Different hemodynamics of basal ganglia between moyamoya and non-moyamoya diseases using intravoxel incoherent motion imaging and single-photon emission computed tomography.

BACKGROUND: Moyamoya disease (MMD) and non-MMD have different pathogenesis, clinical presentation, and treatment policy. PURPOSE: To identify differences in hemodynamics between MMD and non-MMD using intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) and single-photon emission computed tomography (SPECT). MATERIAL AND METHODS: Patients who had undergone 99mTc-ECD or 123I-IMP SPECT, and IVIM imaging were retrospectively studied. IVIM imaging was acquired using six different b-values. Cerebral blood flow ratio (CBFR) in the basal ganglia was calculated using a standardized volume-of-interest template. The cerebellum was used as a reference region. IVIM perfusion fraction (f) was obtained using a two-step fitting algorithm. Elliptical regions of interest were placed in bilateral basal ganglia on the IVIM f map. Patients were classified into MMD and non-MMD groups. The correlation between CBFR and mean IVIM f (fmean) in the basal ganglia was evaluated using Spearman's rank correlation coefficient. RESULTS: In total, 20 patients with MMD and 28 non-MMD patients were analyzed. No significant differences in fmean were observed among MMD, affected hemisphere with non-MMD (non-MMDaff), and unaffected hemispheres with non-MMD (non-MMDunaff). A negative correlation was seen between fmean and CBFR in the MMD group (r = -0.40, P = 0.0108), but not in the non-MMD group (non-MMDaff, r = 0.07, P = 0.69; non-MMDunaff, r = -0.22, P = 0.29). No significant differences were found among MMD and non-MMD patients, irrespective of SPECT tracers. CONCLUSION: The combination of IVIM MRI and SPECT appears to allow non-invasive identification of differences in hemodynamics between MMD and non-MMD.

[Unruptured Fronto-Orbital Artery Aneurysm Anomalously Originating from the Proximal Segment of the Anterior Cerebral Artery(A1)Concurrent with Tuberculum Sellae Meningioma:A Case Report].

We report a case of an unruptured aneurysm arising from the bifurcation of the fronto-orbital artery originating from the proximal segment of the left anterior cerebral artery(A1)concurrent with a tuberculum sellae meningioma. A 46-year-old woman presented with a right visual disturbance and left temporal hemianopsia. Preoperative neuroradiological examination showed a heterogeneously enhanced extra-axial suprasellar tumor expanding to the right optic canal and 3-mm diameter aneurysm arising from the bifurcation of the fronto-orbital artery originating from the proximal segment of the left anterior cerebral artery(A1). She underwent total removal of the tumor and neck clipping of the aneurysm via a right pterional approach without any additional deficits. Postoperative MRI and 3D CTA showed total tumor removal and complete obliteration of the aneurysm. The patient was discharged 21 days after surgery without new or worsened postoperative neurological deficits. Cerebral aneurysm concurrent with meningioma is extremely rare. Preoperative diagnosis and appropriate assessment of both the meningioma and unruptured aneurysm are warranted to prevent severe complications.

[Ruptured Dissecting Aneurysm of the Fenestrated Vertebral Artery:A Case Report].

Fenestration of a vertebral artery(VA)is a rare anomaly that has occasionally been associated with the formation of saccular aneurysms, whereas dissection of a limb of the fenestrated artery is an extremely rare occurrence. We report the case of a ruptured dissecting aneurysm of a fenestrated VA. A 56-year-old man presented with acute-onset headache followed by respiratory failure. Computed tomography(CT)revealed diffuse subarachnoid hemorrhage, and CT angiography(CTA)demonstrated fenestration of the left VA and a fusiform aneurysm of the dorsolateral limb of the fenestrated VA. CT after injection of contrast medium revealed dissection of a limb of the fenestrated VA. A comparison of the 3-dimensional digital subtraction angiogram obtained 2 days later with the initial CTA showed that the dissecting aneurysm had shrunk. Coil embolization of the dissecting limb of the fenestrated VA was achieved, and the patient was discharged without neurologic deficit. Further advancements in neuroimaging modalities will provide more opportunities to treat dissecting aneurysms of fenestrated VAs. The relevant clinical characteristics of VA fenestration and the treatment options for a dissecting aneurysm of a limb of the fenestrated VA are also discussed in this report.

[Rapid Progression in Early-Stage Primary Glioblastoma Multiforme:A Case Report].

The signs and features of early-stage primary glioblastoma multiforme(GBM)are not well-characterized. Here, we report a case of GBM that was presented at an early stage and showed extremely rapid progression within a short period. A 63-year-old woman was incidentally revealed to have a tiny lesion in her right parietal lobe. Magnetic resonance imaging(MRI)showed a hyperintense signal on T2WI, with a ring-enhancement on gadolinium(Gd)-enhanced T1WI. Two weeks later, she was admitted to our hospital for neurosurgical intervention;the MRI at that time showed rapid tumor growth, immediately followed by progressive neurological deterioration. The tumor was urgently removed;its histopathological diagnosis was GBM. This case indicates that primary GBM, even at an early stage, can rapidly progress within an extremely short period. Scheduling prompt neuroradiological assessments and neurosurgical interventions in possible cases of early-stage GBM are important, especially if a Gd-enhancement is seen on MRI.

Detection of proneural/mesenchymal marker expression in glioblastoma: temporospatial dynamics and association with chromatin-modifying gene expression.

Proneural and mesenchymal are two subtypes of glioblastoma identified by gene expression profiling. In this study, the primary aim was to detect markers to develop a clinically applicable method for distinguishing proneural and mesenchymal glioblastoma. The secondary aims were to investigate the temporospatial dynamics of these markers and to explore the association between these markers and the expression of chromatin-modifying genes. One hundred thirty-three glioma samples (grade II: 14 samples, grade III: 18, grade IV: 101) were analyzed. We quantified the expression of 6 signature genes associated with proneural and mesenchymal glioblastoma by quantitative reverse transcription-polymerase chain reaction. We assigned proneural (PN) and mesenchymal (MES) scores based on the average of the 6 markers and calculated a predominant metagene (P-M) score by subtracting the MES from the PN score. We used these scores to analyze correlations with malignant transformation, tumor recurrence, tumor heterogeneity, chromatin-modifying gene expression, and HDAC7 expression. The MES score positively correlated with tumor grade, whereas the PN score did not. The P-M score was able to distinguish the proneural and mesenchymal subtypes. It was decreased in cases of tumor recurrence and malignant transformation and showed variability within a tumor, suggesting intratumoral heterogeneity. The PN score correlated with the expression of multiple histone-modifying genes, whereas the MES score was associated only with HDAC7 expression. Thus, we demonstrated a simple and straightforward method of quantifying proneural/mesenchymal markers in glioblastoma. Of note, HDAC7 expression might be a novel therapeutic target in glioblastoma treatment.

Pediatric glioblastoma with oligodendroglioma component: aggressive clinical phenotype with distinct molecular characteristics.

The 2007 World Health Organization classification defined a new variant of glioblastoma (GBM) containing oligodendroglioma foci as GBM with an oligodendroglioma component (GBMO), which shows a favorable clinical outcome compared with "classic" GBM. However, all of the reported cases of GBMO have been adult cases, with no previous reports of pediatric cases. In this report, we demonstrated molecular characteristics of a pediatric GBMO case, showing aggressive clinical behavior with 8-month overall survival. The case showed neither isocitrate dehydrogenase 1/2 genes (IDH1/2) mutation nor 1p/19q co-deletion, a hallmark of oligodendroglioal tumors. In addition, microsatellite instability, leading to the putative mechanism of temozolomide (TMZ) resistance, was frequently detected. Molecular genetic analysis may provide critical prognostic and therapeutic insights, especially for the pediatric glioma containing oligodendroglioma components.

Usefulness of three-dimensional T1-weighted spoiled gradient-recalled echo and three-dimensional heavily T2-weighted images in preoperative evaluation of spinal dysraphism.

PURPOSE: The aim of this study was to evaluate the usefulness of three-dimensional T1-weighted spoiled gradient-recalled echo (3D T1-GRE) images for the preoperative anatomical evaluation of lumbosacral lipoma, thick filum terminale, and myelomeningocele as a means of compensating for the drawbacks of 3D heavily T2-weighted (3D hT2-W) images. METHODS: Nine patients with lumbosacral lipomas, one patient with tight filum terminale, and five patients with myelomeningoceles were included in this study. 3D T1-GRE images were compared with 3D hT2-W images or conventional magnetic resonance images in terms of delineation of lipomas and other structures in the patients with lipomas and tight filum terminale. For patients with myelomeningoceles, 3D T1-GRE images were compared with 3D hT2-W images in terms of artifacts in the cerebrospinal fluid (CSF) space. RESULTS: The 3D T1-GRE images demonstrated lipomas with good contrast to the spinal cord and CSF space and more clearly delineated the anatomical relationship between lipomas and these structures than did the 3D hT2-W images. The 3D T1-GRE images delineated dural defects through which extradural lipomas penetrated into the intradural space. The 3D T1-GRE images also demonstrated the presence or absence of lipomas in the filum terminale and the absence of artifact in the myelomeningoceles. Furthermore, they were useful for differentiating artifacts observed on the 3D hT2-W images from nerve elements. CONCLUSIONS: The complementary use of 3D T1-GRE and 3D hT2-W images may compensate for the drawbacks of 3D hT2-W images and may eventually improve lesion visualization and surgical decision making.

Dorsal location of the cochlear nerve on vestibular schwannoma: preoperative evaluation, frequency, and functional outcome.

The cochlear nerve is most commonly located on the caudoventral portion of the capsule of vestibular schwannomas and rarely on the dorsal portion. In such a condition, total removal of the tumor without cochlear nerve dysfunction is extremely difficult. The purpose of our study was to identify the frequency of this anatomical condition and the status of postoperative cochlear nerve function; we also discuss the preoperative radiological findings. The study involved 114 patients with unilateral vestibular schwannomas operated on via a retrosigmoid (lateral suboccipital) approach. Locations of the cochlear nerve on the tumor capsule were ventral, dorsal, caudal, and rostral. Ventral and dorsal locations were further subdivided into rostral, middle, and caudal third of the tumor capsule. The postoperative cochlear nerve function and preoperative magnetic resonance (MR) findings were reviewed retrospectively. In 56 patients that had useful preoperative hearing, useful hearing was retained in 50.0% (28 of 56) of patients after surgery. The cochlear nerve was located on the dorsal portion of the tumor capsule in four patients (3.5%), and useful hearing was preserved in only one of these patients (25%) in whom the tumor had been partially resected. This tumor-nerve anatomical relationship was identified in all tumors of <2 cm at preoperative MR cisternography. MR cisternography has the potential to identify the tumor-nerve anatomical relationship, especially in small-sized tumors that usually require therapeutic intervention that ensures hearing preservation. Hence, careful evaluation of the preoperative MR cisternography is important in deciding the therapeutic indications.

Preoperative evaluation and surgical strategies for craniocervical junction dural arteriovenous fistula with multiple feeders: case report and review of the literature.

Craniocervical junction dural arteriovenous fistula (CCJDAVF) fed by bilateral vertebral arteries (VAs) is extremely rare. We report a case of a 63-year-old man presenting with progressive myelopathy caused by a CCJDAVF, which was fed by bilateral VAs and occipital and ascending pharyngeal arteries with multiple shunting points and that drained into intracranial sinus and spinal veins. The dural arteriovenous fistula (DAVF) was successfully treated surgically using stepwise indocyanine green (ICG) videoangiography. After surgery, the DAVF disappeared and myelopathy was markedly improved. We show detailed preoperative images and intraoperative findings of this rare DAVF and emphasize the importance of selective angiography for preoperative evaluation of feeding arteries and the usefulness of intraoperative ICG videoangiography for both identification of the fistula and confirmation of its obliteration.

Focal cortical dysplasia type IIa underlying epileptogenesis in patients with epilepsy associated with Sturge-Weber syndrome.

In patients with epilepsy associated with Sturge-Weber syndrome (SWS), epileptogenesis has been suggested to be caused by chronic ischemia in cortical areas affected by leptomeningeal angiomatosis or by ischemia-related cortical malformations. However, this has not been fully verified electrophysiologically. We herein present two cases of SWS with medically intractable epilepsy in which the epileptogenic area involved focal cortical dysplasia (FCD) type IIa near the region of leptomeningeal angiomatosis. In both cases, the ictal-onset zones were identified by chronic subdural electrodes, and the presence of FCD type IIa was shown histopathologically. In SWS, especially in association with focal leptomeningeal angiomatosis, FCD may thus play a major role in epileptogenesis. FCD should therefore be demonstrated by the collective findings of perioperative neurophysiologic examination, anatomic and functional neuroimaging, and histopathologic examination.

Concurrent spinal nerve root schwannoma and meningioma mimicking single-component schwannoma.

We present a first case of concurrent tumors consisting of schwannoma and meningioma arising at the same spinal level in a patient without neurofibromatosis. A 49-year-old man without clinical evidence of neurofibromatosis presented with a 5-month history of right neck pain. MRI demonstrated an extradural tumor involving the right-sided C2 nerve root with a small intradural component. T1- and T2-weighted and contrast-enhanced MRI could not differentiate the intradural tumor as different from the extradural tumor. Total removal of the tumors was performed. No contiguity of the extradural tumor with the intradural tumor was seen. The intradural tumor attached strongly to the dura mater around the C2 nerve root exits. Intraoperative pathological diagnosis confirmed the extradural tumor as schwannoma and the intradural tumor as meningioma. We therefore thoroughly coagulated the dura mater adjacent to the intradural tumor and resected the dura mater around the nerve root exits together with the tumor. Pathological examination revealed that the resection edge of the extradural component consisted of a spinal nerve with thickened epineurium and was free of neoplastic cells. No schwannoma component was evident in the intradural tumor. No obvious transition thus existed between the extra- and intradural tumors. Distinguishing these tumors prior to surgery is critical for determining an optimal surgical plan, as schwannoma and meningioma require different surgical procedures. We therefore recommend a careful review of preoperative imaging with the possibility of concurrent tumors in mind.

Microsurgical Resection of Tuberculum Sellae Meningioma through Pterional Approach with Extradural Optic Canal Unroofing.

Tuberculum sellae meningiomas pose significant challenges because they are surrounded by crucial neurovascular structures, such as the optic and oculomotor nerves, pituitary stalk, internal carotid artery and its branches, and the anterior cerebral arteries. Even if small, such meningiomas frequently extend to the optic canal that is considered a poor prognostic factor for vision. In this video clip, we illustrate the case of a 60-year-old female who had an approximately 3-cm tuberculum sellae meningioma with optic canal involvement. She underwent surgical resection of the tumor through a pterional approach. After extradural optic canal unroofing, detaching, devascularizing, and debulking the tumor, careful dissection of the meningioma from the surrounding tissues was performed. Next, the tumor extensions into both of the optic canals were removed. Finally, coagulation and resection of the tumor origin on the dura of the tuberculum sellae following Simpson's grade-I resection were performed. Histopathology revealed that the tumor was a World Health Organization (WHO) grade-I meningioma. The patient had an uneventful postoperative course and her visual acuity was preserved, with no visual field defect on postoperative visual examination. In this video, the basic surgical techniques in performing extradural optic canal unroofing, preserving the arachnoid plane, and stay in collect layer, which is the essential technique for dissecting meningiomas and for preserving neurovascular structures, are demonstrated. The link to the video can be found at: https://youtu.be/vD54Iji0C4Q .

Unusual imaging characteristics of cystic meningioma in cerebellopontine angle.

We report a case of cystic meningioma at the left cerebellopontine angle (CPA). Magnetic resonance imaging demonstrated both solid and cystic components in the tumor. The cystic component appeared slightly hyperintense compared to cerebrospinal fluid on fluid-attenuated inversion recovery (FLAIR) imaging. A hypointense tubular structure was identified in the cystic component on 3D driven equilibrium sequencing. These imaging findings are unusual for cystic meningioma. However, awareness of these unusual imaging features is important to determine appropriate treatment strategies although cystic meningioma at the CPA is extremely rare.

Chronic Subdural Hematoma after Craniotomy with Preoperative Embolization of Middle Meningeal Artery: A Case Report.

Endovascular embolization of the middle meningeal artery (MMA) has been reported as an effective method for treating chronic subdural hematoma (CSDH); however, its preventive effect on CSDH following craniotomy is unknown. We present a case in which MMA embolization was ineffective in preventing CSDH following craniotomy. A 56-year-old man who complained of diplopia was diagnosed with sphenoid ridge meningioma with a 3-cm diameter. MMA embolization prior to the operation and total surgical removal of the tumor were performed. Two months postoperatively, the patient complained of headache and hemiparesis of the left side. CSDH with a 15-mm thickness and a midline shift was observed. MMA embolization before inflammation may not play a role in preventing CSDH development because MMA embolization is considered effective in CSDH because it is associated with the blood supply of neovessels that are newly formed due to inflammation. Therefore, MMA embolization might not be effective in preventing the occurrence of CSDH following craniotomy.

Preoperative Prediction of Intracranial Meningioma Grade Using Conventional CT and MRI.

Objective Preoperative diagnosis of tumor grade can assist in treatment-related decision-making for patients with intracranial meningioma. This study aimed to distinguish between high-grade and low-grade meningiomas using conventional CT and MRI. Methodology We retrospectively analyzed 173 consecutive patients with intracranial meningioma (149 low-grade and 24 high-grade tumors) who were treated surgically at the National Hospital Organization Kyushu Medical Center from 2008 to 2020. Clinical and radiological features, including tumor doubling time (Td) and relative growth rate (RGR), were compared between low-grade and high-grade meningiomas. Results Multivariate logistic regression analysis showed that symptomatic tumor (p=0.001), non-skull base location (p=0.006), irregular tumor shape (p=0.043), tumor heterogeneity (p=0.025), and peritumoral brain edema (p=0.003) were independent predictors of high-grade meningioma. In 53 patients who underwent surgery because of tumor progression, progression to symptoms (p=0.027), intratumoral heterogeneity (p<0.001), peritumoral brain edema (p=0.001), larger tumor volume (p=0.005), shorter Td (p<0.001), and higher RGR (P<0.001) were significantly associated with high-grade meningioma. Receiver operating characteristics (ROC) curve analysis showed that the optimal Td and annual RGR cut-off values to distinguish high-grade from low-grade meningioma were 460.5 days and 73.2%, respectively (100% sensitivity and 78.6% specificity). Conclusion Based on our findings, conventional CT and MRI are useful methods to predict meningioma grades before surgery. High-grade lesions are associated with non-skull base location, irregular tumor shape, intratumoral heterogeneity, and peritumoral brain edema. High-grade meningioma should be suspected in tumors that exhibit Td <460.5 days or annual RGR >73.2% or those that develop intratumoral heterogeneity or surrounding brain edema on surveillance imaging.

Discrepancy in the Ki67 labeling index of brain and orbital metastatic lesions from gastrointestinal neuroendocrine tumors: A case report.

Proliferative activity examined by Ki67 labeling index (LI) plays pivotal role for managing gastrointestinal neuroendocrine tumor (GI-NET). Few reports indicated the intra-patient heterogeneity of Ki67-LI among metastatic tumor sites. We report a case of brain and orbital metastases from GI-NET that showed discrepancy of the Ki67-LI. A 71 year-old woman who was diagnosed as GI-NET with liver and bone metastases and performed medical therapy, had headache, right exophthalmos, and pain of right eye and was referred to our department. Magnetic resonance image revealed that tumors in the left occipital region and right orbit. We diagnosed as metastatic brain and orbital tumors from GI-NET. Surgical removal of both symptomatic lesions was performed and the diagnosis was pathologically confirmed. Immunohistochemical studies revealed the discrepancy of the Ki67-LI of the lesions (brain tumor: 8% versus orbital tumor: 22%). Sampling of multiple metastatic sites may prevent underestimate tumor proliferative activity.

Metabolic remodeling of pyrimidine synthesis pathway and serine synthesis pathway in human glioblastoma.

Glioblastoma is the most common brain tumor with dismal outcomes in adults. Metabolic remodeling is now widely acknowledged as a hallmark of cancer cells, but glioblastoma-specific metabolic pathways remain unclear. Here we show, using a large-scale targeted proteomics platform and integrated molecular pathway-level analysis tool, that the de novo pyrimidine synthesis pathway and serine synthesis pathway (SSP) are the major enriched pathways in vivo for patients with glioblastoma. Among the enzymes associated with nucleotide synthesis, RRM1 and NME1 are significantly upregulated in glioblastoma. In the SSP, SHMT2 and PSPH are upregulated but the upstream enzyme PSAT1 is downregulated in glioblastoma. Kaplan-Meier curves of overall survival for the GSE16011 and The Cancer Genome Atlas datasets revealed that high SSP activity correlated with poor outcome. Enzymes relating to the pyrimidine synthesis pathway and SSP might offer therapeutic targets for new glioblastoma treatments.

Five-Year Changes in Cognitive Function and Their Predictor in Adult Moyamoya Disease.

OBJECTIVE: The long-term outcomes of cognitive function in moyamoya disease remain unknown. We aimed to assess 5-year changes in cognitive function in adult moyamoya disease patients and to evaluate the value of the magnetic resonance angiography (MRA) steno-occlusive score to predict cognitive changes. METHODS: Participants comprised 20 consecutive patients whose cognitive functions had been evaluated using the Frontal Assessment Battery (FAB) and Neurobehavioral Cognitive Status Examination (Cognistat) at baseline and reassessed 5 years later. RESULTS: The total FAB score and total Cognistat score were lower after 5 years in 9 patients each. The Wilcoxon signed-rank test showed that subscores for conceptualization and comprehension increased, while subscores for mental flexibility, programming, and inhibitory control significantly decreased after 5 years. The right MRA total score and right posterior cerebral artery score were negatively associated with 5-year changes in the total FAB score and total Cognistat score. The right posterior cerebral artery score was significantly associated with changes in subscores for mental flexibility, programming, sensitivity to interference, and construction. CONCLUSIONS: Specific cognitive domains can decline over time in patients with adult moyamoya disease. MRA findings might be useful for predicting future declines in cognitive function.

Ankle-Brachial Index and Cardio-Ankle Vascular Index as Predictors of Cognitive Decline Over Time After Carotid Endarterectomy.

OBJECTIVE: Patients with carotid stenosis risk cognitive impairment even after carotid endarterectomy (CEA) because of the long-term presence of vascular risk factors. Early prediction of cognitive decline is useful because early appropriate training for impaired cognitive domains can improve their functions. Ankle-brachial index (ABI) and cardio-ankle vascular index (CAVI) are frequently used as general indicators of systemic atherosclerosis and are associated with cognitive function in the general population. This study aimed to evaluate the utility of those vascular biomarkers for predicting cognitive decline in patients after CEA. METHODS: Patients who had undergone both CEA at our institute and cognitive evaluations between March 2016 and January 2022 were invited to participate in this study. Associations between ABI or CAVI three years before baseline and cognitive function at baseline were assessed retrospectively in 94 patients, and associations between ABI or CAVI at baseline and three-year changes in cognitive functions were assessed prospectively in 24 patients. Cognitive functions were assessed using the Frontal Assessment Battery (FAB) and Neurobehavioral Cognitive Status Examination (Cognistat). RESULTS: Low ABI three years before baseline was associated with poor performances on Cognistat and FAB at baseline. ABI, as a continuous measure, three years before baseline, showed positive linear associations with total Cognistat score and subscores for naming, construction, and judgment at baseline. The Wilcoxon signed-rank test showed that the total Cognistat score, total FAB score, and subscores for attention and inhibitory control declined after three years. CAVI at baseline was negatively associated with three-year changes in total Cognistat score and subscores for naming, construction, and memory. CONCLUSION: Cognitive function can decline over time in patients with carotid stenosis even after CEA. ABI and CAVI might be useful to predict cognitive function and its decline among patients who have undergone CEA.

Microsurgical Anatomy of the Inferior Petroclival Vein and its Relation to Surrounding Structures: A Cadaveric and Radiological Study.

BACKGROUND: The inferior petroclival vein (IPV) courses along the extracranial surface of the petroclival fissure. It is occasionally involved in vascular diseases and has recently been used for vascular access to the cavernous sinus. However, detailed descriptions of its anatomy are currently lacking. OBJECTIVE: To define the anatomic relationship between the IPV and its surrounding structures based on cadaveric dissection and radiological analysis. METHODS: A dry skull and an injected cadaver head were examined to reveal the relationships between the IPV and its surrounding structures. The existence of the IPV and its relationships with other venous structures were also examined by contrast-enhanced, fat-suppressed T1-weighted magnetic resonance imaging in 26 patients (51 sides). RESULTS: The entire course of the IPV was shown via stepwise cadaver dissection from below. Its relationships with surrounding structures, such as the jugular bulb, sigmoid sinus, inferior petrosal sinus, petrosal venous confluence, and the posterior, lateral, and anterior condylar veins, were also shown. In the radiological analysis, the IPV was identified on all sides. The rostral end of the vein was connected to the venous plexus around the carotid artery on all sides. The vein drained into the caudal end of the inferior petrosal sinus (49/51 sides, 96.1%) or into the anterior condylar vein (2/51 sides, 3.9%). CONCLUSION: A precise understanding of the anatomy of the IPV will enable endovascular and skull base surgeons to achieve diagnoses and gain safe access to lesions involving the IPV.