No abstract available.
Foramen Magnum* ; Vertebral Artery*

PURPOSE: To evaluate normal tonsillar position at different ages, using MR images. MATERIAL AND METHODS: We measured the position of the cerebellar tonsils with respect to the inferior aspect of the foramen magnum on middle sagittal MR T1 weight images in 210 patients(9 days to 83 years) who were not considered to have any disorder that would affect tonsillar position. RESULTS: The mean distance between tonsillar tip and inferior aspect of the foramen magnum was 0.0 +/-1.9mm in the first decade of life, 0.7 +/-2.8mm in the fourth decade, and3.4 +/-2.3 mm in the eighth and ninth decades. The tonsillar position is significantly lower in youth(first and second decades) than in old age(seventh to ninth decades). CONCLUSION: We believe that a single reference standard that indicates the normal distance of the cerebellar tonsils from the foramen magnum is inappropriate unless age is considered. We suggest that the following distance below the foramen magnum(more than 2 standard deviations out of the normal range) be used as criteria for ectopia of the cerebellar tonsils in koreans : firstand second decades, 5mm ; third to sixth decades, 4mm ; seventh and eighth decades, 3mm.
Foramen Magnum ; Palatine Tonsil*

No abstract available.
Foramen Magnum ; Meningioma* ; Spinal Canal*

No abstract available.
Conus Snail* ; Foramen Magnum* ; Syringomyelia*

Chiari type I malformation is a tonsillar herniation more than 3 mm from the level of foramen magnum, with or without concurrent syringomyelia. Different surgical treatments have been developed for syringomyelia secondary to Chiari's malformations: craniovertebral decompression with or without plugging of the obex, syringo-subarachnoid, syringo-peritoneal, and theco-peritoneal shunt placement. Shunt placement procedures are useful for neurologically symptomatic large-sized syrinx. In this paper, authors define the first successful treatment of a patient with syringomyelia due to Chiari type I malformation using a pre-defined new technique of syringo-subarachnoid-peritoneal shunt with T-tube system.
Decompression ; Encephalocele ; Foramen Magnum ; Humans ; Syringomyelia*

The aim of this study was to produce a simple and inexpensive technique for estimating the obturator foramen area (OFA) from young calves based on the hypothesis that OFA can be extrapolated from simple linear measurements. Three linear measurements - dorsoventral height, craneocaudal width and total perimeter of obturator foramen - were obtained from 55 bovine hemicoxae. Different algorithms for determining OFA were then produced with a regression analysis (curve fitting) and statistical analysis software. The most simple equation was OFA (mm2) = [3,150.538 + (36.111*CW)] - [147,856.033/DH] (where CW = craneocaudal width and DH = dorsoventral height, both in mm), representing a good nonlinear model with a standard deviation of error for the estimate of 232.44 and a coefficient of multiple determination of 0.846. This formula may be helpful as a repeatable and easily performed estimation of the obturator foramen area in young bovines. The area of the obturator foramen magnum can thus be estimated using this regression formula.
Biometry ; Foramen Magnum ; Nonlinear Dynamics ; Osteology

OBJECTIVE: The aim of this study is to evaluate the effectiveness of the syringo-subarachnoid shunt for the syringomyelia, according to the clinical outcome and radiological changes. METHODS: Ten patients who underwent syringo-subarachnoid shunt during last 5 years were included in this analysis. The average age at the presentation was 32.6(range 7 to 51) years. Chiari I malformation was found in four patients, Post-infectious syringomyelia was in three patients, and posttraumatic syringomyelia in two patients. The most common presenting symptoms were motor weakness and pain. Radiological diagnosis was made by magnetic resonance image in all patients. All patients underwent syringo-subarachnoid shunt, and in five patients with Chiari I malformation or achondroplasia, foramen magnum decompression was done as well. RESULTS: Eight showed the significant clinical improvement. Remaining two patients showed stabilization of the symptom. The postoperative magnetic resonance image, performed in seven cases, showed the reduction of the syrinx size in all case. There was no shunt malfunction or infection in our series. The transient cerebospinal fluid leakage was noted in three cases. CONCLUSION: It appears that the syringo-subarachnoid shunt is beneficial surgical method for the syringomyelia of various etiologies.
Achondroplasia ; Decompression ; Diagnosis ; Foramen Magnum ; Humans ; Syringomyelia*

No abstract available.
Foramen Magnum* ; Histiocytosis, Sinus* ; Spinal Cord Compression*

The authors report the experiences of transcondylar approaches for five meningiomas in the low clivus and foramen magnum. These tumors were removed via transcondylar approach. The results show that there was no operative mortality and minimal operative morbidity;one patient had temporary oropharyngeal dysfunction. This approach offers the best direct vision of the ventral structures to low clivus and foramen magnum without additional retraction or manipulation of the brain stem.
Brain Stem ; Cranial Fossa, Posterior* ; Foramen Magnum* ; Humans ; Meningioma* ; Mortality

This study has been made to stress the importance of fracture pattern of the posterior fossa for recognition of traumatic lesions in the posterior fossa. Included in the series are all the cases of clinically significant verified lesions in the posterior fossa due to posterior fossa fractures. The classification of posterior fossa fractures introduced here by author has been based on the linear fracture involving the transverse sinus groove and/or the foramen magnum in Towne's projection. Five types of pattern have occurred. In type I, a linear fracture involves the transverse sinus groove and the foramen magnum. In type II, a linear fracture involves the transverse sinus groove but not the foramen magnum. In type III, a linear fracture involves the lambdoid suture, the transverse sinus groove and the foramen magnum. In type IV, a linear fracture involves the lambdoid suture and the transverse sinus groove, but not the foramen magnum. In type V, a linear fracture of the suboccipital bone involves the foramen magnum, but not the transverse sinus groove. In a total of 33 cases of posterior fossa fracture, 13 cases(39.3%) are of type I, 7 cases(21.2%) are of type II, 5 cases(15.2%) are of type III, 5 cases(15.2%) are of type IV, 3 cases(9.1%) are of type V. It has been shown that the cerebellar hematomas have been verified in type I, epidural and subdural hematomas verified in all the types without regard to the fracture patterns, and subdural hygromas verified in type I, III and V.
Classification ; Foramen Magnum ; Hematoma ; Hematoma, Subdural ; Subdural Effusion ; Sutures