暂无摘要。

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.

OBJECTIVE: The chordae Willisii (CWs), trabecular projections into the lumen of the dural sinuses, are not well understood. We aimed to explore them using magnetic resonance imaging (MRI).
METHODS: Eighty-five patients underwent volumetric contrast-enhanced MRI, while another 30 underwent a fluid-attenuated inversion recovery (FLAIR) sequence in the coronal section.
RESULTS: The CWs were detected as linear filling defects lying in the dural sinuses, adjacent to the surrounding dura mater. They were found in the superior sagittal sinus (SSS) in 68.2% of the patients, most frequently in the middle third, with laminar appearance. In 27.1% of the patients, the CWs divided the SSS lumen into separate channels. The CWs were identified in the transverse sinus, transverse-sigmoid sinus junctional area and sigmoid sinus, and straight sinus in 54.1, 47.1, and 8.2%, respectively. On the FLAIR images, dural septi partially dividing the SSS lumen were identified in all patients. In addition, in 73.3% of the patients, fine linear structures were observed in the lumen with inconstant arrangements.
CONCLUSIONS: The CWs may be constant structures distributed over the lumen of the intracranial dural sinuses. Contrast-enhanced MRI may be useful for detecting laminar CWs. The FLAIR sequence may be advantageous for delineating the dural septi projecting into the lumen of the dural sinuses.

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.
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.
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.
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.

Cerebral vein and dural venous sinus thromboses (CVST) account for 0.5%-1% of all strokes. Some structural factors associated with a potentially higher risk for developing CVST have been described. However, angulation of the dural venous sinuses (DVS) has yet to be studied as a structural factor. The current study was performed because this variable could be related to alterations in venous flow, thus predisposing to a greater risk of CVST development. Additionally, such information could help shed light on venous sinus stenosis (VSS) at or near the transverse-sigmoid junction. The angulations formed in the different segments of the grooves of the transverse (TS), sigmoid (SS), and superior sagittal sinuses (SSS) were measured in 52 skulls (104 sides). The overall angulation of the TS groove was measured using two reference points. Other variables were examined, such as the communication pattern at the sinuses\' confluence and the sinus grooves\' lengths and widths. The patterns of communication between sides were compared statistically. The most typical communication pattern at the sinuses\' confluence was a right-dominant TS groove (82.98%). The mean angulations of the entire left TS groove at two different points (A and B) were 46° and 43°. Those of the right TS groove were 44° and 45°. The median angulations of the left and right SSS-transverse sinus junction grooves were 127° and 124°. The mean angulations of the left and right TS-SSJsv grooves were 111° (range 82°-152°) and 103° (range 79°-130°). Differentiating normal and abnormal angulations of the DVSs of the posterior cranial fossa can help to explain why some patients are more susceptible to pathologies affecting the DVSs, such as CVST and VSS. Future application of these findings to patients with such pathologies is now necessary to extrapolate our results.

OBJECTIVE: Sigmoid Sinus (SS) Wall Reconstruction (SSWR) is the mainstream treatment for pulsatile tinnitus (PT), but it has a high risk of recurrence. The damage of mending material is the key cause of recurrence, and its hemodynamic mechanism is still unclear. The purpose of this study was to investigate the hemodynamic causes of mending material breakage.
METHODS: In this study, six patient-specific geometric models were reconstructed based on the data of the computed tomography angiography (CTA). The transient fluid-structure coupling method was performed to clarify the hemodynamic state of sigmoid sinus and the biomechanical state of the mending material. The distribution of stress and displacement and the flow pattern were calculated to evaluate the hemodynamic and biomechanics difference at the mending material area.
RESULTS: The area of blood flow impact in some patients (2/6) was consistent with the damaged location of the mending material. The average stress (6/6) and average displacement (6/6) of damaged mending material were higher than those of complete mending material. All (6/6) patients showed that the high-stress and high-displacement proportion of the DMM region was higher than that of the CMM region. Moreover, the average stress fluctuation (6/6) and average displacement (6/6) fluctuation degree of damaged mending material is larger than that of complete mending material.
CONCLUSIONS: The impact of blood and the uneven stress and displacement fluctuation of the mending material may be the causes of mending material damage. High stress and high displacement might be the key causes of the mending material damage.

The mastoid foramen (MF) is located on the mastoid process of the temporal bone, adjacent to the occipitomastoid suture or the parietomastoid suture, and contains the mastoid emissary vein (MEV). In retrosigmoid craniotomy, the MEV has been used to localize the position of the sigmoid sinus and, thus, the placement of the initial burr hole. Therefore, this study aimed to examine the exact location and variants of the MF and MEV to determine if their use in localizing the sigmoid sinus is reasonable. The sample in this study comprised 22 adult dried skulls (44 sides). MF were identified and classified into five types based on location, prevalence, whether they communicated with the sigmoid sinus and exact entrance into the groove of the sigmoid sinus. The diameters and relative locations of the MF in the skull were measured and recorded. Finally, the skulls were drilled to investigate the course of the MEV. Additionally, ten latex-injected sides from human cadavers were also dissected to follow the MEV, especially in cases with more than one vein. We found that type I MFs (single foramen) were the most prevalent (50%). These MFs were mainly located on the occipitomastoid suture; only one case on the right side was adjacent to the parietomastoid suture. Type II (paired foramina) was the second most prevalent (22.73%), followed by type III (13.64%), type 0 (9.09%), and type IV (4.55%). The diameter of the external opening in a connecting MF (2.43 ± 0.79) was twice that of a non-connecting MF (1.14 ± 0.56). Interestingly, on one side, two MFs on the external surface shared a single internal opening; the MEV bifurcated. MFs followed three different courses: ascending, almost horizontal, and descending. Regardless of how many external openings there were for the MF, these all ended at a single opening in the groove for the sigmoid sinus. For cadaveric specimens with multiple MEVs, all terminated in the sigmoid sinus as a single vein, with the more medial veins terminating more medially into the sinus. Based on our study, the MF/MEV can guide the surgeon and help localize the deeper-lying sigmoid sinus. Knowledge of this anatomical relationship could be an adjunct to neuronavigational technologies.

BACKGROUND: We aimed to investigate the morphological features of the artery that traverse the sigmoid sinus\'s lateral surface and to discuss this structure\'s clinical relevance.
METHODS: Ten sides from five cadaveric Caucasian heads were used for gross anatomical dissection to investigate the morphological features of the sigmoid sinus artery (SSA), and additional five sides were used for histological observation.
RESULTS: The SSA was found on eight out of ten sides (80%). The mean diameter of the SSA was 0.3 mm. The mean distance from the tip of the mastoid process to the artery was 20.3 mm. Histological observation identified extradural and intradural courses of SSA. The intradural course was further categorized into protruding and non-protruding types. In the protruding type, the SSA traveled within the dura but indented into the bone, making it more or less an intraosseous artery. In the non-protruding type, the SSA traveled within the dura but did not protrude into the bone but rather indented into the lumen of the SS. In all sections, both intradural and extradural courses were identified simultaneously.
CONCLUSIONS: When the mastoid foramen is observed, it does not always only carry an emissary vein but also an artery. The SSA could be considered a \"warning landmark\" during bone drilling for the transmastoid approach.

This study was conducted to evaluate the anatomical and clinical features of Trautman\'s triangle (TT) and to better understand the possible surgical corridor for other surgical approaches involving the petroclival region, especially the presigmoid retrolabyrinthine approach.
In this study, morphological analysis of structures related to TT was performed from cone beam computed tomography images of 134 female and 206 male individuals aged 18-65 years.
The TT area was observed as 5.6% (n = 19) type I, 63.2% (n = 215) type II, and 31.2% (n = 106) type III. It was determined that 87.6% of the sigmoid sinus (SS) was lateral to the posterior semicircular canal and 12.4% was medial. It was determined that the TT area showed a positive correlation with petrous slope and a negative correlation with mastoid aeration. In other words, as the TT area increased, the petrous inclination angle also increased, but the mastoid aeration decreased. It was also found that the TT area was associated with the location of the SS and the largest TT area (164.84 ± 42.29 mm2) was observed in the posteriorly located SS.
The relationship between TT and SS, petroclival angle, mastoid aeration, and subarcuate fossa has a very dynamic structure. Understanding the variations and clinical significance of these structures in the petroclival region is critical in determining the surgical approaches to be applied and understanding the etiology of vestibular system diseases.

OBJECTIVE: There has been limited literature regarding the bridging veins (BVs) of the medulla oblongata around the foramen magnum (FM). The present study aims to analyze the normal angioarchitecture of the BVs around the FM using slab MIP images of three-dimensional (3D) angiography.
METHODS: We collected 3D angiography data of posterior fossa veins and analyzed the BVs around the FM using slab MIP images. We analyzed the course, outlet, and number of BVs around the FM. We also examined the detection rate and mean diameter of each BV.
RESULTS: Of 57 patients, 55 patients (96%) had any BV. The median number of BVs was two (range: 0-5). The BVs originate from the perimedullary veins and run anterolaterally to join the anterior condylar vein (ACV), inferior petrosal sinus, sigmoid sinus, or jugular bulb, inferolaterally to join the suboccipital cavernous sinus (SCS), laterally or posterolaterally to join the marginal sinus (MS), and posteriorly to join the MS or occipital sinus. We classified BVs into five subtypes according to the draining location: ACV, jugular foramen (JF), MS, SCS, and cerebellomedullary cistern (CMC). ACV, JF, MS, SCS, and CMC BVs were detected in 11 (19%), 18 (32%), 32 (56%), 20 (35%), and 16 (28%) patients, respectively. The mean diameter of the BVs other than CMC was 0.6 mm, and that of CMC BV was 0.8 mm.
CONCLUSIONS: Using venous data from 3D angiography, we detected FM BVs in most cases, and the BVs were connected in various directions.