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BackgroundMastoid emissary vein is especially important from the neurosurgical point of view, because it is located in variable number in the area of the occipitomastoid suture and it can become a source of significant bleeding in surgical approaches through the mastoid process, especially in retrosigmoid craniotomy, which is used for approaches to pathologies localized in the cerebellopontine angle. Ideal imaging method for diagnosis of these neglected structures when planning a surgical approach is high-resolution computed tomography. The aim of this work was to provide detailed information about this issue.MethodsWe studied a group of 295 skulls obtained from collections of five anatomy departments and the National Museum. Both quantitative and qualitative parameters of the mastoid foramen were evaluated depending on side of appearance and gender. Individual distances of the mastoid foramen from clearly defined surface landmarks (asterion, apex of mastoid process, foramen magnum) and other anatomical structures closely related to this issue (width of groove for sigmoid sinus, diameters of internal and external openings of mastoid foramen) were statistically processed.ResultsThe most frequently represented type of the mastoid foramen is type II by Louis (41.2%). The differences between right and left sides were not statistically significant. In men there was a higher number of openings on the right side and in qualitative parameters the type III and IV predominated, whereas in women the types I and II were more frequent. In men, greater distances from the mastoid foramen were observed when evaluating qualitative parameters for defined surface landmarks. Mean size of the external opening diameter was 1.3 mm; however, several openings measured up to 7 mm.ConclusionsDespite excellent knowledge of anatomy, however, good pre-operative examination using imaging methods and mastering of microsurgical techniques create the base for successful treatment of pathological structures in these anatomically complex areas.

Introduction 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.

PurposeDuring retrosigmoid craniotomy, the mastoid emissary vein (MEV) can be a source of considerable bleeding during the operation, especially when the larger diameter MEV or sigmoid sinus is torn. In this study, we evaluated the relevant structure of the MEV for their anatomy and applied the data in surgery to summarize their clinical significance.MethodsThe posterior craniocervical regions of 15 silicon-injected Chinese human cadaver specimens were dissected to expose the MEV and adjacent structures. Fifty-one patients who were scheduled to undergo retrosigmoid craniotomy were selected. All patients underwent preoperative routine CT of the head. The relevant data were collected on cadaveric anatomy and CT. Eventually, all patients underwent retrosigmoid craniotomy and the MEV was observed during the operation.ResultsIn cadaver specimens, the prevalence of the MEV was 90.0%. It originated from the middle and lower parts of the posterior wall of the sigmoid sinus and extended in the posterior direction in the mastoid process, usually having 1–2 external openings (86.7%) and only 1 internal opening. The intraosseous courses of the MEV were classified as straight and curved. The straight type accounted for 57.9%, and the curved type for 42.1%. The mean diameter of the MEV was 1.84 ± 0.85 mm, and the straight length of the MEV inside the mastoid process was 11.93 ± 3.58 mm. In 16.7% and 6.7% of all cadaver specimens, the MEV diameter was greater than 2.5 and 4 mm, respectively. In 51 patients (bilateral), routine head CT scan showed the MEV in 49.0% of the patients, and the MEV diameter was greater than 2.5 and 4 mm, respectively, in 17.6% (18/102) and 3.9% (4/102) of the cases. During surgery (unilateral) in the 51 patients, 48 had the MEV and 3 had no MEV. None of the patients had sigmoid sinus tears or massive bleeding.ConclusionIn the process of retrosigmoid craniotomy, detailed anatomical knowledge of the MEV, well-planned CT scan, and meticulous microsurgical techniques are key for successful operation, which can reduce the occurrence of complications.

Purpose The dural sigmoid sinus (SS) is a major surgical landmark. It is aimed to report an extraordinary and clinically significant anatomical variation– the mastoid pouch of the SS, which replaces the mastoid air cells. Method The archived angioCT file of a 45 y.o. male was retrospectively studied on planar sections and by three-dimensional volume renderings. Results An expansive mastoid pouch of the left SS was found, measuring 1.74 cm in transverse diameter and 2.18 cm in sagittal diameter, replacing the typical mastoid air cell system. This SS pouch extended to the mastoid cortex and was covered by a robust (1.41 cm broad) tegmen sinus sigmoidei. The bony wall between the SS pouch and the mastoid portion of the facial canal was 4.65 mm thick. Conclusion The marked venous encroachments into the mastoid region emphasise the necessity for comprehensive preoperative imaging and careful selection of surgical approaches to prevent inadvertent vascular compromise.

Background Walking on an incline demands specific neuronal control because the vestibular system may alter gait patterns to maintain balance with respect to self-orientation to gravity. A previous study confirms the aforementioned hypothesis that walking on inclines with bilateral vestibular disruptions altered spatial–temporal gait parameters in anterior–posterior and vertical directions. This study extended the current knowledge to investigate bilateral mastoid vibration's effect on the Margin of Stability (MoS) while walking on inclines. Methods Eighteen healthy young adults participated in this study. Participants were randomly assigned to eight treadmill trials, encompassing walking at their preferred walking speed on inclines of 0%, 3%, 6%, and 9% with and without bilateral mastoid vibrations. The dependent variables were MoS in both the anterior–posterior (MoSap) and medial–lateral (MoSml) directions, the variability of MoS in both AP (MoSVap) and ML (MoSVml) directions, step length, step length variability, step width, and step width variability. Results We found the significantly greater MoSap (3%: p = 0.005, 6%: p = 0.002, 9%: p < 0.001) and the significantly larger step length (3%: p = 0.008, 6%: p = 0.025, 9%: p < 0.001) while walking on different inclines with bilateral mastoid vibration than without vestibular stimulation. We also noticed MoSml (F 1, 17  = 14.24, p  = 0.002) was significantly smaller while walking with bilateral mastoid vibration than walking without vestibular stimulation. Discussion These results revealed that bilateral mastoid vibrations impact the margin of stability in both directions, and walking on inclines requires adjustment of MoS. This result may facilitate future clinical implications for patients with compromised vestibular functions.

Purpose The location of the sigmoid sinus may change according to the ventilation status of the mastoid bone, in which case the relationship of the sigmoid sinus to the facial nerve and semicircular canals is predicted to change. The purpose of this study was to evaluate the importance of sigmoid sinus distances to the facial nerve and semicircular canals concerning mastoid surgery. Methods The relationship of the sigmoid sinus and the facial nerve with the semicircular canals was analyzed from the cone beam computed tomography images of 75 male and 95 female subjects, aged 18–65 years. First, a line drawn from the posterior semicircular canal to the sigmoid sinus on axial CT images was used to assess whether the sigmoid sinus was lateral or medial. Second, sigmoid sinus typing was performed quantitatively on 3D reconstructed images. The distance between the sigmoid sinus-facial canal, sigmoid sinus-semicircular canals and sigmoid sinus-basal part of the cochlea was measured. Results The sigmoid sinus was found to be lateral to the posterior semicircular canal in 80.8% of cases and medial in 19.2% of cases. The posterior semicircular canal-sigmoid sinus distance was determined to be 11.76 ± 0.99 mm and 9.99 ± 0.93 mm on the right side and 11.99 ± 0.43 mm and 9.87 ± 0.02 mm on the left side, respectively, according to the sigmoid sinus patterns. Conclusion According to our results, it was found that the relationship between the semicircular canals and the facial canal varied according to the location of the sigmoid sinus, and in the medially located sigmoid sinus, the facial canal was very close to all three semicircular canals.

The most common site is the mesotympanum, and the most rare is the mastoid process.?· Though the exact etiology is unknown, middle ear congenital cholesteatoma has been linked to the presence of congenital epithelial rests in the mesotympanum, and temporal bone disease to the migration of epithelial tissue via the Seessel epipharyngeal pouch into the petrous air cells. Temporal bone CT and thin-cut magnetic resonance imaging showed a well-circumscribed mass measuring 6 x 4 x 4 cm, centered within the right posterior mastoid air cells with inner and outer table bony dehiscence (Figure 1). Surgical removal is essential to prevent complications like intracranial extension, hearing loss, and cranial nerve damage.!\"\" Author Contributions: Concept -J.T.R.; Design -J.T.R, M.B., A.W., M.O.; Supervision -J.T.R.; Resources - M.O., A.W.; Materials - М.О., A.W.; Data Collection and/or Processing - M.O., A.W.; Analysis and/or Interpretation - M.B., M.O., A.W, Literature Search -S.K.; Writing - S.K., M.O., A.W.; Critical Review - M.B., JTR.

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.

Objective To evaluate the long-term outcomes of trans-mastoid plugging of superior semicircular canal dehiscence (SSCD), focusing on complicated cases. Methods In this cohort study, we included all patients who underwent trans-mastoid plugging of SSCD between 2009 and 2019. We evaluated the symptoms (autophony, sound-/pressure-induced vertigo, disequilibrium, aural fullness and pulsatile tinnitus) before and 1 year after surgery in the medical records. We systematically assessed the current symptoms 6.2 ± 3 years postoperative (range 2.2–12.3 years) using questionnaires sent by post and validated by telephone interviews. We also documented any complications and the need for further procedures. We compared pure tone and speech audiometry before and 1 year after surgery. Finally, the degree of mastoid pneumatisation and mastoid tegmen anatomy were reviewed on preoperative CT scans. Results We included 24 ears in 23 patients. No complications were recorded, and none required a second procedure for SSCD. Following surgery, oscillopsia and Tullio phenomena resolved in all patients. Hyperacusis, autophony, and aural fullness were also settled in all patients except one. Balance impairment persisted to some degree in 35% of patients. No deterioration over the years was reported regarding the above symptoms. On average, bone conduction pure tone average pre- and 1 year postoperative were 13.7 ± 17 and 20.5 ± 18 dB, respectively ( P  = 0.002). Air bone gaps were reduced from 12.7 ± 8 to 5.9 ± 6 ( P  = 0.001). Two patients had a significant sclerotic mastoid, three had a prominent low-lying mastoid tegmen, and two had both. Anatomy had no effect on outcome. Conclusion Trans-mastoid plugging of SSCD is a reliable and effective technique which achieves long-lasting symptom control, even in cases with sclerotic mastoid or low-lying mastoid tegmen.

To examine the effects of mastoid and middle-ear volume on the anatomical and functional success of type 1 tympanoplasty in paediatric patients. This study included 45 paediatric patients who underwent type 1 cartilage tympanoplasty. Patients' demographic data, pre- and post-operative audiological evaluation results, and post-operative graft status were evaluated. Middle-ear and mastoid cavity volumes were calculated (in cubic centimetres) using temporal bone high-resolution computed tomography. Middle-ear and mastoid cavity volume values were compared between patients with and without post-operative anatomical and functional success. Anatomical success was achieved in 82.2 per cent of patients (n = 37), and functional success in 68.9 per cent (n = 31). When anatomical success and failure groups were compared, a statistically significant difference was found in mean mastoid volume (p = 0.037), while there was no significant difference in relation to mean middle-ear volume (p = 0.827). The comparison of functional success and failure groups revealed no significant difference in mean mastoid volume (p = 0.492) or middle-ear volume (p = 0.941). The study showed that mastoid pneumatisation volume affects surgical success in paediatric tympanoplasty.