Association of Extent of Transverse Sinus Stenosis With Cerebral Glymphatic Clearance in Patients With Idiopathic Intracranial Hypertension.

BACKGROUND AND OBJECTIVES: Idiopathic intracranial hypertension (IIH) is a neurologic disorder characterized by symptoms of elevated intracranial pressure in the absence of a clear cause. There is a developing theory that IIH may, in part, be related to abnormal cerebral glymphatic clearance. In addition, transverse sinus stenosis (TSS) is a common finding in IIH of unclear pathophysiologic significance. Similarly, whether or not TSS is associated with glymphatic outflow in IIH is unknown. The aim of this investigation was to explore the possible association between glymphatic outflow and extent of TSS in patients with IIH. METHODS: The study cohort consisted of patients with IIH and healthy controls who were retrospectively identified from our tertiary care institution located in upstate New York from 2016 to 2023. Patients with IIH were included if they had brain MRIs completed with sufficient sequences for analysis. Brain MRIs were computationally analyzed using diffusion tensor imaging analysis along the perivascular space technique to quantify the glymphatic function in patients with IIH. Glymphatic clearance, the primary outcome, was then correlated with the degree of TSS on MR venography using 2 different scoring systems, the 'Farb score' and 'Carvalho score.' RESULTS: Overall, 81 patients with IIH (70 [86%] female, mean age 29.8 years [SD: 8.2 years], mean BMI 41 [SD: 8.4]) and 10 normal controls were identified with sufficient imaging. Based on the Carvalho TSS score, IIH patients without TSS had significantly lower glymphatic clearance than healthy controls (mean ALPS index: 1.196 [SD: 0.05] vs 1.238 [SD: 0.04], respectively; p = 0.018). Furthermore, IIH patients with TSS had significantly lower glymphatic outflow than healthy controls (1.129 [SD: 0.07] vs 1.238 [SD: 0.04], respectively; p < 0.0001) and IIH patients without TSS (1.129 [SD: 0.07] vs 1.196 [SD: 0.05], respectively; p < 0.0001). In addition, there was a significant association between increasing extent of TSS and declining glymphatic clearance (p < 0.0001, R = 0.62). Finally, IIH patients with severe TSS had significantly lower glymphatic flow than IIH patients with mild stenosis (1.121 [SD: 0.07] vs 1.178 [SD: 0.05], respectively; p < 0.0001). These findings were similarly recapitulated using the Farb TSS scoring system. DISCUSSION: These preliminary findings suggest that the extent of TSS is associated with the degree of glymphatic clearance in IIH, providing novel insights into IIH pathophysiology. Further research is required to clarify the possible causal relationship between TSS and impaired glymphatic clearance in IIH.

[Transverse Sinus / Sigmoid Sinus].

The transverse sinus(TS)and sigmoid sinus(SS)are common sites for dural arteriovenous fistulas, and an understanding of vascular anatomy is important when developing treatment strategies. In recent years, transarterial embolization, with a liquid embolization material, has become the treatment of choice, preserving the sinus without extensive coil filling of the affected sinus. With this expansion of therapeutic options, we feel that an understanding of the microanatomy has become more important. For example, the exact site where the vein of Labbé joins the TS should be determined. This article focuses on the development and anatomy of the TS and SS and makes points that should be considered when treating dural arteriovenous fistulas.

Safety evaluation of sinus patency after stereotactic radiosurgery for transverse-sigmoid sinus dural arteriovenous fistulas: implications of treatment options for patients with Borden type I fistulas.

OBJECTIVE: This study aimed to assess the efficacy and safety of stereotactic radiosurgery (SRS) in treating transverse-sigmoid sinus dural arteriovenous fistulas (TSS DAVFs), and to investigate post-SRS sinus patency, focusing on the risk factors associated with treated sinus occlusion. METHODS: Data from 34 patients treated with SRS between January 2006 and April 2023 were analyzed. Detailed angioarchitecture was confirmed using digital subtraction angiography before SRS. Angiography of the ipsilateral internal carotid artery and vertebral artery was performed to evaluate whether the involved side of the TSS was used for normal venous drainage. TSS stenosis was defined as sinus diameter < 50% of the normal proximal diameter. DAVF shunt obliteration, TSS occlusion, neurological status, and adverse events were also evaluated. RESULTS: Of the 34 patients, 21 had Borden type I and 14 had Borden type II DAVFs. The median age at SRS was 64 years (interquartile range 54-71 years), and the follow-up period was 31 months (interquartile range 15-94 months). Complete shunt obliteration was achieved in 24 (70.6%) patients. The cumulative 2-, 3-, and 5-year shunt obliteration rates were 49.6%, 71.2%, and 86.0%, respectively. Borden type I had higher obliteration rates (60.5%, 83.1%, and 94.4%, respectively) than Borden type II (41.7%, 51.4%, and 75.7%, respectively; p = 0.034). TSS occlusion occurred in 5 patients (14.7%). The cumulative 1-, 5-, and 10-year TSS occlusion rates were 2.9%, 8.3%, and 23.6%, respectively, across the entire cohort. All occlusions occurred exclusively in the sinuses that were not used for normal venous drainage. Cox proportional analyses revealed that TSS stenosis and the sinus not being used for normal venous drainage were significantly associated with a greater risk of TSS occlusion after SRS (HR 9.44, 95% CI 1.01-77.13; p = 0.049). CONCLUSIONS: SRS is effective and safe for TSS DAVF and results in favorable shunt obliteration, symptom improvement, and low complication rates. TSS occlusion after SRS is asymptomatic and is limited to sinuses that are not used for normal venous drainage.

Absence of the torcular, review of venous sinus anatomy, and the simplified dural sinus classification.

BACKGROUND: Classically, the torcular Herophili is described as the symmetric junction between the superior sagittal sinus (SSS), transverse sinuses (TSs), and straight sinus (SS). However, finding this pattern in practice is not standard. Anatomical variations are common, and different drainage patterns should be expected. Existing literature proposes highly detailed descriptions and classifications of this region. Still, a simplified and practical categorization is not available. METHODS: We present an anatomical finding of the torcular Herophili discovered on a cadaveric dissection. Then, we conducted a retrospective study examining the 100 most recent cranial magnetic resonance venographies (MRVs) from the Mayo Clinic, labeling them with a new proposed dural sinus classification system. Images were initially classified by two authors and further validated by a board-certified neurosurgeon and a board-certified neuroradiologist from our institution. To measure consistency in image identification, two additional international neurosurgeons were asked to classify a subset of the same MRV images, and their answers were compared. RESULTS: Of the MRV cohort, 33 patients were male and 67 were female. Their ages ranged from 18 to 86 years, with a mean of 47.35 years and a median of 49 years. Upon examination, 53 patients presented as confluent (53%), 9 as SSS divergent (9%), 25 as SS divergent (25%), 11 as circular (11%), and 2 as trifurcated (2%). The inter-rater reliability ranked very good; agreement between the two neurosurgeons was 83% (κ = 0.830, p < 0.0005). CONCLUSION: The confluence of the venous sinuses is a highly variable anatomical area that is rarely evaluated with neuroimaging before surgery. The classic textbook configuration is not the rule. Using a simplified classification system may increase awareness and hopefully patient safety by preparing the physician for anatomical variations that they will encounter in a surgical or clinical scenario.

A new method for assessing transverse sinus stenosis with CT venography based on the venous trans-stenotic pressure gradient.

BACKGROUND: Evaluation of the transverse sinus stenosis (TSS) is essential for TSS-related diseases. OBJECTIVE: To investigate a new method for the quantitative assessment of TSS based on the correlation between TSS and trans-stenotic pressure gradient (TPG). METHODS: Patients with unilateral pulsatile tinnitus with or without idiopathic intracranial hypertension were retrospectively included. All patients underwent CT venography and venous manometry and were confirmed to have TSS. The cross-sectional diameter/area of TSS, the poststenotic and prestenotic segments, and the superior sagittal sinus (SSS) were measured. The degree of TSS was calculated by dividing the diameter/area of TSS by the diameter/area of the poststenotic segment (M1/M2), prestenotic segment (M3/M4), and SSS (M5/M6). Partial correlation analysis (controlling for the effect of age, sex, outflow laterality, and contralateral stenosis) was performed to evaluate the correlation between M1-M6 and the TPG. Receiver operating characteristic curve analysis of M1-M6 for diagnosing a significant TPG (≥8 mm Hg) was performed. RESULTS: Ninety-nine patients met the inclusion criteria. The partial correlation coefficients between M1-M6 and the TPG were 0.60, 0.61, 0.43, 0.48, 0.39, and 0.54, respectively. The areas under the curve (AUCs) of M1-M6 for diagnosing a significant TPG were 0.81, 0.86, 0.68, 0.69, 0.64, and 0.72, respectively. The AUC of M2 was significantly larger than that of M3 (P=0.002), M4 (P<0.001), M5 (P=0.001), and M6 (P<0.001). CONCLUSIONS: Quantitatively assessing TSS by taking the ratio of the cross-sectional area of TSS to that of the poststenotic segment might be a more efficient method for predicting the TPG.

Outflow Patency Correlates with Radiosurgical Outcomes of Lateral Sinus Dural Arteriovenous Fistula.

OBJECTIVE: To explore the impact of outflow patency on radiosurgical outcomes of lateral sinus dural arteriovenous fistulas (DAVFs). METHODS: We retrospectively examined 83 lateral sinus DAVFs treated with Gamma Knife radiosurgery (GKRS) between 1995 and 2020. Two neuroradiologists blinded to the therapeutic outcomes served as imaging evaluators on pre-GKRS digital subtraction angiography and magnetic resonance images. The sinovenous outflow of lateral sinus DAVF was scored using combined conduit score (CCS), ranging from 0 (total occlusion) to 8 (full patency). The patients' follow-up magnetic resonance and digital subtraction angiography images were used to validate the radiosurgical outcomes (obliteration or non-obliteration) of lateral sinus DAVF. Cox regression and Kaplan-Meier analyses were performed to determine the correlations between the variables and outcomes. RESULTS: Among the 83 cases, 60 (72%) lateral sinus DAVFs achieved obliteration after a GKRS at a median latency period of 24.5 months. After adjustment for aggressive presentation, cortical venous reflux, straight sinus reflux, and optic nerve sheath enlargement, a CCS of >6 was independently associated with lateral sinus DAVF obliteration (hazard ratio: 2.335, P = 0.007). The estimated 36-month probabilities of obliteration were 80% versus 53.6% for lateral sinus DAVFs with a CCS of >6 versus ≤6. CONCLUSIONS: Lateral sinus DAVFs with a CCS of >6, indicating a nearly patent sinovenous outflow, were more likely to be obliterated after GKRS. Sinovenous outflow patency is a factor associated with therapeutic outcomes in radiosurgery for lateral sinus DAVFs.

Sinovenous outflow in lateral sinus dural arteriovenous fistulas after stereotactic radiosurgery: a retrospective longitudinal imaging study.

PURPOSE: To investigate sinovenous outflow restriction (SOR) in lateral sinus dural arteriovenous fistulas (LSDAVFs) after Gamma Knife radiosurgery (GKRS) and its association with complete obliteration. METHODS: We retrospectively (1995-2019) enrolled 39 patients with LSDAVFs who had undergone GKRS alone and evaluated their angiography and magnetic resonance imaging (MRI) before and after GKRS. The LS conduits ipsilateral and contralateral to the DAVFs were scored using a 5-point scoring system, with scores ranging from 0 (total occlusion) to 4 (fully patent). SOR was defined by a conduit score < 2. Demographics, imaging features, and outcomes were compared between patients with and without ipsilateral SOR after GKRS. Logistic regression analysis was performed to estimate the odds ratio (OR) for obliteration with the imaging findings. RESULTS: After a median angiographic follow-up of 28 months for the 39 patients, the ipsilateral LS became more restrictive (median conduit score before and after GKRS: 2 vs. 1, p = .011). Twenty-one patients with ipsilateral SOR after GKRS had a significantly lower obliteration rate (52.4% vs. 94.4%, p = .005) than those without SOR. Follow-up SOR was independently associated with a lower obliteration rate (OR 0.05, p = .017) after adjustment for age, cortical venous reflux, and absent sinus flow void on MRI. CONCLUSION: This study demonstrates a restrictive change of outflow in LSDAVFs after GKRS and a lower obliteration rate in patients with SOR. Follow-up imaging for SOR may help predict outcomes of these patients.

Gradual dilatation of an occluded transverse sinus associated with dural arteriovenous fistula after balloon angioplasty with sinus packing: A case report.

BACKGROUND: There is no consensus as to whether balloon angioplasty alone or stent placement is effective for sinus occlusion associated with dural arteriovenous fistula (DAVF). Herein, we first report a case of transverse sinus occlusion associated with DAVF in which gradual sinus dilatation was observed after balloon angioplasty with embolization of the affected sinus with shunt flow. CASE PRESENTATION: A 69-year-old man presented with executive dysfunction. Magnetic resonance imaging revealed left transverse sinus-sigmoid sinus DAVF with occlusion of the left jugular vein and right transverse sinus. Before endovascular treatment, the patient had symptomatic epilepsy and subarachnoid hemorrhage. Retrograde leptomeningeal venous drainage disappeared with packing of the left transverse sinus-sigmoid sinus. Subsequently, balloon angioplasty of the right occluded transverse sinus was performed to maintain the normal venous drainage and remaining shunt outflow. Dilatation of the right transverse sinus was poor immediately after surgery. However, angiography after 10 days and 6 months revealed gradual dilatation of the right transverse sinus. CONCLUSION: Sinus occlusion, which is thought to be caused by sinus hypertension associated with DAVF rather than chronic organized thrombosis or thrombophilia, may dilate over time after balloon angioplasty and shunt flow reduction if occluded sinus is necessary for facilitating normal venous drainage.

Intracranial venous sinus stenting for the treatment of lateral sinus stenoses: An analysis of 200 patients.

PURPOSE: The purpose of this study was to analyze the long-term efficacy and safety of intracranial venous sinus stenting in a large cohort of patients with any type of presentation of primary lateral venous sinus stenosis (VSS). MATERIALS AND METHODS: A retrospective cohort study was performed including patients treated by venous sinus stenting for symptomatic VSS from 2012 to 2019. Successful primary resolution of symptoms without adjunctive treatment or recurrence, and complications after stenting were analyzed at the last follow-up time point. RESULTS: Two-hundred patients were included. There were 14 men and 186 women with a mean age of 39±14 (SD) years (age range: 13-75 years). Presenting symptoms included venous pulsatile tinnitus in 168 patients (168/200; 84%), idiopathic intracranial hypertension in 100 patients (100/200; 50%) and/or spontaneous cerebrospinal fluid leak in 35 patients (35/200; 17%). The overall rate of successful primary resolution of any typical presenting symptoms was 79% (95% CI: 73-85%). This rate ranged from 74% to 93% depending on the symptom with no significant difference between patients with and those without idiopathic intracranial hypertension (P=0.08). Recurrence rate was 10% (95% CI: 6-14%). No death or permanent morbidity were observed during a median follow-up of 2.2 years (Q1, Q3: 1.4, 3.3; range: 1-7.7 years). CONCLUSION: Our study shows that venous sinus stenting has a low morbidity and high success rate at long-term follow-up for the treatment of idiopathic intracranial hypertension, venous pulsatile tinnitus or spontaneous cerebrospinal fluid leak associated with VSS. The excellent safety suggests considering this treatment as first-line treatment when medical management is ineffective or poorly tolerated.

Hydroacoustic analysis and extraluminal compression surgical insights of venous pulsatile tinnitus.

OBJECTIVE: This study aimed to quantitatively and qualitatively evaluate the hydroacoustic changes from "presence" to "disappearance" of pulsatile tinnitus (PT) with the extraluminal compression surgical technique. The recent issues of concern pertaining to the hydroacoustic characteristics of sigmoid sinus wall anomalies and distal transverse sinus stenosis (dTSS) were discussed. METHODS: This study was based on a retrospective case series. Seventy-seven patients with PT and transverse-sigmoid sinus enlargement with or without transverse-sigmoid sinus junction anomalies and transverse sinus stenosis (TSS) who had undergone extraluminal compression surgery under local anesthesia were included. Management of intractable intraoperative challenges and techniques for reversal extraluminal compression were introduced. Anatomical measurements, intraoperative color-coded Doppler ultrasonography, spectro-temporal analysis, and computational fluid dynamics were employed to analyze the hydroacoustic characteristics of PT. RESULTS: The efficacy of the extraluminal compression technique was evident with the significant reduction in peak turbulent kinetic energy, vorticity, and mean pressure gradient at the transverse-sigmoid junction, resulting in over 20% reduction in PT amplitude. dTSS is a common finding in patients with PT exhibiting transverse-sigmoid sinus enlargement. Patients with dTSS presented with significant differences in hemodynamic characteristics as compared to those without. Linear regression analysis showed that the flow disturbance (turbulent kinetic energy and vorticity) was closely associated with the degree of dTSS, whereas the flow amplitude was not related to the degree or location of TSS. Low-pulsatory vortex flow at the transverse-sigmoid junction was visualized during an intraoperative color-coded Doppler examination, and the displayed low-frequency PT sound corresponded to the patients' subjective perception of PT. CONCLUSION: (1) A reduction of over 20% of the flow-induced noise is the therapeutic goal of extraluminal compression technique. Since reductions in the magnitude of hemodynamic parameters, including turbulent kinetic energy, vorticity, and mean pressure gradient, render the flow-induced noise inaudible, besides sigmoid sinus wall anomalies, it is likely that PT develops from the aggregation of flow-based pathologies. (2) Although dTSS and diverticulum may greatly affect the hemodynamics at the transverse-sigmoid junction, in contrast to dehiscence, dTSS and diverticulum may not be the limiting factors for PT development.

Mid-term assessment of transverse sinus stent patency in 104 patients treated for intracranial hypertension secondary to dural sinus stenosis.

BACKGROUND: Transverse sinus (TS) stenting is a valid treatment alternative for patients with intracranial hypertension caused by underlying bilateral TS stenoses. Its mid-term patency has, however, not been well documented. OBJECTIVE: To assess the 6-month patency of TS stenting using subtracted CT venography (CTV). METHODS: A retrospective analysis of a prospectively collected database of patients undergoing TS stenting was performed. The cohort was a single-center, single-operator series of 125 consecutive patients treated between 2008 and 2018. Mid-term follow-up 320-row detector CTV was available for review in 104 patients. RESULTS: Follow-up CTV was obtained on average 6 months after stenting. Stents in all patients (100%) were patent. Subtracted reconstructions showed no intraluminal thrombus or neointimal hyperplasia. Native reconstructions confirmed the structural integrity of the stents. De novo stenosis proximal to the stent was noted in 10 cases (10%). A total of 10 patients (10%) received additional treatment due to recurrent symptoms. In univariate analysis, both high body mass index and stent size (>6 mm) were associated with development of de novo stenoses: OR 1.12 (95% CI 1.01 to 1.25, p=0.037) and OR 5.63 (95% CI 1.16 to 27.22, p=0.032), respectively. In multivariate analysis, only stent size (>6 mm) remained significant: OR 7.19 (95% CI 1.03 to 50.01, p=0.046). CONCLUSION: TS stenting is an effective treatment for intracranial hypertension secondary to dural sinus stenosis in an appropriately selected patient population. A 320-row dynamic CTV is a high-quality non-invasive imaging method that can assess both the physical integrity of the stent and its patency. At mid-term follow-up, all imaged stents were patent. The occurrence of de novo stenoses proximal to the stent (10%) correlated with stent size (>6 mm).

Resection of carcinoma of the external auditory canal in a patient with a high jugular bulb using temporal craniotomy.

External auditory canal (EAC) carcinoma is a rare and unusual malignancy. The complex anatomy and relationship between the tumor and surrounding tissues in a limited space render it difficult to attain safe resection margins during surgery. A high jugular bulb (HJB) is one such anatomical variation that has important surgical implications that complicate the surgical procedure for EAC carcinoma. A 73-year-old woman presented with a 3-month history of right ear pain. Pathological findings and computed tomography (CT) revealed EAC carcinoma, which was expanding to the middle ear (ME). Although there was no cavity inside the ME, an HJB was detected. Surgical treatment using a temporal incision for temporal craniotomy achieved complete resection of the tumor and preserved facial nerve function. The patient recovered without complications and was discharged 17 days after the operation. Temporal incision and temporal craniotomy is a useful approach for EAC carcinoma with HJB.

Reductions in bilateral transverse sinus pressure gradients with unilateral transverse venous sinus stenting for idiopathic intracranial hypertension.

BACKGROUND: Venous sinus stenting is an effective treatment for papilledema associated with idiopathic intracranial hypertension (IIH). It is unclear whether unilateral transverse-sigmoid sinus (TSS) stenting adequately decompresses the contralateral TSS system in cases of bilateral transverse sinus stenosis. The objective of this study was to compare changes in bilateral TSS pressure gradients following unilateral TSS stenting in a series of patients with IIH. METHODS: Consecutive patients from a single institution who underwent venous sinus stenting for IIH with measurement of bilateral pressure gradients before and after stenting for IIH were enrolled. Pressure gradients in both TSS pre- and post-stenting were measured during the procedure. The TSS with the highest gradient was stented. Changes in TSS pressure gradients following stent placement were calculated for both TSS. Mean changes in pressure gradients of ipsilateral and contralateral TSS were calculated. RESULTS: Sixteen patients with IIH who underwent TSS stenting were included. All were female. Mean age was 36.4 years. The right-sided TSS was the stented side in 12 (75.0%) patients. The mean pre-stent pressure gradient of the ipsilateral TSS was 19.3 mmHg (SD=10.8), which was reduced to a mean of 3.8 mmHg (3.4) following stent placement (P =<0.0001). On the contralateral (non-stented) side, the mean pre-stent gradient of 15.1 mmHg (7.5) was reduced to a mean of 7.8 mmHg (6.6) following stenting (P=0.006). CONCLUSIONS: The use of a single stent provides some venous decompression of the contralateral non-stented stenosis in most cases of IIH treated with endovascular therapy.

Chemotherapy associated dural sinus thrombosis presenting as a cerebrospinal fluid leak.

Despite the well documented increased risk of thrombosis in patients with cancer and during chemotherapy, cerebral venous sinus thrombosis (CVT) remains a rare entity. We present a rare case of cerebrospinal fluid (CSF) rhinorrhoea secondary to a left transverse sinus thrombus which occurred 2 years previously during chemotherapy for breast cancer. The patient underwent a three-layer repair using Neuro-Patch, septal cartilage and middle turbinate pedicle flap and was started on acetazolamide. There was no recurrence at 1-year follow-up. Raised intracranial pressure secondary to cerebral venous occlusion can erode the base of skull and predispose to CSF leaks. Despite the theoretical risk, there have been no cases reported where CSF leaks have occurred following chemotherapy induced CVT. We describe the first case and discuss pathophysiology and management.

Endovascular Treatment of Cerebral Venous Sinus Stenosis Based on Hemodynamic Assessment Using Pressure Wire.

BACKGROUND: A pressure wire offers a dynamic tool to assist in the measurement of the pressure gradient and assessment of the functional significance of stenosis. The author presents a patient with idiopathic intracranial hypertension who was diagnosed with cerebral venous sinus stenosis (CVSS). Venography accompanied by pressure measurement was used to guide the stent placement for CVSS. CASE DESCRIPTION: A 27-year-old woman was referred to our hospital with a chief complaint of headache and neckache lasting for 7 weeks, with an 8-day history of binocular diplopia and blurred vision. Magnetic resonance venography and digital subtraction angiography showed a filling defect in the right transverse sinus. A pressure wire was used before endovascular treatment and showed that the pressure gradient was 10 mm Hg, which meets the surgical indication. After a stent was placed, no pressure gradient was recorded by the pressure wire. CONCLUSIONS: This is the first report about using a pressure wire for CVSS. The finding suggests that use of a pressure wire can be a new approach in the diagnosis and treatment of CVSS.

Individual variations of the superior petrosal vein complex and their microsurgical relevance in 50 cases of trigeminal microvascular decompression.

BACKGROUND: We investigated the understudied anatomical variations of the superior petrosal vein (SPV) complex (SPVC), which may play some role in dictating the individual complication risk following SPVC injury. METHODS: Microvascular decompressions of the trigeminal nerve between September 2012 and July 2016. All operations utilized an SPVC preserving technique. Preoperative balanced fast field echo (bFFE) magnetic resonance imaging, or equivalent sequences, and operative videos were studied for individual SPVC anatomical features. RESULTS: Applied imaging and operative SPVC anatomy were described for fifty patients (mean age, 67.18 years; female sex and right-sided operations, 58% each). An SPVC component was sacrificed intentionally in 6 and unintentionally in only 7 cases. Twenty-nine different individual variations were observed; 80% of SPVCs had either 2 SPVs with 3 or 1 SPV with 2, 3, or 4 direct tributaries. Most SPVCs had 1 SPV (64%) and 2 SPVs (32%). The SPV drainage point into the superior petrosal sinus was predominantly between the internal auditory meatus and Meckel cave (85.7% of cases). The vein of the cerebellopontine fissure was the most frequent direct tributary (86%), followed by the pontotrigeminal vein in 80% of SPVCs. Petrosal-galenic anastomosis was detected in at least 38% of cases. At least 1 SPV in 54% of the cases and at least 1 direct tributary in 90% disturbed the operative field. The tributaries were more commonly sacrificed. CONCLUSIONS: The extensive anatomical variation of SPVC is depicted. Most SPVCs fall into 4 common general configurations and can usually be preserved. BFFE or equivalent sequences remarkably facilitated the intraoperative understanding of the individual SPVC in most cases.

Proximity of Vascular Bone Channel in the Lateral Sinus Wall to Root Apices of Maxillary First Molars: A Cone-beam Computed Tomographic Analysis.

INTRODUCTION: Apical surgery is frequently indicated in maxillary first molars. Occasionally, a vascular anastomosis in the lateral maxillary sinus wall can be observed during surgery. The aim of this study was to examine the distance between the vascular bone channel (VBC) and the root apices of maxillary first molars using cone-beam computed tomographic imaging. METHODS: Cone-beam computed tomographic images of 104 maxillary first molars were oriented in the coronal plane to evaluate the distance between the roots and the VBC. The measurements were only recorded in relation to the buccal roots. In addition, demographic parameters and further measurements such as the diameter of the VBC and the proximity to the periapical pathology were evaluated. RESULTS: A total of 210 VBCs were assessed. The mean distance from the VBC to the apices of the buccal roots of the maxillary first molars was 6.18 mm ± 3.84 mm. The VBC was mostly located intrasinusally (74.3%) and only rarely superficially (0.5%). The diameter of the VBC was on average 0.88 ± 0.32 mm. CONCLUSIONS: In this study, the VBC was usually found closer to the mesiobuccal than to the distobuccal root apex. During preparation of the access window, the existence of the VBC should be kept in mind because the mesiobuccal roots of maxillary first molars undergo apical surgery to the buccally positioned roots only.