region.

Detailed Anatomy of Bridging Veins Around the Foramen Magnum: a Multicenter Study Using Three-dimensional Angiography.

BACKGROUND AND PURPOSE: There has been limited literature regarding the bridging veins (BVs) of the medulla oblongata around the foramen magnum (FM). The present study aims to analyze the normal angioarchitecture of the BVs around the FM using slab MIP images of three-dimensional (3D) angiography. METHODS: We collected 3D angiography data of posterior fossa veins and analyzed the BVs around the FM using slab MIP images. We analyzed the course, outlet, and number of BVs around the FM. We also examined the detection rate and mean diameter of each BV. RESULTS: Of 57 patients, 55 patients (96%) had any BV. The median number of BVs was two (range: 0-5). The BVs originate from the perimedullary veins and run anterolaterally to join the anterior condylar vein (ACV), inferior petrosal sinus, sigmoid sinus, or jugular bulb, inferolaterally to join the suboccipital cavernous sinus (SCS), laterally or posterolaterally to join the marginal sinus (MS), and posteriorly to join the MS or occipital sinus. We classified BVs into five subtypes according to the draining location: ACV, jugular foramen (JF), MS, SCS, and cerebellomedullary cistern (CMC). ACV, JF, MS, SCS, and CMC BVs were detected in 11 (19%), 18 (32%), 32 (56%), 20 (35%), and 16 (28%) patients, respectively. The mean diameter of the BVs other than CMC was 0.6 mm, and that of CMC BV was 0.8 mm. CONCLUSION: Using venous data from 3D angiography, we detected FM BVs in most cases, and the BVs were connected in various directions.

Preserving the cerebellar hemispheric tentorial bridging veins through a novel tentorial cut technique for supracerebellar approaches.

OBJECTIVE: The objective of this study was to describe the distribution pattern of cerebellar hemispheric tentorial bridging (CHTB) veins on the tentorial surface in a case series of perimedian or paramedian supracerebellar approaches and to describe a novel technique to preserve these veins. METHODS: A series of 141 patients with various pathological processes in different locations was operated on via perimedian or paramedian supracerebellar approaches by the senior author from July 2006 through October 2022 and was retrospectively evaluated. During surgery, the number and locations of all CHTB veins were recorded to establish a distribution map on the tentorial surface, divided into nine zones. Patients were classified into four groups according to the surgical technique used to manage CHTB veins: 1) group 1 consisted of CHTB veins preserved without intervention during surgery or no CHTB veins found in the surgical route; 2) group 2 included CHTB veins coagulated during surgery; 3) group 3 included CHTB veins preserved with arachnoid and/or tentorial dissection from the cerebellar or tentorial surface, respectively; and 4) group 4 comprised CHTB veins preserved using a novel tentorial cut technique. RESULTS: Overall, 141 patients were included in the study. Of these 141 patients, 38 were in group 1 (27%), 32 in group 2 (22.7%), 47 in group 3 (33.3%), and 24 in group 4 (17%). The total number of CHTB veins encountered was 207 during surgeries on one side. According to the distribution zones of the tentorium, zone 5 had the highest density of CHTB veins, while zone 7 had the lowest. Of the patients in group 4, 6 underwent the perimedian supracerebellar approach and 18 had the paramedian supracerebellar approach. There were 39 CHTB veins on the surface of the 24 cerebellar hemispheres in group 4. The tentorial cut technique was performed for 27 of 39 CHTB veins. Twelve veins were not addressed because they did not present any obstacles during approaches. During surgery, no complications were observed due to the tentorial cut technique. CONCLUSIONS: Because there is no way to determine whether a CHTB vein can be sacrificed without complications, it is important to protect these veins in supracerebellar approaches. This new tentorial cut technique in perimedian or paramedian supracerebellar approaches makes it possible to preserve CHTB veins encountered during supracerebellar surgeries.

Endoscopic evacuation of chronic subdural hematoma with rigid and flexible endoscope: case report.

Introduction: Subdural haematoma (SDH) is a common neurosurgical condition after head trauma requiring evacuation to prevent secondary brain injury. The first choice of management in these patients is a large craniotomy or burr-hole evacuation. However, sometimes due to lack vision during drain tube insertion or irrigation the authors might land up in a complication like cortical bridging vein rupture, haemorrhage etc. Also, the management of septate chronic SDH (CSDH) with multiple neo-membranes does not have a well-defined surgical approach. Recently, endoscopic evacuation has been reported to a be a feasible method for evacuation in acute, subacute and chronic SDH patients. Presentation of case: A 65-years-old male patient presented with a history of recent head injury and symptoms of headache and urinary incontinence of 7 days (Glasgow Coma Scale Score 15/15). Computed tomography scan revealed CSDH at both fronto-parietal convexity more on right side. Discussion: The authors reported our initial experience on a typical case of an older patient with chronic subdural haematoma and its evacuation with the assistance of both rigid and flexible endoscope. The authors could visualize cortical bridging veins and neo-membranes intraoperatively and guided our drainage tube accordingly to avoid inadvertent haemorrhage. There was no recurrence of symptoms postoperatively. Thus we achieved apparent successful evacuation of the CSDH in this patient in a 6-month follow-up. Conclusion: Endoscopic evacuation of CSDH proves to be an effective minimally invasive modality and more studies are required on larger patient groups with long-term follow-up imaging to confirm its superiority.

Redirection of Persistent Left Superior Vena Cava Using a Turned-In Left Atrial Appendage.

Persistent left superior cava mostly drains into the right atrium via the coronary sinus. It rarely drains into the left atrium. Extracardiac and intracardiac repair techniques have been described for the repair of persistent left superior vena cava draining into the left atrium. Herein, we report the successful application of a new intracardiac repair technique by using a turned-in left atrial appendage in a 3-year-old male patient with a persistent left superior vena cava draining into the left atrium.

Is bridging vein rupture/thrombosis associated with subdural hematoma at birth?

BACKGROUND: The combination of bridging vein rupture/thrombosis and subdural hematoma in infants has recently gained attention as highly suggestive of abusive head trauma. While subdural hematomas are frequently observed at birth, there are no previous studies of bridging vein rupture/thrombosis prevalence in that context. OBJECTIVE: To evaluate the prevalence of bridging vein rupture/thrombosis in newborns with and without subdural hematoma. MATERIALS AND METHODS: This bicentric retrospective study (2012-2019) looked at all brain MRIs performed in neonates. We noted delivery method, demographic data and intracranial injuries and analyzed any clots at the vertex as potential markers of bridging vein rupture/thrombosis. RESULTS: We analyzed 412 MRIs in 412 neonates. Age was (mean ± standard deviation [SD]) 5.4±2.2 days and 312 (76%) infants were full term (38.3±2.9 weeks from last menstrual period). The delivery method was vaginal birth for 42% (n=174), cesarean section for 43% (n=179), and unknown for 14% (n=59). Subdural hematoma was present in 281 MRIs (68.0%, [95% confidence interval = 63.3-72.5]). Six MRIs showed at least one clot at the vertex, assumed to be possible bridging vein rupture/thrombosis (1.5%, [0.5-3.1%]). Only one MRI showed more than two clots at the vertex, in a context of maternal infection. There was no significant difference in terms of gestational age at birth, delivery method or the presence of subdural hematoma or parenchymal injuries between those 6 infants and the 406 others. CONCLUSION: Bridging vein rupture/thrombosis at birth is very rare and unlikely to be related to subdural hematoma.

Endovascular treatment of medullary bridging vein-draining dural arteriovenous fistulas: foramen magnum vs. craniocervical junction lesions.

PURPOSE: Dural arteriovenous fistulas (AVFs) draining to medullary bridging vein (MBV) are located at foramen magnum (FM) and craniocervical junction (CCJ). Such fistulas are rare but pose a challenge to endovascular management. This study was undertaken to assess clinical manifestations, angiographic features, and outcomes of endovascular treatment in patients with MBV dural AVFs. METHODS: A number of our patients (N = 22) were diagnosed with MBV dural AVF and treated by endovascular means. There were 9 FM lesions and 13 CCJ lesions. We reviewed clinical records and imaging studies to define clinical characteristics, vascular anatomic details, and treatment outcomes, comparing FM- and CCJ-level subsets. RESULTS: Subjects ranged from 37 to 74 years of age (mean, 57.7 years) with male predominance (2.7:1). They presented with intracranial hemorrhage (11/22, 50%), myelopathy (8/22, 36%), or nonspecific symptoms (3/22, 14%). In 17 patients (77.3%), the shunts showed complete or near-complete occlusion following endovascular treatment (FM, 100%; CCJ, 61.5%). However, seven patients experienced ischemic events (FM, 11.1%; CCJ, 46.2%) and one patient sustained a hemorrhagic complication. No hemorrhages recurred during follow-up monitoring, and myelopathic symptoms abated. CONCLUSION: MBV dural AVFs are highly aggressive lesions for which proper diagnosis and treatment are of utmost importance. Although transarterial embolization proved highly successful in FM lesions, shunt occlusion was less frequent in the CCJ subset, with greater risk of ischemic complications.

Venous injury in pediatric abusive head trauma: a pictorial review.

Abusive head trauma (AHT) is the leading cause of fatal head injuries in children younger than 2 years. An intracranial pathology can exist even in the setting of a normal physical exam. A delay in the diagnosis of AHT can have serious life-threatening consequences for the child and increases the potential the child will be abused again. In this article, we review the traumatic subdural hematoma as well as various morpho-structural patterns of shearing injuries and thrombosis of intracranial bridging veins. This work serves as a summary of patterns of imaging features of intracranial venous injury in AHT, as described in the literature, to facilitate familiarity and early detection of abusive head trauma in the pediatric population. Essentially, in AHT there is a traumatic injury to the bridging vein with either partial or complete tear. This can secondarily result in thrombosis at the terminal end of the bridging vein with blood clots adjacent to the bridging vein.

Bridging veins of the cerebellum: a magnetic resonance imaging study.

PURPOSE: To date, no study has yet explored the bridging veins (BVs) of the cerebellum using neuroimaging modalities. Therefore, this study aimed to characterize them using magnetic resonance imaging (MRI). METHODS: A total of 90 patients with intact cerebellar hemispheres and intracranial dural sinuses underwent thin-sliced, contrast-enhanced MRI. RESULTS: The BVs were classified into six routes based on the draining pattern into the dural sinuses. The superior vermian vein emptying into the straight sinus was delineated in 100% of the patients. The inferior vermian vein emptying into the confluence of the sinuses was identified in 66.7% of the patients. The inferior hemispheric and cerebellar cortical veins emptying into the transverse sinus were identified in 54.4% and 26.7% of the patients, respectively. The inferior vermian and cerebellar cortical veins emptying into the straight sinus were identified in 77.8% and 12.2% of the patients, respectively. The cerebellar cortical vein emptying into the tentorial sinus was identified in 83.3% of the patients; it was delineated on 54 sides with an average number per right hemisphere of 1.9 and 63 sides with an average number per left hemisphere of 2. The pontine-trigeminal and anterior hemispheric veins emptying into the superior petrosal sinus were identified in 42.2% of the patients. CONCLUSIONS: The BVs of the cerebellum can be classified into six distinct routes. Radiological classification may be useful for understanding the drainage pattern of the cerebellum.

What is the risk of venous cerebellar infarction in the supracerebellar infratentorial approach?

The supracerebellar infratentorial approach (SCITA) is a standard approach used in a neurosurgical practice. It carries some risk of associated complications including cerebellar venous infarction with possible serious sequelae. The objective of this study is to address the incidence of cerebellar venous infarction in SCITA. A search through the currently available literature was performed in September 2019 from the year 2000 until September 2019 dealing with 'supracerebellar infratentorial approach'. Out of the 578 patients found in thirteen case series, two venous infarctions were present; the remaining four patients were published as case reports. By analysing the case series, we calculated the risk of such a complication to be 0.345% (95% CI [0.061%, 1.248%]). Case reports were not included. The real risk is estimated to be higher. The risk of cerebellar venous infarction is an unpredictable, infrequent but real complication with potentially dreadful sequelae. Each neurosurgeon using this approach should be aware of this event when employing this approach. The avoidance of cerebellar venous infarction can be lowered by leaving as many bridging veins intact as possible.

Cortical and bridging veins of the upper cerebral convexity: a magnetic resonance imaging study.

PURPOSE: There is no study exploring the cortical veins (CVs) and connecting bridging veins (BVs) with neuroimaging modalities. The present study aimed to characterize these veins of the upper cerebral convexity. METHODS: A total of 89 patients with intact cerebral hemispheres and covering meninges underwent thin-sliced, contrast magnetic resonance imaging (MRI). In addition, three injected specimens were dissected in this study. RESULTS: In cadaver dissection, the BVs were observed to course in the arachnoid sheaths, suspended from the dura mater. The medial parts of the BVs, located near the superior sagittal sinus (SSS)-BV junction site, were occasionally exposed subdurally. The CVs were formed by venous channels arising from the cerebral gyri and those emerging from the sulci. On MRI, the CVs and connecting BVs were identified in the medial and latera convexity areas and medial surface of the cerebrum. These veins were highly variable in number, thickness, length, course, and distribution. In the medial convexity area, the CVs arising from the gyri were identified in 58% of patients, while they were found only in 11% of patients in the lateral convexity area. CONCLUSION: In the medial convexity area, involving the parasagittal region, the CVs connect more densely with the BVs that may predispose to injury during neurosurgical procedures. Mechanical impact exerted the area, diameter of the veins in the craniocaudal direction, and number of venous afferences may affect the SSS-BV junctional region in an indirect manner and lead to the development of acute subdural hematoma.

The characteristics of brain injury following cerebral venous infarction induced by surgical interruption of the cortical bridging vein in mice.

Cerebral venous infarction (CVI) caused by the injury of cortical bridging veins (CBVs), is one of the most serious complications following neurosurgical craniotomy. Different from cerebral artery infarction, this CVI pathological process is more complicated, accompanied by acute venous hypertension, brain edema, cerebral ischemia and hemorrhage in the veins bridged brain area. Therefore, a reliable and stable small animal model is particularly important for the pathological study of CVI induced by surgical CBV interruption (CBVi). A mouse model established by cutting off the right CBVs from bregma to lambda with microsurgical technique is used for the assessment of the pathological process. Adult male mice underwent craniotomy after transection of the parietal skin under anesthesia. The right CBVs were exposed by removing the right skull along the right lateral edge of the sagittal sinus (forming a 4 mm × 3 mm bone window from bregma to lambda) with a drill under the operating microscope. Following the final inspection of the cerebral veins, the CBVs (30% one, 60% two, 10% none) were sacrificed using bipolar coagulation technique. Intracranial pressure (ICP) monitoring, motor function examination, brain edema assessment and brain histopathological observation after perfusion were performed at different time points (6 h, 12 h, 24 h, and 48 h) in the postoperative mice. Cerebral hemisphere swelling, midline shift and subcortical petechial hemorrhage were found on histological sections 6 h after CBVs dissection. The change of ICP was consistent with cerebral edema and peaked at 12 h after surgery, as well as the disruption of the blood-brain barrier assessed by Evans Blue staining. Tissue necrosis, nerve cell loss and monocytes infiltration were also dynamically increased in the postoperative hemispheric cortex. Behavioral tests showed obvious somato- and forelimb-motor dysfunction, and severe somatosensory disorder on the operative mice at 12 h, which were substantially recovered at 48 h. Our study provided a novel mouse model of CVI caused by surgical CBVi that was close to clinical practice, and preliminarily confirmed its pathological process. This model might become an important tool to study the clinical pathology and the molecular mechanism of nerve injury following CVI.

Lumbar Subdural Hematoma Detected After Surgical Treatment of Chronic Intracranial Subdural Hematoma.

BACKGROUND: Spinal subdural hematoma (SSDH), which can cause lower back pain, leg pain, and leg weakness, is rare and will usually be associated with a bleeding tendency, trauma, spinal vascular malformation, intraspinal tumor, or iatrogenic invasion. Only a few cases of SSDH after intracranial chronic subdural hematoma (CSDH) have been reported. We report a case of lumbar SSDH in the absence of predisposing factors after reoperation for recurrent intracranial CSDH, which improved with conservative treatment. CASE DESCRIPTION: Approximately 1 month after falling, a 63-year-old woman was experiencing left hemiparesis and impaired orientation that was diagnosed as right intracranial CSDH using computed tomography. Surgical treatment of the CSDH led to immediate improvement of her symptoms. On postoperative day 29, the right CSDH had recurred with left hemiparesis, and successful reoperation relieved the symptoms within a few hours postoperatively. However, 1 day after the second operation, very small acute subdural hematomas in regions along the left tentorium cerebelli and left falx cerebri were found on computed tomography. On day 31, she complained of sitting-induced bilateral radiating lower limb pain. Magnetic resonance imaging on day 34 showed an acute SSDH at the L4-L5 level and a sacral perineural cyst filled with hematoma, although her radiating pain was showing improvement. She was treated conservatively and was discharged without symptoms on day 44. CONCLUSIONS: Although SSDH is rare, it is important for neurosurgeons and physicians to consider the possibility of a SSDH when lower limb pain or paresis occurs after procedures that will result in rapid intracranial pressure alterations such as drainage of an intracranial CSDH.

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.

The sensitivity to inter-subject variability of the bridging vein entry angles for prediction of acute subdural hematoma.

Acute subdural hematoma (ASDH) is one of the most frequent traumatic brain injuries (TBIs) with high mortality rate. Bridging vein (BV) ruptures is a major cause of ASDH. The KTH finite element head model includes bridging veins to predict acute subdural hematoma due to BV rupture. In this model, BVs were positioned according to Oka et al. (1985). The aim of the current study is to investigate whether the location and entry angles of these BVs could be modelled using data from a greater statistical sample, and what the impact of this improvement would be on the model's predictive capability of BV rupture. From the CT angiogram data of 78 patients, the relative position of the bridging veins and their entry angles along the superior sagittal sinus was determined. The bridging veins were repositioned in the model accordingly. The performance of the model, w.r.t. BV rupture prediction potential was tested on simulations of full body cadaver head impact experiments. The experiments were simulated on the original version of the model and on three other versions which had updated BV positions according to mean, maximum and minimum entry angles. Even though the successful prediction rate between the models stayed the same, the location of the rupture site significantly improved for the model with the mean entry angles. Moreover, the models with maximum and minimum entry angles give an insight of how BV biovariability can influence ASDH. In order to further improve the successful prediction rate, more biofidelic data are needed both with respect to bridging vein material properties and geometry. Furthermore, more experimental data are needed in order to investigate the behaviour of FE head models in depth.

Retrospective review of a venous sparing approach to resection of parasagittal meningiomas.

Parasagittal meningiomas make up 20-30% of intracranial meningiomas. Their proximity to, and often invasion of, the superior sagittal sinus (SSS) may preclude complete surgical resection. Repair and reconstruction of the SSS in pursuit of Simpson grade I resection is associated with increased morbidity. We retrospectively reviewed 76 parasagittal meningiomas. Our surgical technique emphasized preservation of bridging cortical veins and the SSS. In cases where the SSS was already occluded by tumor, this portion of the sinus and adjacent falx were resected. In cases where the SSS was not occluded by tumor, maximal tumor resection without entering the SSS was performed. The post-op neurologic exam was unchanged or improved in 91% of patients. Only one patient (1%) experienced new persistent neurologic symptoms, which consisted of contralateral numbness. Sixteen patients (21%) experienced tumor recurrence that was deemed appropriate for additional intervention (radiosurgery, re-operation, or re-operation + radiosurgery). Age, sex, location, recurrence, size, presence of edema, degree of sinus involvement, or pathology were not statistically significant predictors of recurrence. Length of follow-up was the only statistically significant predictor of recurrence. A surgical strategy emphasizing preservation of cortical bridging veins and the SSS appears to be safe and effective for the treatment of parasagittal meningiomas. The use of adjuvant therapy for the treatment of residual intrasinusal tumor encountered in this approach may be reserved for cases of tumor progression.

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.

Measurement and Finite Element Model Validation of Immature Porcine Brain-Skull Displacement during Rapid Sagittal Head Rotations.

Computational models are valuable tools for studying tissue-level mechanisms of traumatic brain injury, but to produce more accurate estimates of tissue deformation, these models must be validated against experimental data. In this study, we present in situ measurements of brain-skull displacement in the neonatal piglet head (n = 3) at the sagittal midline during six rapid non-impact rotations (two rotations per specimen) with peak angular velocities averaging 51.7 ± 1.4 rad/s. Marks on the sagittally cut brain and skull/rigid potting surfaces were tracked, and peak values of relative brain-skull displacement were extracted and found to be significantly less than values extracted from a previous axial plane model. In a finite element model of the sagittally transected neonatal porcine head, the brain-skull boundary condition was matched to the measured physical experiment data. Despite smaller sagittal plane displacements at the brain-skull boundary, the corresponding finite element boundary condition optimized for sagittal plane rotations is far less stiff than its axial counterpart, likely due to the prominent role of the boundary geometry in restricting interface movement. Finally, bridging veins were included in the finite element model. Varying the bridging vein mechanical behavior over a previously reported range had no influence on the brain-skull boundary displacements. This direction-specific sagittal plane boundary condition can be employed in finite element models of rapid sagittal head rotations.