Intraforaminal Dural Septations of the Jugular Foramen: A Cadaveric Study

The investigation of cranial fossae in the intracranial cavity of fixed cadaveric skull bases: associations with sex, laterality, and clinical significance

PURPOSE

Our study aims to investigate three parts of the intracranial cavity, their distances to essential anatomical landmarks, and the correlations between these distances with sex, laterality, and surgical significance.

METHODS

The cranial nerve foraminae and essential surgical landmarks of each fossa were investigated bilaterally in 30 adult formalin-fixed cadaveric heads. Measurements, including lengths, depths, diameters, and horizontal distances to each other, to the midline of the skull, and to the outer lateral margin of the skull, were recorded on both sides.

RESULTS

The optic canal (OC) depth, internal auditory meatus (IAM) width, CNVII and CNIX diameters, and accessory hypoglossal canal (HC) distance were significantly greater on the left side (p < 0.05). CNVI length, CNV diameter, CNXI length, and the distances of the HC and accessory HC from the skull were significantly greater on the right side (p < 0.05). In males, correlations were found between the length of the left CNVIII and the right IAM diameter (r = 0.864, p = 0.001), right CNVIII length (r = 0.709, p = 0.022), right accessory HC length (r = 0.847, p = 0.016), and right-sided skull distance (r = 0.829, p = 0.042). In females, correlations were noted between IAM depth and length, right IAM location relative to the skull, left CNIX and CNX lengths, left CNXII length, left accessory HC location relative to the skull, and accessory HC length.

CONCLUSIONS

The findings of the current study indicate inherent asymmetry, sexual dimorphism, and variability in certain cranial nerves among cadaveric heads, which could have implications for surgical procedures, neuroanatomical studies, and clinical assessments. The study revealed side disparities and correlations within cranial fossa formations and essential surgical landmarks in both genders.

Assessing the frequency and variability of accessory zygomatic sutures in dry skulls: clinical insights and potential implications

PURPOSE

This study aimed to determine the presence and incidence of accessory sutures and bipartite zygomatic bone types, and their effects on population affinity and clinical significance.

METHODS

We examined 120 dry skulls and 50 zygomatic bones to evaluate the presence, frequency, and location of accessory zygomatic sutures as well as subtypes of bipartite zygomatic bones. Morphometric analysis included measuring the total width and length of the zygomatic bone with accessory sutures (ASs), the total length of the AS, and the shortest distance between the AS and various anatomical landmarks.

RESULTS

Bipartite zygomatic bone was observed in 14 of 120 dry skulls (11.6%) and 1 of 50 zygomatic bones (2%), indicating an overall incidence of 16 occurrences (8.82%). The ASs were predominantly located posterolaterally in 11 cases (six males, five females), anteromedially in two cases (one male, one female), superiorly in one case (male), and superolaterally in one case (male). Significant differences were noted in the distribution of the ASs (p < 0.001). Notably, a vertical inferior bipartite zygomatic type, which has not been reported in the literature, was identified. Correlations were observed between the various anatomical landmarks. Among females, the length of AS was significantly different (p = 0.038). Significant differences were also noted in the shortest distance between the AS and the zygomaticofacial foramen (ZFF) based on the body side (p = 0.034).

CONCLUSIONS

Our study suggests that the bipartite zygomatic bone is not a common occurrence, indicating its significance as a morphological variation present in certain individuals. The type VII bipartite zygomatic bone exhibited the highest incidence rate, suggesting potential ethnic-specific differences in the prevalence of certain subtypes. The consistent pattern of suture distribution, along with the asymmetry and variability in suture patterns, emphasizes its potential clinical relevance.

Morphological analysis of the jugular foramen in dry human skulls in northeastern Brazil

The jugular foramen (JF) is located between the temporal and occipital bones. The JF is a primary pathway for venous outflow from the skull and passage of nerves. Variations are common in this region and may have clinical and surgical implications. To analyze the sexual dimorphism and JF morphology in skulls from Northeastern Brazil. 128 human skulls from the Anatomy Laboratory of the Federal University of Paraíba, 64 male and 64 female, were selected and the JFs analyzed for bone septation and the presence of a dome. Data analysis considered P<0.05 as significant. On at least one side, complete septation was observed in 26 skulls (20.3%), incomplete septation in 93 skulls (72.6%) and 61 skulls (47.6%) did not present septation. In 114 skulls (89%), 47.6% female and 41.4% male, have a unilateral presence of the dome and 71 (55.4%) have it bilaterally. Posterolateral compartment diameters and JF area had higher values on the right side in the total sample and separated by sex (P<0.05). Most morphometric variables of the anteromedial compartment were higher in male than in female (P<0.05), fact that was not observed in the posterolateral compartment (P>0.05). This study showed a higher prevalence of complete septation in males compared to females. Morphometric analysis presented a peculiar morphology of the JF in this study. These results suggests that the surgical approach to diseases that affect the JF may be peculiar to the studied population, confirming the importance of morphological analysis of the skull base.

Anatomical variations of foramen of the diaphragma sellae and neighboring structures: a cadaveric study

The aim of our study was to examine the variations and types of foramen of diaphragma sellae (FDS) and their relationship with nearby surgical landmarks on cadavers.Twenty adult (9 male, 11 female) formalin-fixed cadaveric heads were bilaterally used to analyze the anatomical relationships around the supradiaphragmatic region of sella turcica. Lengths and distances of nearby surgical landmarks were measured by a digital microcaliper. SPSS version 25 was used to analyze the comparison between genders and body sides. Dorsum sellae distances to tuberculum sellae and the optic chiasm(OC) were higher in males than females (p < 0.05). Type 8 infundibulum passage was the most common variation with 50%. There was no finding related to types 1-4 of infundibulum passage. Thus, the present study has indicated that the infundibulum passes mostly from the posterior half of the foramen. The shape of the foramen was irregular in 45%, circular in 20%, sagittally oval in 20%, and horizontally oval in 15% of the cases. The OC was noted normal in 60%, prefixed in 35%, and postfixed in 5% of the cases. Comprehensive anatomical knowledge about the types of the FDS and their neighboring structures is crucial for preoperative planning of sellar region diseases in terms of navigating the region when accessing the foramen. Discrimination of variations of FDS, OC, and pituitary stalk, their relationships, and differences between genders is useful to minimize potential surgical complications.

The Use of the Suboccipital Transtentorial Approach to the Posterior Inferior Incisural Space

Objective To describe our experience with the microsurgical technique of the suboccipital transtentorial (SOTT) approach in the removal of posterior fossa lesions located in the posterior incisural space. Method Between 2002 and 2020 we reviewed all patients who underwent microsurgical resection of lesions of the posterior incisural space at the Department of Neurosurgery, Essex Neuroscience Centre, London, England (eight patients, male to female 3:5, mean age: 51, range 35-69). We describe the preoperative symptoms, radiological findings, surgical techniques, histology and postoperative outcomes in this cohort of patients. Results Eight patients with tumours located in the posterior incisural space underwent surgery during the study period including four meningiomas (50%), two haemangioblastomas (25%), one metastasis (13%) and one giant prolactinoma (13%). Gross or near total resection was achieved in six patients (75%): the giant prolactinoma could not be radically removed and one of the meningiomas required a small fragment to be left in place to protect the Vein of Galen. No patient developed a visual field deficit due to occipital lobe retraction. One patient developed a temporary trochlear nerve palsy (13%). Five patients had mild disability (Glasgow Outcome Scale (GOS) = 5), and four had moderate disability (GOS = 4). Conclusion In our series, the SOTT approach provided excellent access for all cases of tumours in the posterior incisural space. The tumour's size and relationship to the deep venous system contributed to the choice of approach and in one patient who had previously undergone surgery via the supracerebellar route, the SOTT approach enabled the avoidance of gliotic scar tissue. Success is dependent on careful case selection, though from our series of 8 patients, we conclude that this approach allows safe access to the posterior incisural space, with acceptable outcomes with regard to postoperative disability and cranial nerve palsy. As such, the approach should be in the armamentarium of any neurosurgeon who regularly deals with posterior fossa pathology.

Explanted Skull Flaps after Decompressive Hemicraniectomy Demonstrate Relevant Bone Avitality-Is Their Reimplantation Worth the Risk?

BACKGROUND

Reimplantations of autologous skull flaps after decompressive hemicraniectomies (DHs) are associated with high rates of postoperative bone flap resorption (BFR). We histologically assessed the cell viability of explanted bone flaps in certain periods of time after DH, in order to conclude whether precursors of BRF may be developed during their storage.

METHODS

Skull bone flaps explanted during a DH between 2019 and 2020 were stored in a freezer at either -23 °C or -80 °C. After their thawing process, the skulls were collected. Parameters of bone metabolism, namely PTH1 and OPG, were analyzed via immunohistochemistry. H&E stain was used to assess the degree of avital bone tissue, whereas the repeated assays were performed after 6 months.

RESULTS

A total of 17 stored skull flaps (8 at -23 °C; 9 at -80 °C) were analyzed. The duration of cryopreservation varied between 2 and 17 months. A relevant degree of bone avitality was observed in all skull flaps, which significantly increased at the repeated evaluation after 6 months (p < 0.001). Preservation at -23 °C (p = 0.006) as well as longer storage times (p < 0.001) were identified as prognostic factors for higher rates of bone avitality in a linear mixed regression model.

CONCLUSIONS

Our novel finding shows a clear benefit from storage at -80° C, which should be carefully considered for the future management and storage of explanted skull flaps. Our analysis also further revealed a significant degree of bone avitality, a potential precursor of BFR, in skull flaps stored for several weeks. To this end, we should reconsider whether the reimplantation of autologous skull flaps instead of synthetic skull flaps is still justified.

Investigation of accessory transverse foramen in dry cervical vertebrae: incidence, variations, types, locations, and diagnostic implications

Background

This research aimed to determine the incidence, variations, types, and potential locations of the accessory transverse foramen (ATF) in dry cervical vertebrae. A total of 250 Turkish dry cervical vertebrae were examined, with 500 transverse foramina investigated. The cervical vertebrae were categorized into five groups (C3–C7), and each cervical vertebra was assessed bilaterally to determine the location, incidence, and side of the ATF.

Results

ATF was observed in 21 vertebrae (8.4%) and was distributed posteriorly (76.2%), posterolaterally (19.04%), and posteromedially (4.8%) in relation to the location of the TF. The incidence of ATF was 4.8% in C3, 28.6% in C4, 9.5% in C5, 23.8% in C6, and 33.3% in C7. Furthermore, a statistically significant difference was observed in the unilateral or bilateral occurrence of the ATF (F = 3.079; p = 0.047, p < 0.05).

Conclusions

In this study, we have presented an investigative approach and discussed the potential implications of identifying the ATF in dry cervical vertebrae. The presence of ATF can be crucial in the diagnosis of variations in the vertebral artery (VA) and underlying disorders, potentially aiding in the determination of the cause of death or ancestry. Additionally, the posterior location of the ATF and its asymmetric distribution should be taken into account when evaluating dry cervical vertebrae, which may offer valuable information for the identification of variations.

Investigation of accessory transverse foramen in dry cervical vertebrae: incidence, variations, types, locations, and diagnostic implications

Background

This research aimed to determine the incidence, variations, types, and potential locations of the accessory transverse foramen (ATF) in dry cervical vertebrae. A total of 250 Turkish dry cervical vertebrae were examined, with 500 transverse foramina investigated. The cervical vertebrae were categorized into five groups (C3–C7), and each cervical vertebra was assessed bilaterally to determine the location, incidence, and side of the ATF.

Results

ATF was observed in 21 vertebrae (8.4%) and was distributed posteriorly (76.2%), posterolaterally (19.04%), and posteromedially (4.8%) in relation to the location of the TF. The incidence of ATF was 4.8% in C3, 28.6% in C4, 9.5% in C5, 23.8% in C6, and 33.3% in C7. Furthermore, a statistically significant difference was observed in the unilateral or bilateral occurrence of the ATF (F = 3.079; p = 0.047, p < 0.05).

Conclusions

In this study, we have presented an investigative approach and discussed the potential implications of identifying the ATF in dry cervical vertebrae. The presence of ATF can be crucial in the diagnosis of variations in the vertebral artery (VA) and underlying disorders, potentially aiding in the determination of the cause of death or ancestry. Additionally, the posterior location of the ATF and its asymmetric distribution should be taken into account when evaluating dry cervical vertebrae, which may offer valuable information for the identification of variations.

Wormian bone types: investigating their appearance, correlation to sex, population affinity, and clinical syndromes

Background

The types of Wormian bones may play a role in population affinity and differential diagnosis of several clinical syndromes. This study investigates the distribution of types in adult skulls, their correlation to sex, population affinity, and several impairments based on the literature. One hundred ten adult Turkish skulls, 80 (72.7%) males and 30 (27.2%) females, were investigated according to type, frequency, location, and sex. Horizontal and vertical diameters and distances from the mastoid process (MP) were measured with a digital caliper. SPSS 25 was used for all statistical analyses.

Results

A total of 58 (52.72%) Wormian bones were identified from 110 skulls, 38 (65.5%) males and 20 (34.5%) females. The types of Wormian bones revealed significant differences between being on the right, left, or center (p = 0.012). The most frequent type was type 6 (n = 14, 24.1%) in males and type 7 (n = 8, 13.8%) in females. The most frequent type was type 7 in the lambdoid suture and type 8 in the parietomastoid suture.

Conclusions

The present study revealed significant differences regarding the asymmetric distribution of Wormian bones and unilateral asymmetrical types in Turkish skulls. Several factors could contribute to this, including underlying clinical syndrome, deficiencies in embryological development, and population affinity.

Wormian bone types: investigating their appearance, correlation to sex, population affinity, and clinical syndromes

Background

The types of Wormian bones may play a role in population affinity and differential diagnosis of several clinical syndromes. This study investigates the distribution of types in adult skulls, their correlation to sex, population affinity, and several impairments based on the literature. One hundred ten adult Turkish skulls, 80 (72.7%) males and 30 (27.2%) females, were investigated according to type, frequency, location, and sex. Horizontal and vertical diameters and distances from the mastoid process (MP) were measured with a digital caliper. SPSS 25 was used for all statistical analyses.

Results

A total of 58 (52.72%) Wormian bones were identified from 110 skulls, 38 (65.5%) males and 20 (34.5%) females. The types of Wormian bones revealed significant differences between being on the right, left, or center (p = 0.012). The most frequent type was type 6 (n = 14, 24.1%) in males and type 7 (n = 8, 13.8%) in females. The most frequent type was type 7 in the lambdoid suture and type 8 in the parietomastoid suture.

Conclusions

The present study revealed significant differences regarding the asymmetric distribution of Wormian bones and unilateral asymmetrical types in Turkish skulls. Several factors could contribute to this, including underlying clinical syndrome, deficiencies in embryological development, and population affinity.

Reappraisal of the types of hypoglossal canal: endocranial approach

This study aims to classify the endocranial variations inside the Hypoglossal Canal (HC) and evaluate the elements of the HC region in terms of sizes, diameters, and distances to the nearby surgical landmarks. The present study was done on 18 adult human fixed cadaver heads bilaterally. The internal opening of HC was examined for the presence of dural or osseos septations in the canal and was classified into five types (Type 1-5). The dimensions of hypoglossal nerve (CN XII) and the distance of intracranial openings of HC from the jugular foramen and jugular tubercle were measured. The prevalence of endocranial HC types were determined on both sides as follows: type 1 (23.53% left, 6.25% right), type 2 (37.5% right, 5.88% left), type 3 (52.94% left, 25% right), type 4 (18.75% right, 17.65% left), type 5 (12.5% right). Understanding the endocranial HC types is crucial for neurosurgeons in the differential diagnosis of various intracranial pathologies for the posterior cranial fossa approach. Knowing the anatomical relationships between the adjacent structures and symmetrical organization of the HC according to the types is crucial in determining surgical strategies and preserving adjacent structures.

The influences of porus acusticus internus on ethnicity and importance in preoperative and intraoperative approaches

PURPOSE

The influences of porus acusticus internus (PAI) on ethnicity and differences between populations have not been investigated so far. Therefore, we performed this study to elucidate further the relationship between the different morphologies of PAI and ethnicity and to discuss their effects on surgery.

METHODS

One hundred twenty dry adult human temporal bones (61 male, 59 female) were investigated in the study. Their horizontal diameter (HD), vertical diameter (VD), shape, prevalence of the shapes of PAI, and the distance from the sulcus for the sigmoid sinus (SSS), sulcus for superior petrosal sinus (SSPS), and jugular foramen (JF) of dry Turkish temporal bones were recorded.

RESULTS

Forty-three (35.8%) elliptical (or transverse) and 77 (64.1%) oval (or round) PAI were detected in the Turkish dry temporal bones. On both sides, round PAI were identified more frequently than elliptical ones (32; 26.6% (left); 39; 32.5% (right)) (p < 0.05). There was a similarity between the Indian and Turkish dry temporal bones in terms of distance from the PAI to the SSPS (7-8 mm) and SSS (19-20 mm) (p = 0.01) and prevalence of morphology of PAI (oval and elliptical) (p = 0.04, p < 0.05).

CONCLUSION

The findings of the present study provided a detailed understanding of the preoperative and intraoperative identification of different morphologies of PAI and ethnicity. The ethnicity might contribute to morphology of the PAI and it can be explain the similar forms and distances between the various ethnic populations.

Reappraisal of the types of trigeminal porus and importance in surgical applications

OBJECTIVE

The detailed information regarding the types of trigeminal porus (TP) and related surgical approach is lacking in the literature. Therefore, we performed this study to elucidate further the types of TP and the relationships with critical surgical landmarks in the skull base.

METHODS

The study was performed on 19 formalin-fixed cadavers of the cranial base (52.6% male, n = 10; 47.4% female, n = 9) on both sides. Calculations were made of the vertical dimension (VD), horizontal dimension (HD), and types of TP, the thickness of the TP, the HD and VD of the internal acoustic meatus, the distance between the TP-IAM, the thickness of the ossifying tissue that forms the TP, the trigeminal nerve (CN V) in both types and the distance between the CN V-VI.

RESULTS

The elliptical (42.1% left, 36.8% right), oval (52.6% left, 36.8% right) and slit-like (5.3% right) types of TP were detected (X² = 11.722). The HD of the TP was, on average, 8.02 mm (female) and 9.2 mm (male) on the right side, and 8.26 mm (female) and 8.81 mm (male) on the left side. The VD of the TP was, on average, 1.99 mm (female) and 2.65 mm (male) on the right side, and 2.42 mm (female) and 2.94 mm (male) on the left side.

CONCLUSIONS

In our study, ellipse and slit-like types of TP are taken into account in order to plan the surgical approaches to remove or prevent the extension of tumors. A combined surgical technique is recommended to reach the TP easily without damaging the nearby surgical structures during surgery. The oval type of TP allows a wide range of movements, so it is more advantageous in skull base surgery.