Foramen Magnum Lesions Research Articles

Benign Enhancing Foramen Magnum Lesions.

Benign enhancing foramen magnum lesions have been previously described as T2-hyperintense small, enhancing lesions located posterior to the intradural vertebral artery. We present the first case with pathologic correlation. These lesions are fibrotic nodules adhering to the spinal accessory nerve. While they can enlarge with time on subsequent examinations, on the basis of the imaging characteristics and location, they do not necessitate surgical resection.

Approaching Intradural Lesions of the Anterior Foramen Magnum and Craniocervical Junction: Anatomical Comparison of the Open Posterolateral and Anterior Extended Endonasal Endoscopic Approaches

Lesions of the foramen magnum (FM) and craniocervical junction area are traditionally managed surgically through anterior, anterolateral, and posterolateral skull-base approaches. This anatomical study aimed to compare the usefulness of a modified extended endoscopic approach, the so-called far-medial endonasal approach (FMEA), versus the traditional posterolateral far-lateral approach (FLA). Ten fixed silicon-injected heads specimens were used in the Skull Base ENT-Neurosurgery Laboratory of the University Hospital of Strasbourg, France. A total of 20 FLAs and 10 FMEAs were realized. A high-resolution computed tomography scan was performed for quantitative analysis of the different approaches. The analysis aimed to estimate the extent of surgical exposure and freedom of movement (maneuverability) through the operating channel using a polygonal surface model to obtain a morphometric estimation of the area of interest (surface and volume) on postdissection computed tomography scans using Slicer 3D software. FMEA allows for a more direct route to the anterior FM, with wider brainstem exposure compared with the FLA and an excellent visualization of all anterior midline structures. The limitations of the FMEA include the deep and narrow surgical corridor and difficulty in reaching lesions located laterally over the jugular foramen and hypoglossal canal. The FMEA and FLA are both effective surgical routes to reach FM and craniocervical junction lesions. Modern skull base surgeons should have a good command of both because they appear complementary. This anatomical study provides the tools for comprehensive preoperative evaluations and selection of the most appropriate surgical approach.

Endovascular treatment of medullary bridging vein-draining dural arteriovenous fistulas: foramen magnum vs. craniocervical junction lesions.

Dural arteriovenous fistulas (AVFs) draining to medullary bridging vein (MBV) are located at foramen magnum (FM) and craniocervical junction (CCJ). Such fistulas are rare but pose a challenge to endovascular management. This study was undertaken to assess clinical manifestations, angiographic features, and outcomes of endovascular treatment in patients with MBV dural AVFs. A number of our patients (N = 22) were diagnosed with MBV dural AVF and treated by endovascular means. There were 9 FM lesions and 13 CCJ lesions. We reviewed clinical records and imaging studies to define clinical characteristics, vascular anatomic details, and treatment outcomes, comparing FM- and CCJ-level subsets. Subjects ranged from 37 to 74years of age (mean, 57.7years) with male predominance (2.7:1). They presented with intracranial hemorrhage (11/22, 50%), myelopathy (8/22, 36%), or nonspecific symptoms (3/22, 14%). In 17 patients (77.3%), the shunts showed complete or near-complete occlusion following endovascular treatment (FM, 100%; CCJ, 61.5%). However, seven patients experienced ischemic events (FM, 11.1%; CCJ, 46.2%) and one patient sustained a hemorrhagic complication. No hemorrhages recurred during follow-up monitoring, and myelopathic symptoms abated. MBV dural AVFs are highly aggressive lesions for which proper diagnosis and treatment are of utmost importance. Although transarterial embolization proved highly successful in FM lesions, shunt occlusion was less frequent in the CCJ subset, with greater risk of ischemic complications.

Far Lateral Transcondylar Approach for Anterior Foramen Magnum Lesions

Objective: To study the efficacy and safety of far-lateral transcondylar approach for anterior foramen magnum lesions with early experience at our Institute.
 Material and Methods: We treated six patients, with lesion anterior to the foramen magnum and posterior to the brainstem and cervical cord in a period of 2 years, March 2017 to March 2018.Initial assessment was made by history and examination followed by CT scan and contrast MRI. All were treated using far-lateral transcondylar approach.
 Result: Among six patients, there were two were male and four were female. Three of these patients had a meningioma while two patients had neurofibromas and one clival chordoma. Total excision was achieved in five neoplastic cases, while subtotal excision was done in one case. There were no fresh postoperative deficits in any of the other patients. One patient had an unexplained sudden cardiorespiratory arrest 18h after the surgery and succumbed. One patient had cerebrospinal fluid (CSF) discharge from the wound, which was satisfactorily managed by lumber CSF drainage.
 Conclusion: This approach provides an excellent approach to lesions located anterior to foramen magnum posterior to the brainstem and upper cervical cord. Gross total excision of these benign and malignant lesions is safely possible through this approach.
 Keywords: Craniovertebral Junction, Far-Lateral Transcondylar Approach, Anterior Foramen Magnum, Brain Stem, Chordoma.

Endoscopic Endonasal Focal Transclival-Medial Condylectomy Approach for Resection of a Foramen Magnum Meningioma: 2-Dimensional Operative Video.

The endoscopic endonasal approach (EEA) provides direct access to foramen magnum meningiomas; however, it often requires extensive exposure including septal flap elevation with septum removal, complete sphenoidotomy, and panclivectomy.We present a case of a 54-yr-old-female with an incidental foramen magnum lesion followed up with serial imaging who presented 10 mo later with progressive neck discomfort and episodes of dizziness, with confirmed tumor progression and further brainstem compression. A focal transclival EEA with medial condylectomy was performed preserving the upper two-thirds of the clivus, the nasal septum, and the sphenoid sinus. Gross total removal of a meningioma WHO Grade-1 was achieved with dura resection on the majority of the tumor (Simpson 2). Closure was achieved with a random pedicled inverted V nasaopharyngeal flap. There were no complications, all symptoms improved, and no recurrence was seen in 12 mo of follow-up.IRB approval was neither required nor saught for this single case report. The patient gave informed consent.

Far-lateral Transcondylar Approach to Anterior Foramen Magnum Lesions - Our Experience.

Background:Initial surgical management of the anterior foramen magnum lesions through the posterior approaches was fraught with unacceptable morbidity, mortality, and incomplete removal. The far-lateral approach provides excellent exposure and access to these lesions resulting in complete excision of these lesions with reduced frequency of unwanted complications.Materials and Methods:Eight patients with lesions anterior to the brainstem and upper cervical cord were surgically treated using the far-lateral transcondylar approach. Two of these patients had a meningioma while three patients had “white epidermoid.” One patient had a vertebral artery (VA) aneurysm while another was a rare case of lower brainstem compression by the VA and the last was a clival chordoma. The technical aspects of this surgical procedure are briefly illustrated in this article.Results:Total excision was achieved in five neoplastic cases while subtotal excision was done in one case. The VA aneurysm was satisfactorily clipped while in the brainstem compression patient, microvascular decompression was done. The VA aneurysm patient developed postoperative lower cranial nerve palsies. There were no fresh postoperative deficits in any of the other patients. One patient had an unexplained sudden cardiorespiratory arrest 18 h after the surgery and succumbed. One patient had cerebrospinal fluid (CSF) otorrhea which was satisfactorily managed by intrathecal CSF drainage.Conclusion:The far-lateral transcondylar approach provides excellent approach to lesions located anterior to the brainstem and upper cervical cord. Total excision of these benign lesions is safely possible through this approach.

Key Aspects in Foramen Magnum Meningiomas: From Old Neuroanatomical Conceptions to Current Far Lateral Neurosurgical Intervention.

Foramen magnum meningiomas represent a challenge for neurosurgeons. These tumors require careful surgical manipulation as they are often located in proximity to critical neurovascular structures and the cranial nerves. The far lateral approach is considered the safest neurosurgical approach for excising foramen magnum lesions. It facilitates the access to the anterior foramen magnum and reduces the retraction of vital structures. We describe key historical, epidemiological, genetic, epigenetic, clinical, and neurosurgical aspects of foramen magnum meningiomas. We emphasize the far lateral approach for lesions arising in the foramen magnum, as well as the most appropriate patient positioning for such approach. Caring for these aspects will be rewarded with the best perioperative neurosurgical outcomes.

Pituitary Carcinoma in a Patient with an SDHB Mutation

We present the first case of pituitary carcinoma occurring in a patient with a succinate dehydrogenase subunit B (SDHB) mutation and history of paraganglioma. She was initially treated for a glomus tumour with external beam radiotherapy. Twenty-five years later, she was diagnosed with a non-functioning pituitary adenoma, having developed bitemporal hemianopia. Recurrence of the pituitary lesion (Ki-67 10% and p53 overexpressed) occurred 5 years after her transsphenoidal surgery, for which she underwent two further operations followed by radiotherapy. Histology showed large cells with vacuolated clear cytoplasm with positive immunostaining for steroidogenic factor 1 (SF1) and negative staining for pituitary hormones. Four years after the pituitary radiotherapy, two metastatic deposits were identified: a foramen magnum lesion and an intradural extra-medullary cervical lesion at the level of C3/C4. There was also significant growth of the primary pituitary lesion with associated visual deterioration. A biopsy of the foramen magnum lesion, demonstrating cells with vacuolated, clear cytoplasm and positive SF1 staining confirmed a pituitary carcinoma, for which she was commenced on temozolomide chemotherapy. There was dramatic clinical improvement after three cycles and reduction in the size of the lesions was observed following six cycles of temozolomide, and further shrinkage after 10 cycles. The plan is for a total of 12 cycles of temozolomide chemotherapy. SDH mutation-related pituitary tumours have an aggressive phenotype which, in this case, led to metastatic disease. SF1 immunostaining was helpful to identify the tissue origin of the metastatic deposit and to confirm the pituitary carcinoma.

Benign Enhancing Foramen Magnum Lesions: Clinical Report of a Newly Recognized Entity.

Intradural extramedullary foramen magnum enhancing lesions may be due to meningioma, nerve sheath tumor, aneurysm, or meningeal disease. In this clinical report of 14 patients, we describe a novel imaging finding within the foramen magnum that simulates disease. The lesion is hyperintense on 3D-FLAIR and enhances on 3D gradient-echo sequences but is not seen on 2D-TSE T2WI. It occurs at a characteristic location related to the posterior aspect of the intradural vertebral artery just distal to the dural penetration. Stability of this lesion was demonstrated in those patients who underwent follow-up imaging. Recognition of this apparently benign lesion may prevent unnecessary patient anxiety and repeat imaging.

Lower third clivus and foramen magnum intradural tumor removal: The plea for a simple posterolateral approach

BackgroundAnterior or anterolateral lesions of the lower third clivus and/or foramen magnum require a surgical exposure that provides a clear visualization of both pathological and normal anatomy without retraction of neural or vascular structures. The posterolateral approach permits access to the anterolateral intradural aspect of the brainstem. The aim of this study was to stress that there is no need for vertebral artery transposition, occipital condyle drilling, occipitocervical fixation or trans-oro-pharyngeal access to remove these lesions. MethodsAll five consecutive patients treated surgically for an intradural foramen magnum lesion in the Department of Neurosurgery at Angers University Hospital, between May 2012 and January 2015, were included in this retrospective study. In 4 cases, patients were referred to us for a second opinion after an initial surgical proposal at another institution. For all patients, the data collected were age at diagnosis, clinical signs, and quality of rostral and caudal exposure of the lesion, quality of resection, complications and postoperative neurological deficits. ResultsAll patients were operated on with a control of the rostrocaudal part of the lesion, without touching the vertebral artery, or the use of occipital condyle drilling. There was no need for occipitocervical fixation. Total resection was achieved in 4 cases, subtotal resection in one. All had watertight dural closure with no dural patch, or postoperative neurological deficits. No recurrence occurred between 6 and 30 months after surgery. ConclusionBased on these results, the posterolateral approach was a simple, effective and safe procedure for anterior and anterolateral intradural lesion of the foramen magnum.

Endoscopic Endonasal Transclival Transcondylar Approach for Foramen Magnum Meningiomas: Surgical Anatomy and Technical Note.

The endoscopic endonasal approach provides a direct route to ventral foramen magnum (FM) lesions like meningiomas, which are difficult to access. Endonasal access at the FM is limited laterally by the occipital condyles and inferiorly by the C1 anterior arch and the odontoid process, which may need partial resection. We investigated the surgical anatomy and technical nuances for endonasally increasing the surgical corridor at the FM region both laterally and inferiorly. Unique to our report, we quantified the amount of required medial condyle resection to obtain exposure of the lateral aspects of the FM. Five fresh human head silicone-injected specimens underwent endonasal inferior transclival, transcondylar approaches. The lateral limit of medial condyle resection was defined using a vertical line extending inferiorly from foramen lacerum and its intersection with the occipital condyle. The condylectomy was limited posteriorly by the cortical bone surrounding the hypoglossal canal. The volume of the resected condyle (cubic centimeters) for 10 sides was measured using the pre- and postdissection computed tomography-volumetric analysis. The mean percentage condylar volume resected during a unilateral medial condylectomy was 18% (9.7%-28.3%). The surgical corridor was extended inferiorly in all specimens without violating the transverse ligament by drilling the superior aspects of C1 anterior arch and the exposed odontoid tip. These operative nuances were successfully applied in the operating room. Anatomical landmarks can reliably guide an endonasal anteromedial condyle resection. Minimal condyle resection is required to widen lateral access at the FM, which minimizes the risk of craniocervical instability.

Spinal neurenteric cysts: Associated developmental anomalies and rationale of surgical approaches.

Neurenteric cysts (NC) occur due to failure of separation of neurectoderm from endoderm at the 3rd week of embryogenesis. This study focuses on key clinico-radiological features of NCs, with emphasis on surgical nuances involved in resecting anteriorly placed NC, especially at the foramen magnum (FM). Sixteen consecutive patients having a spinal NC were included. Their clinico-radiological status, surgical nuances and follow-up status were noted. The duration of spasticity/paraparesis/quadriparesis ranged from 15 days to 48 months. Twelve patients had an intradural extramedullary (IDEM; nine anterior and three anterolateral) cyst and four had an intramedullary (IM) cyst. Six of them had an anteriorly placed FM lesion (five IDEM and one IM). Amongst ten subaxial NCs, four were anterior, two antero-lateral and one postero-lateral; three were IM. Three patients had the characteristic stigmata of occult spinal dysraphism: two, a large mesenteric cyst, and one, a posterior mediastinal cyst. Excision was total in 13 patients. Subtotal excision of tumour capsule was performed for two recurrent cysts and an IM cyst. A far lateral approach was adopted for anteriorly placed FM lesions and posterior laminectomy for subaxial lesions. Histopathology revealed eight type A cysts, four type B cysts and four type C cysts. At follow-up (range, 8 months to 12 years; median, 60 ± 45.84 months), complete neurological recovery occurred in seven patients; six patients had persistent spasticity but only minor disability; two patients had difficulty in walking; and one patient with an anteriorly placed thoracic recurrent NC had sustained neurological deterioration. Surgical difficulties in addressing NCs are related to their anterior or IM location, presence of adhesions and inability to dissect the tumour capsule from the spinal cord due to fibrous or lipomatous connections. The associated developmental anomalies must be specifically sought and addressed.

Resection of Bilateral C1 Neurofibromas Using a Unilateral Modified Far-Lateral Approach

Resection of foramen magnum lesions through a lateral approach can be technically challenging. Surgical avenues to foramen magnum lesions include a suboccipital craniectomy with C1 laminectomy, a modified far lateral approach with little condylar drilling, or via an anterior approach. The authors report their surgical experience in the treatment of a 36-year-old male with bilateral C1 dumbbell neurofibromas using a unilateral modified far-lateral approach (no condylar drilling performed). The unilateral modified far-lateral approach allowed for an efficient and safe corridor to this patient’s bilateral foramen magnum tumors.

A minimal access far-lateral approach to foramen magnum lesions.

Objectives The far-lateral approach is widely used to treat pathology of the ventral foramen magnum. Numerous methods of exposure have been described, most of which utilize long skin incisions and myocutaneous flaps. Here we present our experience with gaining exposure through a small paramedian incision using a muscle-splitting technique. Design A cadaveric anatomical study was first performed to verify the feasibility of the approach. We then describe our experience with using the approach in 13 patients. A retrospective chart review was performed and data regarding pathology, imaging, and complications were collected. Results The cadaveric study confirmed that a small paramedian muscle-splitting approach allows sufficient exposure to approach many foramen magnum lesions. Our case series included 10 patients with meningioma, one brainstem glioblastoma, one posterior inferior cerebellar artery aneurysm, and one odontoid pannus. The exposure was adequate in all cases. For the meningioma patients, six had gross total resections and four had subtotal resection because of tumor adherence to neurovascular structures. Two patients experienced postoperative cardiovascular complications. There were no new neurologic deficits, cerebrospinal fluid leaks, or wound complications. Conclusions A small paramedian incision may be used to gain exposure and perform successful far-lateral approaches. The small exposure is likely to reduce the risk of local complications such as cerebrospinal fluid fistula and pseudomeningocele when compared with larger exposures.

Approaches to anterior and anterolateral foramen magnum lesions: A critical review

Foramen magnum (FM) lesions represent some of the most complex cases for the modern neurosurgeon because of their location near vital brainstem structures, the vertebral arteries, and lower cranial nerves. In particular, anterior or anterolaterally located FM tumors have traditionally been most difficult to resect with high morbidity and mortality resulting from approaches through the posterior midline or transorally. For many neurosurgeons, the far lateral, extreme lateral approach, and more recently, endoscopic endonasal approaches have become the preferred modern methods for the resection of anterior or anterolateral FM tumors. In this review, we examine both operative and non-operative approaches to FM tumors, including surgical anatomy, surgical technique, and indications for operative intervention in these complex cases. In addition, we compared outcomes from prior series.

CyberKnife Radiosurgery for Lesions of the Foramen Magnum

The region of the foramen magnum (FM) presents an especially difficult area for therapeutic intervention. Indeed, this location is challenging to access surgically, particularly in the case of intramedullary and anterior lesions. Therefore, the potential for morbidity associated with therapy to the foramen magnum, most frequently in the form of lower cranial nerve deficits, has encouraged the search for methods that can effectively treat lesions of this region while sparing the important neighboring structures. We report our experience in the use of Cyberknife radiosurgery as a treatment option for these lesions. Thirty-five patients (17 men, 18 women; mean age, 51 yr; range, 18-83) with 35 lesions either spanning or approximating the foramen magnum were treated with the CyberKnife radiosurgical system. Histologies were determined either by prior surgery or radiographic criteria and included 25 benign tumors (nine meningiomas, five schwannomas, four neurofibromas, three hemangioblastomas, two ependymomas, one chordomas, and one pilocytic astrocytoma) along with 10 malignant growths (nine metastases and one chondrosarcoma). Twenty-seven (77%) patients presented with at least one sign and/or symptom, while eight (23%) patients were completely asymptomatic. The most common symptoms were headache, limb numbness, and limb/truncal ataxia, all of which were reported by ten (29%) patients. Among cranial neuropathies, CN XII dysfunction was evident in four (11%) patients. The specific fractionation schedule (mean of 1.8 sessions; range, 1-5) was based on the size of the treated lesion. The mean dose utilized was 19 Gy. Radiographic follow-up was obtained for twenty-three (66%) patients. Nine of the twenty-three (39%) were stable in size, ten lesions decreased in size (43%), and four lesions increased in size (17%). In terms of symptom relief, follow-up was collected for twenty-four (69%) patients. Eleven (46%) of these patients experienced no change in their signs or symptoms, while seven (29%) patients experienced improvement. Six (25%) patients witnessed deterioration in their signs and symptoms. Overall, eighteen (75%) patients had their signs and symptoms either stabilize or improve. There were eleven (31%) deaths in our series, eight of which were related to the disease (though not directly related to CyberKnife treatment) and three of which were from unrelated causes. Complications directly related to CyberKnife radiosurgery were noted in four (11%) of the thirty-five patients. These included one case of temporary emesis immediately following treatment, one case of cystic enlargement two months out, and two cases of radiation necrosis (occurring 1.5 yrs and 2.5 yrs out from treatment). Cyberknife radiosurgery can be an effective treatment for many foramen magnum lesions.

Spontaneous Resolution of Syringomyelia Without Chiari Malformation-Case Report-

A 30-year-old woman presented with a cervical syrinx manifesting as hemihypesthesia. Neuroimaging found no evidence of Chiari malformation or tight cisterna magna. Serial magnetic resonance imaging studies over a 6-year period demonstrated spontaneous and complete resolution of the syrinx accompanied by an asymptomatic clinical course. The natural history of syringomyelia is highly unpredictable. The outcome of surgical treatment for patients with syringomyelia is not always satisfactory, so the indications for surgery are controversial. Spontaneous resolution of syringomyelia unrelated with foramen magnum lesion has various causes. Close follow up of the patient is necessary to monitor for recurrence.

Two-staged operation on C2 neoplastic lesions: anterior excision and posterior stabilization.

This retrospective study included eight consecutive cases with C2 vertebral body neoplastic lesions. The anterior retropharyngeal approach was used to remove the lesions and decompress the spinal cord. Spinal stabilization with occipitocervical plating in a second-stage operation makes the treatment more tolerable for patients. The object of this study was to determine the effectiveness of a two-stage operation strategy for these lesions. Eight patients were operated on via anterior retropharyngeal approach and then stabilized with occipitocervical plates posteriorly in a second sitting. All neck pain and all dysphagia problems resolved. Partial neurologic improvement was achieved in three out of four patients. No postoperative infection was seen. The retropharyngeal approach to the upper cervical spine and anterior foramen magnum lesions is an effective alternative to transoral surgery because of low complication rates. Neoplastic lesions in the upper cervical spine can safely and effectively be operated with this technique. The general medical status of patients with malignancies does not permit too long, time-consuming operations. Stabilization of the spine in a separate operation increases patient tolerability without any morbidity.

Choroid plexus papilloma and meningioma: coincidental posterior fossa tumors: Case report and review of the literature

Objective We report an unusual case of an extraventricular choroid plexus papilloma (CPP) occupying the right ventral foramen magnum and lower right cerebellopontine angle (CPA), occurring together with a petro-tentorial meningioma. The clinical presentation, preoperative imaging, differential diagnosis, surgical treatment and histologic features of the two tumors are discussed. Case description The patient presented with a 2-month history of headache, altered facial sensation, dysphagia, and gait unsteadiness. Neurologic examination confirmed a wide-based, unsteady gait, hoarse voice, anisocoria, and partial right vocal cord paralysis. Diagnostic imaging demonstrated right petro-tentorial and right ventral foramen magnum lesions, both hyperintense on contrasted images and suggestive of meningiomas. A right suboccipital craniotomy and far lateral approach was used to resect both tumors. The petro-tentorial tumor was a histologically confirmed meningioma, but the ventral foramen magnum tumor was an extraventricular CPP. Conclusion This is a rare occurrence of concomitant meningioma and CPP. There is no known link between these two tumors. An exophytic 4th ventricular CPP must be considered in the differential diagnosis of a CPA or foramen magnum tumor.

Response properties of upper cervical spinothalamic neurons in cats. A possible explanation for the unusual sensory symptoms associated with upper cervical lesions in humans.

Lesions in the foramen magnum and upper cervical spinal cord often cause an unusual array of sensory changes and atrophic weakness, primarily involving the ipsilateral forelimb. Furthermore, small midline myelotomies performed at C1 often lead to widespread analgesia covering most of the body in patients with chronic pain. These observations challenge physicians' understanding of anatomy and physiology in the upper cervical region. Using single cell recording techniques the authors have shown that spinothalamic neurons in the second cervical segment of cats have complex response properties, often responding to stimuli throughout the body. These findings together with a review of clinical and basic science literature are used to provide explanations for the unusual signs and symptoms observed in patients with upper cervical and foramen magnum lesions.