Foramen Magnum Tumors Research Articles

MNGA-06 MANAGEMENT OF FORAMEN MAGNUM TUMORS, EXPERIENCE OF THE SERVICE OF THE ARRAZI HOSPITAL OF THE CHU MOHAMMED VI OF MARRAKECH

Abstract Tumors of the foramen magnum (FM) are intra or extradural expansive processes located in a region, very complex anatomically, limited, according to George and Al. Meningiomas and neuromas are the main tumors encountered intradurally, while extradural ones are mainly represented by chordomas and bone tumors. The objective of this work was to study the radio-clinical and anatomopathological characteristics, the place of surgery in the therapeutic management, as well as the prognostic factors of this pathological entity through a series of 10 cases collected at the service of Neurosurgery of the Mohamed VI of Marrakech, with literature review. The FM, unusual seat of expansive processes, gives passage to several vital anatomical structures which make the gravity and the particularity of this pathological entity. The preposterous clinical symptomatology, where no sign is pathognomonic, can simulate several other neurological disorders. MRI is the most useful and least invasive examination for the diagnosis and management of foramen magnum tumors. The optimal therapeutic option is total excision of the tumour. However, given the location, nature and tumor volume as well as the involvement of the vertebral artery, the surgical procedure may be limited to subtotal excision. Several surgical approaches have been described to increase efficiency and minimize operative morbidity. A midline posterior approach combined with microsurgical techniques yields good results. Postoperative complications can be dramatic and should be anticipated. The histological spectrum essentially includes meningiomas and neuromas. The prognosis largely depends on the early diagnosis and treatment, the preoperative neurological state, the location and extent of tumor excision, as well as the quality of care provided postoperatively.

Surgical management of a foramen magnum tumor via a far-lateral approach using an oblique straight incision: a case series report and technique note.

To review our single-institution experience in the surgical management of foramen magnum tumors via a far-lateral approach using an oblique straight incision. From October 2023 to January 2024, four cases of tumors in the foramen magnum area treated at the Capital Medical University-affiliated XuanWu hospital neurosurgery department were involved in this study. All cases were managed with a far-lateral approach using an oblique straight incision. We retrospectively reviewed the clinical and imaging data, as well as the surgical strategies employed. Three cases of foramen magnum meningiomas and one case of glioma of the ventral medulla. All cases underwent a far-lateral approach using an oblique straight incision; all cases had a gross total resection, and the wounds healed well without cerebral fluid leakage or scalp hydrops. Except for one case of right foramen magnum meningioma, which had dysphagia and pneumothorax, the other cases were without any postoperative complications. A far-lateral approach using an oblique straight incision can preserve muscle integrity and minimize subcutaneous exposure, allowing for complete anatomical reduction of muscles. This craniectomy method is simple and replicable, making it worthy of further clinical practice.

Craniovertebral junction aneurysms

ObjectiveThe course of the vertebral artery and its relationship to the C0–1–2 structures render it particularly vulnerable to mechanical trauma. In the present study, we investigated the course of vertebral arteries along the craniovertebral junction (CJ) to cast light on the biomechanical aspects of aneurysm formation, focusing mainly on the relation of the vertebral artery injuries to the CJ bony landmarks. Herein, we report our experience with fourteen cases of craniovertebral junction vertebral artery (CJVA) aneurysms and their presentations, management, and outcomes. Materials and methodsWe extracted from 83 vertebral artery aneurysms only those 14 cases whose aneurysms were located at the C0–1–2. We reviewed all medical records, including operative reports and radiologic images. We divided the CJVA into 5 segments and then carefully reviewed the cases, largely focusing on the CJVA segments involved in the aneurysm. Angiographic outcomes were determined by angiography, which was scheduled at 3–6 months, 1, 2.5, and 5 years postoperatively. ResultsA total of 14 patients with CJVA aneurysms were included in the present study. 35.7 % had cerebrovascular risk factors, while 23.5 % had other predisposing factors such as an AVM, an AVF, or a foramen magnum tumor. Predisposing factors in the form of neck trauma, both direct and indirect, were identified in 50 % of cases. The segmental distribution of aneurysms was as follows: three (21.4 %) at CJV 1, one (7.1 %) at CJV 2, four (28.6 %) at CJV 3, two (14.3 %) at CJV 4, and four (28.6 %) isolated to the CJV 5 segment. Of the 6 indirect traumatic aneurysms, 1 (16.7 %) was located at CJV 1, 4 (66.7 %) were located at CJV 3 and 1 (16.7 %) was located at CJV 5. The 1/1 direct traumatic aneurysm (100 %) from the penetrating injury was located at CJV 1. 100 % of cases with cerebrovascular risk factors, the affected vessels were on the dominant side. 42.9 % of cases presented symptoms of a vertebrobasilar stroke. All 14 aneurysms were managed only endovascularly. 85.8 % of patients we implemented flow diverters only. 57.1 % of follow-up cases were completely occluded angiographically, and 42.9 % of cases were near-completely or incompletely occluded at 1, 2.5, and 5-year follow-ups. ConclusionsThe current article is the first report of a series of vertebral artery aneurysms located in CJ. Herein, the association of vertebral artery aneurysm, hemodynamics, and trauma is well established. We clarified all segments of the CJVA and showed that the segmental distribution of CJVA aneurysms significantly differs between traumatic and spontaneous cases. We showed that treatment with flow diverters should be the mainstay of CJVA aneurysm treatment.

Dejerine Syndrome Variant Due to Medullary Perforating Artery Ischemia During Foramen Magnum Meningioma Resection: 2-Dimensional Operative Video.

Foramen magnum meningiomas are a formidable disease entity whose resection requires intimate knowledge of the relevant neurovascular anatomy. Due attention is given to the anterior spinal artery and the importance of its preservation to avoid devastating deficits from anterior spinal artery syndrome. There is an underappreciated but clinically significant set of perforating arteries arising from the distal vertebral arteries at the vertebrobasilar junction that supply the medial and anterior medulla through the ventrolateral sulcus.1-3 Injury to or occlusion of these arteries causes a brainstem infarction known as medial medullary syndrome, or Dejerine syndrome, which mainly involves the pyramidal tracts, hypoglossal nucleus, and medial lemniscus.4 Here, we describe an incomplete variant of Dejerine syndrome exclusively involving the pyramids, occurring during surgical resection of a foramen magnum meningioma. These arteries are analogous to the perforators of the distal basilar artery whose importance was highlighted by Drake's seminal work.5,6 The patient underwent resection of a ventral foramen magnum meningioma, complicated by the need for vertebral artery stenting. The patient promptly lost motor-evoked potentials while somatosensory-evoked potentials remained perfectly at baseline. The patient was initially densely quadriplegic postoperatively, without sensory or cranial nerve deficits. MRI demonstrated T2 hyperintensity limited exclusively to the pyramids. After a long convalescence, she fortunately made a full recovery. We highlight the knowledge and preservation of the perforators at the vertebrobasilar junction during resection of foramen magnum tumors. The patient consented to surgery and publication of her images. Images at 6:50 from Yaşargil MG,3 and Bassetti C et al, Medial Medullary Stroke, Neurology, 48(4), 1997; both reused with permission. {"href":"Single Video Player","role":"media-player-id","content-type":"play-in-place","position":"float","orientation":"portrait","label":"","caption":"","object-id":[{"pub-id-type":"doi","id":""},{"pub-id-type":"other","content-type":"media-stream-id","id":"1_9i4ea1gx"},{"pub-id-type":"other","content-type":"media-source","id":"Kaltura"}]}

Surgical management of foramen magnum tumours – experiences with 20 cases

Surgical management of foramen magnum tumours – experiences with 20 cases

Far lateral approach without occipital condylar resection for intradural ventral/ventrolateral foramen magnum tumors and aneurysms of V4 segment of vertebral artery: Review of surgical results

BackgroundControversies exist regarding the need and extent of condylar resection for safe surgical management of intradural ventral/ventrolateral foramen magnum (VFM) tumors and aneurysms of V4 segment of vertebral artery (VA) by far lateral approach. This retrospective study was conducted to evaluate the results of basic far lateral approach(retrocondylar approach) without upfront occipital condylar resection. Methods and ResultsTwenty one patients underwent surgery via far lateral approach for intradural VFM tumors and aneurysms of V4 segment of VA at Sri Sathya Sai Institute of Higher Medical Sciences during 9 years(2008–2016) study period. Eight patients had VA aneurysms and 13 patients had intradural VFM tumors. After basic far lateral approach(retrocondylar approach), dura was opened and checked if the exposure was adequate for safe surgery. Retrocondylar approach provided adequate exposure for all these lesions and resection of occipital condyle/jugular tubercle was not required in any of these cases. Skeletonization or transposition of VA was not done in any of these cases. Gross total resection of the tumor could be done in 9 patients(9/13–69.2 %) and near total excision (>95 %) in 4 patients (4/13–30.8 %). Seven of the 8 VA aneurysms were successfully clipped. Outcome at a final follow up of 3 months or more was good(mRS<2) in 19 patients(19/21–90.5 %) and poor in 2 patients. Complications included lower cranial nerve deficits [transient-2/21(9.5 %), persisting-2/21(9.5 %)], motor deficits(2/21−9.5%), seventh nerve paresis(1/21−4.8%), sixth nerve paresis(2/21−9.5%) and pseudomeningocele(1/21−4.8%). ConclusionBasic far lateral (retrocondylar) approach provides excellent exposure for majority of VFM tumors and aneurysms of V4 segment of VA. Condylar resection(transcondylar approach), drilling of jugular tubercle (transtubercular approach), skeletonization/transposition of VA might not be required for safe surgical management of majority of these lesions.

Continuous progression of hemorrhage of sphenoid ridge meningioma causing cerebral hernia: A case report and literature review

The aim of the present study was to explore the clinical characteristics of repeated hemorrhages of meningioma and analyze the causes of hemorrhage. Meningiomas are mostly benign tumors that rarely manifest hemorrhagic strokes. In the present study, a case of sphenoid ridge meningioma with repeated hemorrhages is reported. Internal hemorrhage was first observed, which, on further aggravation, formed a hematoma in the brain parenchyma and finally led to the development of a hernia. No neurological deficit was present after surgery and rehabilitation. A postoperative pathological examination showed increased levels of Ki-67, abnormal blood vessels in the tumors and the presence of progesterone, which indicate possible causes of the hemorrhage. A review of associated previous studies revealed that hemorrhages originate mainly from inside the meningioma. Two cases of meningiomas with repeated hemorrhages have been reported; one in the foramen magnum region and the other in the pineal gland area. The foramen magnum tumor had an interval of 1.33 months between two hemorrhagic episodes. Collecting relevant data from the latter case was not possible. In the present case report, the interval between two bleeding episodes was 3 days. The literature review also revealed that the average age of onset of meningioma is relatively young at only 28.00±6.24 years. In conclusion, repeated hemorrhages in meningiomas are extremely rare and the causes have not yet been identified. Increased Ki-67 and abnormally proliferating blood vessels may be potential causes of hemorrhage. Early diagnosis and rapid surgical intervention are essential to prevent further episodes of bleeding, which may otherwise have fatal consequences for the patients.

External syringomyelia in longstanding benign foramen magnum tumors.

Background: The effect of benign foramen magnum tumours on cranial and spinal dimensions and cerebrospinal fluid (CSF) spaces is unclear. In this study, we measured alterations in cerebrospinal fluid (CSF) spaces in the spinal canal and in the posterior cranial fossa distant from the site of benign foramen magnum tumors.Methods: Twenty-nine magnetic resonance imaging scans of patients with foramen magnum tumors (8 meningiomas and 21 C2 neurinomas) were identified for radiological morphometric analysis and compared with normal control scans. The anterior-posterior distance between the pontomedullary junction and the clivus, the spinal canal diameter, spinal cord diameter, and cord-canal ratios were measured at the C6 and T2 levels.Results: The mean spinal canal diameter was significantly higher in tumor scans at both the C6 and T2 spinal levels than in controls (13.8 mm vs. 11.4 mm at C6; p<0.0001, and 12.9 mm vs. 11.9 mm at T2; P=0.01). Further, the mean cord:canal ratio was significantly lower in tumor scans at both levels (0.49 vs. 0.64 at C6; P<0.0001, and 0.45 vs. 0.54 at T2; P=0.0009). There was no significant difference in mean anteroposterior distance from the clivus to the pontomedullary junction (10.4 mm vs. 10.3 mm; P=0.91).Conclusion: In the presence of benign foramen magnum tumors, the spinal canal diameter and CSF volume in the spinal canal increased at the C6 and T2 levels, distant from the tumor site, a phenomenon we describe as “external syringomyelia”.

Tailored Surgical Approaches for Foramem Magnum Tumors

Objective To describe our surgical techniques, analyze their safety and their postoperative outcomes for foramen magnum tumors (FMTs). Methods From 1986 to 2014, 34 patients with FMTs underwent surgeries using either the lateral suboccipital approach, standard midline suboccipital craniotomy, or the far lateral approach, depending on the anatomic location of the lesions. Results In the present series, there were 22 (64.7%) female and 12 (35.2%) male patients. The age of the patients ranged from 12 to 63 years old. We observed 1 operative mortality (2.9%). A total of 28 patients (82.3%) achieved a score of 4 or 5 in the Glasgow Outcome Scale (GOS). Gross total resection (GTR) was obtained in 22 (64.7%) patients. After the surgery, 9 (26%) patients developed lower cranial nerve dysfunction (LCNd) weakness. The follow-up varied from 1 to 24 years (mean: 13.2 years). Conclusion The majority of tumors located in the FM can be safely and efficiently removed using either the lateral sub occipital approach, standard middle line sub occipital craniotomy, or the far lateral approach, depending on the anatomic location of the lesions.

Three-Dimensional Computed Tomography Angiography Assisted Resection of Ventral Foramen Magnum and Jugular Foramen Tumours via Modified Far Lateral Suboccipital Approach

Objective: The anatomical relationship of ventral foramen magnum and jugular foramen tumour is complex and the operation is very difficult. The aim of this study was to summarize the microsurgical experience of the removal of the ventral foramen magnum and jugular foramen tumours via the modified far lateral suboccipital approach assisted by three-dimensional computed tomography angiography (3D-CTA). Methods: The clinical data and follow-up results of 13 cases of 3D-CTA assisted suboccipital far lateral approach from July 2011 to September 2017 were analyzed retrospectively. There were 5 males and 8 females. Preoperative CT and MRI were used for routine imaging diagnosis, and the 3D-CTA simulated surgical approach was performed. The preoperative operation scheme was established, and the risk of operation was evaluated according simulated operation. After individualized exposure, the modified far lateral suboccipital approach was completed under the neuroelectrophysiological monitoring technique. Results: The preoperative images were completely consistent with the findings in the surgery. There were 9 cases of jugular foramen tumour and 4 cases of ventral foramen magnum tumour. Of the 13 cases, only 1 case of jugular glomus tumour had extra-cranial residual, while the whole intracranial tumour was removed. In other 12 cases, the tumours were completely removed under the microscope. After operation, the headache disappeared, and hearing loss was improved. There was no perioperative deaths, infection and cerebrospinal fluid leakage. The facial paralysis was occurred in 1 patient. After 3–39 months of follow-up, there was no recurrence of tumour, or new nerve function defect. Hoarseness, choking of drinking water and numbness of limbs were all improved at the end of the follow-up period. The symptoms of postoperative facial paralysis were also improved during the follow-up period. Conclusion: After the preoperative simulation and evaluation by 3D-CTA, the ventral foramen magnum and jugular foramen tumours can be rescted safely and effectively via far modified lateral suboccipital approach.

Pre- and Intra-Operative Supporting Technology for Brain Tumors(9)Surgery for Foramen Magnum Tumors

Pre- and Intra-Operative Supporting Technology for Brain Tumors(9)Surgery for Foramen Magnum Tumors

Predictors of Acute Vertebrobasilar Vasospasm following Tumor Resection in the Foramen Magnum Region.

ObjectiveCerebral vasospasm can occur after skull base tumor removal. Few studies concentrated on the posterior circulation vasospasm after tumor resection in the posterior fossa. We aimed to identify the risk factors associated with postoperative vertebrobasilar vasospasm after tumor resection in the foramen magnum.MethodsWe retrospectively reviewed the data of 62 patients with tumors in the foramen magnum at our institution from January 2010 to January 2015. The demographic data, tumor features, surgical characteristics were collected. Vertebrobasilar vasospasm was evaluated by bedside transcranial Doppler before surgery and on postoperative day 1, 3, 7. Univariate and multivariate analyses were performed to determine the predictors of postoperative vasospasm in the posterior circulation.ResultsVertebrobasilar vasospasm was detected in 28 (53.8%) of the 62 patients at a mean time of 3.5 days after surgery. There were 5 (8%) patients with severe vasospasm according to the grading criteria. Age, tumor type, tumor size, vertebral artery encasement, and surgical time were significantly related to vasospasm in the univariate analysis. Further multivariate analysis demonstrated that only age and vertebral artery encasement were independent risk factors predicting the occurrence of postoperative vertebrobasilar vasospasm.ConclusionsThe incidence of acute vertebrobasilar vasospasm is not uncommon after foramen magnum tumor resection. Age and vertebral artery encasement are significantly correlated with postoperative vasospasm. Close monitoring of vasospasm should be given to patients with younger age and the presence of vertebral artery encasement on the preoperative imaging to facilitate early diagnosis and intervention.

Extramedullary foramen magnum tumors and their surgical management: An experience with 29 cases.

Introduction:Surgical management of foramen magnum (FM) tumors is challenging by virtue of their location and vital neurovascular relationships. The ideal approach to anterior/anterolateral tumors continue to evoke controversy even in the modern era. In this article, we present and discuss our experience in the surgical management of these tumors.Materials and Methods:This retrospective study includes 29 consecutive patients (mean age 36.6 years, M: F = 2.63:1) of extramedullary tumors at the surgical foramen magnum, operated at our center, between 2007 and 2012.Results:Their mean duration of symptoms was 14. 6 months. A majority of the patients presented with motor symptoms (quadri/paraparesis, n = 21, 72.4%), neck pain with/without suboccipital radiation (n = 16, 55.2%) and sensory symptoms like tingling/numbness (n = 16, 55.2%). There were nine extradural (31%) and 20 intradural tumors (69%). Most of the tumors were located posterolateral to the neuraxis (n = 13, 44.8%). Nerve sheath tumors (n = 11, 38%) and meningiomas (n = 5, 17.2%) were the most commonly encountered histologies in our series. The standard posterior approach was the most frequently employed surgical approach (n = 20, 69%). Operative mortality and morbidity were 3.4 and 18.9%, respectively. At a mean follow-up of 27.3 months, 13 out of the 18 available patients improved.Conclusion:A majority of the foramen magnum tumors are amenable to excision via the standard posterior approach. Small anterior dural-based meningiomas/recurrent tumors may require a lateral approach like the far lateral approach.

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.

MS-07 * MENINGIOMA OF THE PEDIATRIC SKULL BASE: A REVIEW

Pediatric skull base meningiomas are rare and complex clinical entities. Meningioma is a relatively uncommon brain tumor in children, and only about 27% involve the skull base. Some evidence suggests that these tumors are more likely to be atypical or malignant in children than adults. The absence of female preponderance in pediatric meningiomas is reflected in the skull base subpopulation. Skull base meningiomas in children are most likely to be found in the anterior or middle fossa base, or involving the orbit and optic nerve sheath. Petroclival, suprasellar/parasellar, cerebellopontine angle, cavernous sinus, and foramen magnum tumors are very rare. Meningiomas constitute a small proportion of reported cases of pediatric skull base pathology, and are entirely absent from many case series. Initial gross total resection is consistently associated with superior outcomes. Surgical approaches to the pediatric skull base must take additional factors into consideration including relatively smaller anatomy, immature dentition, incompletely aerated sinuses and air cells, and altered configurations of structures such as the pterional bony complex. Multidisciplinary expertise is essential to optimizing treatment outcomes.

Meningiomas of the pediatric skull base: a review.

Pediatric skull base meningiomas are rare and complex clinical entities. Meningioma is a relatively uncommon brain tumor in children, and only ∼ 27% involve the skull base. Some evidence suggests that these tumors are more likely to be atypical or malignant in children than adults. The absence of female preponderance in pediatric meningiomas is reflected in the skull base subpopulation. Skull base meningiomas in children are most likely to be found in the anterior or middle fossa base, or involving the orbit and optic nerve sheath. Petroclival, suprasellar/parasellar, cerebellopontine angle, cavernous sinus, and foramen magnum tumors are very rare. Meningiomas constitute a small proportion of reported cases of pediatric skull base pathology, and they are entirely absent from many case series. Initial gross total resection is consistently associated with superior outcomes. Surgical approaches to the pediatric skull base must take additional factors into consideration including relatively smaller anatomy, immature dentition, incompletely aerated sinuses and air cells, and altered configurations of structures such as the pterional bony complex. Multidisciplinary expertise is essential to optimizing treatment outcomes.

Clinical classification and microsurgical treatment of foramen magnum tumors

Objective To explore the clinical classification,microsurgical operation methods and techniques of the tumors located at foramen magnum region.Methods 102 cases of foramen magnum tumors were resected by microsurgical operations in neurosurgery department of West China Hospital of Sichuan University from September 2005 to September 2013,and the clinical data of all cases were retrospectively analyzed.According to the results of clinical imaging,these cases with foramen magnum tumors were classified into 3 clinical types as follows:(1) Ventral type:tumor was located at ventral of medulla oblongata-cervical spinal cord,and there were 3 cases (2.9％) of meningioma belonging to such type; (2) Lateral type:tumor was located at lateral,ventrolateral or dorsolateral of medulla oblongata-cervical spinal cord,and there were 85 cases (83.3％) belonging to such type,including 35 cases of meningioma,48 cases of schwannoma and 2 cases of epidermoid cyst; (3)Intramedullary type:tumor was located in medulla of medulla oblongata-cervical spinal cord,and there were 14 cases (13.7％) belonging to such type,including 5 cases of ependymoma,7 cases of hemangioblastom a,and 2 cases of cavernous hemangioma.All cases of these foramen magnum tumors were resected in one-stage,and these tumors were resected by different microsurgical operation methods according to clinical classification.The tumors of ventral and intramedullary types were reseeted by posterior occipitocervical bilateral approach,while the lateral type by posterior occipitocervical unilateral approach.Results 96(94.1％) cases of foramen magnum tumors were totally resected,4 subtotally resected,and 2 partially resected.The follow-up period ranged from 3 months to 8 years (mean duration:3.6 years).The clinical manifestation was improved in 97(95.1％)cases,aggravated in 5,4 recurred and there was no spinal deformity.Conclusions Using the clinical classification of foramen magnum tumors to guide the choice of surgical approach not only improved the totally removal rate of tumors,but also helped to reduce the surgical trauma.Furthermore,it could maximally maintain the stability of the occipital-cervical junction area. Key words: Foramen magnum ; Tumor; Clinical classification ; Microsurgery

Foramen magnum syndrome from a tumor in a neurofibromatosis type 1 patient

Foramen magnum tumors are rare in neurofibromatosis type 1. They may present with bizarre symptoms and may mimic many neurological conditions. We report a case of foramen magnum syndrome secondary to tumor misdiagnosed as cervical spine tuberculosis.

Microsurgical treatment of tumours in foramen magnum:58 cases report

Objective To explore the optimal diagnosis and treatment strategy of tumors at the foramen magnum,the clinical characteristics were analyzed retrospectively.Methods The clinical data of 58 cases with foramen magnum tumors treated with microsurgery in our department were collected and analyzed retrospectively.And intraoperative neurophysiological monitoring was employed in later 21 cases.Results Gross total resection was achieved in 48 of the 58 cases ; Five of the 10 patients with VA encased by tumors were totally resected.Full resection was achieved in 43 of the last 48 cases.Forty-three of the 47 cases with intradural tumors got complete resection,and total resection was achieved in 3 and 2,respectively,in 9 intra-extradural communicated tumors and 2 extradural ones.Symptoms were significantly improved in 50 cases,worsened in 5 patients,and maintained stable in the last 3 patients.Post-operative symptoms were obviously improved in the later 21 cases with intraoperative neurophysiological monitoring employed and the therapeutic effect of the treatment was much better than the former cases.Three patients died postoperatively.Fifty cases got complete follow-up from 6 months to 3 years.Among them,forty-four patients had a KPS score of 80-100,but the other 6 patients less than 80.Conclusion Microsurgical treatment for foramen magnum tumors is effective.Optimal surgical approaches and precise micro-operative techniques are crucial for the tumor removing.It is quite difficult and risky to fully resect the intra-extradural communicated tumors and the ones encasing vertebral artery.Preoperative evaluation should be profound.The application of intra-operative electrophysiological monitoring and the timely management of post-operative complications can improve the prognosis obviously. Key words: Foramen magnum; Tumor; Intraoperative neurophysiological monitoring; Microneurosurgery

Transcondylar Fossa (Supracondylar Transjugular Tubercle) Approach: Anatomic Basis for the Approach, Surgical Procedures, and Surgical Experience

The authors clarify the anatomic basis and the usefulness of the transcondylar fossa approach (T-C-F A), in which the posterior portion of the jugular tubercle is removed extradurally through the condylar fossa with the atlanto-occipital joint intact. The authors first performed an anatomic study to identify the area to be removed using cadaveric specimens and then applied the T-C-F A to foramen magnum surgeries. The surgeries included clipping a vertebral artery-posterior inferior cerebellar artery aneurysm in 11 cases, microvascular decompression for glossopharyngeal neuralgia in 15 cases, and removing intradural foramen magnum tumors in 17 cases. Only the condylar fossa was removed, but the approach offered very good visualization of the lateral part of the foramen magnum and sufficient working space. These surgeries were performed safely without major complications. This skull base approach is minimally invasive and is not difficult. Therefore, it can be a standard approach for accessing intradural lesions of the foramen magnum. It can be combined with the transcerebellomedullary fissure approach from the lateral side and can also be easily changed to the transcondylar approach, if necessary.