Influence of Perioperative Three-Dimensional Computed Tomography (CT) Angiography and Surgical Clipping for Unruptured Cerebral Aneurysms on Renal Function in Patients with Chronic Kidney Disease.

BACKROUND: Surgical clipping is a valuable treatment option for unruptured intracranial aneurysms in patients with chronic kidney disease (CKD). However, the comprehensive impact of clipping and perioperative three-dimensional computed tomography angiography (3D-CTA) on renal function remains unclear. This study aimed to evaluate the effects of perioperative 3D-CTA and surgical clipping on renal function in patients with CKD. METHODS: We retrospectively analyzed 529 patients who underwent surgical clipping and perioperative 3D-CTA. An estimated glomerular filtration rate (eGFR) < 60 was defined as CKD. Patients were stratified according to their renal function (group 1: eGFR ≥60, group 2: 45 ≤ eGFR <60, group 3: 30 ≤ eGFR <45, group 4: eGFR <30 ml/min/1.73 m2), and eGFR was assessed preoperatively and 1 week and several months postoperatively. RESULTS: Of the 529 patients, 442 did not have CKD and 87 had CKD. Hypertension, hyperlipidemia, and hyperuricemia were significantly more common in those with CKD. After the surgery and perioperative series of 3D-CTA, renal function deterioration was not observed in any group, whether in the acute or chronic postoperative period. Notably, eGFR significantly increased in groups 2 (66.7 ± 10.1, P < 0.01) and 3 (48.9 ± 9.2, P = 0.02) 1 week postoperatively, despite the CKD. CONCLUSIONS: Surgical clipping of unruptured intracranial aneurysms and perioperative 3D-CTA with normal-dose contrast media did not impair renal function in patients with CKD. These results could be valuable in determining treatment strategies for those with CKD and intracranial aneurysms.

Assessing anatomical variations of the inferior mesenteric artery via three-dimensional CT angiography and laparoscopic colorectal surgery: a retrospective observational study.

To assess the anatomy of the inferior mesenteric artery (IMA) and its branches by reviewing laparoscopic left-sided colorectal cancer surgery videos and comparing them with preoperative three-dimensional computed tomography (3D-CT) angiography, to verify the accuracy of 3D-CT vascular reconstruction techniques. High-definition surgical videos and preoperative imaging data of 200 patients who underwent laparoscopic left-sided colorectal cancer surgery were analysed, and the alignment of the IMA and its branches in relation to the inferior mesenteric vein (IMV) was observed and summarized. The above two methods were used to measure the length of the IMA and its branches. Of 200 patients, 47.0% had the sigmoid arteries (SAs) arise from the common trunk with the superior rectal artery (SRA), and 30.5% had the SAs arise from the common trunk with the left colic artery (LCA). In 3.5% of patients, the SAs arising from both the LCA and SRA. The LCA, SA, and SRA emanated from the same point in 13.5% of patients, and the LCA was absent in 5.5% of patients. The range of D cm (IMA length measured by intraoperative silk thread) and d cm (IMA length measured by 3D-CT vascular reconstruction) in all cases was 1.84-6.62 cm and 1.85-6.52 cm, respectively, and there was a significant difference between them. (p < 0.001). The lengths between the intersection of the LCA and IMV measured intraoperatively were 0.64-4.29 cm, 0.87-4.35 cm, 1.32-4.28 cm and 1.65-3.69 cm in types 1A, 1B, 1C, and 2, respectively, and there was no significant difference between the groups (p = 0.994). There was only a significant difference in the length of the IMA between the 3D-CT vascular reconstruction and intraoperative observation data, which can provide guidance to surgeons in preoperative preparation.

Robot-assisted thoracoscopic right upper lobectomy with displaced B3 and absence of minor fissure: a case report.

INTRODUCTION: B3 downward-shifting is a rare bronchial anomaly characterized by abnormal pulmonary arteries associated with downward displacement of B3 and complete fusion between the right upper and middle lobes. CASE PRESENTATION: We report a case of robot-assisted thoracoscopic right upper lobectomy in a patient with lung cancer with B3 downward-shifting. An 81-year-old male was diagnosed with non-small cell lung cancer in S3 of the right upper lung. Preoperative three-dimensional computed tomography angiography revealed a B3 bronchus derived from the middle lobe bronchus and an anterior segmental pulmonary artery variation. Robot-assisted thoracoscopic surgery right upper lobectomy with ND2a-1 was performed via four-port incisions and an assist incision. No interlobar fissure was observed between the right upper and middle lobes. After dissecting B1+2, the displaced B3 root was dissected. The displaced A3a was difficult to dissect because of an extremely severe complete fissure. Therefore, we dissected the bronchus preceding from the cranial side. To confirm a minor fissure, indocyanine green was administered intravenously, and the interlobar boundary was identified as the line separating the dark and green lung parenchyma. The boundary was divided using mechanical staples. No surgical complications occurred. CONCLUSIONS: Using three-dimensional reconstruction imaging and systemic indocyanine green administration, we successfully performed a right upper lobectomy through robot-assisted thoracic surgery.

Vascular anatomical study of persistent descending mesocolon in patients undergoing laparoscopic surgery for colorectal cancer.

INTRODUCTION: Persistent descending mesocolon (PDM) is a rare congenital atypia of fixation of the descending colon, and currently, very few detailed studies exist on its vascular anatomy. This study was conducted to evaluate the features of the vascular anatomy of PDM to help avoid intraoperative lethal injury and subsequent postoperative complications in laparoscopic colorectal surgery. METHODS: We retrospectively analyzed the data of 534 patients who underwent laparoscopic left-sided colorectal surgery. PDM was diagnosed using preoperative axial computed tomography (CT) view. The vascular anatomical features were compared between PDM and non-PDM cases based on three-dimensional (3D)-CT angiography findings. Additionally, the perioperative short-term outcomes of laparoscopic surgery in the 534 patients were also compared between PDM and non-PDM cases. RESULTS: Of the total 534 patients, 13 patients (2.4%) presented with PDM. No branching pattern of the inferior mesenteric artery (IMA) specific to PDM was found. In the running direction of the IMA and sigmoidal colic artery (SA), the midline-shift of IMA and the right-shift of SA were significantly more in PDM than in non-PDM cases, respectively (38.5% vs. 2.5%, P ≤ .0001; 61.5% vs. 4.6%, P ≤ .0001). The perioperative short-term outcomes of laparoscopic surgery in the 534 patients were similar between PDM and non-PDM cases. CONCLUSION: Because changes in the direction of the vascular running are often observed due to adhesions and shortening of the mesentery in PDM cases, performing a detailed preoperative evaluation of vascular anatomy using imaging modalities such as 3D-CT angiography is important.

[Evaluation of the Usefulness of Variable-speed Injection Method in Neck to Lower-extremity Three-dimensional Computed Tomography Angiography].

PURPOSE: The purpose of this study was to investigate the contrast effect of arteries and the distribution of contrast medium along the z-axis in three-dimensional computed tomography angiography from neck to lower extremity (neck-lower-extremity 3D-CTA) using the F variable-speed injection method. METHOD: The subjects were 112 patients who underwent neck-lower-extremity 3D-CTA. In the fixed-speed injection method, contrast medium was injected at the same rate for 35 s. In the variable-speed injection method, contrast medium was injected for 35 s at varying rates. CT values were measured in the common carotid artery (CCA), ascending aorta (AAo), abdominal aorta (AA), superficial femoral artery (SFA), popliteal artery (PA), anterior tibial artery (ATA), and dorsalis pedis artery (DPA). We normalized the CT values of each artery for each patient, defined the contrast uniformity, and compared them. We also performed a four-level visual evaluation. RESULT: A significant difference was found in the PA, ATA, and DPA, with the variable-speed injection method showing a higher CT value than the fixed-speed injection method (p<0.01). There were no significant differences in the CCA, AAo, AA, and SFA. Similarly, the variable-speed injection method scored significantly higher in the visual evaluation. CONCLUSION: The variable-speed injection method is useful in neck-lower-extremity 3D-CTA.

Clinical outcomes and radiological assessment of vascular anatomy in patients who underwent D3 left hemicolectomy.

Background: Adequate blood supply is one of the key factors for colorectal anastomosis healing. Various variants of vascular anatomy often come as a surprise to surgeons during operations. Objectives: The aims of this study were to carry out a comparative analysis of three-dimensional-computed tomography (3D-CT) angiography data with intraoperative data and a detailed analysis of variants of the anatomy of splenic flexure. Material and methods: In this study, we included 103 patients (56 males and 47 females; mean age 64.2 ± 11.6) with the left-sided colon and rectal cancer who underwent preoperative 3D-CT angiography at Ternopil University Hospital between 2016 and 2022. Results: According to the recently proposed classification, there are four types of blood supply to the splenic flexure of the colon: Our analysis showed that type 1 was found in 83 (80.6%) patients, type 2 in 9 (8.7%), type 3 in 10 (9.7%), and type 4 in 1 (1%). All patients underwent local left radical hemicolectomy with resection of complete mesocolic excision (CME), central vascular ligation (CVL) and resección (R0). Seven cases were operated laparoscopically; and the median quantity of removal lymph nodes was 21.54 ± 7.32. Positive lymph nodes were revealed in 24.3% cases. AL was diagnosed in one patient. Conclusions: Careful pre-operative analysis of vascular anatomy on 3D-CT angiography will assess the vascularization of the splenic flexure of the colon, reduce intraoperative time to identify structures, and develop a personalized strategy for surgery which potentially can reduce the risk of anastomotic leakage.

Antecedentes: El suministro de sangre adecuado es uno de los factores clave para la curación de la anastomosis colorrectal. Varias variantes de la anatomía vascular a menudo sorprenden a los cirujanos durante las operaciones. Objetivo: Realizar un análisis comparativo de los datos de la angiografía tridimensional por tomografía computarizada (3D-TC) con los datos intraoperatorios y un análisis detallado de las variantes de la anatomía del ángulo esplénico. Método: Se incluyeron en el estudio 103 pacientes con cáncer de colon y recto del lado izquierdo que se sometieron a una angiografía 3D-TC preoperatoria en el Hospital Universitario de Ternopil. Resultados: De acuerdo con la clasificación propuesta recientemente, existen cuatro tipos de irrigación del ángulo esplénico del colon. Nuestro análisis mostró que el tipo 1 se encontró en 83 (80.6%) pacientes, el tipo 2 en 9 (8.7%), el tipo 3 en 10 (9.7%) y el tipo 4 en 1 (1%). Todos los pacientes fueron sometidos a hemicolectomía radical izquierda local con resección de escisión mesocólica completa (CME), ligadura vascular central (CVL) y resección (R0). Siete pacientes fueron operados por vía laparoscópica. La mediana de ganglios extirpados fue de 21.54 ± 7.32. Se revelaron ganglios linfáticos positivos en el 24.3% de los casos. Se diagnosticó fuga anastomótica en un paciente. Conclusiones: El análisis preoperatorio cuidadoso de la anatomía vascular en la angiografía 3D-TC evaluará la vascularización del ángulo esplénico del colon, reducirá el tiempo intraoperatorio para identificar estructuras y desarrollará una estrategia personalizada para la cirugía.

Three-dimensional CT angiography facilitates uniportal thoracoscopic anatomic lung resection for pulmonary sequestration: a retrospective cohort study.

BACKGROUND: Pulmonary sequestration (PS) is a rare lesion with independent blood supply from an anomalous systemic artery. A timely resection is considered as the best treatment for PS. Three-dimensional computed tomography angiography (3D-CTA) has been widely utilized for precise thoracic surgery. This study aimed to investigate the role of preoperative 3D-CTA and resection simulation in uniportal video-assisted thoracoscopic surgery (VATS) anatomical lung surgery for PS. METHODS: The data of 20 consecutive PS patents undergoing anatomic lung resection between April 2011 and May 2021 in a single centre were retrospectively reviewed. These patients were divided into the 3D-CTA group (10 patients) and the control group (10 patients) according to the initial surgical planning with or without 3D-CTA. The perioperative parameters regarding safety and fluency such as the incidence of conversion to open thoracotomy, operation time, blood loss, complications and chest tube duration were analyzed. RESULTS: This cohort included 12 female and 8 male patients, with a mean age of 45 years old (range 24-60 years). Nine cases demonstrated recurrent febrile, cough, or hemoptysis; whereas the other 11 patients were asymptomatic on admission. Eighteen (90.0%) intralobar and 2 extralobar PS were confirmed, whereas 18 (90.0%) lesions were located in the left thorax. The feeding vessels originated from the thoracic aorta in 16 patients (80.0%), the abdominal aorta in 3 (15.0%), and the inferior phrenic artery in 1 patient (5.0%). There was no major bleeding or 30 days mortality. The initial surgical planning included 9 uniportal and 1 two-port VATS in the 3D-CTA group, as compared with 10 two-port VATS in the control group. Thirteen lobectomies, 5 segmentectomies and 2 mass excisions were performed. However, no conversion was needed in the 3D-CTA group; whereas 6 (60.0%) conversions (4 to multiple-port and 2 to thoracotomy) occurred in the control group, indicating a significant difference (P = 0.003). In addition, the operation time in the 3D-CTA group was significantly shorter than those in the control group [(108.5 ± 24.9) min vs. (154.5 ± 39.4) min, P = 0.006]. The other surgery-related outcomes were similar between the two groups. CONCLUSION: Preoperative 3D-CTA facilitates the safe and fluent performance of uniportal VATS anatomical lung resection for PS with shortened operation time and lessened surgical conversions.

Anatomical analysis of variations in the bronchus pattern of the left upper lobe using three-dimensional computed tomography angiography and bronchography.

Background: The number of sublobar resections performed is increasing, thoracic surgeons must be familiar with bronchus anatomy and preoperative planning plays an important role in predicting anatomical variations. However, there is few report showing anatomic variations of the left upper lobe (LUL) using three-dimensional computed tomography angiography and bronchography (3D-CTAB), and no in Chinese population. The present study aimed to use 3D-CTAB to describe variations of the pulmonary bronchus of LUL in Chinese population. Methods: In this retrospective study, we analyzed 3D-reconstruction from patients that performed lobectomy, segmentectomy or subsegmentectomy of the LUL in 2020 at Fujian Medical University Cancer Hospital's Department of Thoracic Surgery. Patients with previous LUL surgery or absence of 3D-reconstruction or without surgery were excluded. Results: One hundred and sixty-six patients met our criteria. Branching of the left upper bronchus was classified into bifurcated type (99.4%) or trifurcated type (0.06%). The left upper divisional bronchus (B 1+2+3) arise as bifurcated (65.65%) or trifurcated type (34.34%). Apicodorsalis bronchus (B 1+2) always originated as bifurcated type, while ventralis bronchus (B 3) was either bifurcated (94.45%) or trifurcated (5.55%). Lingular bronchus (B 4+5) was observed as bifurcated (96.38%) or trifurcated (3.62%) type. When analyzing sublobar divisions of bronchi a total of 14 subtypes were identified, 6 of them were found in the upper divisional bronchus. Conclusions: Bronchial anatomy of LUL is highly variable, especially in upper divisional bronchus. 3D-CTAB is a useful tool to identify variations in the bronchi pattern, we recommend preoperative planning for sublobar resection.

Hemodynamic Risk Factors for the Development of Carotid Stenosis in Patients with Unilateral Carotid Stenosis.

BACKGROUND: It is difficult to predict the development of carotid stenosis by means of the known risk factors. Using a computational fluid dynamics analysis, we examined the hemodynamic risks for carotid stenosis, focusing on wall shear stress (WSS) disturbances. METHODS: In 59 patients with unilateral carotid stenosis, the plaque was removed from the original three-dimensional computed tomography angiographic images, and the vessel shape before stenosis was artificially reproduced. A multivariate regression analysis was performed to determine the associations between the degree of area stenosis and hemodynamic and morphologic factors after adjustment for 6 known risk factors. RESULTS: Metrics for WSS disturbances were higher at and distal to a bifurcation in the carotid arteries after plaque removal compared with the normal carotid arteries, and metrics for WSS magnitudes were lower. In the plaque-removed arteries, the degree of stenosis was significantly negatively correlated with the ratio of stenotic to distal values of metrics for WSS disturbances and the diameter ratio of the external to common carotid artery, and positively correlated with the ratio of proximal to stenotic values of metrics for WSS magnitudes. CONCLUSIONS: Rapid increases in WSS from the common carotid artery toward the bifurcation, rapid decreases in WSS disturbance from the bifurcation toward the internal carotid artery, and lower diameter ratio of the external to common carotid artery are more likely than other risk factors to cause future severe stenosis. In patients with these hemodynamic risks, underlying diseases should be controlled more strictly, with imaging examinations at shorter intervals.

Bilateral vertebral artery fenestrations in the craniocervical junction region: the clinical role of 3D computed tomography angiography.

Fenestration of the vertebral artery (FVA) is a rare occurrence that comprises only 2% of fenestrations formed in the intracranial arteries. Herein, we report a unique case of bilateral FVA in the craniocervical junction (CCJ) region using conventional magnetic resonance angiography (MRA) and three-dimensional computed tomography angiography (3D-CTA). Compared to MRA, 3D-CTA was more sensitive in delineating the FVAs located in the region. Furthermore, it effectively depicted the relationships between the VAs and surrounding bony structures. The clinical implications of FVAs can be better understood in relation to the surrounding bony structures. 3D-CTA is mandatory when performing endovascular and open surgical interventions in and around the VA segments in the CCJ region.

Three-dimensional computed tomography is effective in diagnosing uterine arterial pseudoaneurysm, a cause of secondary postpartum hemorrhage: A case report.

Uterine artery pseudoaneurysm is a rare cause of secondary postpartum hemorrhage. Herein, we report a case of uterine artery pseudoaneurysm, with postpartum hemorrhage commencing 22 days after uncomplicated vaginal delivery. Intermittent bleeding occurred during conservative observation. Transvaginal ultrasound color Doppler imaging revealed swollen vascular structures that suggested arteriovenous malformations, and a saccular dilatation of blood vessels. However, it was insufficient to definitively diagnose the condition as pseudoaneurysm. Meanwhile, the three-dimensional computed tomography angiogram was effective in demonstrating a pseudoaneurysm in the uterus, and an absent early venous return sign, leading to the final diagnosis of a pseudoaneurysm. The patient was successfully treated with transarterial embolization using gelatin sponge pledgets. No bleeding or recurrence of the pseudoaneurysm was observed 2 months after embolization.

[Usefulness of Trapezoidal Cross-injection in Aortic 3D-CTA].

PURPOSE: This study aimed to compare the contrast effects of administration via the subclavian vein, the superior vena cava and right ventricular venous tract, and the aorta in three-dimensional computed tomography angiography (3D-CTA) using one-step injection and trapezoidal cross-injection. METHOD: The subjects were 56 patients who underwent aortic 3D-CTA. In the one-step injection method, a 30-second injection of contrast medium was followed by saline injected at the same rate as the 30-ml contrast medium. In the trapezoidal cross-injection method, after injecting the contrast agent for 15 seconds, a variable mixture of the contrast agent and saline was injected for 15 seconds, followed by 20 ml saline injected at the same rate as the initial contrast agent injection. CT values were measured in the subclavian vein, superior vena cava, right ventricle, and aorta. RESULT: A significant difference was found in the subclavian vein and right ventricle, with the trapezoidal cross-injection method showing a lower CT value than the one-step injection method (p<0.01). There were no significant differences in the CT values in the superior vena cava and the aorta. CONCLUSION: The trapezoidal cross-injection method for aortic 3D-CTA produced lower CT values in venous pathways than those via the one-step injection method, but no changes were observed in the aortic CT values. These results suggest that the trapezoidal cross-injection method is useful in aortic 3D-CTA.

Early detection of large-vessel occlusion stroke after cardiac surgery using CT angiography leading to early recanalization with endovascular thrombectomy.

CT angiography may be useful for early diagnosis of ischemic stroke after cardiac surgery. When patients diagnosed with large-vessel occlusion, endovascular thrombectomy may be a therapeutic option and may improve their neurological complications.

The dataset on the clipped cerebral aneurysm and their radiological findings in three-dimensional computed tomography, time-of-flight magnetic resonance angiography (TOF-MRA), and Pointwise Encoding Time Reduction with Radial Acquisition (PETRA)-MRA.

These data present the 141 intracranial arterial branches' visibilities near the 72 cerebral aneurysms in postoperative 58 patients treated with titanium or cobalt-chromium-nickel-molybdenum (CCNM) alloy clips. The visibilities were evaluated using time-of-flight magnetic resonance angiography (TOF-MRA), pointwise encoding time reduction with radial acquisition (PETRA)-MRA, which uses MRA with ultrashort echo time (UTE-MRA) and subtraction technique between saturated and non-saturated images, and three-dimensional computed tomography angiography (3DCTA). We retrospectively acquired the data from the medical records of Suwa Red Cross Hospital. Each method's appearance was compared, and associations between visibility on PETRA-MRA, arterial diameter, clip numbers, clip shapes, clip materials, and amounts of hematoma were summarized. Our article on PETRA-MRA's usefulness for proximal and branched arteries evaluation after cerebral aneurysm clipping [1] was based on these data. This dataset would be useful for reference value for other neurosurgeons or radiologists for further analysis on PETRA-MRA and another UTE-MRA like SILENT-MRA after cerebral aneurysm clipping.

Eagle syndrome with hidden stylocarotid syndrome examined using dynamic ultrasonography: illustrative case.

BACKGROUND: Eagle syndrome, or elongated styloid process syndrome, is a rare cause of cerebral infarction. When the styloid process is elongated but the internal carotid artery (ICA) is morphologically normal on three-dimensional computed tomography angiography (3D-CTA), determining the causal relationship between elongation and cerebral infarction is difficult. OBSERVATIONS: The patient was a 27-year-old man who experienced two left cerebral infarctions in 3 months. On 3D-CTA, the styloid process was elongated, but the structure of the ICA was normal. When the patient's neck was rotated leftward, the peak systolic velocity and pulsatility index increased (shown via dynamic subtraction ultrasonography) and ICA stenosis was evident (shown via subtraction angiography). The styloid process was removed, and the cerebral infarction did not recur in the 2 years after surgery. LESSONS: This is the first report to document that indirect compression of ICA by the styloid process can cause Eagle syndrome. The blood flow changes of the ICA on dynamic ultrasonography revealed morphological changes that were hidden on 3D-CTA or nondynamic subtraction angiography.

Selection of approach and bypass for fetal-type posterior cerebral artery aneurysm: illustrative cases.

BACKGROUND: Unlike in aneurysms of the adult-type posterior cerebral artery (PCA), in aneurysms of the fetal-type PCA, parent artery occlusion (PAO) results in vascular insufficiency and major ischemic strokes. Preservation or reconstruction of fetal-type PCAs is necessary to prevent these complications. Furthermore, it is necessary to select an appropriate bypass method and approach for revascularization of the PCA. OBSERVATIONS: The authors report 2 cases of aneurysms of fetal-type PCAs that were successfully treated with PAO with revascularization. A 38-year-old man with a large unruptured right PCA aneurysm at the postcommunicating (P2) segment underwent trapping with superficial temporal artery-PCA bypass via the anterior temporal and subtemporal approaches. In addition, a 45-year-old woman with a left PCA aneurysm at the quadrigeminal (P3)-cortical (P4) segments resulting in subarachnoid hemorrhage underwent proximal clipping of the P3 segment via the occipital interhemispheric approach with an occipital artery-PCA bypass. Although she had perforator infarction, major ischemic stroke was prevented, and aneurysm occlusion was accomplished in both cases. LESSONS: Aneurysms of fetal-type PCAs pose a risk of ischemia due to PAO. The combined use of bypass and revascularization should be considered to prevent major ischemic stroke after occlusion of the fetal-type PCA. However, perforator infarction is a concern.

Repeated cerebellar infarction in the affected nondominant vertebral artery distribution with reversible vertebral artery occlusion elicited by head tilt: illustrative case.

BACKGROUND: Bow hunter's syndrome or stroke (BHS) is characterized by rotational vertebrobasilar insufficiency elicited by rotation of the neck. It is caused by dynamic and reversible occlusion of the vertebral artery (VA). Reversible symptoms of rotational vertebrobasilar insufficiency are described as bow hunter's syndrome, although brain infarction is rarely reported as bow hunter's stroke. OBSERVATIONS: A 70-year-old man experienced repeated cerebellar infarctions three times in the posterior inferior cerebellar artery (PICA) distribution of the nondominant right VA connecting the basilar artery. The onset of symptoms indicating cerebellar infarcts and the patient's head position changes were unrelated. Dynamic digital angiography (DA) revealed that the nondominant right VA was occluded by an osteophyte from the C4 vertebral body, and the right PICA branches were shown to be passing through the distal right VA from the left VA. These findings were observed when the patient's head was tilted to the right. An arterio-arterial embolic mechanism was suggested as the cause of repeated cerebellar infarctions. LESSONS: Transient nondominant VA occlusion has been rarely reported as a cause of BHS when the head is tilted. To confirm the diagnosis of BHS, additional head tilt is recommended when performing dynamic DA in patients with a cervical osteophyte.

An aberrant venous channel mimicking the perilabyrinthine cells in the petrous bone of a patient with vestibular schwannoma: illustrative case.

BACKGROUND: Anatomical variations, such as high jugular bulbs and air cell development in the petrosal bone, should be evaluated before surgery. Most bone defects in the internal auditory canal (IAC) posterior wall are observed in the perilabyrinthine cells. An aberrant vascular structure passing through the petrous bone is rare. OBSERVATIONS: A 48-year-old man presented with a right ear hearing disturbance. Magnetic resonance imaging revealed a 23-mm contrast-enhancing mass in the right cerebellopontine angle extending into the IAC, consistent with a right vestibular schwannoma. Preoperative bone window computed tomographic scans showed bone defects in the IAC posterior wall, which ran farther posteroinferiorly in the petrous bone, reaching the medial part of the jugular bulb. The tumor was accessed via a lateral suboccipital approach. There was no other major vein in the cerebellomedullary cistern, except for the vein running from the brain stem to the IAC posterior wall. To avoid complications due to venous congestion, the authors did not drill out the IAC posterior wall or remove the tumor in the IAC. LESSONS: Several aberrant veins in the petrous bone are primitive head sinus remnants. Although rare, their surgical implication is critical in patients with vestibular schwannomas.