BACKGROUND: In recent years some reports have been published propagating microsurgical resection of ventral foramen magnum meningiomas (VFMMs). Operative approaches to these lesions have been studied by various author...BACKGROUND: In recent years some reports have been published propagating microsurgical resection of ventral foramen magnum meningiomas (VFMMs). Operative approaches to these lesions have been studied by various authors, but remain controversial. OBJECTIVE: To discuss the operative technique and outcome in patients with VFMMs who had been treated via a far lateral suboccipital approach. DESIGN: Retrospectively clinic case investigation. SETTING: Department of Neurosurgery, the Ninth People's Hospital, Medical School of Shanghai Jiao Tong University. PARTICIPANTS: Between January 1997 and June 2003, 10 patients were treated surgically with VFMMs in Department of Neurosurgery, the Ninth People's Hospital, Medical School of Shanghai Jiao Tong University. In the series of 10 patients, ages ranged from 37 to 72 years, mean (53±10) years, were consisted of 6 males and 4 females. All the subjects were informed of the treatment plan and agreed to join the experiment. Early symptoms included headache and upper cervical pain. The time between the first occurrence of symptoms and the diagnosis ranged from 6 months to 17 months, mean (10.3±3.4) months. Main presenting symptoms were unilateral upper extremity sensory and motor deficits in 6 cases, swallowing difficulties in 2 and spastic quadriparesis in 2. VFMMs were demonstrated as round by the computed tomographic (CT) scan and magnetic resonance imaging (MRI) in all patients. The maximum diameter of tumors ranged from 2 to 4 cm, mean (2.55±0.57) cm, including 2 cm in one case, 2.0-3.0 cm in six and 3.0-4.0 cm in three. METHODS: ①All tumors were removed via the far lateral suboccipital approach. Resection of the posterior 5 mm of the condyle was necessary in one patient whose tumors' diameter were 2 cm. The patient was situated in the lateral decubitus position. The head was fixed in a Mayfield headrest. A C-shaped incision made behind the ear 2 cm medial to the mastoid process, turning vertically down to the level C4, to expose the extradural segment of the vertebral artery (VA). After the dura was opened longitudinally behind VA entry point, the tumor was revealed to identify the complete cranial nerves and the intracranial VA under magnification of the surgical microscope. Every attempt should be made to keep the arachnoid and the dentate ligament was sectioned. Then the tumor was debulked significantly, and dissected away from the cranial nerves and the blood vessels with microsurgical techniques. If it was risk to dissect tumor from the vertebral artery, its branches, or any cranial nerve, the progression was discontinued and portion of the tumor was left behind. After resection of the tumor, the site of its attachment was coagulated and the involved layer of dura was resected. ②The degree of tumor resection was classified based on Al-Mefty's grade into three categories: gross-total resection: excision of the dural attachment and drilling of adjacent bone; near-total resection: a few millimeters of insulated and cauterized tumor were left on the vertebral artery or other vital; subtotal resection: more than 50% of the tumor mass were removed. ③All patients underwent clinical examination for lower cranial nerves or long tract deficits on the first day postoperatively. CT or MRI and neurological examinations were performed at 3 months of follow-up. MAIN OUTCOME MEASURES: Operative effect. RESULTS: All ten patients with VFMMs were treated via a far lateral suboccipital approach. Gross total resection was achieved in 6 patients, near-total resection was carried out in 2 and subtotal resection in 2 patients. One patients died in the postoperative period due to acute respiratory distress syndrome, five patients kept normal neurological status, whereas other four patients suffered from lower cranial nerve deficits and aspiration pneumonia was observed in two of them. The data of following up for 3 months showed that 2 patients still had lower cranial nerve deficit and others recovered from their illness. No tumor relapse or increment was found in CT or MRI scans. CONCLUSION: Most of VFMMs could be totally removed via a far lateral suboccipital approach with or without resection of the occipital condyle according to the tumor size, allowing most of these patients to achieve a good outcome in a 3 months follow-up.展开更多
Objective To investigate the methods and effectiveness to treat Chiari malformation with surgical decompression of foramen magnum under endoscope. Methods 23 cases with Chiari malformation. (withoutatlanto-axial dislo...Objective To investigate the methods and effectiveness to treat Chiari malformation with surgical decompression of foramen magnum under endoscope. Methods 23 cases with Chiari malformation. (withoutatlanto-axial dislocation and basilar invagination) diagnosed by magnetic resonance imaging(MRI) were operated with the surgical decompression for foramen magnum under the endoscope. Results 23展开更多
LIMAS and Tio1 proposed the term meningeal melanocytoma first time in 1972 to describe a primary melanotic tumor of the leptomeninges with prolonged clinical course and benign histology.Meningeal melanocytoma of the c...LIMAS and Tio1 proposed the term meningeal melanocytoma first time in 1972 to describe a primary melanotic tumor of the leptomeninges with prolonged clinical course and benign histology.Meningeal melanocytoma of the central nervous system is rare and benign primary meningeal melanocytoma (PMM) is more exceptional,and also less usual than the malignant types.2 This rare tumor falls under the subclassification of primary melanocytic lesions in the World Health Organization's classification of central nervous system tumors.3 PMM located in the foramen magnum region is an unusual cause of bulbus medullae and fourth ventricle compression.Here we report a 48-year-old man with a PMM which is located in the foramen magnum inducing supratentorial obstructive hydrocephalus.展开更多
Intracranial dermoid cysts are nonneoplastic lesions that present a rare clinical entity. They account for 0.04% to 0.6% of all intracranial tumors. Such cystic lesions usually contain different ectodermal derivatives...Intracranial dermoid cysts are nonneoplastic lesions that present a rare clinical entity. They account for 0.04% to 0.6% of all intracranial tumors. Such cystic lesions usually contain different ectodermal derivatives including hairs, sebaceous glands, apocrine gland and teeth. Dermoid cysts of foramen magnum occur very rarely, with few cases reported in the literature. Computed tomography (CT) and magnetic resonance imaging (MRI) are two main diagnostic tools. Here in this paper, we described a case of intracranial (foramen magnum) dermoid cyst presented with neurologic deficits that completely removed surgically.展开更多
Background To investigate the classification and microsurgical treatment of foramen magnum meningioma(FMM).Methods We retrospectively analyzed 76 patients with FMM and classified them into two classifications,classifi...Background To investigate the classification and microsurgical treatment of foramen magnum meningioma(FMM).Methods We retrospectively analyzed 76 patients with FMM and classified them into two classifications,classification ABS according to the relationship between the FMM and the brainstem and classification SIM according to the relationship between the FMM and the vertebral artery(VA).All patients underwent either the far lateral approach(54 cases)or the suboccipital midline approach(22 cases).Results Of the 76 cases,47 cases were located ahead of the brainstem(A),16 cases at the back of the brainstem(B),and 13 cases were located laterally to the brainstem(S).There were 15 cases located superior to the VA(S),49 cases were inferior(I),and 12 cases were mixed type(M).Among 76 cases,71 cases were resected with Simpson grade 2(93.42%),3 with Simpson grade 3(3.95%),and 2 with Simpson grade 4(2.63%).We summarized four anatomical triangles:triangles SOT,VOT,JVV,and TVV.The mean postoperative Karnofsky performance score was improved in all patients(p<0.05).However,several complications occurred,including hoarseness and CSF leak.Conclusion ABS and SIM classifications are objective indices for choosing the surgical approach and predicting the difficulty of FMMs,and it is of great importance to master the content,position relationship with the tumor,and variable anatomical structures in the four"triangles"for the success of the operation.展开更多
The foramen magnum (FM), being a vital landmark at the base of the skull, includes interests to many fields of medicine. Many authors haverecounted the usefulness of the FM in gender determination. The emphasis of thi...The foramen magnum (FM), being a vital landmark at the base of the skull, includes interests to many fields of medicine. Many authors haverecounted the usefulness of the FM in gender determination. The emphasis of this study is to evaluate the shape and dimensions of the FM among males and females and to establish its role in sexual dimorphism using cone-beam computed tomography (CBCT). Furthermore, to evaluate the area and FM index (FMI) among males and females and finally to evaluate the differences in FM measurements if any in twodifferent regions of an Indian population. One hundred and ten CBCT scans (55 males and 55 females;age range, 20–80 years) were selectedfor this study. The sagittal diameter, transverse diameter, area, FMI, and circumference of FM were measured, and data were subjected to discriminant analysis for the evaluation of sexual dimorphism. The area of FM was the best discriminant parameter which was used to study the sexual dimorphism with an overall accuracy of 90.9%. It can be concluded that the reconstructed CBCT image provides valuable measurements for the FM and could be used for gender determination.展开更多
Background:Radiological imaging plays a pivotal role in forensic anthropology.As have the imaging techniques advances,so have the digital skeletal measurements inched towards precision.Secular trends of the population...Background:Radiological imaging plays a pivotal role in forensic anthropology.As have the imaging techniques advances,so have the digital skeletal measurements inched towards precision.Secular trends of the population keep on changing in modem times.Hence,finding the precise technique of bone measurement,with greater reproducibility,in modem population is always needed in making population specific biological profile.Aim and Objective:The aim of this study was to estimate the accuracy of the foramen magnum measurement,obtained by three dimensional multi-detector computed tomography using volume rendering technique with the cut off value of each variable,in sex determination of an individual.Materials and Methods:Two metric traits,an antero-posterior diameter(APD)and transverse diameter(TD),were measured digitally in an analysis of 130 radiological images having equal proportion of male and female samples.Foramen magnum index and area of foramen magnum(Area by Radinsky's[AR],Area by Teixeira5s[AT])were derived from APD and TD.Results:Descriptive statistical analysis,using unpaired t-test,showed significant higher value in males in all the variables.Using Pearson correlation analysis,maximum correlation was observed between area(AT and AR r=0.999)and between area and TD(AR r=0.955 and AT r=0.945 respectively).When used individually,TD had the highest predictive value(67.7%)for sex detennination among all the parameters followed by AT(65.4%)and AR(64.6%).Cutoff value of variables TD,AR and AT were 29.9 mm,841.80 mm2 and 849.70 mm2 respectively.Receiver operating characteristic curve predicted male and female sex with 96.2%and 89.2%accuracy respectively.The overall accuracy of the model was 92.7%.Conclusion:Measurements from 3D CT using volume rendering technique were precise,and the application of logistic regression analysis predicted the sex with more accuracy.展开更多
Background:Sexual dimorphism of the foramen magnum has increased its interest in forensic science.Gender determination is an important preliminary step in the identification of unknown skeletal remains.This study aime...Background:Sexual dimorphism of the foramen magnum has increased its interest in forensic science.Gender determination is an important preliminary step in the identification of unknown skeletal remains.This study aimed at determining the dimensions of the foramen magnum in Delta State Nigeria and their role in gender discrimination.Materials and Methods:We retrospectively analyzed computed tomographic images of336 patients(199 males and 137 females)aged>18 years,archived in the Radiology Department of a Teaching Hospital in Nigeria.Ethical approval was granted by the hospitaFs ethical board.The length,width,and area of the foramen magnum were measured and analyzed using the Statistical Package for the Social Sciences software version 23.We used an independent Mest and analysis of variance to evaluate the association of these dimensions with sex and age,respectively.The percentage accuracy of sex discrimination and the association between variables were assessed using discriminant functional analysis and Pearson's correlation test correspondingly.The results were considered significant at P<0.05.Results:The foramen magnum length,width,and area showed a statistically significant gender difference(P<0.05).The width was the best sex discriminating variable(64.3%)and the overall accuracy of correct sex allocation using all the variables was 75%.All the parameters measured showed a significant strong positive correlation with each other(0.5<r<1,P<0.05).Conclusion:The foramen magnum length width and area were sexually dimorphic.Their high overall accuracy(75%)in gender discrimination implies that they may collectively be utilized in the sex estimation of unknown skulls in Delta State Nigeria.展开更多
Background:sex identification by morphological assessment of various bones of the skeleton had been one of the oldest approaches in forensic anthropology and medico-legal cases.Aim and Objective:The aim of this study ...Background:sex identification by morphological assessment of various bones of the skeleton had been one of the oldest approaches in forensic anthropology and medico-legal cases.Aim and Objective:The aim of this study was to make the morphometric measurements of the foramen magnum in determining the feasibility of sex determination using computed tomography(CT).Materials and Methods:The data for our study was obtained from 100 patients having CT scan of the head and neck region(Siemens Somatom 256 slice CT scanner)with 1mm contiguous axial scans using bone window settings(2000 HU with 400 HU in centre),scan time of one second and exposure parameters 140 kVp and 70mA.The different measurements taken include the antero-posterior(AP)diameter,transverse diameter and area of the foramen magnum.Results:There were 50 males and 50 females with the age range of 18 to 75 years.Males have a higher average value than females in all of the parameters measured on foramen magnum.By using Studenfs T-test,all the measured parameters showed significant difference between the sexes(p<0.01).Conclusion:The expression of sexual dimorphism in the foramen magnum region shows significant difference between the sexes,therefore this area of the skull should be considered a useful area in the identification of sex.展开更多
Objective To explore classification and surgical approach of magnum foramen tumor. Methods A retrospective analysis was performed for 43 surgically treated patients with tumors involving foramen magnum. According to t...Objective To explore classification and surgical approach of magnum foramen tumor. Methods A retrospective analysis was performed for 43 surgically treated patients with tumors involving foramen magnum. According to the site of tumor,the classification was divided into:Type Ⅰ,located at dorsal,Ⅰ a extra-medullary,展开更多
文摘BACKGROUND: In recent years some reports have been published propagating microsurgical resection of ventral foramen magnum meningiomas (VFMMs). Operative approaches to these lesions have been studied by various authors, but remain controversial. OBJECTIVE: To discuss the operative technique and outcome in patients with VFMMs who had been treated via a far lateral suboccipital approach. DESIGN: Retrospectively clinic case investigation. SETTING: Department of Neurosurgery, the Ninth People's Hospital, Medical School of Shanghai Jiao Tong University. PARTICIPANTS: Between January 1997 and June 2003, 10 patients were treated surgically with VFMMs in Department of Neurosurgery, the Ninth People's Hospital, Medical School of Shanghai Jiao Tong University. In the series of 10 patients, ages ranged from 37 to 72 years, mean (53±10) years, were consisted of 6 males and 4 females. All the subjects were informed of the treatment plan and agreed to join the experiment. Early symptoms included headache and upper cervical pain. The time between the first occurrence of symptoms and the diagnosis ranged from 6 months to 17 months, mean (10.3±3.4) months. Main presenting symptoms were unilateral upper extremity sensory and motor deficits in 6 cases, swallowing difficulties in 2 and spastic quadriparesis in 2. VFMMs were demonstrated as round by the computed tomographic (CT) scan and magnetic resonance imaging (MRI) in all patients. The maximum diameter of tumors ranged from 2 to 4 cm, mean (2.55±0.57) cm, including 2 cm in one case, 2.0-3.0 cm in six and 3.0-4.0 cm in three. METHODS: ①All tumors were removed via the far lateral suboccipital approach. Resection of the posterior 5 mm of the condyle was necessary in one patient whose tumors' diameter were 2 cm. The patient was situated in the lateral decubitus position. The head was fixed in a Mayfield headrest. A C-shaped incision made behind the ear 2 cm medial to the mastoid process, turning vertically down to the level C4, to expose the extradural segment of the vertebral artery (VA). After the dura was opened longitudinally behind VA entry point, the tumor was revealed to identify the complete cranial nerves and the intracranial VA under magnification of the surgical microscope. Every attempt should be made to keep the arachnoid and the dentate ligament was sectioned. Then the tumor was debulked significantly, and dissected away from the cranial nerves and the blood vessels with microsurgical techniques. If it was risk to dissect tumor from the vertebral artery, its branches, or any cranial nerve, the progression was discontinued and portion of the tumor was left behind. After resection of the tumor, the site of its attachment was coagulated and the involved layer of dura was resected. ②The degree of tumor resection was classified based on Al-Mefty's grade into three categories: gross-total resection: excision of the dural attachment and drilling of adjacent bone; near-total resection: a few millimeters of insulated and cauterized tumor were left on the vertebral artery or other vital; subtotal resection: more than 50% of the tumor mass were removed. ③All patients underwent clinical examination for lower cranial nerves or long tract deficits on the first day postoperatively. CT or MRI and neurological examinations were performed at 3 months of follow-up. MAIN OUTCOME MEASURES: Operative effect. RESULTS: All ten patients with VFMMs were treated via a far lateral suboccipital approach. Gross total resection was achieved in 6 patients, near-total resection was carried out in 2 and subtotal resection in 2 patients. One patients died in the postoperative period due to acute respiratory distress syndrome, five patients kept normal neurological status, whereas other four patients suffered from lower cranial nerve deficits and aspiration pneumonia was observed in two of them. The data of following up for 3 months showed that 2 patients still had lower cranial nerve deficit and others recovered from their illness. No tumor relapse or increment was found in CT or MRI scans. CONCLUSION: Most of VFMMs could be totally removed via a far lateral suboccipital approach with or without resection of the occipital condyle according to the tumor size, allowing most of these patients to achieve a good outcome in a 3 months follow-up.
文摘Objective To investigate the methods and effectiveness to treat Chiari malformation with surgical decompression of foramen magnum under endoscope. Methods 23 cases with Chiari malformation. (withoutatlanto-axial dislocation and basilar invagination) diagnosed by magnetic resonance imaging(MRI) were operated with the surgical decompression for foramen magnum under the endoscope. Results 23
文摘LIMAS and Tio1 proposed the term meningeal melanocytoma first time in 1972 to describe a primary melanotic tumor of the leptomeninges with prolonged clinical course and benign histology.Meningeal melanocytoma of the central nervous system is rare and benign primary meningeal melanocytoma (PMM) is more exceptional,and also less usual than the malignant types.2 This rare tumor falls under the subclassification of primary melanocytic lesions in the World Health Organization's classification of central nervous system tumors.3 PMM located in the foramen magnum region is an unusual cause of bulbus medullae and fourth ventricle compression.Here we report a 48-year-old man with a PMM which is located in the foramen magnum inducing supratentorial obstructive hydrocephalus.
文摘Intracranial dermoid cysts are nonneoplastic lesions that present a rare clinical entity. They account for 0.04% to 0.6% of all intracranial tumors. Such cystic lesions usually contain different ectodermal derivatives including hairs, sebaceous glands, apocrine gland and teeth. Dermoid cysts of foramen magnum occur very rarely, with few cases reported in the literature. Computed tomography (CT) and magnetic resonance imaging (MRI) are two main diagnostic tools. Here in this paper, we described a case of intracranial (foramen magnum) dermoid cyst presented with neurologic deficits that completely removed surgically.
基金supported by the Scientific Research Fund of Liaoning Provincial Education Department(CN)(FWZR2020006)
文摘Background To investigate the classification and microsurgical treatment of foramen magnum meningioma(FMM).Methods We retrospectively analyzed 76 patients with FMM and classified them into two classifications,classification ABS according to the relationship between the FMM and the brainstem and classification SIM according to the relationship between the FMM and the vertebral artery(VA).All patients underwent either the far lateral approach(54 cases)or the suboccipital midline approach(22 cases).Results Of the 76 cases,47 cases were located ahead of the brainstem(A),16 cases at the back of the brainstem(B),and 13 cases were located laterally to the brainstem(S).There were 15 cases located superior to the VA(S),49 cases were inferior(I),and 12 cases were mixed type(M).Among 76 cases,71 cases were resected with Simpson grade 2(93.42%),3 with Simpson grade 3(3.95%),and 2 with Simpson grade 4(2.63%).We summarized four anatomical triangles:triangles SOT,VOT,JVV,and TVV.The mean postoperative Karnofsky performance score was improved in all patients(p<0.05).However,several complications occurred,including hoarseness and CSF leak.Conclusion ABS and SIM classifications are objective indices for choosing the surgical approach and predicting the difficulty of FMMs,and it is of great importance to master the content,position relationship with the tumor,and variable anatomical structures in the four"triangles"for the success of the operation.
文摘The foramen magnum (FM), being a vital landmark at the base of the skull, includes interests to many fields of medicine. Many authors haverecounted the usefulness of the FM in gender determination. The emphasis of this study is to evaluate the shape and dimensions of the FM among males and females and to establish its role in sexual dimorphism using cone-beam computed tomography (CBCT). Furthermore, to evaluate the area and FM index (FMI) among males and females and finally to evaluate the differences in FM measurements if any in twodifferent regions of an Indian population. One hundred and ten CBCT scans (55 males and 55 females;age range, 20–80 years) were selectedfor this study. The sagittal diameter, transverse diameter, area, FMI, and circumference of FM were measured, and data were subjected to discriminant analysis for the evaluation of sexual dimorphism. The area of FM was the best discriminant parameter which was used to study the sexual dimorphism with an overall accuracy of 90.9%. It can be concluded that the reconstructed CBCT image provides valuable measurements for the FM and could be used for gender determination.
文摘Background:Radiological imaging plays a pivotal role in forensic anthropology.As have the imaging techniques advances,so have the digital skeletal measurements inched towards precision.Secular trends of the population keep on changing in modem times.Hence,finding the precise technique of bone measurement,with greater reproducibility,in modem population is always needed in making population specific biological profile.Aim and Objective:The aim of this study was to estimate the accuracy of the foramen magnum measurement,obtained by three dimensional multi-detector computed tomography using volume rendering technique with the cut off value of each variable,in sex determination of an individual.Materials and Methods:Two metric traits,an antero-posterior diameter(APD)and transverse diameter(TD),were measured digitally in an analysis of 130 radiological images having equal proportion of male and female samples.Foramen magnum index and area of foramen magnum(Area by Radinsky's[AR],Area by Teixeira5s[AT])were derived from APD and TD.Results:Descriptive statistical analysis,using unpaired t-test,showed significant higher value in males in all the variables.Using Pearson correlation analysis,maximum correlation was observed between area(AT and AR r=0.999)and between area and TD(AR r=0.955 and AT r=0.945 respectively).When used individually,TD had the highest predictive value(67.7%)for sex detennination among all the parameters followed by AT(65.4%)and AR(64.6%).Cutoff value of variables TD,AR and AT were 29.9 mm,841.80 mm2 and 849.70 mm2 respectively.Receiver operating characteristic curve predicted male and female sex with 96.2%and 89.2%accuracy respectively.The overall accuracy of the model was 92.7%.Conclusion:Measurements from 3D CT using volume rendering technique were precise,and the application of logistic regression analysis predicted the sex with more accuracy.
文摘Background:Sexual dimorphism of the foramen magnum has increased its interest in forensic science.Gender determination is an important preliminary step in the identification of unknown skeletal remains.This study aimed at determining the dimensions of the foramen magnum in Delta State Nigeria and their role in gender discrimination.Materials and Methods:We retrospectively analyzed computed tomographic images of336 patients(199 males and 137 females)aged>18 years,archived in the Radiology Department of a Teaching Hospital in Nigeria.Ethical approval was granted by the hospitaFs ethical board.The length,width,and area of the foramen magnum were measured and analyzed using the Statistical Package for the Social Sciences software version 23.We used an independent Mest and analysis of variance to evaluate the association of these dimensions with sex and age,respectively.The percentage accuracy of sex discrimination and the association between variables were assessed using discriminant functional analysis and Pearson's correlation test correspondingly.The results were considered significant at P<0.05.Results:The foramen magnum length,width,and area showed a statistically significant gender difference(P<0.05).The width was the best sex discriminating variable(64.3%)and the overall accuracy of correct sex allocation using all the variables was 75%.All the parameters measured showed a significant strong positive correlation with each other(0.5<r<1,P<0.05).Conclusion:The foramen magnum length width and area were sexually dimorphic.Their high overall accuracy(75%)in gender discrimination implies that they may collectively be utilized in the sex estimation of unknown skulls in Delta State Nigeria.
文摘Background:sex identification by morphological assessment of various bones of the skeleton had been one of the oldest approaches in forensic anthropology and medico-legal cases.Aim and Objective:The aim of this study was to make the morphometric measurements of the foramen magnum in determining the feasibility of sex determination using computed tomography(CT).Materials and Methods:The data for our study was obtained from 100 patients having CT scan of the head and neck region(Siemens Somatom 256 slice CT scanner)with 1mm contiguous axial scans using bone window settings(2000 HU with 400 HU in centre),scan time of one second and exposure parameters 140 kVp and 70mA.The different measurements taken include the antero-posterior(AP)diameter,transverse diameter and area of the foramen magnum.Results:There were 50 males and 50 females with the age range of 18 to 75 years.Males have a higher average value than females in all of the parameters measured on foramen magnum.By using Studenfs T-test,all the measured parameters showed significant difference between the sexes(p<0.01).Conclusion:The expression of sexual dimorphism in the foramen magnum region shows significant difference between the sexes,therefore this area of the skull should be considered a useful area in the identification of sex.
文摘Objective To explore classification and surgical approach of magnum foramen tumor. Methods A retrospective analysis was performed for 43 surgically treated patients with tumors involving foramen magnum. According to the site of tumor,the classification was divided into:Type Ⅰ,located at dorsal,Ⅰ a extra-medullary,
