Virtual reconstruction and geometric morphometric analysis of the Kocabas hominin fossil from Turkey: Implications for taxonomy and evolutionary significance.

The Kocabas specimen comes from a travertine quarry near the homonymous village in the Denizli basin (Turkey). The specimen comprises three main fragments: portions of the right and left parietal and left and right parts of the frontal bone. The fossil was assumed to belong to the Homo erectus s.l. hypodigm by some authors, whereas others see similarities with Middle Pleistocene fossils (Broken Hill 1/Kabwe, Bodo, or Ceprano). Here, we present the first attempt to make a complete reconstruction of the missing medial portion of the frontal bone and a comprehensive geometric morphometric analysis of this bone. We restored the calotte by aligning and mirroring the three preserved fragments. Afterward, we restored the missing portion by applying the thin-plate spline interpolation algorithm of target fossils onto the reconstructed Kocabas specimen. For the geometric morphometric analyses, we collected 80 landmarks on the frontal bone (11 osteometric points, 14 bilateral curve semilandmarks, and 41 surface semilandmarks). The comparative sample includes 21 fossils from different chronological periods and geographical areas and 30 adult modern humans from different populations. Shape analyses highlighted the presence in Kocabas of features usually related to Middle Pleistocene Homo, such as a developed supraorbital torus associated with a relatively short frontal squama and reduced post-toral sulcus. Cluster analysis and linear discriminant analysis classification procedure suggest Kocabas being part of the same taxonomic unit of Eurasian and African Middle Pleistocene Homo. In light of our results, we consider that attributing the Kocabas hominin to H. erectus s.l. may be unwarranted. Results of our analyses are compatible with different evolutionary scenarios, but a more precise chronological framework is needed for a thorough discussion of the evolutionary significance of this specimen. Future work should clarify its geological age, given uncertainties regarding its stratigraphic provenance.

The influence of biological relatedness on sexual dimorphism and sex classification based on external morphology of the frontal bone.

The most significant sexual differences in the human skull are located in the upper third of the face (the frontal bone), which is a useful research object, mainly in combination with virtual anthropology methods. However, the influence of biological relatedness on sexual dimorphism and frontal bone variability remains unknown. This study was directed at sexual difference description and sex classification using the form and shape of the external surface of the frontal bones from a genealogically documented Central European osteological sample (nineteenth to twentieth centuries). The study sample consisted of 47 cranial CT images of the adult members of several branches of one family group over 4 generations. Three-dimensional virtual models of the frontal bones were analyzed using geometric morphometrics and multidimensional statistics. Almost the entire external frontal surface was significantly different between males and females, especially in form. Significant differences were also found between this related sample and an unrelated one. Sex estimation of the biologically related individuals was performed using the classification models developed on a sample of unrelated individuals from the recent Czech population (Cechová et al. in Int J Legal Med 133: 1285 1294, 2019), with a result of 74.46% and 63.83% in form and shape, respectively. Failure of this classifier was caused by the existence of typical traits found in the biologically related sample different from the usual manifestation of sexual dimorphism. This can be explained as due to the increased degree of similarity and the reduction of variability in biologically related individuals. The results show the importance of testing previously published methods on genealogical data.

Fully Endoscopic Resection of Frontal Osteomas.

BACKGROUND: Osteomas are the most common primary bone tumors of the calvaria, with an incidence of less than 0.5%. In skull vault osteomas, the exostotic form that grows from the outer table is more common than the enostotic ones which arise from the inner table and grow intracranially. Osteomas of the forehead are very noticeable and disfiguring; patients usually seek medical advice for cosmetic reasons. Forehead osteomas were traditionally excised via either a direct incision over the lesion using the naturally occurring creases or a conventional bicoronal flap. More recently, endoscopic approaches for excision of forehead osteomas were introduced. The results were very encouraging and the technique was adopted by many groups worldwide yet with many technical variations. In this chapter we elaborate on the surgical technique and nuances of the fully endoscopic resection of frontal osteomas. METHODS: From a prospective database of endoscopic procedures maintained by the senior author, clinical data, imaging studies, operative charts, and videos of cases of forehead osteomas were retrieved and analyzed. The pertinent literature was also reviewed. RESULTS: The surgical technique of the fully endoscopic resection of frontal osteomas was formulated. CONCLUSION: The endoscopic technique has many advantages over the conventional procedures. In our hands, the technique has proven to be less time-consuming, efficient, and minimally invasive with excellent cosmetic results.

Isolated infantile myofibroma of the calvarium: Report of a case with a literature review.

OBJECTIVE: Infantile myofibromatosis is a rare entity of childhood characterized by benign myofibroblastic tumors in the soft tissues, the bones, and occasionally the viscera. Solitary skeletal lesions are relatively uncommon. Calvarial involvement should be distinguished from more aggressive tumors for appropriate treatment. METHODS: We reviewed solitary infantile myofibroma of the calvarium and discussed the relevant computed tomography and magnetic resonance imaging findings along with differential diagnosis. A case study of the frontal bone in a 5-month-old girl was also presented. RESULTS: Fourteen cases were reviewed, including the current case. Of the 13 cases with known sex, eight were male and five female. The mean age was 3.03 with an age range of 0.41-9 years. Nine of the 14 tumors were in the frontal bone. The lesions were intradiploic with tabula interna and/or externa of the calvaria involvement. The mean largest diameter was 22.3 mm. Upon computed tomography, all the lesions were expansile and lytic, and hypoattenuated, isoattenuated or occasionally hyperatenuated. Calcification was not seen. On magnetic resonance imaging, most neoplasms were hypointense on T1-weighted and T2-weighted images. Neoplasms showed hypointense signal on diffusion-weighted imaging and hyperintense on apparent diffusion coefficient, without restricted diffusion in three cases. All lesions were intensely enhanced after gadolinium administration. Treatment was total surgical resection and recurrence was not observed during follow-up. CONCLUSIONS: Infantile myofibromas are rare, typically intradiploic expansile lytic lesions with tabula interna and/or externa involvement. Distinctive imaging features include the presence of hipointense signals on T2-weighted magnetic resonance images without restricted diffusion on diffusion-weighted imaging. A slow-growing, firm, painless, and nontender mass with supportive imaging findings should raise suspicion of the disease.

A Case Report of Craniofacial Intraosseous Xanthoma in a Patient Seeking Facial Feminization Surgery.

BACKGROUND: Fibrous dysplasia (FD) is a benign developmental disorder of the bone that causes normal skeletal tissue to be replaced by excess fibrous tissue and poorly differentiated osteoblasts. Intraosseous xanthomas are benign intraosseous tumor growths characterized microscopically by the presence of lipid-laden foamy histiocytes, often with cortical expansion or disruption. Although FD commonly occurs in craniofacial bones, primary intraosseous xanthomas of the skull or facial skeleton are extremely rare. Although 2 distinct conditions, each may be difficult to differentiate on CT imaging when occurring in the facial skeleton. METHODS: We report a case of an incidental finding on craniofacial CT of a frontal bone lesion originally thought to be FD. The finding was in a 55-year-old transgender woman who was assigned male at birth before receiving multiprocedural facial feminization surgery. RESULTS: The clinical features, radiological findings, and treatment are discussed. Postoperatively, the patient had no sequelae secondary to facial feminization surgery or to the orbital lesion biopsy procedure. Bone graft appeared stable on CT imaging, although FD did not appear to resolve completely. CONCLUSIONS: Diagnosis of such lesions is challenging and may require both radiographic and histopathologic assessment. As in the case of this patient, intraosseous xanthomas may also be misdiagnosed as other benign lesions such as FD. In most known cases, surgical intervention leads to complete resolution without recurrence of the lesion.

Surgical Treatment of Trigonocephaly, Simplified Technique for Moderate Cases.

BACKGROUND: The prevalence of trigonocephaly has increased worldwide over the past 2 decades. Early identification and appropriate treatment are critical. The aim of this study is to evaluate the outcomes and the effect of metopic suture excision, perisutural frontal bone shave, and bilateral pericranial flap method on the shape of the forehead after surgical correction in infants with moderate trigonocephaly. METHODS: The present study was performed as a cross-sectional study on 40 infants of 3 to 12 months old with trigonocephalus who underwent metopic suture excision and pericardial flap surgery in Mofid Pediatric Hospital from 2016 to 2022. The definitive diagnosis of patients' trigonocephaly was made based on clinical signs and computed tomography scan findings by a plastic surgeon. RESULTS: Overall in 40 patients operated by this technique, 23 (57.5%) of cases were males, and 17 (42.5%) were females. The mean age of patients was 7.86 ± 2.22 months. Hospital stay was 2 to 4 days (mean: 3 d), intensive care unit admission was in 33 cases for 24 hours, and no intensive care unit admission for 7 cases. Blood was transfused during surgery for 25 patients, and 15 patients did not require blood transfusion use. Results were evaluated in 6 to 12 months after surgery by 3 independent plastic surgeons, with pre and postoperative photos. Satisfaction with the results of forehead shape was excellent for 60% of patients, good for 37.5%, and moderate for 2.5%. Only one female patient had a recurrence after the surgery. CONCLUSION: This study showed that the pericranial flap method after full metopic suture excision and frontal shave was very effective in the treatment of infants with moderate trigonocephaly.

The clinical manifestations of hyperostosis frontalis interna: A qualitative systematic review of cases.

Hyperostosis frontalis interna (HFI) is a condition defined as abnormal bone growth on the posterior aspect of the frontal bone. Despite uncertainties regarding its etiology and prognosis, clinicians typically consider HFI a benign pathology. There are no studies organizing all the possible manifestations of the disease. The present study aims to organize all the clinical manifestations of HFI within the current case report/series literature. A blinded PRISMA-guided search of HFI case reports and case series yielded 43 relevant articles and provided 110 patients for analysis. The symptoms presenting alongside HFI were extracted and tabulated. We found high-frequency clinical manifestations of HFI (>20% of patients) to include headaches, obesity, vertigo/dizziness symptoms, cognitive decline, and depression. An additional 15 symptoms were tabulated at frequencies found to be less than 20%. Based on our analysis, we suggest the constellation of high-frequency symptoms can offer a more comprehensive clinical picture of symptomatic HFI which may be valuable to consider for clinicians and future researchers in the field of HFI.

Management of Total Frontal Bone Loss After Surgery for Craniosynostosis: The Modified Visor Bone Flap With Brain Cage.

Complications after craniosynostosis surgery occur in 11% to 36% of cases and may be precipitated by poor soft tissue coverage and concomitant exposure of non-sterile regions; sequelae may result in infection, osteomyelitis, and bone loss requiring complex reconstruction. In the pediatric population, autologous cranioplasty remains the gold standard due to growth potential and a more favorable complication profile than synthetic cranioplasty. Virtual surgery planning (VSP) and computer-assisted design (CAD)/computer-assisted manufacturing (CAM) technology can be utilized to create innovative, patient-specific autologous solutions, similar to the approach with synthetic cranioplasty. A novel surgical approach using VSP was used for an 18-month-old female with near total bifrontal bone loss. Surface area measurements were used to determine the amount of bone available to replace the infected frontal bone. VSP was utilized to determine the most efficient construct configuration possible to achieve maximal coverage via calculation of cranial bone surface area measurements. Surgical reconstruction of the defect was planned as a Modified Visor Bone Flap with Posterior Brain Cage. A construct was fashioned from available cranial bone struts to obtain widespread coverage. 3D Recon images from before and after surgery demonstrate almost complete re-ossification of the cranial vault with significant resulting clinical improvement. Reconstruction of total frontal bone loss is possible by utilizing this technique. VSP can improve the safety and efficiency of complex autologous cranial bone reconstructions. We propose a treatment algorithm to address the problem of near total frontal bone loss in young children for whom alloplastic implants are not suitable.

Unreported variant foramen of the frontal bone: the latero-orbital foramen.

Variant foramina of the skull can lead to misdiagnosis on medical imaging and potentially, intraoperative complications if not appreciated. Here, we report an unusual foramen found superior to the frontozygomatic suture. The foramen was located on the left side at the superolateral rim of the orbit, 2.36 cm inferolateral to the supraorbital foramen. It was positioned 2.5 mm superior to the frontozygomatic suture. The foramen had a length of 3.1 mm and a width of 1.3 mm. The internal opening of the foramen was located 1.45 cm superolateral to the zygomaticotemporal foramen. We suggest that this foramen is a pathway for either a branch of the zygomatic nerve or lacrimal nerve and/or their vascular bundles. Although the prevalence of such a finding cannot be confirmed, such a case is of archival value as a comparison for future similar cases.

Average thickness of the bones of the human neurocranium: development of reference measurements to assist with blunt force trauma interpretations.

The accurate interpretation of a blunt force head injury relies on an understanding of the case circumstances (extrinsic variables) and anatomical details of the individual (intrinsic variables). Whilst it is often possible to account for many of these variables, the intrinsic variable of neurocranial thickness is difficult to account for as data for what constitutes 'normal' thickness is limited. The aim of this study was to investigate the effects of age, sex and ancestry on neurocranial thickness, and develop reference ranges for average neurocranial thickness in the context of those biological variables. Thickness (mm) was measured at 20 points across the frontal, left and right parietals, left and right temporals and occipital bones. Measurements were taken from post-mortem computed tomography scans of 604 individuals. Inferential statistics assessed how age, sex and ancestry affected thickness and descriptive statistics established thickness means. Mean thickness ranged from 2.11 mm (temporal squama) to 19.19 mm (petrous portion). Significant differences were noted in thickness of the frontal and temporal bones when age was considered, all bones when sex was considered and the, right parietal, left and right temporal and occipital bones when ancestry was considered. Furthermore, significant interactions in thickness were seen between age and sex in the frontal bone, ancestry and age in the temporal bone, ancestry and sex in the temporal bone, and age, sex and ancestry in the occipital bone. Given the assorted influence of the biological variables, reference measurement ranges for average thickness incorporated these variables. Such reference measurements allow forensic practitioners to identify when a neurocranial bone is of normal, or abnormal, thickness.

Intraosseous malignant peripheral nerve sheath tumor at the frontal bone in a child: a rare cause of proptosis.

We report a nine-year-old male having malignant peripheral nerve sheath tumor (MPNST) of the frontal bone, represented with a twelve-month history of ptosis and proptosis in his right eye and enlarged rapidly in the last three months. Except for slight numbness at his one-third of the right forehead, he had no neurological deficit. The patient's both eyes were having normal eye movements, and he had no visual acuity or field loss. After surgery, we observed the patient with no recurrence for 4 years.

Long-term aesthetic and photogrammetric outcomes in non-syndromic unicoronal synostosis: comparison of fronto-orbital distraction osteogenesis and fronto-orbital advancement and remodeling.

BACKGROUND: Fronto-orbital advancement and remodeling (FOAR) is among the most common surgical approaches for unicoronal craniosynostosis (UCS), although some data demonstrate failure to achieve long-term aesthetic normalcy, leading some to seek alternative treatment paradigms such as fronto-orbital distraction osteogenesis (FODO). This study compares long-term aesthetic outcomes of patients with UCS treated with FOAR and FODO. METHODS: Twenty patients (four males) with non-syndromic UCS presenting to our institution and undergoing distraction were compared to a matched cohort of 20 patients (six males) undergoing FOAR. Clinical photographs and ImageJ were used to quantify periorbital anatomy including palpebral fissures, pupil-to-brow distance (PTB), and margin-reflex distance (MRD1) in pixels. Whitaker classification was blindly assigned by craniofacial surgeons. RESULTS: Photogrammetric analysis and Mann-Whitney U tests demonstrated significantly improved postoperative symmetry in distraction patients for palpebral width (p = 0.020), MRD1 (p = 0.045), and canthal tilt (p = 0.010). Average Whitaker classification scores between FOAR (1.94) and distraction (1.79) cohorts were similar (p = 0.374). CONCLUSIONS: UCS patients demonstrated significant postoperative improvements in periorbital symmetry, with distraction patients demonstrating superior results in palpebral width and canthal tilt. FOAR and FODO patients achieved similar Whitaker classification scores. These cohorts will be followed until craniofacial maturity prior to making any definitive conclusions.

Growing skull fracture in a child with Ehlers-Danlos syndrome: case report and literature review.

INTRODUCTION: Growing skull fracture (GSF) is a rare complication of head trauma in the pediatric population, commonly observed in children younger than 3 years. DISCUSSION: In this report, the authors describe a case of a 3-year-old male child, with clinical features of Ehlers-Danlos syndrome (EDS), who developed a GSF in frontal bone after a crib fall, treated with duraplasty and cranioplasty with autologous craft. Here, pertinent literature was reviewed with an emphasis on surgical techniques, and correlation with the mentioned syndrome. CONCLUSION: This is the first case of GSF in association with EDS in the literature. The relevance of the case described concerns the rarity of the condition itself, the atypical presentation, and the intraoperative findings, which showed the important fragility of the dura mater, probably due to EDS. Therefore, this syndrome, besides having influenced the pathogenesis, was also a challenging factor in the surgical treatment.

Orbital Schwannoma With Frontal Bone Lysis.

Orbital schwannoma is an exceptionally rare cause of ptosis. Diagnosis may be elusive given its slow rate of growth and its various presentations depending on localization. Herein, we report the case of a 50-year-old male who presented to our clinic with a complaint of unilateral, recurrent ptosis of the left eye. He underwent levator palpebrae resection, which was unsuccessful at improving his ptosis. He later represented with acute-onset diplopia for which magnetic resonance imaging was obtained. Magnetic resonance imaging showed a lesion in the superior orbit with secondary bony dehiscence of the orbital roof. Through a vertical lid-split incision, the lesion was removed, and the frontal lobe was observed protruding through the defect in the orbital roof. This case highlights the importance of diagnostic skepticism in the face of recurrent ptosis and emphasizes the utility of the vertical lid-split approach for anterior lesions of the superior orbit.

Neoforehead Remodelling Techniques for Fronto-Orbital Advancement and Remodelling in the Oxford Craniofacial Unit: Lateral Remodelling and a Novel Central Self-Stabilizing S-Osteotomy Technique.

Fronto-orbital advancement and remodelling (FOAR) has undergone many modifications over the years, aimed at improving outcomes and reducing risks for patients. This work describes 2 techniques for remodelling the neoforehead used by the Oxford Craniofacial Unit since 1995: lateral remodelling and a central S-Osteotomy. Both methods adopt bone from the vertex as a neoforehead, but they differ in their techniques to adapt its shape to that of the newly remodelled orbital bandeau. The novel S-Osteotomy technique can be successfully applied to all FOAR procedures, irrespective of underlying synostosis and calvarial symmetry. It was originally developed for when 2 separate bony panels were required to create a neoforehead in asymmetrical cases, but was adopted for single panel neoforehead designs in metopic synostosis with the idea it may reduce temporal hollowing. An investigation of temporal hollowing in these patients who underwent either of the described methods was undertaken to assess this hypothesis with no statistically significant difference seen ( P =0.1111). Both techniques on average resulted in minimal hollowing that was not felt to require any revision, supporting the belief that temporal hollowing is a multifactorial issue. This work describes 2 successful methods of neoforehead remodelling and introduces the S-Osteotomy technique that can be applied in all FOAR procedures.

Machine Learning in Metopic Craniosynostosis: Does Phenotypic Severity Predict Long-Term Esthetic Outcome?

BACKGROUND: There have been few longitudinal studies assessing the effect of preoperative phenotypic severity on long-term esthetic outcomes in metopic craniosynostosis. This study evaluates the relationship between metopic severity and long-term esthetic outcomes using interfrontal angle (IFA) and CranioRate, a novel metopic synostosis severity measure. METHODS: Patients with metopic craniosynostosis who underwent bifrontal orbital advancement and remodeling between 2012 and 2017 were reviewed. Preoperative computed tomography head scans were analyzed for IFA and CranioRate, a machine learning algorithm which generates quantitative severity ratings including metopic severity score (MSS) and cranial morphology deviation (CMD). Long-term esthetic outcomes were assessed by craniofacial surgeons using blinded 3-rater esthetic grading of clinical photos. Raters assessed Whitaker score and the presence of temporal hollowing, lateral orbital retrusion, frontal bone irregularities and/or "any visible irregularities." RESULTS: Preoperative scans were performed at a mean age of 7.7±3.4 months, with average MSS of 6/10, CMD of 200/300, and IFA of 116.8±13.8 degrees. Patients underwent bifrontal orbital advancement and remodeling at mean 9.9±3.1 months. The average time from operation to esthetic assessment was 5.4±1.0 years. Pearson correlation revealed a significant negative correlation between MSS and age at computed tomography ( r =-0.451, P =0.004) and IFA ( r =-0.371, P =0.034) and between IFA and age at surgery ( r =-0.383, P =0.018). In multinomial logistic regression, preoperative MSS was the only independent predictor of visible irregularities (odds ratio=2.18, B =0.780, P =0.024) and preoperative IFA alone significantly predicted Whitaker score, with more acute IFA predicting worse Whitaker score (odds ratio=0.928, B =-0.074, P =0.928). CONCLUSIONS: More severe preoperative phenotypes of metopic craniosynostosis were associated with worse esthetic dysmorphology. Objective measures of preoperative metopic severity predicted long-term esthetic outcomes.

Heterotopic Ossification Bone Formation in the Frontal Bones of an African Grey Parrot (Psittacus erithacus).

A 5-year-old, male African grey parrot (Psittacus erithacus) was presented with multiple, slow-growing, firm, bilateral masses around the dorsal orbital rims. Computer tomographic imaging revealed mild, incomplete bridging bone formation on the rostrodorsal aspects of the head. A moderate amount of smooth bone formation was identified at the rostrodorsal aspect to the left orbit, with minimal associated soft tissue swelling. Surgical biopsies were collected from the masses and histopathological analysis of the most rostral right mass showed well-differentiated bone, surrounded by dense fibrous connective tissue. Scattered, well-differentiated osteocytes were present within the bone. No evidence of neoplastic changes or infectious agents were identified. The histopathological changes were consistent with metaplastic bone formation. History obtained from the owner revealed recent head trauma, which likely induced the cranial heterotopic ossification in the African grey parrot.

Craniofacial orientation and parietal bone morphology in adult modern humans.

In adult humans, the orbits vary mostly in their orientation in relation to the frontal bone profile, while the orientation of the cranial base and face are associated with the anteroposterior dimensions of the parietal bone. Here we investigate the effect of parietal bone length on the orientation of the orbits, addressing craniofacial integration and head orientation. We applied shape analysis to a sample of computed tomography scans from 30 adult modern humans, capturing the outlines of the parietal and frontal bones, the orbits, and the lateral and midline cranial base, to investigate shape variation, covariation, and modularity. Results show that the orientation of the orbits varies in accordance with the anterior cranial base, and in association with changes in parietal bone longitudinal extension. Flatter, elongated parietal bones are associated with downwardly oriented orbits and cranial bases. Modularity analysis points to a significant integration among the orbits, anterior cranial base, and the frontal profile. While the orbits are morphologically integrated with the adjacent structures in terms of shape, the association with parietal bone size depends on the spatial relationship between the two blocks. Complementary changes in orbit and parietal bone might play a role in accommodating craniofacial variability and may contribute to maintain the functional axis of the head. To better understand how skull morphology and head posture relate, future studies should account for the spatial relationship between the head and the neck.

Sex estimation through geometric morphometric analysis of the frontal bone: an assessment in pre-pubertal and post-pubertal modern Spanish population.

Sex estimates is a key step of biological profile assessment in a forensic or anthropologic context. In this study, the sexual dimorphism of the frontal bone was analyzed to assess the accuracy of sex estimates using a geometric morphometric approach in a pre-pubertal and post-pubertal sample. The shape of the frontal bone was digitized on the lateral cephalograms of 87 pre-pubertal subjects (42 males, mean age 10.14, SD ± 1.48 years; 45 females mean age 10.02, SD ± 1.11 years) and 103 post-pubertal ones (53 males, mean age 29.33 SD ± 11.88 years; 50 females, mean age 26.77 SD ± 11.07 years). A generalized Procrustes analysis (GPA) was performed for shape analyses, filtering the effects of position, rotation, translation, and size. A principal component analysis (PCA) was performed on the GPA transformed variables, and a multiple logistic regression model was used to assess the accuracy of sex estimates. In both age groups, the average size of the centroid was significantly larger in males. The females presented shapes with a shorter distance between P2 (glabella) and P1 (supratoral) and a general narrowing of the structure on the sagittal plane. In the pre-pubertal group, the shape difference was not statistically significant. In the post-pubertal group, the mean shape was significantly different between the sexes. The method displayed a high accuracy for sex estimates (88.7% males, 90.3% females) also when applied in a validation sample (82.6% males and 94.1% females). The described morphometric analysis of the frontal bone is based on a limited number of landmarks, which allows sex estimates with high accuracy in post-pubertal subjects, while it is not applicable in pre-pubertal ones.

Sexual dimorphism in shape and size of the neurocranium.

Sex identification is a primary step in forensic analysis of skeletal remains. The accuracy of sex estimation methods greatly depends on the sexual dimorphism manifested by the target anatomical region. The study aims to evaluate the sexual dimorphism in shape and size of the neurocranium and to compare the potential of shape and size of different cranial regions to classify correctly the male and female crania. The study was carried out on computed tomography images of 373 Bulgarian adults (161 males and 212 females). Three-dimensional coordinates of 32 landmarks were acquired. The landmarks were arranged in 4 configurations: neurocranium, frontal bone, parietotemporal region, and occipital bone. For each configuration, the presence of significant sex differences in shape and size was tested. Principal component analysis (PCA) was applied to explore the shape variation. The classification power of size and shape was tested using discriminant analysis and k-means clustering. The neurocranium shows significant sex differences in shape and size. The parietotemporal region is the most dimorphic neurocranial part in size and the frontal bone is the most differing one in shape. The size of the parietotemporal region and frontal bone classifies correctly more than 80% of the crania. The discrimination ability based on shape is rather low as the highest values of about 70% are obtained for the frontal and occipital bone. The PCA plots show large overlapping of the male and female crania. It can be inferred that the sex-specific size differences in the neurocranium are more important than the shape differences.