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Meningioma of the foramen magnum: a series of 40 cases.

BACKGROUND: Surgical treatment of foramen magnum meningiomas (FM meningiomas) has been improved by the recently developed posterolateral and anterolateral approaches. The choice of these approaches and the extent of bone resection, however, need to be defined according to the tumor location. METHODS: Over a short period (1980-1993), 40 cases of FM meningiomas were treated either by the posterolateral (N = 31), the anterolateral (N = 5), or the midline posterior approaches (N = 4). The choice of surgical technique (surgical approach, extent of bone drilling, and dural opening) was made according to the tumor location, which is defined by three parameters: the horizontal plane (anterior N = 18, lateral N = 21, and posterior N = 1); the vertebral artery (above N = 4, below N = 20, and on both sides N = 16); the dura mater (intradural N = 24, extradural N = 2, and intraextradural N = 4). RESULTS: Intradural anterior and lateral FM meningiomas were operated by the posterolateral approach. The bone drilling was limited either to the occipital condyle or to the lateral mass of the atlas, depending on whether the tumor location is above or below the vertebral artery, respectively. Intradural posterior meningiomas were treated by the midline posterior approach. FM meningiomas with an extradural component were resected by the anterolateral approach alone or combined with a midline posterior approach. The rate of complete resection was 94% for intradural FM meningiomas and 50% for the extradural ones. FM meningiomas with an extradural component generally have aggressive features invading the adjacent bone and soft tissues; this explains the difficulty of performing a complete resection. The clinical condition improved in 90%, worsened in 7.5%, and did not change in 2.5%. The worsened group consisted of three deaths (one case of air embolism, one case of pulmonary embolism, and one case with preoperative coma and tetraplegia). Similar results were obtained in both anterior and lateral locations. CONCLUSION: FM meningiomas can be completely and safely removed in most cases, using an appropriate surgical technique. The technique must be chosen after precise and correct analysis of the tumor location. The lateral approaches are very effective in the treatment of lateral and anterior FM meningiomas.

Adolescent↗

Microscopic anatomy of the infraorbital canal, nerve, and foramen.

OBJECTIVE: We performed this study to investigate the morphologic and topographic anatomy, and variations of the infraorbital canal (IOC), infraorbital nerve (ION), and infraorbital foramen (IOF). STUDY DESIGN AND SETTING: This study was performed at the Anatomy Department of Ankara University School of Medicine between 1999 and 2000. The morphometry of these anatomic areas on cadaver heads were studied microscopically. The morphologic and topograpic anatomies of IOC, ION, and IOF were carried out microscopically with x 25 to x 40 magnification on 10 cadaver heads (20 sides). RESULTS: We found the shape of the IOF as oval in 30% (6 sides), round in 40% (8 sides), and semilunar in 30% (6 sides) of the cadaver heads. We detected the IOF as single in 90% (18 sides), double in 5% (1 side), and triple in 5% (1 side) of the cases. We determined a complete roof (we called it as "canal") in 50% of cases and groove plus canal in 50% of the heads. The mediolateral relationship of the vessels to the nerve while emerging from the IOF was investigated, and the artery was always found in a mediosuperior position and the vein was inferior to it. In all specimens, the ION was found to be consisting of 3 to 8 fascicles interwoven with the artery and the vein in the loose connective tissue sheath. CONCLUSION: A detailed knowledge of the anatomic morphometry of this area is necessary for a surgeon while performing maxillofacial surgery and regional block anesthesia. Anatomic variations on this area may take place and a surgeon must take this into consideration so as to increase the surgical success.

Female↗

Interobserver and intraobserver variability in detection of patent foramen ovale and atrial septal aneurysm with transesophageal echocardiography.

BACKGROUND: An accurate diagnosis of patent foramen ovale (PFO) and atrial septal aneurysm (ASA) may be of decisional importance in the management of patients with ischemic stroke. Very few studies have been devoted to observer agreement in the diagnosis of these atrial septum abnormalities using contrast transesophageal echocardiography, which is considered as the method of choice for the diagnosis. The aim of this study was to assess interobserver and intraobserver variability in the diagnosis of PFO and ASA with contrast echocardiography. METHODS: Three sonographers independently reviewed 100 contrast studies stored on videotape on 2 occasions each. The interobserver and intraobserver variability was assessed by calculating kappa statistics. RESULTS: The overall interobserver and intraobserver kappa values for the assessment of degree of shunting through a PFO were 0.77 (first and second reading) and 0.82, respectively. The best kappa statistics were obtained when no and small shunts (less than 10 microbubbles) were pooled and compared with larger shunts. For the diagnosis of ASA, the overall interobserver kappa value was 0.45 for the first reading and 0.71 for the second reading, whereas the overall intraobserver kappa value was 0.74. CONCLUSION: Interobserver and intraobserver agreements for the diagnosis of PFO and ASA by transesophageal echocardiography are not perfect and need to be improved, particularly for ASA. This variability has to be taken into account when deciding on a potential risky treatment to prevent recurrent strokes.

Adult↗

Oral ulcerations as the first sign of a foramen magnum meningioma.

We report the case of a patient with oral ulcerations that were likely traumatic in origin caused by biting of the tongue. Physical examination showed only deviation, fasciculations, and hemiatrophy of the right side of the tongue. Neurologic examination disclosed an isolated XII nerve palsy. A magnetic resonance image showed a lesion in the posterior fossa displacing the brain stem at a bulbar level. This was consistent with the diagnosis of a meningioma, later confirmed by the histopathologic study. It is very unusual that a meningioma produces a selective involvement of the XII nerve. Early diagnosis of a foramen magnum meningioma is important, both to improve prognosis and to avoid neurologic sequelae.

Aged↗

Stereotactic radiosurgery of the foramen magnum region and upper neck lesions: technique modification.

A modification of the stereotactic radiosurgical procedure to permit treatment of lesions in the foramen magnum and upper cervical regions is described. The modification consists of placing the frontal pins of the stereotactic head ring in the zigoma bone, with no changes in the position of the occipital pins, so the final BRW head ring is oblique to the orbito-meatal plane. In this new position there is room enough in the posterior part of the guide for the support scrubs. This is unhampered by the patient's shoulders and the lesion is far enough to permit setting the axial coordinate sufficiently above the head ring plane.

Foramen Magnum↗

Posterior midline approach for large anterior/anterolateral foramen magnum tumours.

The standard surgical approaches described for excision of anterior or anterolaterally placed foramen magnum (FM) tumours are the far lateral approach, the extreme lateral approach and the transoral approach. In general the posterior midline approach is considered not suitable for these lesions. We have operated on 27 patients with benign anterior/anterolaterally placed FM tumours in the last 8 years. Thirteen of these were operated via the posterior midline approach. All these 13 patients had large or giant tumours displacing the cervicomedullary region posteriorly and laterally. This allowed adequate access through this approach with minimal handling of neural tissue. For small lesions, the far lateral approach was used. Most of the patients improved significantly neurologically. We recommend the standard midline posterior approach for large/giant FM tumours as the tumour size itself provides enough working space for the surgeon. For small lesions, the far lateral approach is preferred.

Adolescent↗

Sex identification utilizing the size of the foramen magnum.

The sex of unidentified skeletons is not always easily and correctly determined by the general medical examiner with no formal training in forensic anthropology. Sometimes the diagnostic procedure may be extremely complicated when handling fragmented bones. The present preliminary observations concern the evaluation of the size of the foramen magnum in 40 skulls (20 of each sex). Our results indicate that this method may be useful in the sexing of skeletal remains under the above-mentioned conditions as well as when an expert in forensic anthropology or a crime laboratory is not available.

Anthropometry↗

Relation between intracranial volume and the surface area of the foramen magnum.

Several investigators have estimated the intracranial volume (ICV) in the past which indirectly reflects the brain volume. Most of these studies have been made on the dry skulls using linear dimensions, packing methods or occasionally radiological methods. It is also reported that the etiology of cerebellar tonsillar herniation is closely related to the size of the foramen magnum (FM). In the present study the ICVs have been estimated in 28 dry skulls using filling water method and the surface area of FMs were measured planimetry method. The estimated mean ICV was 1,311 +/- 133 cm. Surface area of FM was 760 +/- 144 mm. Antero-posterior and lateral direct roentgenograms of the skulls were also taken and the width, height and length (WHL) of the skull were measured by means of the cephalometry on radiograms. The relationship between the ICV, WHL and surface area of FM were analyzed statistically. The ICV, WHL and surface area of FM was correlated well (r = 0.271, P < 0.005; r = 0.265, P < 0.005, respectively) and a regression formula was proposed. Our results showed that skulls with larger ICV and WHL have larger FM surface area. We also suggested a regression formula that could be used to predict the surface area of FM regarding to the ICV and WHL values. In the next step, we took roentgenograms of skulls and obtain ICV measuring the width, length and height of skulls by means of cephalometry and investigate the relation between the findings of cephalometry and surface area of FM. The cephalometry could apply on living subjects and, thereby, our findings could provide some data to evaluate the etiology of Arnold Chiari malformation and achondroplasia for living subjects.

Adult↗

Benign extramedullary foramen magnum tumors: diagnosis by computed tomography.

This paper reports two cases of benign extramedullary tumors of the foramen magnum studied by computed tomography (CT). The first case was a neurinoma; the second was a meningioma. Several different CT findings allowed a correct preoperative diagnosis of the location and nature of the tumors. In view of the invasiveness of traditional diagnostic methods and of the encouraging, although limited, experience of the present cases, the role of CT in the diagnosis of these lesions is promising.

Adult↗

Foramen magnum syndrome secondary to calcium pyrophosphate crystal deposition in the transverse ligament of the atlas.

STUDY DESIGN: This report illustrates two rare cases of foramen magnum syndrome caused by a retro-odontoid mass in which calcium pyrophosphate dihydrate crystals were found. OBJECTIVES: To analyze the preoperative studies and the diagnostic criteria and to discuss the surgical treatment. The present cases will be compared with previous ones described in the literature. SUMMARY OF BACKGROUND DATA: Deposition of calcium pyrophosphate dihydrate crystals occurs into the fibrous and hyaline cartilage of the joints and intervertebral discs of the spine. Half of the patients known to have a chondrocalcinosis had asymptomatic calcification in the odontoid region. Ten patients were published in the literature as having a spinal cord syndrome secondary to calcium pyrophosphate dihydrate deposition in the odontoid region. METHODS: In both cases the preoperative studies were analyzed, and the retro-odontoid mass was resected and histologically examined. Both had an anterior transoral approach and have been followed for 1 year. RESULTS: According to the preoperative radiographs the diagnosis was suspected and confirmed histologically. Transoral approach was done with no need in either case for a posterior stabilization. CONCLUSIONS: Compression of the spinal cord by calcium pyrophosphate dihydrate deposition may occur. The preoperative diagnosis may be highly suspected after radiographic study and histologically confirmed. Transoral resection is the treatment of choice. Posterior stabilization should be considered only in cases of craniovertebral instability.

Aged↗

Melanocytoma of the foramen magnum.

This report concerns a 66-year-old man with a melanocytoma arising at the foramen magnum. Magnetic resonance imaging disclosed a well-circumscribed tumor extending from the medulla oblongata to C1 with gadolinium enhancement. A heavily pigmented tumor located under the leptomeninges was removed surgically. Although the patient died 8 months later of renal cell carcinoma, no recurrence or metastasis of the melanocytoma was detected by radiographic examination. Microscopically, the resected tumor was composed of polygonal to spindle-shaped cells containing large amounts of melanin. The bland nuclei of the tumor cells were of uniform size. No mitotic figures were seen. The tumor cells were positively immunostained for S-100 protein and by antibody HMB-45. They were not stained using the Ki-67 (MIB-1) antibody, indicating low proliferative activity. The ultrastructural examination revealed numerous mature melanosomes and basal laminae surrounding nests of cells. The tumor was diagnosed as a melanocytoma on the bases of its microscopic features and the lack of Ki-67 immunoreactivity. The ultrastructural and immunohistochemical features of melanocytomas are distinct from those of meningiomas. It is likely that melanocytomas and melanotic schwannomas represent opposite extremes of the continuous spectrum of neuroectodermal tumors derived from the neural crest.

Aged↗

Electromyographic studies in a case of foramen magnum meningioma.

Atrophy of muscles innervated by the lower cervical cord is a well-known feature in patients with foramen magnum tumours. Electromyographic evidence of denervation in the atrophic muscles is presented. The significance and possible mechanisms are reviewed and discussed.

Aged↗

Extradural masses at the foramen magnum in children.

This report describes the clinical features, treatment, and sequelae in 3 children with extradural masses in the region of the foramen magnum. Such lesions are rare, their nature diverse, and their treatment hazardous. The common presenting feature was neck stiffness.

Child↗

Transoral transclival removal of anteriorly placed meningiomas at the foramen magnum.

Anteriorly placed meningiomas at the level of the foramen magnum are rare, are difficult to diagnose, and present technical problems for a conventional posterior fossa removal. The authors describe the successful transoral transclival excision of two such tumors. Cerebrospinal fluid (CSF) fistula can be avoided by dural repair using a thrombin glue and long term CSF diversion. This modification enables the transoral route to be considered for anteriorly placed intradural lesions.

Female↗

Complete resection of a spinal meningioma extending from the foramen magnum to the second thoracic vertebral body via the anterior approach: case report.

The authors treated a patient with a huge, ventrally located spinal meningioma, extending from the foramen magnum to the second thoracic vertebral body. Vertebral body corpectomies were performed between the bottom of the second cervical vertebral body and the top of the first thoracic vertebral body, and the tumor was completely resected. Neurological symptoms and signs improved postoperatively.

Adult↗

Surgical indication and results of foramen magnum decompression versus syringosubarachnoid shunting for syringomyelia associated with Chiari I malformation.

Several surgical procedures have been used for the treatment of syringomyelia associated with Chiari I malformation at our institute. The purpose of this article is to evaluate the results of two major surgical procedures, foramen magnum decompression (FMD) and syringosubarachnoid (SS) shunting. The series consisted of 70 patients with syringomyelia associated with Chiari I malformation who were surgically treated. Their ages ranged from 3 to 59 years (median, 29.4 yr). FMD was performed on 33 patients, and SS shunting was performed on 37 patients. The follow-up period ranged from 6 months to 12.5 years, with a mean of 60 months. The clinical and radiological outcomes were analyzed comparing the two groups. We principally performed FMD in patients with symptoms of Chiari I malformation and/or a small syrinx. We prefer to use SS shunting in patients with large syringes. Postoperative magnetic resonance imaging demonstrated that the syrinx had collapsed or decreased in size in 94% of the patients who underwent FMD and in 100% of the patients who underwent SS shunting. Neurological improvements were observed in 82% and in 97% of the patients who underwent FMD and SS shunting, respectively. In particular, the relief of pain was more fully achieved after SS shunting than after FMD. The average time for the syrinx to collapse was 6.3 weeks after surgery in the FMD group and 1.8 weeks in the SS shunting group. These results indicate that clinical symptoms and radiological findings improved much more quickly in the SS shunting group than in the FMD group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

Unusual transoral penetrating injury of the foramen magnum: case report.

OBJECTIVE AND IMPORTANCE: Penetrating injuries of the cranium and spine are frequent to the civilian neurosurgical practice. Although a variety of unusual objects have been reported, to our knowledge, there has never been a craniocerebral or spinal injury caused by a fish. An unusual case of transoral penetration of the foramen magnum by a billed fish is described. The history, radiographic studies, and treatment are presented. CLINICAL PRESENTATION: A fisherman struck by a jumping fish initially presented with severe neck pain and stiffness, bleeding from the mouth, and a laceration in the right posterior pharynx. A computed tomographic scan of the cervical spine revealed a wedge-shaped, hyperdense object extending from the posterior pharynx into the spinal canal between the atlas and the occiput. Because of the time factor involved, the fisherman was brought directly to surgery for transoral removal of the object. INTERVENTION: The patient was placed under general anesthesia, and with a tonsillar retractor, a kipner, and hand-held retractors, the object was visualized and identified as a fish bill. Further dissection above the anterior aspect of the atlas permitted removal of the object by means of a grabber from an arthroscopic set. No expression of cerebrospinal fluid was noted, and a Penrose drain was placed. CONCLUSION: The patient was treated under the assumption that penetrating foreign objects in continuity with the cerebrospinal fluid space and the outside environment should be removed as soon as possible. The patient was provided appropriate antibiotics to treat potential infection of normal pharyngeal flora and organisms unique to the marine environment. The patient recovered and did not experience any residual neurological deficit.

Adult↗

Avulsion fracture of the foramen magnum treated with occiput-to-c1 fusion: technical case report.

OBJECTIVE AND IMPORTANCE: A 31-year-old woman presented with an avulsion fracture of the foramen magnum via bilateral occipital condyles with extension through the inferior aspect of the clivus. CLINICAL PRESENTATION: The patient had no neurological deficits and was initially immobilized in a halo brace. INTERVENTION: To preserve rotational motion at C1-C2, we performed an occiput-to-C1 fusion with bilateral C1 lateral mass screws attached with rods to occipital keel screws. Postoperatively, the patient remained neurologically intact. Three-month follow-up imaging revealed no abnormal motion. Follow-up computed tomographic scan showed an intact construct and bony fusion. CONCLUSION: This rare injury, a bony variant of occipitoatlantal dislocation, was successfully treated with a unique occiput-to-C1 fusion.

Adult↗