A novel theory for rapid localization of the transverse-sigmoid sinus junction and "keyhole" in the retrosigmoid keyhole approach: micro-anatomical study, technique nuances, and clinical application.

To determine a rapid and accurate method for locating the keypoint and "keyhole" in the suboccipital retrosigmoid keyhole approach. (1) Twelve adult skull specimens were selected to locate the anatomical landmarks on the external surface of the skull.The line between the infraorbital margin and superior margin of the external acoustic meatus was named the baseline. A coordinate system was established using the baseline and its perpendicular line through the top point of diagastric groove.The perpendicular distance (x), and the horizontal distance (y) between the central point of the "keyhole" and the top point of the digastric groove in that coordinate system were measured. The method was applied to fresh cadaveric specimens and 53 clinical cases to evaluate its application value. (1) x and y were 14.20 ± 2.63 mm and 6.54 ± 1.83 mm, respectively (left) and 14.95 ± 2.53 mm and 6.65 ± 1.61 mm, respectively (right). There was no significant difference between the left and right sides of the skull (P > 0.05). (2) The operative area was satisfactorily exposed in the fresh cadaveric specimens, and no venous sinus injury was observed. (3) In clinical practice, drilling did not cause injury to venous sinuses, the mean diameter of the bone windows was 2.0-2.5 cm, the mean craniotomy time was 26.01 ± 3.46 min, and the transverse and sigmoid sinuses of 47 patients were well-exposed. We propose a "one point, two lines, and two distances" for "keyhole" localization theory, that is we use the baseline between the infraorbital margin and superior margin of the external acoustic meatus and the perpendicular line to the baseline through the top point of the digastric groove to establish a coordinate system. And the drilling point was 14.0 mm above and 6.5 mm behind the top point of the digastric groove in the coordinate system.

Endovascular stenting using a sagittal sinus approach for sigmoid sinus wall dehiscence related to intractable pulsatile tinnitus: a case series.

BACKGROUND: Sigmoid sinus wall dehiscence can lead to pulsatile tinnitus with a significant decrease in quality of life, occasionally leading to psychiatric disorders. Several surgical and endovascular procedures have been described for resolving dehiscence. Within endovascular procedures, the sagittal sinus approach could be a technical alternative for tracking and accurate stent positioning within the sigmoid sinus when the jugular bulb anatomy is unfavorable. CASE PRESENTATION: A retrospective case series of three patients with pulsatile tinnitus due to sigmoid sinus wall dehiscence without intracranial hypertension was reviewed from January 2018 to January 2022. From the participants enrolled, the median age was 50.3 years (range 43-63), with 67% self-identifying as female and 33% as male. They self-identified as Hispanic. Sigmoid sinus dehiscence was diagnosed using angiotomography, and contralateral transverse sinus stenosis was observed in all patients. Patients underwent surgery via a navigated endovascular sagittal sinus approach for sigmoid sinus stenting. No neurological complications were associated with the procedure. Pulsatile tinnitus improved after the procedure in all patients. CONCLUSIONS: Superior sagittal sinus resection for sigmoid sinus wall stenting is a safe and effective technique. Pulsatile tinnitus due to sigmoid sinus wall dehiscence could be treated using the endovascular resurfacing stenting technique. However, further research is needed to evaluate the potential benefit of contralateral stenting for removing sinus dehiscence when venous stenosis is detected. However, resurfacing sigmoid sinus wall dehiscence results in symptomatic improvement.

Surgical Technique for Draining a Concomitant Supra-and Infratentorial Epidural Hematomas.

AIM: To assess clinical and radiological characteristics of simultaneous acute supra- and infratentorial epidural hematomas. MATERIAL AND METHODS: We retrospectively reviewed the clinical and radiological data of 18 patients with a concomitant acute supra- and infratentorial epidural hematoma, who were treated and followed up at our hospital. RESULTS: The Glasgow Coma Score was 3-8 in four patients, was 9-12 in seven, and was 13-15 in seven patients. While the concomitant supra- and infratentorial hematoma did not cross the midline in 15 of the patients, it did in three of them. The dural venous sinus rupture was repaired in five of the patients. Functional healing was observed in 14 of the 18 patients. Two of the patients died during the postoperative period. CONCLUSION: A simultaneous supra- and infratentorial epidural hematoma rarely occurs in neurosurgical practice. Mortality and morbidity rates are high if these are not addressed in time. The radiological images of patients should be evaluated carefully preoperatively. In patients with a concomitant infra- and supratentorial hematoma, transverse sinus damage, which is a surgical challenge, should be considered. Herein, we describe a surgical technique (supra- and infratentorial craniotomy leaving the bone bridge over the transverse sinus) for draining a concomitant supra- and infratentorial epidural hematoma; this technique is an effective surgical choice in select patients.

Idiopathic Intracranial Hypertension.

Idiopathic intracranial hypertension is defined by headaches and a decline in visual acuity due to increased intracranial pressure. Treatment options historically included weight loss, acetazolamide, and/or cerebrospinal fluid diversion surgery. Recent understanding of the contributions of dural venous sinus hypertension and stenosis has led to venous sinus stenting as a treatment option.

Causes of Pulsatile Tinnitus and Treatment Options.

Pulsatile tinnitus (PT) requires detailed workup to evaluate for an underlying structural cause. With advances in neuroimaging, structural venous abnormalities that can cause PT have becoming increasingly recognized. A number of anomalies, including dural arteriovenous fistulas, idiopathic intracranial hypertension, transverse sinus stenosis, sigmoid sinus wall abnormalities, jugular venous anomalies, and hypertrophied emissary veins, have been implicated in flow disruption and turbulence in the vicinity of auditory structures, resulting in PT. Endovascular treatment options, including stenting, coiling, and embolization with liquid agents, have demonstrated high efficacy and safety. These treatments can lead to symptomatic relief in carefully selected cases.

Venous Sinus Stent to Treat Paralysis.

Transvenous treatment of paralysis is a concept less than a decade old. The Stentrode (Synchron, Inc, New York, USA) is a novel electrode on stent device intended to be implanted in the superior sagittal sinus adjacent to the motor cortex. Initial animal studies in sheep demonstrated the safety of the implant as well as its accuracy in detecting neural signals at both short and long term. Early human trials have shown the safety of the device and demonstrated the use of the Stentrode system in facilitating patients with paralysis to carry out daily activities such as texting, email, and personal finance. This is an emerging technology with promise, although certainly more research is required to better understand the capabilities and limitations of the device.

[Angioarchitecture and Associated Dural Arteriovenous Fistulas of the Superior Petrosal Sinus and Petrosal Vein].

The superior petrosal sinus and petrosal vein are important drainage routes for the posterior cranial fossa, with some variations and collateral vessels. An anterolateral-type tentorial dural arteriovenous fistula, which occurs around the petrosal vein, often develops aggressive symptoms due to venous reflux to the brainstem and cerebellum. Neuroendovascular treatment of this fistula is usually challenging because transarterial embolization has a high risk and indications for transvenous embolization are limited. In the cavernous sinus and transverse sinus/sigmoid sinus dural arteriovenous fistulas, venous reflux to the petrosal vein is dangerous, and a treatment strategy with the occlusion of the petrosal vein is indispensable. Furthermore, attention should be paid to venous approaches through the superior petrosal sinus.

[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.

Parasagittal Meningiomas: The Impact of Sinus Opening and Grade of Resection on Clinical Outcome and Recurrence in a Consecutive Series of Patients.

BACKGROUND: Surgical management of parasagittal meningiomas (PMs) remains controversial in the literature. The need to pursue a resection as radical as possible and the high risk of venous injuries contribute to making the sinus opening a widely argued choice. This study aimed to analyze factors affecting the risk of recurrence and to assess clinical outcomes of patients who underwent surgical resection of PMs with conservative or aggressive management of the intrasinusal portion. METHODS: A single-institution retrospective review of all patients with PM surgically treated between January 2013 and March 2021 was conducted. RESULTS: Among 56 patients, the sinus was opened in 32 patients (57%), and a conservative approach was used in 24 patients (43%). The sinus opening was found to be a predictive factor of radical resection (Simpson grade [SG] I-II) (P = 0.007). SG was the only predictive factor of recurrence (P < 0.001). The radical resection group (SG I-II) showed recurrence-free survival at 72 months of about 90% versus 30% in the non-radical resection group (SG III-IV) (log-rank test = 14.21, P < 0.001). Aggressive management of the sinus and radical resection were not found to be related to permanent deficit (P = 0.214 and P = 0.254) or worsening of Karnofsky performance scale score (P = 0.822 and P = 0.933). CONCLUSIONS: Removal of the intrasinusal portion of the tumor using standard procedures is not associated with a higher risk of permanent deficit or worsening of Karnofsky performance scale and reduces the risk of recurrence.

The Posterior Auricularis Muscle as Superficial Landmark for the Sigmoid Sinus and Transverse-Sigmoid Sinus Junction: An Anatomical Study.

OBJECTIVE: Neuronavigation systems coupled with previously reported external anatomical landmarks assist neurosurgeons during intracranial procedures. We aimed to verify whether the posterior auricularis muscle (PAM) could be used as an external landmark for identifying the sigmoid sinus (SS) and the transverse-sigmoid sinus junction (TSSJ) during posterior cranial fossa surgery. METHODS: The PAM was dissected in 10 adult cadaveric heads and after drilling the underlying bone, the relationships with the underlying SS and TSSJ were noted. The width and length of the PAM, and the distance between the muscle and reference points (asterion, mastoid tip, and midline), were measured. RESULTS: The PAM was identified in 18 sides (9 left, 9 right). The first 20 mm of the muscle length (mean 28.28 mm) consistently overlay the mastoid process anteriorly and the proximal half of the SS slightly posteriorly on all sides. The superior border was a mean of 2.22 mm inferior to the TSSJ and, especially when the muscle length exceeded 20 mm, this border extended closer to the transverse sinus; it was usually found at a mean of 3.11 mm (range 0.0-13.80 mm) inferior to the distal third of the transverse sinus. CONCLUSIONS: Superficial landmarks give surgeons improved surgical access, avoiding overexposure of deep neurovascular structures and reducing brain retraction. On the basis of our cadaveric study, the PAM is a reliable and accurate direct landmark for identifying the SS and TSSJ. The PAM could potentially be used for guiding the retrosigmoid approach.

Foundations of the Diagnosis and Management of Idiopathic Intracranial Hypertension and Pulsatile Tinnitus.

Venous sinus stenosis has garnered increasing academic attention as a potential etiology of idiopathic intracranial hypertension (IIH) and pulsatile tinnitus (PT). The complex anatomy of the cerebral venous sinuses and veins plays a crucial role in the pathophysiology of these conditions. Venous sinus stenosis, often found in the superior sagittal or transverse sinus, can lead to elevated intracranial pressure (ICP) and characteristic IIH symptoms. Stenosis, variations in dural venous anatomy, and flow dominance patterns contribute to aberrant flow and subsequent PT. Accurate imaging plays a vital role in diagnosis, and magnetic resonance (MR) venography is particularly useful for detecting stenosis. Management strategies for IIH and PT focus on treating the underlying disease, weight management, medical interventions, and, in severe cases, surgical or endovascular procedures. Recently, venous sinus stenting has gained interest as a minimally invasive treatment option for IIH and PT. Stenting addresses venous sinus stenosis, breaking the feedback loop between elevated ICP and stenosis, thus reducing ICP and promoting cerebrospinal fluid outflow. The correction and resolution of flow aberrances can also mitigate or resolve PT symptoms. While venous sinus stenting remains an emerging field, initial results are promising. Further research is needed to refine patient selection criteria and evaluate the long-term efficacy of stenting as compared to traditional treatments.

Challenges in the use of Venous Sinus Stenting in the Treatment of Idiopathic Intracranial Hypertension and Pulsatile Tinnitus.

Although numerous case series and meta-analyses have shown the efficacy of venous sinus stenting (VSS) in the treatment of idiopathic intracranial hypertension and idiopathic intracranial hypertension-associated pulsatile tinnitus, there remain numerous challenges to be resolved. There is no widespread agreement on candidacy; pressure gradient and failed medical treatment are common indications, but not all clinicians require medical refractoriness as a criterion. Venous manometry, venography, and cerebral angiography are essential tools for patient assessment, but again disagreements exist regarding the best, or most appropriate, diagnostic imaging choice. Challenges with the VSS technique also exist, such as stent choice and deployment. There are considerations regarding postprocedural balloon angioplasty and pharmacologic treatment, but there is insufficient evidence to formalize postoperative decision making. Although complications of VSS are relatively rare, they include in-stent stenosis, hemorrhage, and subdural hematoma, and the learning curve for VSS presents specific challenges in navigating venous anatomy, emphasizing the need for wider availability of high-quality training. Recurrence of symptoms, particularly stent-adjacent stenosis, poses challenges, and although restenting and cerebrospinal fluid-diverting procedures are options, there is a need for clearer criteria for retreatment strategies. Despite these challenges, when comparing VSS with traditional cerebrospinal fluid-diverting procedures, VSS emerges as a favorable option, with strong clinical outcomes, lower complication rates, and cost-effectiveness. Further research is necessary to refine techniques and indications and address specific aspects of VSS to overcome these challenges.

Future Directions and Innovations in Venous Sinus Stenting.

This review explores the future role of venous sinus stenting (VSS) in the management of idiopathic intracranial hypertension and pulsatile tinnitus. Despite its favorable safety profile and clinical outcomes compared with traditional treatments, VSS is not yet the standard of care for these conditions, lacking high-level evidence data and guidelines for patient selection and indications. Current and recently completed clinical trials are expected to provide data to support the adoption of VSS as a primary treatment option. Additionally, VSS shows potential in treating other conditions, such as dural arteriovenous fistula and cerebral venous sinus thrombosis, and it is likely that the procedure will continue to see an expansion of its approved indications. The current lack of dedicated venous stenting technology is being addressed with promising advancements, which may improve procedural ease and patient outcomes. VSS also offers potential for expansion into modulation of brain electrophysiology via endovascular routes, offering exciting possibilities for neurodiagnostics and treatment of neurodegenerative disorders.

Direct superior sagittal sinus puncture via a surgical burr hole for curative embolization of the complex transverse-sigmoid sinus dural arteriovenous fistula: How I do it.

BACKGROUND: Transvenous embolization of high-grade dural arteriovenous fistulas (dAVFs) is challenging particularly when the direct sinus access is favorable due to the complex venous anatomy which prohibits endovascular access via the transfemoral approach. METHOD: The procedure was conducted in the hybrid operating suite, where a burr hole was performed, followed by direct catheterization of the superior sagittal sinus. Coil embolization was then executed to achieve complete obliteration of the fistula. CONCLUSION: The direct puncture of the superior sagittal sinus is a safe and effective method for treating complex dAVFs. This approach grants access to the fistula channel which facilitates curative embolization.

Venous sinus stenting for idiopathic intracranial hypertension: An updated Meta-analysis.

BACKGROUND: Idiopathic intracranial hypertension (IIH) is characterized by elevated intracranial pressure and primarily affects obese women of reproductive age. Venous sinus stenting (VSS) is a surgical procedure used to treat IIH, but its safety and efficacy are still controversial. METHODS: A systematic review and meta-analysis were conducted following PRISMA guidelines. Multiple databases were searched for studies evaluating the safety and efficacy of VSS in IIH patients and meta-analysis was performed to pool the data. RESULTS: A total of 36 studies involving 1066 patients who underwent VSS were included. After VSS, a significant reduction in trans-stenotic gradient pressure was observed. Patients also showed significantly lower cerebrospinal fluid (CSF) opening pressure. Clinical outcomes demonstrated improvement in tinnitus (95%), papilledema (89%), visual disturbances (88%), and headache (79%). However, 13.7% of patients experienced treatment failure or complications. The treatment failure rate was 8.35%, characterized by worsening symptoms and recurrence of IIH. The complications rate was 5.35%, including subdural hemorrhage, urinary tract infection, stent thrombus formation, and others. CONCLUSION: VSS appears to be a safe and effective treatment option for IIH patients who are unresponsive to medical therapy or have significant visual symptoms. However, long-term outcomes and safety of the procedure require further investigation.

Endovascular stenting for cerebral venous sinus stenosis secondary to meningioma invasion.

INTRODUCTION: Symptomatic intracranial hypertension (IH) due to venous outflow obstruction secondary to dural venous sinus (DVS) tumoral invasion affects up to 3% of intracranial meningioma patients. The literature regarding endovascular therapies of such patients is limited to a few case reports and a recent single-centre case series. PURPOSE: We describe our single-centre experience of endovascular therapy in patients with clinically symptomatic IH secondary to DVS meningioma invasion. METHODS: We performed a retrospective review of clinical and radiological data of all patients with refractory IH and meningiomas invading the DVS who were referred for possible DVS venoplasty and stenting. Seven endovascular procedures in six female patients were done. Presumed secondarily induced lateral transverse sinus stenosis was also stented in four patients as part of the primary intervention. RESULTS: All patients experienced complete symptomatic resolution at 6-month follow-up. Five patients had no symptom recurrence over a mean follow-up period of 3.5 years. One patient with multiple meningiomas developed recurrent IH 2 years following stenting secondary to in-stent tumour re-invasion. This was re-stented with consequent 6 months post-retreatment symptomatic relief at the time of writing. No procedure-related complications occurred. CONCLUSION: In the setting of DVS stenosis secondary to meningioma invasion, endovascular therapy is a safe and successful therapeutic option with promising mid-term results. The procedure should be considered in cases where complete surgical tumour resection is unlikely or carries a significant risk. If present, secondarily induced stenoses at the lateral ends of the transverse sinuses should also be considered for treatment.

Surgical treatment of marginal sinus dural arteriovenous fistula: a narrative review.

BACKGROUND: Dural arteriovenous fistulas of the marginal sinus (DAVFms) are uncommon and complex, with varied symptoms. Their complexity is heightened by the region's dense anastomotic network, posing risks for endovascular treatment. Surgical intervention can be effective, but this depends on thorough pre-operative understanding and optimal intra-operative visualization of the fistula. OBJECTIVE: To review the relevant anatomy, presentation patterns of DAVFms, and provide insights for surgical treatment. METHODS: Recent literature on DAVFms was reviewed, and three surgical cases are discussed to highlight treatment principles. RESULTS: The symptoms of a DAVFms vary depending on its venous drainage pattern. Drainage may be either ascending towards the cranial compartment or descending towards the spinal canal. Patients suffering from DAVFms may experience hemorrhage, particularly when venous drainage is directed upwards. Congestive symptoms of the spinal cord or brainstem can occur in cases of downward venous drainage. Compared to the endovascular approach, open surgery has a higher success rate in obliterating the fistula and yields better outcomes in cases of perimedullary venous drainage. Achieving surgical success necessitates thorough preoperative evaluation and adequate surgical exposure. Brainstem hyperintensity observed on T2-weighted MRI scans is linked to a poorer prognosis for recovery. CONCLUSION: Treating complex DAVFms often requires surgery, as endovascular methods may not be feasible. Successful surgery hinges on a precise understanding of the fistula's venous architecture and its spatial relationships, assessed using digital substraction angiography (DSA), angio-MRI, and angio-CT. Optimal intraoperative exposure is crucial for effective surgery.

Surgical Outcome of Torcula Herophili Meningioma: An Institutional Experience.

INTRODUCTION: Resection of meningiomas (THMs) at the torcular Herophili poses challenges to surgeons due to complex regional anatomy. The current study aims to evaluate factors affecting the extent of resections, progression-free survival, and the role of radiation. METHODS: We did a retrospective study of all the THM patients treated at our institute between May 1987 and June 2022. The demographic data, signs and symptoms, surgical notes, postoperative details, and radiotherapy were gathered retrospectively. Survival analysis was done with Kaplan-Meier tests along with predictors of the extent of resection as well as recurrence. RESULTS: A total of 39 patients qualified to be included in the study, with 10 male patients (male:female 1:2.9) and an average age of 50.8 years. The average follow-up duration was 75.9 months. Simpson's grade 2 excision was achieved in 19 (48.7%) patients, followed by Simpson's grade 3 excision in 17 patients (43.6%). Progression-free survival in subtotal resection was 60 months, and 100 months in gross total resection. Statistically, the extent of the resection was determined by the involvement of sinuses/torcula and the number of quadrants involved around torcula. A total of 16 patients received radiosurgery for the residual or small reccurrence of the lesion. Follow-up revealed reccurrence in 5 cases. CONCLUSIONS: Torcular meningiomas are relatively uncommon, described in few reports, and represent a therapeutic dilemma. Though some experts recommend complete removal of tumor and reconstruction of the sinus, others suggest maximum safe resection, followed by radiosurgery. The present study reflects reasonable control of the residual lesion with radiosurgery after maximum safe resection.

Simultaneous Parkinsonism and Dementia as Initial Presentation of Intracranial Dural Arteriovenous Fistulas: A Systematic Review.

BACKGROUND: Intracranial dural arteriovenous fistulas (IDAVFs) are abnormal vascular connections between dural arteries and various venous structures within the brain. IDAVFs, rarely present with parkinsonism and dementia concurrently, making this a unique and underexplored clinical scenario. To the best of our knowledge, this is the first systematic review to comprehensively analyze cases of IDAVFs manifesting as both parkinsonism and dementia. METHODS: We assessed databases from inception to September 18, 2023. We identified studies describing patients with IDAVFs initially presenting with dementia or parkinsonism. Inclusion criteria encompassed case reports and case series, while excluding review articles, guidelines, technical notes, comments, conference abstracts, and editorials. RESULTS: The systematic search resulted in the initial screening of 383 studies, with 33 articles meeting the inclusion criteria. Among these, 29 were case reports, often describing 3 or fewer patients. From the remaining 4 case series, data pertinent to patients presenting both parkinsonism and dementia were selectively extracted, yielding a total study population of 43 patients. The anatomical distribution of IDAVFs within this cohort was diverse, with the transverse and sigmoid sinuses being the most common locations. Although most of these patients received endovascular therapy, a few underwent microsurgical occlusion or combined surgical and endovascular treatment. CONCLUSIONS: IDAVFs presenting with both parkinsonism and dementia represent a rare clinical entity. This systematic review provides valuable insights into the clinical characteristics, treatment options, and outcomes for such cases. However, additional research involving larger cohorts is essential to better comprehend the underlying mechanisms and establish standardized therapeutic guidelines.