Comparative Analysis of Patients Undergoing Microvascular Decompression for Trigeminal Neuralgia Caused by Solely Arterial or Solely Venous Compression.

OBJECTIVE: Trigeminal neuralgia (TN) due to venous compression is far less common than that due to arterial compression, and its pathogenesis is less clear. We investigated the clinical and imaging features of TN caused by solely venous compression by measuring the morphologies of the posterior cranial fossa (PCF) and the trigeminal nerve. METHODS: We retrospectively reviewed records of TN patients who underwent microvascular decompression at our institution and extracted cases with solely arterial or solely venous compression. Preoperative magnetic resonance imaging was used to find the length (Y), width (X), height (Z), and volume (V) of the PCF, the angle between the trigeminal nerve and pons, and the distance between Meckel's cave and the root entry zone of the trigeminal nerve. RESULTS: Of 152 patients, 24 had TN caused solely by venous compression. The value of Y was significantly smaller in the venous group than the arterial group (P < 0.01). The trigeminal nerve and pons was significantly smaller in the venous group (P < 0.01). We hypothesized that TN patients with solely venous compression had a characteristic PCF morphology with a short anteroposterior diameter (Y), such that age-related changes in brain morphology could alter the course of the trigeminal nerve and cause compression by a vein. CONCLUSIONS: The morphological features of the PCF differed between patients with TN of venous and those with TN of arterial etiology. Age-related changes in brain morphology and changes of course of the trigeminal nerve may also add to the possibility of developing TN, especially of venous etiology.

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.

Nonaneurysmal Perimesencephalic Subarachnoid Hemorrhage Associated with an Anomalous Anastomotic Cisternal Vein.

A 54-year-old woman with no relevant medical history presented with severe headache, nausea, and vomiting for 8 days. Imaging examination revealed a subarachnoid hemorrhage in the left interpeduncular cistern without aneurysms. Computed tomography angiography and digital subtraction angiography found an anomalous vein near the site of the hemorrhagic clots, indicating abnormalities in cerebral venous drainage that provided an anastomosis between the drainage system of the deep middle cerebral, petrosal, and lateral mesencephalic veins. In the primitive pattern, the basal vein of Rosenthal drains into the lateral mesencephalic vein and to the petrosal sinus. This anomalous flow may predispose to subarachnoid hemorrhage, emphasizing the association between nonaneurysmal perimesencephalic hemorrhage and venous anomalies.

Middle third falcine meningiomas-surgical nuances for cortical venous preservation.

PURPOSE: To improve postoperative outcome in middle third falcine meningiomas by cortical venous preservation. BACKGROUND: Falcine meningiomas arise from the falx and do not involve the superior sagittal sinus (SSS). Their complete resection is often associated with the risk of venous infarction in the eloquent cortex due to overlying superficial cortical veins on the tumors. METHOD: We report one case of middle third falcine meningioma, where we used the posterior interhemispheric corridor for tumor approach. CONCLUSION: Use of the posterior interhemispheric approach, carefully raised bone flap, along with sharp dissection and vein reinforcement using fibrin glue can help to preserve the cortical veins while resecting the falcine meningiomas.

Developmental Venous Anomalies.

Developmental venous anomalies (DVAs) are the most common vascular malformation detected on intracranial cross-sectional imaging. They are generally benign lesions thought to drain normal parenchyma. Spontaneous hemorrhages attributed to DVAs are rare and should be ascribed to associated cerebral cavernous malformations, flow-related shunts, or venous outflow obstruction. Contrast-enhanced MRI, susceptibility-weighted imaging, and high-field MRI are ideal tools for visualizing vessel connectivity and associated lesions. DVAs are not generally considered targets for treatment. Preservation of DVAs is an established practice in the microsurgical or radiosurgical treatment of associated lesions.

Basal vein of Rosenthal classification: the key to venous outflow of the deep sylvian fissure.

OBJECTIVE: Mastery of sylvian fissure dissection is essential to access lesions within the deep basal cisterns. The deep sylvian vein and its tributaries play a major role during access to and beyond the carotid cistern through the sylvian fissure and determine the complexity of microdissection. Preserving the venous outflow during sylvian fissure dissection is the best reliable strategy to prevent postoperative venous strokes or venous hypertension. The authors report the role of the basal vein of Rosenthal (BVR) in the venous outflow pattern of the deep sylvian cistern. METHODS: The authors analyzed 262 consecutive surgical cases involving sylvian fissure dissection from 2015 to 2017. Inclusion criteria were complete sylvian fissure dissection for the treatment of intracranial aneurysms. Exclusion criteria were giant size (aneurysm diameter > 24 mm), meningitis, subarachnoid hemorrhage within the sylvian cistern, absence of 4D CT angiography, and previous surgery. Retrospective radiological and operative video reviews were carried out to assess the association between the superficial sylvian vein and the BVR. The authors analyzed the course of the BVR and the patterns of venous drainage of the sylvian cistern. The surgical difficulty of sylvian fissure dissection was rated by the authors to study the operative significance of the venous patterns encountered. Two clinical cases are described to illustrate the proposed BVR classification. RESULTS: A total of 97 patients met the selection criteria. The most frequent type of BVR was immature (diameter < 0.5 mm, 68%). When the BVR was incompletely developed or absent (immature type), the deep sylvian veins drained through a middle sylvian vein in 70% of cases, requiring advanced sylvian fissure dissection techniques. However, when the BVR was completely developed (32%), the middle sylvian vein was found in a minority of cases (6%), which allowed for an unobstructed transsylvian corridor. Interrater and test-retest reliability of the surgical difficulty was greater than 0.9. CONCLUSIONS: Preoperative assessment of the BVR anatomy is key to predict the deep sylvian venous pattern. The authors provide objective evidence supporting the reciprocal relationship between the type of BVR and the presence of a middle sylvian vein and the deep sylvian venous outflow. An immature BVR should alert the neurosurgeon of the high likelihood of finding a complex deep venous pattern, which may drive surgical planning.

[Microvascular Decompression for Trigeminal Neuralgia Due to Venous Compression].

In microvascular decompression surgery for trigeminal neuralgia, the veins are essential as an anatomical frame for the microsurgical approach and as an offending vessel to compress the trigeminal nerve. Thorough arachnoid dissection of the superior petrosal vein and its tributaries provides surgical corridors to the trigeminal nerve root and enables the mobilization of the bridging, brainstem, and deep cerebellar veins. It is necessary to protect the trigeminal nerve by coagulating and cutting the offending vein. We reviewed the clinical features of trigeminal neuralgia caused by venous decompression and its outcomes after microvascular decompression. Among patients with trigeminal neuralgia, 4%-14% have sole venous compression. Atypical or type 2 trigeminal neuralgia may occur in 60%-80% of cases of sole venous compression. Three-dimensional MR cisternography and CT venography can help in detecting the offending vein. The transverse pontine vein is the common offending vein. The surgical cure and recurrence rates of trigeminal neuralgia with venous compression are 64%-75% and 23%, respectively. Sole venous compression is a unique form of trigeminal neuralgia. Its clinical characteristics differ from those of trigeminal neuralgia caused by arterial compression. Surgical procedures to resolve venous compression include nuances in safely handling venous structures.

A new classification of parasagittal bridging veins based on their configurations and drainage routes pertinent to interhemispheric approaches: a surgical anatomical study.

OBJECTIVE: Opening the roof of the interhemispheric microsurgical corridor to access various neurooncological or neurovascular lesions can be demanding because of the multiple bridging veins that drain into the sinus with their highly variable, location-specific anatomy. The objective of this study was to propose a new classification system for these parasagittal bridging veins, which are herein described as being arranged in 3 configurations with 4 drainage routes. METHODS: Twenty adult cadaveric heads (40 hemispheres) were examined. From this examination, the authors describe 3 types of configurations of the parasagittal bridging veins relative to specific anatomical landmarks (coronal suture, postcentral sulcus) and their drainage routes into the superior sagittal sinus, convexity dura, lacunae, and falx. They also quantify the relative incidence and extension of these anatomical variations and provide several preoperative, postoperative, and microneurosurgical clinical case study examples. RESULTS: The authors describe 3 anatomical configurations for venous drainage, which improves on the 2 types that have been previously described. In type 1, a single vein joins; in type 2, 2 or more contiguous veins join; and in type 3, a venous complex joins at the same point. Anterior to the coronal suture, the most common configuration was type 1 dural drainage, occurring in 57% of hemispheres. Between the coronal suture and the postcentral sulcus, most veins (including 73% of superior anastomotic veins of Trolard) drain first into a venous lacuna, which are larger and more numerous in this region. Posterior to the postcentral sulcus, the most common drainage route was through the falx. CONCLUSIONS: The authors propose a systematic classification for the parasagittal venous network. Using anatomical landmarks, they define 3 venous configurations and 4 drainage routes. Analysis of these configurations with respect to surgical routes indicates 2 highly risky interhemispheric surgical fissure routes. The risks are attributable to the presence of large lacunae that receive multiple veins (type 2) or venous complex (type 3) configurations that negatively impact a surgeon's working space and degree of movement and thus are predisposed to inadvertent avulsions, bleeding, and venous thrombosis.

Synchronous Superficial Middle Cerebral Vein Outflow Correlates Favorable Tissue Fate After Mechanical Thrombectomy for Acute Ischemic Stroke.

RATIONALE AND OBJECTIVES: The purpose of this study was to determine the association between hemispheric synchrony in venous outflow at baseline and tissue fate after mechanical thrombectomy (MT) for acute ischemic stroke (AIS). MATERIALS AND METHODS: A two-center retrospective analysis involving AIS patients who underwent MT was performed. The four cortical veins of interest include the superficial middle cerebral vein (SMCV), sphenoparietal sinus (SS), vein of Labbé (VOL), and vein of Trolard (VOT). Baseline computed tomography perfusion data were used to compare the following outflow parameters between the hemispheres: first filling time (△FFT), time to peak (△TTP) and total filling time (△TFT). Synchronous venous outflow was defined as △FFT = 0. Multivariable regression analyses were performed to evaluate the association of venous outflow synchrony with penumbral salvage, infarct growth, and intracranial hemorrhage (ICH) after MT. RESULTS: A total of 151 patients (71.4 ± 13.2 years, 65.6% women) were evaluated. Patients with synchronous SMCV outflow demonstrated significantly greater penumbral salvage (41.3 mL vs. 33.1 mL, P = 0.005) and lower infarct growth (9.0 mL vs. 14.4 mL, P = 0.015) compared to those with delayed SMCV outflow. Higher △FFTSMCV (ß = -1.44, P = 0.013) and △TTPSMCV (ß = -0.996, P = 0.003) significantly associated with lower penumbral salvage, while higher △FFTSMCV significantly associated with larger infarct growth (ß = 1.09, P = 0.005) and increased risk of ICH (odds ratio [OR] = 1.519, P = 0.047). CONCLUSION: Synchronous SMCV outflow is an independent predictor of favorable tissue outcome and low ICH risk, and thereby carries the potential as an auxiliary radiological marker aiding the treatment planning of AIS patients.

An isolated Sinus Intracranial Dural Arteriovenous Fistula with Unusual Drainage Pattern.

Isolated sinus dural arteriovenous fistulas (DAVFs) involve a dural sinus with occlusion on both sides of the diseased sinus segment. Because of venous drainage refluxing from the isolated sinus into the cortical veins, all isolated sinus DAVFs are Borden type III or Cognard type Ⅲ/Ⅳ. Venous drainage typically involves temporo-occipital cortical veins or the superior petrosal sinus and tributaries of the petrosal vein. However, drainage veins involving the perimedullary venous system are extremely rare. Here, we present a case of Cognard type V isolated sinus DAVF successfully treated with balloon catheter and Onyx.

Evaluation of Venous Structures that Are Involved in Transsylvian Approach Using 3D Rotational Venography.

In the transsylvian (TS) approach, as characterized by clipping surgery, the presurgical visualization of the superficial middle cerebral vein (SMCV) can help change the surgical approach to ensure safe microsurgery. Nevertheless, identifying preoperatively the venous structures that are involved in this approach is difficult. In this study, we investigated the venous structures that are involved in the TS approach using three-dimensional (3D) rotational venography (3D-RV) and evaluated the effectiveness of this method for presurgical simulation. Patients who underwent 3D-RV between August 2018 and June 2020 were involved in this retrospective study. The 3D-RV and partial maximum intensity projection images with a thickness of 5 mm were computationally reconstructed. The venous structures were subdivided into the following three portions according to the anatomic location: superficial, intermediate, and basal portions. In the superficial portion, predominant frontosylvian veins were observed on 31 (41%) sides, predominant temporosylvian veins on seven (9%) sides, and equivalent fronto- and temporosylvian veins on 28 (37%) sides. The veins in the intermediate (deep middle cerebral and uncal veins) and basal portions (frontobasal bridging veins) emptied into the SMCV on 57 (75%) and 34 (45%) sides, respectively. The 3D-RV images were highly representative of the venous structures observed during microsurgery. In this study, 3D-RV was utilized to capture the details of the venous structures from the superficial to the deep portions. Presurgical simulation of the venous structures that are involved in the TS approach using 3D-RV may increase the safety of microsurgical approaches.

Rational sacrifice of the superior petrosal vein.

During surgeries of the posterior cranial fossa, sacrificing the superior petrosal vein (SPV) can enhance visualization of the operative field but may also lead to postoperative venous infarction with potentially fatal consequences. We previously proposed that the safety of SPV sacrifice depends on whether there are collaterals that can take on the venous flow of the SPV after its sacrifice. Here, we propose several practical strategies that may be able to evaluate the presence of collaterals to the SPV, so that the safety of SPV sacrifice can be assessed.

Sphenoparietal Sinus Transposition: Operative Technique for Optimizing Pretemporal Posterior Circulation Access While Preserving the Sylvian Venous Complex.

BACKGROUND: Transsylvian approaches are a cornerstone of complex cranial operations, with wide applicability across cerebrovascular, skull base, and neuro-oncology operations. Deep lesions, especially those involving the basilar apex, midbrain, or interpeduncular fossa, require wide exposures that may be inhibited by the presence of a large complex of superficial sylvian veins (SSV) draining into the sphenoparietal sinus. This report describes technical and clinical aspects of the sphenoparietal sinus transposition (SPST) technique. METHODS: Technical case report of the SPST technique, including a step-by-step neuroanatomic description, overview of common indications, clinical pearls and pitfalls, and illustrative case examples. RESULTS: Once the benefits of proceeding with SPST have been established, the maneuver is initiated with 2 stepwise dural incisions: an incision from lateral to medial along the lateral margin of the lesser sphenoid wing, followed by an orthogonal cut across the temporal pole down the middle fossa floor. The pretemporal dura is peeled off the lateral wall of the cavernous sinus, allowing mobilization of the SSV complex and temporal pole posteriorly without disrupting or straining the connection point at the sphenoparietal sinus. Illustrative case examples include a clip reconstruction of a basilar apex aneurysm for which earlier endovascular treatment had failed and microsurgical resection of a peduncular cavernous malformation. CONCLUSIONS: SPST is a simple but versatile technique with important applications in complex cranial surgery. By mobilizing the SSV complex together with its dural attachment, the transsylvian corridor can be markedly widened, allowing access to the basilar apex region and ventral midbrain.

Spontaneous thrombosis of vein of Galen malformation managed with surgical resection: a case­based review.

INTRODUCTION: Vein of Galen malformation (VOGM) is an exceptionally uncommon form of congenital intracranial vascular malformations. It is highly unusual for this lesion to spontaneously thrombose. The clinical presentation of a patient may range from being asymptomatic to critically ill. The underlying pathophysiological mechanisms that cause spontaneous thrombosis are still poorly understood. METHODS AND RESULTS: The literature on spontaneous thrombosis of VOGM was systematically reviewed, analyzed, and summarized with a focus on its pathophysiology, types, clinical presentations, diagnosis, management, and outcomes. It was also illustrated with a case presentation. The case presents an unusual presentation and location of a VOGM in a 2-year-old boy who was successfully treated with surgical resection. CONCLUSIONS: A handful of cases of thrombosed VOGM have been reported worldwide where surgery was used to treat the condition. Low-flow fistulas of the mural type are prone to spontaneous thrombosis, have delayed clinical presentations, and are typically diagnosed in young children. Among the many possible manifestations, hydrocephalus is by far the most common. In the absence of blood flow, MRI is the diagnostic test of choice. Depending on the patient's symptoms, surgery to either remove the aneurysm or divert the cerebrospinal fluid usually results in a good prognosis.

Comprehensive Venous Outflow Predicts Functional Outcomes in Patients with Acute Ischemic Stroke Treated by Thrombectomy.

BACKGROUND AND PURPOSE: Cortical venous outflow has emerged as a robust measure of collateral blood flow in acute ischemic stroke. The addition of deep venous drainage to this assessment may provide valuable information to further guide the treatment of these patients. MATERIALS AND METHODS: We performed a multicenter retrospective cohort study of patients with acute ischemic stroke treated by thrombectomy between January 2013 and January 2021. The internal cerebral veins were scored on a scale of 0-2. This metric was combined with existing cortical vein opacification scores to create a comprehensive venous outflow score from 0 to 8 and stratify patients as having favorable-versus-unfavorable comprehensive venous outflow. Outcome analyses were primarily conducted using the Mann-Whitney U and χ2 tests. RESULTS: Six hundred seventy-eight patients met the inclusion criteria. Three hundred fifteen were stratified as having favorable comprehensive venous outflow (mean age, 73 years; range, 62-81 years; 170 men), and 363, as having unfavorable comprehensive venous outflow (mean age, 77 years; range, 67-85 years; 154 men). There were significantly higher rates of functional independence (mRS 0-2; 194/296 versus 37/352, 66% versus 11%, P < .001) and excellent reperfusion (TICI 2c/3; 166/313 versus 142/358, 53% versus 40%, P < .001) in patients with favorable comprehensive venous outflow. There was a significant increase in the association of mRS with the comprehensive venous outflow score compared with the cortical vein opacification score (-0.74 versus -0.67, P = .006). CONCLUSIONS: A favorable comprehensive venous profile is strongly associated with functional independence and excellent postthrombectomy reperfusion. Future studies should focus on patients with venous outflow status that is discrepant with the eventual outcome.