Morphometric assessment methods for estimation of sexual dimorphism from cranial occipital condyles / Métodos de evaluación morfométrica para la estimación del dimorfismo sexual de los cóndilos occipitales craneales

SUMMARY: Identification of fragmentary human remains is an integral par of medico legal investigations. Occipital region is commonly not affected in traumatic injuries and accidents due to its secluded position which makes it the integral part in determination of sex in the absence of entire skeleton. Occipital condylar region is also the most common area for degenerative and neoplastic diseases. So thorough knowledge of anatomy of occipital condyle is very essential during surgical interventions. 86 skulls were studied from osteological collections of Department of Anatomy, Yenepoya Medical College. Maximum length and breadth of the occipital condyle, anterior intercondylar distance and posterior intercondylar distance was measured with the help of vernier callipers. Descriptive statistics was calculated for the parameters considered. Metric data of right and left sides were compared with student t test and p value was calculated.All data obtained was subjected for discriminant function analysis to derive the statistical model. All the measurements were significantly high in males compared to females. Condylar length and width, anterior and posterior intercondylar distance can be used to derive formula for determination of sex in south Indian population with an accuracy of 66.3 %.

RESUMEN: La identificación de restos humanos fragmentarios es una parte integral de las investigaciones médico legales. La región occipital comúnmente no se ve afectada en lesiones traumáticas y accidentes debido a su posición apartada que la convierte en parte integral en la determinación del sexo en ausencia de un esqueleto completo. La región condilar occipital es también el área más común de enfermedades degenerativas y neoplásicas. Por lo tanto, el conocimiento integral de la anatomía del cóndilo occipital es esencial durante las intervenciones quirúrgicas. Se estudiaron 86 cráneos de colecciones osteológicas del Departamento de Anatomía, Facultad de Medicina de Yenepoya. Se midió el largo y ancho máximo del cóndilo occipital, la distancia intercondilar anterior y la distancia intercondilar posterior con la ayuda de un calibrador vernier. Se calculó la estadística descriptiva para los parámetros considerados. Los datos métricos de los lados derecho e izquierdo se compararon con la prueba t de Student y se calculó el valor de p. Todos los datos obtenidos se sometieron a análisis de función discriminante para derivar el modelo estadístico. Todas las medidas fueron significativamente altas en los hombres en comparación con las mujeres. La longitud y el ancho del cóndilo, la distancia intercondilar anterior y posterior se pueden utilizar para derivar la fórmula para determinar el sexo en la población del sur de la India con una precisión del 66,3 %.

Three￣dimensional digital measurement of occipital condyle and foramen magnum in Inner Mongolia / 解剖学报

Objective To measure the anatomical structure of the occipital condyle (OC) and the occipital foramen (FM) by three-dimensional reconstruction, and to analyze the morphological characteristics and relative positional relationship of the occipital condyle and occipital foramen, in order to provide anatomical parameters for the imaging diagnosis of the craniocervical junction and the choice of surgical approach. Methods Sixty normal subjects were selected with CT scans of the skull and upper cervical spine, including 30 males and 30 females, aged 20-65 (48. 18±16. 17) years old. The data were imported into the Syngo.via VB10B software, and the skull was reconstructed in three dimensions. To observe the shape of the occipital condyle and occipital foramen, and to measure the occipital condyle length, width, height, condyle inclination angle(CIA), longitudinal diameter, transverse diameter, area of the occipital foramen, the maximum distance between the cranial eyebrow and the posterior cranial point (SML), the crimson eyebrow on the SML line, the distance from the interpoint to the posterior margin of the occipital condyle (GOCP), the vertical distance between the anterior edge of the occipital foramen to the posterior margin of the occipital condyle (AOCP), and the distance from the medial margin of the left and right occipital condyles to the Y axis (OC-M), left and right occipital condyle posterior margin to X axis distance (OC-P); occipital condyle classification index (OCI), occipital condyle relative index of head (SOCI), midpoint on the SML straight line to the occipital condyle Marginal connection distance (COCP,COCP =GOCP-SML/ 2), and determine the type of relative positional relationship between left and right occipital condyles. Results The differences in anatomical length, width and height of the occipital condyle were statistically significant (P<0. 05), and men were larger than women; the occipital foramen area, longitudinal diameter of the occipital foramen, SML, GOCP, AOCP had statistical differences (P<0. 05). The lateral differences of occipital condyle inclination were statistically significant (P<0. 05), and the left side was greater than the right side. The differences in OC-M and OC-P sides were statistically significant (P<0. 05). The former was larger on the right than on the left; the latter was larger on the left than on the right. The longitudinal diameter of the occipital foramen was positively correlated with the area of the occipital foramen and AOCP; OCI classification result were as follows: typeⅠ(OCI<0. 45) had 8 cases (13. 33%), type Ⅱ (0. 45≤OCI<0. 50) had 47 cases (78. 33%), type Ⅲ (OCI≥0. 50) had 5 cases (8. 33%). SOCI classification result were as follows: type Ⅰ (SOCI< 0. 60) had 2 cases (3. 33%), type Ⅱ (0. 60≤SOCI<0. 75) had 54 cases (90. 00%), type Ⅲ (SOCI≥0. 75) had 4 cases (6. 67%). Conclusion The anatomical parameters of the occipital condyle in Inner Mongolia can be implanted with occipital condylar screws. The position of the occipital condyle relative to the foramen magnum and the skull is highly variable.

Morphometric Analysis Of The Occipital Condyles And Their Correlation With Hypoglossal Canal In Dry Skulls Of South Indians

Background: Morphometric analysis of the occipital condyles is essential for craniovertebral junction surgeries.There are no studies done yet on correlation of hypoglossal canal and occipital condyle, therefore the presentstudy is carried out to find differences of parameters of OC in different races and to find out the correlation ofvarious parameters of occipital condyle with orifices of hypoglossal canal.Method: The size, shape and anterior, posterior inter condylar distances of occipital condyles and the locationsof the extracranial and intracranial orifices of the 108 hypoglossal canal were studied in 55 dry skulls.Result: The Mean length, height, width were 21.64±2.97, 11.06±2.2, 6.15±1.44 respectively.Anterior, posteriorinter condylar distances mean were ranged between 13.30-32.93 and 21.46– 46.77 respectively and most commonshape of occipital condyles was oval. Location of hypoglossal canal extra cranially was 3,whereas intra craniallyit was 4 for both right and left sides. There was strong correlation between length of occipital condyle and widthbut the same was not with location of hypoglossal canal.Conclusion: The measurements of occipital condyles were found to have some similarities and some dissimilariesamong different races. These differences could be useful for anthropometric analysis and forensic sciencesstudies. Significant correlation was found between length and width, width and height, height and length.However no correlation could be found between various parameters of occipital condyle and orifices of hypoglossalcanal.

Morphometry And Morphology Of Occipital Condyle Related To The Transcondylar Approach In Dry Skulls

Introduction: The occipital condyles are small, bilateral inferior extensions of the occipital bones. They areintimately related to the foramen magnum and skull base by a number of ligamentous attachments. A variety ofdisease processes may affect the craniovertebral junction. Various lateral approaches have been used to accessthese lesions. Understanding the bony anatomy and variations of occipital condyle is important for theseapproaches. The aim of the present study is to study occipital condyle in detail.Materials and methods: 120 dry human skulls (83 males, 37 females) were studied. The length, width anddifferent shapes of occipital condyle were noted. Various other parameters were measured like anteriorintercondylar distance, posterior intercondylar distance, distance between anterior and posterior end of occipitalcondyle and opisthion.Results: The mean value of occipital condyle length (2.32cm(M) vs 2.22cm(F)) and width (1.29cm(M) vs 1.26cm(F))were present in male and female skulls. The anterior intercondylar distance and posterior intercondylar distanceswere 2.06cm and 4.14cm respectively. Shape of occipital condyle was classified into different types as followingoval, kidney, s shaped, figure of eight, two portioned and deformed. The most common shape of occipital condylewas oval on both sides in males and females.Conclusions: Thorough knowledge of occipital condyle will enable the neurosurgeons to have safe surgery andreduce the morbidity to minimum

Comparison of Occipital Condyle Morphometry in Various Populations with Respect to Skull Base Surgery

Background: The craniovertebral junction is made up of the occiput, upper two cervical vertebrae. Occipital condyle is one the landmarks on the skull base. Morphometric values of these condyles in a specific population is to be known by surgeons to deal with pathologies affecting the cranial base without disturbing the neurovascular structures by doing appropriate condylectomy and to ensure occipito-cervical fusion in case of instability. Methods: The study was performed by comparing the morphometric values of occipital condyles with other populations (Greek, Turkish, Korean, Chinese, American, European and Indian). The data regarding the morphometric values of occipital condyles was taken from our previously published article with a sample of hundred occipital condyles of unsexed dry human skulls of unknown age and compared with the studies of other population. The measurements compared were the length, breadth and thickness of the occipital condyle, intercondylar distance in anterior, middle and posterior parts of the occipital condyles, the angle of the occipital condyle to the sagittal plane and coronal planes and shape of the occipital condyles. Results: Most of the morphometric values of OC in South Indian were lesser than the other populations like breadth, thickness,anterior intercondylar distance, posterior intercondylar distance, angle of the occipital condyle to the sagittal plane. Conclusion: This information has to borne in mind while performing surgical procedures like occipito-cervical screw fixation, condylar drilling in cranial base surgery in South Indian population.

Morphological Analysis on the Occipital Condyles and Review of the Literature / Análisis Morfológico de los Cóndilos Occipitales y Revisión de la Literatura

Most anatomical and biomechanical studies on the craniovertebral junction have involved morphological or morphometric analysis on the occipital condyles. Some of these studies have provided important findings based on different surgical procedures. The shape, size and angle of the occipital condyles and the locations of the intracranial and extracranial orifices of the hypoglossal canal are highly important because they may affect the lateral approaches to the craniovertebral junction. To determine the frequency of occurrence of different morphological types of occipital condyle. 214 occipital condyles in 107 dry human skulls were analyzed and the classification of their morphological types was determined through assessing digitized photographic images. Among the 107 skulls analyzed, 59.8 % were male and 40.2 % were female. Their ages ranged from 11 to 91 years, with a mean of 57.56 years. Of the total of 10 morphological types of occipital condyle that were found, more than 50 % were of the "8", "S" and ring types. Condyles of "8" and "S" shape were the main types found in male skulls: the "8" shape prevailed on the left side and the "S" shape on the right side. However, in female skulls, these two types had equal bilateral distribution.

La mayor parte de los estudios anatómicos y biomecánicos de la unión cráneo-vertebral han sido realizados sobre el análisis morfológico o de la morfometría de los cóndilos occipitales. Algunos de estos trabajos tienen previsto importantes hallazgos basados en diferentes procedimientos quirúrgicos. De tal forma, el tamaño y ángulo del cóndilo occipital bien como su localización de los orificios intracraneales y extracraneales del canal hipogloso son de gran importancia, ya que pueden afectar a los enfoques laterales de la unión cráneo-vertebral. El objetivo del estudio fue determinar la prevalencia de los tipos morfológicos de cóndilos occipitales. Fueron analizados 214 cóndilos de 107 cráneos secos de humanos y la clasificación de los tipos morfológicos fue determinada a partir de los análisis de estudio de imágenes fotográficas digitalizadas. De los 107 cráneos que fueron analizados, 59,8 % eran de sexo masculino y 40,2 % de sexo femenino, cuyas edades comprendidas entre 11 y 91 años con una media de 57.56 años. De un total de 10 tipos morfológicos de los cóndilos occipitales encontrados, más del 50 % eran de tipo ocho, S y anillo. Los cóndilos en forma de "8" y "S" fueron los principales tipos encontrados, en el sexo masculino, la forma en "8" prevaleció en el lado izquierdo, y el tipo morfológico en "S", en el lado derecho del cráneo. Mientras que en el sexo femenino esos dos tipos tuvieron una equitativa distribución bilateral.

Computed Tomography-Based Occipital Condyle Morphometry in an Indian Population to Assess the Feasibility of Condylar Screws for Occipitocervical Fusion

STUDY DESIGN: A retrospective computed tomography (CT)-based morphometric study of 82 occipital condyles in the Indian population, focusing on critical morphometric dimensions with relation to placing condylar screws. PURPOSE: This study focused on determining the feasibility of placing occipital condylar screws in an Indian population using CT anatomical morphometric data. OVERVIEW OF LITERATURE: The occipital condylar screw is a novel technique being explored as one of the options in occipitocervical stabilization. Sex and ethnic variations in anatomical structures may restrict the feasibility of this technique in some populations. To the best of our knowledge, there are no CT-based data on an Indian population that assess the feasibility of occipital condylar screws. METHODS: We measured the dimensions of 82 occipital condyles in 41 adults on coronal, sagittal, and axial reconstructed CT images. The differences were noted between the right and left sides and also between males and females. Statistical analysis was performed using the t-test, with a p-value of < 0.05 considered significant. RESULTS: Mean sagittal length and height were 17.2±1.7 mm and 9.1±1.5 mm, respectively. Mean condylar angle/screw angle was 38.0°±5.5° from midline, with mean condylar length and width of 19.6±2.6 mm and 9.5±1.0 mm, respectively. Average coronal height on the anterior and posterior hypoglossal canal was 10.8±1.4 mm and 9.0±1.4 mm, respectively. The values in females were significantly lower than those in males, except for screw angle and condylar width. Based on Lin et al.'s proposed criteria, eight of 82 condyles were not suitable for condylar screws. CONCLUSIONS: Preliminary CT morphometry data of the occipital condyle shows that condylar screws are anatomically feasible in a large portion of the Indian population. However, because a small number of population may not be suitable for this technique, meticulous study of preoperative anatomy using detailed CT data is advised.

Occipital Condyle Fractures in Traumatic Brain Injury­A Review / Fraturas de côndilo occipital no trauma cranioencefálico ­ uma revisão

É bem estabelecido que o diagnóstico da fratura de côndilo occipital tem aumentado nas últimas décadas, provavelmente devido à disponibilidade e ao uso comum da tomografia computadorizada durante a investigação do trauma craniano, além da maior gravidade dos mecanismos de trauma. Por causa da baixa especificidade da apresentação clínica, e também pelo pouco conhecimento sobre o mecanismo de lesão, o diagnóstico desta condição é um desafio para neurocirurgiões. A abordagem terapêutica destes pacientes é baseada em estudos com baixa casuística e em relatos de caso. Uma revisão sobre este tema foi realizada a fim de discutir alguns aspectos controversos sobre o manejo da fratura de côndilo occipital. As fraturas de côndilo occipital são eventos raros, entretanto podem relacionar-se à alta morbidade em pacientes que sofreram trauma encefálico. Alguns sintomas, como intensa dor cervical, podem estar associados com esta fratura; portanto, paciente com suspeita de fratura de côndilo occipital deve ser submetido a investigação radiológica detalhada da região. O diagnóstico precoce desta fratura permite investigação apropriada, minimizando a chance de sequelas.

It is well established that diagnoses of occipital condyle fracture have increased in past decades, probably because of the availability and common use of computed tomography for investigating traumatic brain injuries, as well as themajor seriousness of trauma mechanism. Because of the low specificity of clinical presentation besides the lesion mechanism not well known, this condition is a diagnostic challenge for neurosurgeons. Therapeutic approaches of these patients are based on studies with low samples and case reports. A review of this theme was performed objecting to discuss some controversial topics about management of occipital condyle fracture. The occipital condyle fracture is a rare event, and it, however, could be related to high morbidity in patients who suffered traumatic brain injury. Some symptoms such as severe neck pain are related with this fracture, and thus patients suspicious of this fracture should undergo detailed radiologic investigation of this region. Early diagnosis of this fracture allows appropriate investigation, thus minimizing the risk of sequelae.

Non-operative management of occipital condyle frature: report of three cases and literature review

Occipital condyle fractures (OCF) had been difficult to diagnose, but the widespread use of computed tomography (CT) as a diagnostic tool in patients with significant cranio-cervical injury has led to increased recognition of this injury. The incidence of OCF in severely injured blunt trauma patients is estimated at 0.1 - 4.4 percent and as high as 16 percent overall when less severely injured patients are included. OCFs are important because they may be associated with instability of the occipito-atlanto-axial joint complex and there is wide variability in the clinical presentation of individuals with an OCF. This cranio-cervical injury may result in increased morbidity associated with long-term cranio-cervical pain and reduced neck mobility. Patient outcomes tend to reflect the severity of additional injuries rather than independent OCF pathology. We described three OCF cases with severe traumatic brain injury, treated without surgery with favorable outcome and we performed a literature review.

Radiological and anatomical study of posterior occipital condyle screw trajectory / 中华创伤杂志

Objective To investigate the optimal trajectory of posterior occipital condyle screw fixation via radiological and anatomical study.Methods Twelve adult craniocervical junction complete specimens were selected.The length,width and height of occipital condyle and the inclination angle of the longest axis were measured by CT scanning and reconstruction.Subsequently,occipital condyle screws were inserted with reference to CT measurements.After screw fixation,accuracy and safety of the placement of occipital condyle screw were verified by gross observation and CT scanning.Results Preoperative measurements of height and width of the occipital condyles indicated the placement of 4.0 mm bicortical screws was secure.Left vertebral artery horizontal sections of 2 specimens were slightly pressed without damage.CT scanning identified no damage to the inner or outer wall of the occipital condyle and the hypoglossal canal.Trajectory parameters between the right and left sides were slightly different,but no significant difference was observed (P ＞ 0.05).Average screw channel length and inclination angle were (20.8 ±2.6)mm and (37.1 ± 4.7)°respectively.Angle between screw and skull base tangent was observed as (8.5 ± 1.7) °.Distance between screw axis and hypoglossal canal was observed as (3.1 ± 1.1) mm.And the distance averaged (4.6 ± 1.4) mm between occipital condyle screw entry point and skull base and (6.1 ± 1.5) mm between entry point and inside edge of the occipital condyle.Conclusion Occipital condyle can be used as a new alternative fixed point in occipitocervical fusion.

Occipital Condyle Fracture With Isolated Unilateral Hypoglossal Nerve Palsy

Occipital condyle fractures (OCFs) with selective involvement of the hypoglossal canal are rare. OCFs usually occur after major trauma and combine multiple fractures. We describe a 38-year-old man who presented with neck pain and a tongue deviation to the right side after a traffic accident. Severe limitations were detected during active and passive range of neck motion in all directions. A physical examination revealed a normal gag reflex and normal mobility of the palate, larynx, and shoulder girdle. He had normal taste and general sensation in his tongue. However, he presented with a tongue deviation to the right side on protrusion. A videofluoroscopic swallowing study revealed piecemeal deglutition due to decreased tongue mobility but no aspiration of food. Plain X-ray film findings were negative, but a computed tomography study with coronal reconstruction demonstrated a right OCF involving the hypoglossal canal. An electrodiagnostic study revealed evidence of right hypoglossal nerve palsy. We report a rare case of isolated hypoglossal nerve palsy caused by an OCF.

Morphometric analysis related to the transcondylar approach in dry skulls and computed tomography / Análisis morfométrico del acesso transcondilar en cráneos secos y en tomografia computarizada

The transcondylar approach (TA) has been used in surgeries to access lesions in areas close to the foramen magnum (FM) and is performed directly through the occipital condyle (OC) or through the atlanto-occipital joint and adjacent portions of the same. The objective of this study is to examine anatomical variations related to the TA by morphometric parameters of the FM, OC and of the hypoglossal canal (HC) in dry skulls and in computed tomography (CT). In 111 skulls, characteristics of the HC, and measures related to the FM, the HC and to the OC were examined. In CT, the measurements obtained bilaterally in 10 patients who underwent examination of the skull base in 1 mm-thick axial helical cuts were the distances from the outer half of the clivus to the opening of the HC; from the lower portion of the OC to the middle of HC; from the inner half of the clivus to the intracranial opening of the HC and to the midpoint of the HC; from the HC extracranial opening to the lower portion of the OC and to the outer half of the clivus. The results of CT measurements are consistent to previous studies of morphometric variations related to the TA, with no significant difference between the measurements obtained in the right and in the left sides, or related to gender. The data obtained by three-dimensional CT images are important in assessing the morphometric variations of pre-surgical patientsof TA.

El acceso transcondilar (AT)ha sido utilizado comoun procedimiento quirúrgico para lesiones cercanas al foramen magnum(FM)y se realizadirectamente a través delcóndilooccipital (CO)o por medio delas porciones atlanto-occipitalconjuntay adyacentesde lamisma.El objetivo del presenteestudio fue examinarlas variaciones anatómicas relacionadas con el AT mediantelos parámetros morfométricos del FM, CO y el canal delhipogloso (CH) en cráneossecos y tomografía computadorizada (CT). En 111 cráneos fueron examinadas las característicasdel CH y tomadas medidas relacionadas con el FM, CO y CH. En la CT, las mediciones se obtuvieron de forma bilateral en10 pacientes que se sometieron a exámen de la base del cráneo en corte axial helicoidal de 1mm de espesor. Las medidas tomadas fueron las distancias: de la mitad exterior del clivus a la apertura del CH; de la parte inferior de las emisiones de CO a la mitad del CH; de la mitad interna del clivus a la apertura intracraneal del CH y hasta el punto medio del CH; de la apertura extracraneal del CH a la parte inferior de las emisiones de CO y hasta la mitad exterior del clivus. Los resultados de las mediciones de CT son consistentes con estudios prévios de los cambios morfométricos en relación con AT, sin diferencia significativa entre las mediciones obtenidas en el lado derecho e izquierdo y ni en relación con el sexo. Los datos obtenidos a través de imágenes en tres dimensiones de CT son importantes para evaluarlas variaciones morfométricas de pre-quirúrgicos en el AT.

Traumatic retroclival epidural hematoma and unilateral occipital condylar fracture in an adult patient

Retroclival epidural hematoma is rare, with fewer than 30 cases reported in the literature. Almost all of the previously reported cases occurred in children, with only a few cases affecting adults. Among these adult patients, only two suffered from the associated occipital condyle fracture (OCF), which is another rare injury. The patient involved in this study suffered from retroclival epidural hematoma and unilateral occipital condyle fracture, as demonstrated on both CT and MRI scans. The patient also suffered from an associated right brachial plexus injury without any other neurological deficits, a condition that has not previously been reported. This paper reviews the underlying mechanisms of these rare injuries and seeks to form an understanding of them before proposing the mechanism of injury in the patient involved in the study

Traumatic Atlanto-occipital Dislocation (AOD)

OBJECTIVE: Traumatic atlanto-occipital dislocation (AOD) results from high energy trauma and is an uncommon and usually fatal injury due to an injury to the cervicomedullary junction. Recently, improved prehospital management, early diagnosis and effective treatment led to increasing reports of survival. This study of patients with AOD initial imaging modalities recognizes the clinical features and diagnostic considerations for a quick diagnosis. METHODS: In this article, five survived adult patients with traumatic AOD are presented and retrospectively reviewed. Diagnosis was made by lateral cervical spine x-ray, cervical computed tomography (CT), or magnetic resonance imaging(MRI). Treatment consisted of early immobilization, respiratory support, and subsequent occipitocervical fusion. RESULTS: Four patients were male and the other one was female. Three were diagnosed early and the others were delayed in confirmations. One was type I AOD and four were type II AOD. All patients were applied occipitocervical fusion. Two cases were worse; neurological states and the other three that showed no change. Lateral X-ray film of all patients in the prevertebral soft tissue swelling at the C2 level was noted. The mean thickness of prevertebral soft tissue C2 level was 17.88 mm(15.18 to 20.17mm). Two were in the normal range of dens-basion index(DBI), three showed abnormalities, and Power's ratio was abnormal in 3 patients. CONCLUSION: As for damages caused by a strong external force in patients with severe prevertebral soft tissue swelling at C2 level abnormaly, the doctor determines whether more should be carefully AOD and considers 3D CT or MRI to confirm AOD in these patients.

Traumatic Atlanto-occipital Dislocation (AOD)

OBJECTIVE: Traumatic atlanto-occipital dislocation (AOD) results from high energy trauma and is an uncommon and usually fatal injury due to an injury to the cervicomedullary junction. Recently, improved prehospital management, early diagnosis and effective treatment led to increasing reports of survival. This study of patients with AOD initial imaging modalities recognizes the clinical features and diagnostic considerations for a quick diagnosis. METHODS: In this article, five survived adult patients with traumatic AOD are presented and retrospectively reviewed. Diagnosis was made by lateral cervical spine x-ray, cervical computed tomography (CT), or magnetic resonance imaging(MRI). Treatment consisted of early immobilization, respiratory support, and subsequent occipitocervical fusion. RESULTS: Four patients were male and the other one was female. Three were diagnosed early and the others were delayed in confirmations. One was type I AOD and four were type II AOD. All patients were applied occipitocervical fusion. Two cases were worse; neurological states and the other three that showed no change. Lateral X-ray film of all patients in the prevertebral soft tissue swelling at the C2 level was noted. The mean thickness of prevertebral soft tissue C2 level was 17.88 mm(15.18 to 20.17mm). Two were in the normal range of dens-basion index(DBI), three showed abnormalities, and Power's ratio was abnormal in 3 patients. CONCLUSION: As for damages caused by a strong external force in patients with severe prevertebral soft tissue swelling at C2 level abnormaly, the doctor determines whether more should be carefully AOD and considers 3D CT or MRI to confirm AOD in these patients.

A Case of Occipital Condyle Syndrome Associated with Hepatocellular Carcinoma

Occipital condyle syndrome, which consists of unilateral occipital region pain associated with ipsilateral 12th cranial nerve paresis, is a rare, but stereotypic syndrome. Herein, we report a patient with occipital condyle syndrome associated with metastasis at the skull base from the hepatocellular carcinoma.

Ventral Foramen Magnum Meningioma: Case Report

We report a case of a ventral foramen magnum meningioma in a 73-year-old woman presenting with swallowing difficulty, posterior neck pain, gaiting difficulty, progressive motor and sensory deficits in all extemities, and intrinsic muscle atrophy in both hands. Magnetic resonace imaging revealed a huge mass, 4x4x4.5cm in size, located in anterior foramen magnum. We removed the mass by partial condylectomy via far lateral transcondylar approach without neurological deficit and postoperative craniovertebral instability.

Microsurgical anatomy on the design of the far-lateral supracondylar keyhole approach / 中华显微外科杂志

Objective To explore the posibility of removing the jugular tubercle precisely and design a new far-lateral supraeondylar keyhole approach based on keyhole idea.Methods Eight cadaveric heads fixed by 10% formalin and perfused intracranial vessels with colored silicone were used in this study.Before the operation,navigation data of these cadaveric heads were established and circumscriptions of jugular tuber- cle were outlined in the navigation system in order to aid drilling it in operation.A 7cm longitudinal“S”shaped skin incision as we reported was performed.After inverting suboccipital muscles and exposing the far lateral of the occipital bone,occipital condyle,jugular tubercle,hemilamina of C_1,vertebral artery and pos- terolateral portion of foramen magnum,a 3cm retro-condylar bone window was made.Under the microscope, anatomic structures were observed and important structures were measured after jugular tubercle removal assis- ted by neuro-navigation.Results The 7cm longitudinal“S”shaped skin incision with its superior border 2cm behind the middle point of mastoid and inferior margin at the level of C_2 can fully meet the needs of the far-lateral supracondylar keyhole approach;jugular tubercle can be drilled satisfactorily with the help of neuro- navigation;inferior segment of basilar artery[long(15.65?1.34)mm]and anterior inferior cerebellar artery [long(20.36?4.18)mm] can be exposed.Conchlsion Owing to the area of middle clivus is increasingly exposed after removal of jugular tubercle,it is feasible to perform the far-lateral supracondylar keyhole ap- proach on the operations of vertebral-basilar artery aneurysm,anterior inferior cerebellar artery aneurysm and tumor located inferior and middle clivi or jugular foramen.

Delayed Hypoglossal Nerve Palsy Following Fracture of the Occipital Condyle: Case Report

Fracture of the occipital condyle is rare. We report the case of a patient with this fracture who presented with negative plain films and delayed hypoglossal nerve palsy. Diagnosis was estabilished with high resolution computed tomography. In a trauma patient with neck or occipital pain, with or without cranial nerve palsy, this fracture should be considered, even if a plain radiograph is negative.

Fracture of the OccipitalvCondyle Associated with Lower Cranial Nerve Palsy

We describe the case of a 59-year-old man whose occipital condyle was fractured in a traffic accident, resulting in severe neck pain and blurred vision. Neurological examination revealed palsy of the right side sixth cranial and ipsilateral lower cranial nerve. In fracture of the occipital condyle, persistent neck pain and lower cranial nerve palsy may be common clinical features. Conventional plain radiography may often be inadequate for the detection and evaluation of this lesion, and high-resolution CT and coronal reconstruction is the diagnostic modality of choice. The patient was treated conservatively using a Philadelphia collar, and this led to excellent clinical improvement. To demonstrate this rare form of traumatic lesion in patients with sustained post-traumatic neck pain and lower cranial nerve palsy, the authors recommend CT of the craniocervical junction.