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

Quantitative analysis of surgical landmarks of the face in fixed cadaveric heads: clinical and anatomical implications

PURPOSE

This study aimed to examine and analyze the presence of sexual dimorphism and symmetry/asymmetry in fixed cadaveric heads and their contributions to clinical practice.

METHODS

Measurements were conducted on 6 cadavers and 24 fixed cadaveric heads (n = 30) using a digital microcaliper to assess cranial dimensions, including surgical landmarks, facial index (FI), orbital index (OI), and the danger triangle of the face, offering crucial references for surgeons during surgical interventions.

RESULTS

Analyses were conducted on cadavers consisting of 10 females (33.3%) and 20 males (66.7%). Males demonstrated significantly higher values than females in terms of Zy-Zy (Zy = Zygion), nasal body, and width/length of the columella. Hyperleptoprosop types were the most frequently observed, followed by the leptoprosop type. Females exhibited megaseme characteristics according to OI on both sides. Additionally, the danger triangle of the face was greater in males compared than in females, suggesting a higher risk of infection in this region among males.

CONCLUSION

The observed sex differences in facial and nasal dimensions, along with facial indices, are crucial for customizing surgical procedures to individual patients. For example, the greater distance in the danger triangle among males highlights the importance of considering anatomical variations to avoid complications, such as septic cavernous sinus thrombosis. Integrating these measurements into preoperative planning can enhance the precision of facial reconstruction and aesthetic surgeries, thereby improving patient outcomes and safety.

Geometric morphometric analysis of the brainstem and cerebellum in Chiari I malformation

Background

Chiari I malformation (CMI) is characterized by inferior descent of the cerebellar tonsils through the foramen magnum and is associated with headache and neck pain. Many morphometric research efforts have aimed to describe CMI anatomy in the midsagittal plane using classical measurement techniques such as linear dimensions and angles. These methods are less frequently applied to parasagittal features and may fall short in quantifying more intricate anatomy with fewer distinct homologous landmarks.

Methods

Landmark-based geometric morphometric techniques were used to asses CMI morphology in five anatomical planes of interest.

Results

Significant shape differences between CMI and age/sex-matched controls were found in the midsagittal (Pseudo-F = 5.4841, p = 0.001) and axial planes through the rostral medulla (Pseudo-F = 7.6319, p = 0.001). In addition to tonsillar descent, CMI principal component 1 (PC1) scores in the midsagittal protocol were associated with marked anterior concavity of the brainstem and generalized verticality of the cerebellum with anterior rotation of its anterior lobe. In the axial medulla/cerebellum protocol, CMI PC1 scores were associated with greater anterior-posterior (A-P) dimension with loss of medial-lateral (M-L) dimension.

Discussion

These results suggest that CMI is associated with greater curvature of the brainstem and spinal cord, which may perturb normal neural activities and disrupt cerebrospinal fluid movements. Previous reports on the A-P diameter of the posterior fossa in CMI have conflicted; our findings of greater A-P cerebellar dimensionality with concomitant loss of width alludes to the possibility that more caudal aspects of the posterior cranial fossa are more bowl-like (homogenous in axial dimensions) and less trough-like or elongated in the M-L direction.

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.

Morphometric and morphological evaluation of the nasolacrimal groove in 150 dry bones in the Anatolian population

PUPOSE

In this study, we aimed to evaluate the anatomical features of the nasolacrimal groove in detail by providing a morphological classification based on morphometric evaluations of the nasolacrimal groove.

METHODS

A total of 150 sagittal dry bones in the Department of Anatomy, Faculty of Medicine, Istanbul University were evaluated. The length and the width at different points of the nasolacrimal canal were calculated. According to the widths of the nasolacrimal canal ten different morphological types were revealed.

RESULTS

The length of the canal was found as mean 13.62 ± 2.42 mm on the right and 12.44 ± 2.68 mm on the left side. The entrance, the base, the upper and the lower thirds of nasolacrimal canal were 6.22 ± 1.19 mm, 7.95 ± 1.85 mm, 5.85 ± 1.06 mm, 6.60 ± 1.54 mm, on the right and 6.08 ± 1.16 mm, 7.24 ± 1.64 mm, 5.45 ± 1.29 mm, 6.23 ± 1.48 mm, on the left side, respectively. The width of the entrance of the nasolacrimal canal was the narrowest width compared to the base, upper and lower thirds in 7/10 types of 71/150 cranial bones.

CONCLUSION

This comprehensive morphological classification of the nasolacrimal groove sheds new light on its complex variations. We support that the finding of this study has the potential to improve the precision of diagnostic assessments and guide specific therapeutic interventions for patients with lacrimal drainage disorders.

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.

Incidental Petrous Apex Cephalocele Presenting With Transient Global Amnesia: A Case Report and Rapid Literature Review

Transient global amnesia (TGA) constitutes a rare clinical entity that manifests with temporary memory without any other neurological manifestation. Several pathogenetic mechanisms have been implicated, including temporal hypoperfusion, venous congestion, and cortical spreading potentials. Accordingly, the only relevant imaging findings are hippocampal CA1 areas of restricted diffusion on diffusion-weighted images. In the current case report, we present the rare case of a patient with TGA associated with bilateral petrous apex cephalocele (PAC). A 63-year-old female presented with a single episode of transient memory. The brain MRI showed a bilateral PAC and an empty sella. The patient was neurologically intact upon examination and was conservatively managed. There was no symptom recurrence during the six months of follow-up. We hypothesize that the presence of the meningocele could be associated with the pathogenesis of TGA. To the best of our knowledge, this is the first case of a petrous apex meningocele presenting with TGA. Most previously reported patients were females in their fourth decade of life, usually presenting with headaches or incidentally. Almost half of the cases were bilateral, with an empty sella. Surgical treatment was reserved for symptomatic patients with cerebrospinal fluid leaks and excruciating trigeminal neuralgia. Patients with TGA may be associated with temporal lesions, including PAC. Likewise, PAC is an extremely rare clinical entity that could occasionally present with TGA.

Investigating the Effects of Trigeminal Impression and Internal Acoustic Opening Morphology Differences for Possible Surgical Applications

PURPOSE

The exhaustive information regarding the types of trigeminal pore (TP) or trigeminal impression (TI), internal acoustic opening (IAO), and related surgical approaches is lacking in the literature. Therefore, this study is performed to further elucidate the types of TP or TI, IAO, and the relationships with critical surgical landmarks in the skull base.

METHODS

Trigeminal impression (TI) and internal acoustic opening (IAO) found in 11 dry skulls, 24 right temporal bones, and 25 left temporal bones were examined on both sides to define their relationship to each other and nearby structures. The age and sex of these bones were not identified. Besides these, 77 skulls were examined by radiologic imaging methods. These skulls were identified by gender.

RESULTS

According to test results, there was a significant difference between the left and right internal acoustic opening in the case of horizontal dimension (HD). The left HD-IAO is bigger than the right one. In addition, right HD-IAO, vertical dimension (VD) of right internal acoustic opening, left HD-IAO, and left VD-IAO values differed significantly in male and female patients.

CONCLUSIONS

Investigating the relationship of TI and IAO with relevant structures suggests that surgical approaches involving the TP and IAO indicated that surgical approaches considering the TI and IAO variations may be used in the development of surgical processes and primary surgical interventions.

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.

The Infratrigeminal Suprafloccular Approach to Intrapontine Lesions: An Anatomical Overview and Relevance for the Approach to Intrapontine Lesions

Background and objectives Brainstem lesions have long been considered complex pathologies that may lead to permanent deficits or life-threatening complications, posing significant challenges for surgical removal. Among these lesions, intrapontine lesions are particularly challenging in the field of neurosurgery. However, with advancements in microsurgical anatomy knowledge and technology, these lesions have become more amenable to surgical treatment. In this study, the authors examine an infratrigeminal suprafloccular approach, which has been shown to be a safe surgical route, resulting in fewer postoperative complications, while evaluating the anatomical nuances of the approach and route. Methods Twenty cadaveric brainstem specimens were analyzed to assess the anatomy, focusing on the lateral aspect of the pons as a potential safe entry zone for intrapontine lesions. The authors consistently analyzed twenty brainstem specimens, carefully examining the pontine microsurgical anatomy. A triangular area of entrance was measured, with three sides or walls (X, Y, and Z) aiming to identify the safe zone that would spare the distinct pontine nuclei, ascending sensory pathways, corticospinal, corticonuclear, and corticopontine tracts of the brainstem. An illustrative case was adapted to the described safe entry zone for corroboration purposes. Results The authors measured three distinct lines on the lateral surface of the pons, named X, Y, and Z, forming a triangle in shape. Line X extended from the midpoint anteroposteriorly of the flocculus of the cerebellum to the apparent trigeminal exit in the lateral aspect of the pons. Line Y ran from the trigeminal exit in the pons to the apparent exit of the facial-vestibulocochlear complex in the far lateral aspect of the pontomedullary sulcus in the cerebellopontine fissure. Line Z represented the measurement from the vestibulocochlear complex to the midpoint anteroposteriorly of the flocculus of the cerebellum. The mean measurements were as follows: X = 14.41mm (range: 10mm to 20mm), Y = 13.1mm (range: 10mm to 21mm), and Z = 3mm (range: 2mm to 5mm). The mean surface area of the analyzed specimens within the triangle (formed by X, Y, and Z) was 20.1mm² (range: 10mm² to 40mm²). This area was identified as a safe zone for the entry of microsurgical approaches to intrapontine lesions, involving less retraction of the anterior pons and potentially sparing critical structures, such as the corticospinal tracts, pontine perforating arteries, tegmentum pontis, cranial nerve nuclei, substantia reticulata dorsally, and transverse pontine fibers. Microsurgical anatomical findings, combined with intraoperative monitoring in an illustrative case, consistently demonstrated that this entry area predicted less functional instability of the analyzed tracts and resulted in fewer postoperative complications. Conclusion Deep-seated pontine lesions present a complex range of pathologies with a high potential for devastating outcomes, particularly those involving hemorrhage. This study identifies and describes a presumed safe entry zone that allows for the creation of a surgical corridor for biopsy or microsurgical resection of these lesions, reducing morbidity in a previously considered impenetrable region.

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.

Microanatomical study of arachnoid granulations and meningeal architecture around Meckel's cave

Although the microanatomy of Meckel's cave (MC) has been well studied, there are still controversies regarding the meningeal architecture of the space. Moreover, there are only general mentions of the arachnoid granulations near MC in just a few sources. This study is aimed at determining the frequency, location, and anatomical variability of the main clusters of arachnoid granulations around MC. The dissection involved 26 isolated specimens of MC fixed in formalin (neutral buffered, 10%). This number included five freshly harvested specimens examined histologically. Additional paraffin block with MC horizontal section was taken from our neuroanatomical collection. Carefully selected anatomical and histological techniques were applied to assess the complex relationships between the arachnoid granulations and adjacent structures. Arachnoid granulations were found around MC in all specimens with different anatomical variations. The main clusters of arachnoid granulations were close to the trigeminal ganglion and its divisions. The dorsolateral wall of MC was a thick layer formed by interweaving bundles of collagen fibers arranged in various directions. The entire MC was surrounded by a dural sleeve (envelope). This sleeve separated MC from the lateral sellar compartment. At its anterior (rostral) end, it formed a cribriform area pierced by individual fascicles of the trigeminal nerve's primary divisions. The connective tissue forming the sleeve was not only continuous with the epineurium but also shifted to the perineuria surrounding individual nerve fascicles. The meningeal architecture around MC has a complex and multilayer arrangement with a collagenous sleeve closely related to the trigeminal ganglion. Arachnoid granulations are typically found around MC.

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.