V3 segment of the right vertebral artery taking an anomalous posterosuperior course and penetrating occipital bone (wall of the jugular foramen) diagnosed by magnetic resonance angiography.

PURPOSE: To describe a case of an anomalous posterosuperior course of the V3 segment of the right vertebral artery (VA) that penetrated the occipital bone (wall of the jugular foramen). METHODS: A 33-year-old healthy woman underwent cranial magnetic resonance (MR) imaging and MR angiography from the upper cervical to the intracranial region using a 3-Tesla scanner to screen for asymptomatic brain lesions, including cerebrovascular diseases. RESULTS: MR angiography showed no pathological arterial lesions such as aneurysms; however, there was an anomalous posterosuperior course of the V3 segment of the right VA. On MR angiographic source images and coronal reformatted images, the right VA was observed to penetrate the occipital bone lateral to the right hypoglossal canal and is located on the inferoposteromedial wall of the right jugular foramen and enter the posterior fossa at a higher level than the foramen magnum. CONCLUSION: We present a case in which the right VA showed an anomalous posterosuperior course at the craniovertebral junction. It is extremely rare for a VA to take a higher course. To our knowledge, this is the first report of such a VA variation in the relevant English-language literature. We speculated that the right VA of our patient was formed by the persistence of one more cephalad primitive artery than the first intersegmental artery, not by the persistence of the primitive hypoglossal artery. Careful observation of MR angiographic source is useful and important for identifying the VA penetrating the occipital bone.

Correlation of spheno-occipital synchondrosis and mandibular condylar cortication with chronological age using computed tomography in Indian population- A cross-sectional study.

BACKGROUND: Forensic age estimation is a procedure which utilises many methods to estimate the age of both living and deceased individuals, including those who have died in natural disasters or man-made catastrophes. The pattern and closure of spheno-occipital synchondrosis (SOS) fusion, along with subchondral ossification of the mandibular condyle, can be used to estimate age. AIM AND OBJECTIVES: This study aims to estimate age using computed tomographic (CT) images of spheno-occipital synchondrosis fusion (SOS) and mandibular condylar cortication (MCC), and to correlate these findings with chronological age. MATERIALS AND METHODS: The present study included 435 CT images of individuals aged 10-25 years. SOS fusion was assessed using a four-stage system, and MCC was assessed bilaterally using a three-stage system on the sagittal plane. Data on fusion stages and cortication types were entered along with chronological age, and then statistically analysed. RESULTS: SOS fusion stage 2 occurred at similar age in males (19.82 ± 2.67 years) and females (19.23 ± 2.93 years). Earlier fusion of other stages was observed in females by a mean age of 2 years. MCC was completed 1 year earlier in females, with statistically significant differences (p ≤ 0.001). When comparing cortication types and different fusion stages, only type II cortication showed statistically significant differences compared to different fusion stages (p ≤ 0.001). CONCLUSION: Mandibular condylar cortication (MCC) and spheno-occipital synchondrosis (SOS) fusion were positively correlated with chronological age, suggesting that these parameters can be used as an adjunct method for age estimation.

Outcome and Management of Occipitofrontal Contrecoup Head Injury.

Contrecoup brain injury refers to the classical opposite of the primary impact. Tamil Nadu has the highest rate of road traffic accident in India. Madurai has peak mortality due to accidents in India. Previous studies done on contrecoup head injury had shown patterns of injuries and mechanism of injury. Outcome and management of only occipitofrontal contrecoup head injury has been taken in this study. Mortality in this specific group is very high. Seventy-six patients of this specific head injury were admitted at Government Rajaji Hospital, Madurai. Patients were assessed for Glasgow coma scale (GCS), age, sex, progression of volume, mortality, traumatic brain injury-induced coagulopathy, and pillion rider outcome. Fourteen patients were surgically treated by decompressive craniectomy. Conservative management was done by antiepileptic and antiedema measures. Mostly affected were males ( n = 54) followed by females ( n = 22). GCS on admission mean value 9. In our study, mortality was 32% with sudden death of three patients due to hypothalamic compression. Hospital stay of the patient was significantly increased with progression of lesion with mean 9 days and p -value less than 0.01. Pillion riders ( n = 18) were also affected in our study. Traumatic brain injury-induced coagulopathy ( n = 12) was also detected, which was treated by injection tranexamic acid and injection vitamin K, thereby not leading to any death due to coagulopathy with significant p -value less than 0.01. We recommend helmet for both main and pillion rider with strict speeding regulations.

Hinge Craniotomy for Posterior Cranial Vault Expansion: Using the Keel to the Surgeon's Advantage.

Cranial vault reconstructions are a common craniofacial procedure utilized to treat chronically elevated intracranial pressure and its sequelae for children with craniosynostosis. These surgeries often involve split-thickness autologous grafts to facilitate intracranial volume expansion. The hinge craniotomy was developed by neurosurgeons in the early 2000s as an alternative to the hemicraniectomy to allow for greater space and simplified re-securing of the bone flap. In our report, we introduce a novel application of hinge craniotomy in total cranial vault reconstruction for a pediatric patient with microcephaly secondary to congenital cytomegalovirus infection. We performed bilateral barrel stave cuts to the occipital bone as well as an undercut along the midline keel to form a hinge craniotomy. Complex reconstruction followed to augment intracranial volume and restructure the cranial vault. This technique maximized intracranial volume expansion while minimizing the need for prolonged reconstruction. It also allowed for retained vascularization of the bone flap by maintaining the connection with the intact cranial base and pericranium to further support bony healing. Our study presents a novel utilization of hinge craniotomy, using the occipital keel as a natural hinge, to create ample space during cranial vault reconstruction. This technique offers potential advantages in terms of intracranial volume expansion and bony healing.

Management of paracondylar process fracture in three horses.

BACKGROUND: Fractures of the paracondylar process of the occipital bone may cause headshaking, neck pain and neurologic deficits. The condition is being recognised more frequently with increasing availability of computed tomography. However, to date only limited information is available as to presentation, treatment, surgical approach and outcome. OBJECTIVES: To describe the clinical signs, imaging findings, treatment, surgical approach and outcome in three horses diagnosed with paracondylar process fracture. STUDY DESIGN: Retrospective case series. METHODS: Clinical records and diagnostic images of affected cases were reviewed. RESULTS: Two cases had ventral nonunion fractures-one of these presented with neck pain, headshaking and behavioural changes, while in the other the fracture was a suspected incidental finding in a case of poor performance. A third case with a more dorsal fracture presented with acute facial nerve paralysis. Diagnosis was by computed tomography in all cases, although imaging of ventral fractures by radiography was found to be feasible. Where clinical signs could be associated confidently with the fracture, conservative management resulted in improvement but not complete resolution. Repeated recurrence of clinical signs after prolonged periods of remission necessitated surgical removal in one case, which was readily accomplished with the aid of ultrasound guidance, and led to rapid resolution of clinical signs without significant post-operative complications. The surgical approach is described. MAIN LIMITATIONS: Limited follow-up was available. CONCLUSIONS: Paracondylar process fracture should be considered as a differential diagnosis for headshaking, neck pain, poor performance and facial paresis, and is a justification for performing computed tomography in such cases. A multi-disciplinary approach is beneficial due to the potential for orthopaedic, neurologic, ophthalmologic and behavioural clinical signs, with additional need for expertise in diagnostic imaging and pain management. Surgical fragment removal should be considered for ventral fractures.

A Global Bibliometric and Visualization Analysis of Craniovertebral Junction Bony Abnormalities Based on VOSviewer and Citespace.

OBJECTIVE: Recent years have witnessed a rapidly growing interest in CVJ bony abnormalities, and a qualitative and quantitative analysis of relevant literatures is necessary. This study aims to identify and summarize the published articles related to craniovertebral junction bony abnormalities, to analyze and visualize the current research trends and major contributors. METHODS: We collected data from Web of Science, excluding certain article types. Two researchers screened articles for relevance. Data were organized with EndnoteX9, and analyzed using VOSviewer and CiteSpace for co-authorship, co-occurrence, keyword burst, and co-citation analyses to identify research trends and collaborations. RESULTS: A total of 2,776 articles were included, revealing an increasing trend in annual publications of CVJ bony abnormalities. The USA was the leading country. King Edward Memorial Hospital was the most prolific institution, and Seth GS Medical College had the most citations. The Spine is the most popular journal with the highest number of publications and citations. Professor Goel Atul from India emerged as the most influential pioneer in this field. Keyword analysis highlighted surgical techniques, diagnosis, and anatomy as the primary research hotspots and Fixation, Placement, and Basilar invagination gradually become the new research trend. However, there is a relative weakness in basic research and epidemiology. CONCLUSIONS: This study provides valuable insights into the current research trends and critical contributors in CVJ bony abnormalities, guiding evidence-based decisions and fostering international collaborations to advance knowledge in this field.

An Anatomorphometric Study of Occipital Spurs and Their Association With Dental Occlusion.

Background and objective The occipital spur (OS) can be described as an abnormal elongation of the external occipital protuberance (EOP); its etiology is multifactorial and may involve biomechanical, immunological, and/or genetic factors. This study aimed to determine the frequency and characteristics of elongated EOP or OS as well as the relationship of OS with occlusion in a group of Turkish dental patients. Materials and methods Lateral cephalometric radiographs of 1925 patients taken in 2022 were retrospectively analyzed. The frequency, types, and dimensions of OS were determined based on gender and age groups. Molar occlusion and incisal bite were also evaluated. Results Of the 1925 patients, 679 were males and 1246 were females. The mean age of the cohort was 18.17 ±5.03 years (range: 4-61). OS was detected in 483 (25.1%) patients and was more common in males (p<0.001); 133 (27.5%) of the OSs were flat, 247 (51.1%) crest, and 103 (21.3%) spin type. The incidence of OS increased depending on age groups (p<0.001). There was no statistically significant association between OS presence and molar occlusion (p>0.05). However, a statistically significant association was observed between anterior incisal bite (p=0.001) and OS presence. There was a statistically significant difference in terms of OS sizes in males and females; the sizes of OS were larger in males than in females (length: p<0.05, base and thickness: p<0.001). Conclusions The frequency of OS was quite high in our cohort; it was more common and of larger size in males and older age groups. The most common type was the crest type. While there was no statistically significant association between OS frequency and molar occlusion, there was a significant relationship with incisal bite. The frequency of OS was highest in people with anterior crossbite.

Primary Ewing's sarcoma of the occipital bone: A case report and review of the literature.

Background: Primary Ewing's sarcoma (ES) arising from cranial bones is an extremely rare entity that accounts for only 1-4% of all ES cases. Case Description: A 21-year-old woman presented with ES of the skull affecting the occipital region. The patient underwent surgical excision following radiotherapy and chemotherapy. No recurrence or metastasis occurred over a 10-month follow-up. Conclusion: ES reaches adolescents. The mainstay of treatment includes surgical removal of the tumor, followed by radio- and chemotherapy.

Relationship of the Fusion Stage of Spheno-Occipital Synchondrosis with Midpalatal and Zygomaticomaxillary Sutures on Cone-Beam Computed Tomography Scans of Patients Aged Between 7 and 21 Years.

Objective: This study assessed the relationship of the fusion stage of spheno-occipital synchondrosis (SOS) with midpalatal (MPS) and zygomaticomaxillary (ZMS) sutures on cone-beam computed tomography (CBCT) scans of 7 to 21-year-old patients. Methods: This cross-sectional study evaluated the CBCT scans of 176 patients between 7 and 21 years presenting to a maxillofacial radiology clinic. The fusion stage of SOS was determined using a five-stage classification system. The percentage of opening depth of MPS was measured on two middle coronal cuts in the anterior and posterior half of the palate. To assess ZMS, suture fusion was evaluated in four age groups in the axial cut visualizing its maximum length. Data were analyzed using the Kruskal-Wallis, Mann- Whitney U, and Bonferroni tests and regression models. Results: The percentage of MPS opening significantly decreased in both the anterior and posterior halves with age (p<0.002). With an increase in SOS grade, the percentage of MPS opening in both the anterior and posterior halves significantly decreased (p<0.001). By an increase in the ZMS stage, the SOS grade significantly increased (r=0.565, p<0.001). Conclusion: The MPS opening percentage in the anterior and posterior halves decreased with age, with a greater reduction in the posterior half. A significant inverse correlation exists between the SOS fusion stage and the percentage of MPS opening. In SOS grades I-III, the mean percentage of MPS opening was 100% in all age groups (with the highest frequency of ZMS stage I), indicating a higher chance of success for orthodontic treatments such as rapid maxillary expansion in these individuals.

Rectus capitis lateralis muscle revisited: a histological study using human fetuses.

BACKGROUND: Rectus capitis lateralis muscle (RCLM) is located at the border between the ventral and dorsal muscle groups, but the nerve topographical anatomy around the muscle is obscure. MATERIALS AND METHODS: We observed the RCLM in histological sections of 12 midterm and 10 near-term fetal heads (9-18 and 26-40 weeks of gestational age). RESULTS: At midterm, the RCLM wrapped around the inferiorly protruding inferolateral corner of the cartilaginous occipital bone. The muscle was adjacent to, or even continued to, the intertransversarius muscle between the atlas and axis. At near-term, the jugular process of the occipital bone, that is, the RCLM upper insertion, was either cartilaginous or bony, depending on age. The process formed a collar supporting the internal jugular vein from the inferior side. Moreover, the muscle is tightly attached to or inserted into the venous wall itself. The cartilaginous jugular process was adjacent to Reichert's cartilage, and the uppermost muscle fibers passed through a narrow space between these cartilages. The RCLM appeared to accelerate the jugular process elongation, resulting in complete union of the occipital and temporal bones. The ventral ramus of the first cervical nerve passed between the RCLM and rectus capitis anterior muscle to reach the longus capitis muscle. No nerve passed between the RCLM and the obliquus capitis superior muscle (a muscle at the suboccipital triangle). CONCLUSION: The dorsoventral position of the RCLM seemed to correspond to the scalenus posterior muscle in a laminar arrangement of the cervical axial musculature.

Occipital bone and tumor-induced osteomalacia: a rare tumor site for an uncommon paraneoplastic syndrome.

INTRODUCTION: Tumor-induced osteomalacia (TIO) is an uncommon paraneoplastic syndrome due to the overproduction of fibroblast growth factor 23 (FGF23). It is predominantly caused by mesenchymal tumors and cured upon their complete removal. Non-surgical treatment is an alternative option but limited to specific clinical conditions. METHODS: We report a challenging case of TIO caused by a tumor involving the occipital bone. We also performed a literature review of TIO caused by tumors localized at this site, focusing on clinical findings, treatment, and outcomes. RESULTS: The patient, a 62-year-old male, presented with a long-lasting history of progressive weakness. Biochemical evaluation revealed severe hypophosphatemia due to low renal tubular reabsorption of phosphate with raised intact FGF23 values. A 68 Ga-DOTATATE PET/TC imaging showed a suspicious lesion located in the left occipital bone that MRI and selective venous catheterization confirmed to be the cause of TIO. Stereotactic gamma knife radiosurgery was carried out, but unfortunately, the patient died of acute respiratory failure. To date, only seven additional cases of TIO have been associated to tumors located in the occipital bone. Furthermore, the tumor involved the left side of the occipital bone in all these patients. CONCLUSION: The occipital region is a difficult area to access so a multidisciplinary approach for their treatment is required. If anatomical differences could be the basis for the predilection of the left side of the occipital bone, it remains to be clarified.

Comparison of structural occipital and iliac bone grafts for instrumented atlantoaxial fusions in pediatric patients: Radiologic research and clinical outcomes.

Background: Structural autografts harvested from the iliac bone have been used in atlantoaxial fusion; they have been the gold standard for years. However, emerging occipital bone grafts have the advantage of avoiding donor-site morbidity and complications. Thus, we compared the clinical outcomes of structural autografts from the occipital bone or iliac crest and discussed the clinical significance of occipital bone grafts in pediatric patients. Methods: Pediatric patients who underwent posterior fusion using occipital bone grafts (OBG) or iliac bone grafts (IBG) between 2017 and 2021 were included in this study. Data on clinical outcomes, including operation time, estimated blood loss, length of hospitalization, complications, fusion rate, and fusion time, were collected and analyzed. Additionally, 300 pediatric patients who underwent cranial computed tomography scans were included in the bone thickness evaluation procedure. The central and edge thicknesses of the harvested areas were recorded and analyzed. Results: Thirty-nine patients were included in this study. There were no significant differences in patient characteristics between the OBG and IBG groups. Patients in both groups achieved a 100% fusion rate; however, the fusion time in the OBG group was significantly longer than that in the IBG group. Estimated blood loss, operation time, and length of hospitalization were significantly lower in the OBG group than those in the IBG group. The surgery-related complication rate was lower, but not significantly, in the OBG group than that in the IBG group. For occipital bone thickness evaluation, a significant difference in the central part of the harvesting area was found between the young and old groups, with no significant sex differences. Conclusion: The use of OBG for atlantoaxial fusion is acceptable for pediatric patients with atlantoaxial dislocation, avoiding donor-site morbidity and complications.

Full-endoscopic technique for posterior fossa decompression in Chiari malformation type I: An anatomical feasibility study in human cadavers.

Although endoscope-assisted techniques have been described, a full-endoscopic approach is yet to be performed for posterior fossa decompression (PFD) in Chiari malformation type I (CM-I). This study aims to describe the full-endoscopic PFD technique and evaluate its feasibility. Five fresh-frozen anonymized adult human cadavers were operated on using an endoscope with an oval shaft cross-section with a diameter of 9.3 mm, a working length of 177 mm, and a viewing angle of 20°. It also had an eccentric working channel with a diameter of 5.6 mm, a light guide, a sheath for continuous irrigation, and a rod lens system. The instruments were introduced from the working channel. Posterior craniocervical structures were dissected, and PFD was achieved. The planned steps were performed in all five cadavers. The endoscope was introduced to the posterior craniocervical region, dissecting the structures to easily expose the suboccipital bone and C1 posterior arch. Important structures, such as the C1 posterior tubercle, rectus capitis posterior minor muscles, and posterior atlantooccipital membrane, were used as landmarks. PFD was feasible even with the dural opening. Using the full-endoscopic approach, posterior craniocervical structures can be reached, and PFD can be performed successfully. The instruments used are well-defined for spinal usage; thus, this full-endoscopic technique can be widely used in the surgical treatment of patients with CM-I.

Desenvolvimento da Órtese de Descompressão Occipital (ODO) para pacientes críticos em unidades de terapia intensiva / Development of an Occipital Decompression Orthosis (ODO) for critically ill patients in intensive care units

Resumo Introdução Lesões por pressão são causadas por prolongado contato da pele com alguma superfície, levando a danos consideráveis de difícil recuperação. Terapeutas ocupacionais podem atuar na prevenção desses agravos por meio da confecção de dispositivos de tecnologia assistiva. Objetivos Apresentar o desenvolvimento de um dispositivo para prevenir e tratar lesões por pressão na região occipital: a Órtese de Descompressão Occipital. Método Esta é uma pesquisa exploratória aplicada através do método de gestão de projetos desenvolvida em quatro etapas. O dispositivo começou a ser desenvolvido em 2017 em um hospital de traumas referência na região metropolitana de Belém, PA, Brasil. Resultado Foi realizado um levantamento dos dispositivos disponíveis no mercado e, a partir disso, desenvolvida a Órtese de Descompressão Occipital. Essa órtese utiliza o colchão piramidal, que é um material de baixo custo que promove a baixa pressão constante no segmento occipital do paciente, e foi confeccionada a partir de avaliação antropométrica. Com base na literatura e em um estudo financeiro, criou-se um modelo aplicável na descompressão do segmento. Esse modelo alternativo apresenta baixo custo e é eficiente para prevenir lesões por pressão. Conclusão A Órtese de Descompressão Occipital segue em processo de aperfeiçoamento. Apesar de se embasar na literatura atual abordando a prevenção de lesões por pressão, ainda é necessário realizar um estudo científico criterioso para verificar sua eficácia. A Órtese de Descompressão Occipital apresenta limitações, principalmente quanto à aprovação de sua utilização por instituições hospitalares.

Abstract Introduction Pressure ulcers (PU) are caused by prolonged contact of the skin with a surface, leading to significant damage that is difficult to recover from. Occupational therapists can play a role in preventing these injuries through the creation of assistive technology devices. Objectives To present the development of a device to prevent and treat PU in the occipital region: the Occipital Decompression Orthosis (ODO). Method This is an exploratory study applied using the project management method and developed in four stages. The device began to be developed in 2017 in a reference trauma hospital in the metropolitan region of Belém, state of Pará, Brazil. Results A survey of devices available on the market was conducted, from which the ODO was developed. This orthosis uses the pyramidal mattress, a low-cost material that provides constant low pressure on the patient's occipital segment and was designed through an anthropometric assessment. Based on a literature review and a financial study, a model was created for decompression of the segment. This alternative model is low-cost and effective in preventing PU. Conclusion The ODO is still under a refinement process. Although it is based on current literature addressing pressure injury prevention, it is still necessary to conduct a rigorous scientific study to verify its efficacy. The ODO presents limitations, especially regarding its approval for use by hospitals.

Surgical management of giant cell tumor invading the occipital bone: A case report and literature review.

Background: Giant cell tumor of bone (GCTB) rarely originates in the skull, particularly in the occipital bone. Although benign, it can severely destroy the surrounding tissue and undergo an unpredictable clinical course. We report the successful resection of a GCTB invading the occipital bone in a Hispanic adult woman and present a comprehensive review of the literature on this rare pathology by focusing on the occipital area. Case Description: A 40-year-old Hispanic woman presented with a 3-month history of neck pain and a bulging lesion on the retromastoid area. Brain magnetic resonance imaging (MRI) revealed an extradural, expansive, and contrast-enhancing lesion in the right occipital bone with multiple thin septa and evidence of bleeding. The patient underwent an uneventful gross total resection (GTR) of the lesion. The histopathological examination findings included numerous scattered osteoclast-type giant multinucleated cells. At a 10-month follow-up, the patient has not developed any neurological deficits, impairment of life functioning, or signs of recurrence in MRI. Conclusion: GCTB rarely originates in the skull, being the occipital bone the most infrequent site of presentation. When feasible, total surgical resection effectively reduces the risk of recurrence. Nonetheless, radiation and adjuvant therapies have been employed when GTR could not be achieved. A close follow-up with a brain MRI is advised to control recurrence.

The foramen magnum in scaphocephaly.

PURPOSE: The foramen magnum (FM) presents various alterations in craniosynostoses, such as brachycephaly or Crouzon syndrome. However, to date, no study has been devoted to its morphology and morphometry in scaphocephaly, which is the most common of cranial deformities resulting from premature fusion of cranial sutures. METHODS: We assessed the morphology and morphometry of FM using preoperative thin-cut CT scans of 107 children with non-syndromic sagittal craniosynostosis aged 1-12 months (mean age 5.38 months). A series of sagittal and transverse dimensions were taken and the FM area was calculated in each case. Obtained data were compared to the age-matched control group of 101 normocephalic children. RESULTS: Dolichotrematous type of FM was dominant in the scaphocephaly group and observed in 63/107 cases (58.9%). The mean FM area in the scaphocephaly group was 519.64 mm2 and was significantly smaller compared to the control group (p = 0.0011). The transverse diameter and anterior sagittal diameter were also significantly smaller (p = 0.0112 and p = 0.0003, respectively). CONCLUSION: The area of FM in scaphocephaly is smaller compared to normal individuals. This is associated with a significant reduction of the width of FM in children with sagittal craniosynostosis. FM in scaphocephaly is larger than in other reported series of children with brachycephaly or Crouzon syndrome.

Giant Cell Tumour Of The Occipital Bone In A 13-Year Old Male.

Giant Cell Tumours (GCT) are usually found at the extremities of the long bones and their presence in the skull being less than 1%. In the skull, sphenoidal bone and temporal bone are the commonest sites. There have been very few reports of GCTs of the occipital bone. Total excision surgery is the ideal treatment of choice. If surgery poses a problem, then adjuvant radiotherapy can be administered too. We present a case of 13-year-old male child who was diagnosed with GCT of the occipital bone. He was successfully operated and is symptom free 6 months post his surgery till now.

Chondroblastoma of the Occipital Bone With Atypical Genetic Markers: A Case Report.

Chondroblastoma is a rare bone tumor, most often found in epiphyseal plates of long bones. It has infrequently been reported in the skull, most often in the temporal bone. We present a case of chondroblastoma of the occipital bone in a pediatric patient presenting with a bony protuberance of the occiput and imaging consistent with obstructive hydrocephalus, which persisted even after removal of the obstructing tumor. Pathological examination demonstrated that this unusually placed tumor also lacked the classic genetic markers typically associated with chondroblastoma.

Reduction of giant parietooccipital fibrous dysplasia using dynamic mirror image guidance: a case report and review of the literature.

BACKGROUND: Craniofacial fibrous dysplasia (CFD) typically occurs in the facial bones and anterior cranial vault and can produce both disfigurement and functional limitations for patients disfigurement. Treatment consists of reducing the abnormal bone. Bone contouring can become challenging when the exposure does not extend to the corresponding normal contralateral structures for comparison or when normal landmarks are not available, which may compromise the overall aesthetic outcome. We describe a technique using dynamic mirroring to accurately contour the involved part of the cranium in a case of giant CFD. OBSERVATIONS: A 49-year-old male presented with a giant deforming fibrous dysplasia of the right mastoid and parieto-temporo-occiput that was causing functional limitations due to the size of the bony mass. This was managed with multidisciplinary bony reduction. Several neurovascular structures were in proximity to the areas of planned drilling of the expansile lesion, and dynamic mirroring of the uninvolved left skull was utilized to maximize safety and symmetry of reduction. High-speed drilling of the right occipital bone was performed until the navigation system alerted the surgeon that symmetric depth had been achieved. There were no complications from the procedure and this technique maximized the limits of symmetric reduction without significantly increasing surgical complexity or duration. LESSONS: Dynamic mirroring of bony structures in the posterior cranium is not commonly employed in neurosurgical practice. This technique may help improve the aesthetic outcomes of bony reduction in craniofacial dysplasia and a variety of similarly managed bony lesions, contour cranioplasties, and in unilateral craniosynostosis surgery.

Modified surgical method of supra- and infratentorial epidural hematoma and the related anatomical study of the squamous part of the occipital bone.

BACKGROUND: Supra- and infratentorial acute epidural hematoma (SIEDH) is a common posterior cranial fossa epidural hematoma located at the inner surface of the squamous part of the occipital bone (SOB). Traditionally, surgical treatment of the SIEDH requires a combined supra-infratentorial craniotomy. AIM: To analyze the morphological characteristics of the SOB and introduce a single supratentorial craniotomy for SIEDH. METHODS: Skull computed tomography (CT) scan data from 32 adult patients were collected from January 1, 2019 to January 31, 2020. On the median sagittal plane of the CT scan, the angle of the SOB (ASOB) was defined by two lines: Line A was defined from the lambdoid suture (LambS) to the external occipital protuberance (EOP), while line B was defined from the EOP to the posterior edge of the foramen magnum (poFM). The operative angle for the SIEDH (OAS) from the supra- to infratentorial epidural space was determined by two lines: The first line passes from the midpoint between the EOP and the LambS to the poFM, while the second line passes from the EOP to the poFM. The ASOB and OAS were measured and analyzed. RESULTS: Based on the anatomical study, a single supratentorial craniotomy was performed in 8 patients with SIEDH. The procedure and the results of the modified surgical method were demonstrated in detail. For males, the ASOB was 118.4 ± 4.7 and the OAS was 15.1 ± 1.8; for females, the ASOB was 130.4 ± 5.1 and the OAS was 12.8 ± 2.0. There were significant differences between males and females both in ASOB and OAS. The smaller the ASOB was, the larger the OAS was. The bone flaps in 8 patients were designed above the transverse sinus intraoperatively, and the SIEDH was completely removed without suboccipital craniotomy. The SOB does not present as a single straight plane but bends at an angle around the EOP and the superior nuchal lines. The OAS was negatively correlated with the ASOB. CONCLUSION: The single supratentorial craniotomy for SIEDH is reliable and effective.