Foramen magnum meningiomas--experience with the posterior suboccipital approach

[Minimally invasive surgical treatment of extramedullary tumors at the level of craniovertebral junction: experience of the Burdenko Neurosurgical Center]

OBJECTIVE

To describe own experience of treating patients with extramedullary tumors at the level of craniovertebral junction using minimally invasive surgical approaches.

MATERIAL AND METHODS

The study included 29 patients who underwent minimally invasive microsurgical resection of extramedullary tumors at the level of craniovertebral junction. We analyzed the main clinical and surgical parameters.

RESULTS

Gross total resection was achieved in most patients with high degree of safety. Two patients required redo surgery due to CSF leakage and soft tissue cyst. Mean length of hospital-stay was 7 days. VAS score of pain syndrome at discharge was 2 points and 0 points after 3 months. No significant differences in neurophysiological monitoring indicators were observed (p=0.76).

CONCLUSION

Minimally invasive posterior approaches to extramedullary tumors at the level of craniovertebral junction can significantly reduce surgical trauma with equal extent of resection.

[Benign extramedullary spinal cord tumors at the level of craniovertebral junction: a systematic review]

Extramedullary spinal cord tumors at the level of craniovertebral junction are a rare group of neoplasms with their own characteristics. Taking into account the peculiarities of clinical course and complex anatomy of craniovertebral complex, these tumors present a complex diagnostic and surgical problem. A systematic review of literature data on epidemiology, clinical picture, diagnostic methods and dorsal minimally invasive methods of surgical treatment of patients with extramedullary spinal cord tumors of craniovertebral junction was performed.

Transmastoid Trautman's Triangle Combined Low Retrosigmoid Approach for Foramen Magnum Meningiomas: Surgical Anatomy and Technical Note

Objective  This study was aimed to assess the potential of utilizing a transmastoid Trautman's triangle combined low retrosigmoid approach for ventral and ventrolateral foramen magnum meningiomas (FMMs) surgical treatment. Methods  We simulated this transmastoid Trautman's triangle combined low retrosigmoid approach using five adult cadaveric heads to explore the associated anatomy in a step-by-step fashion, taking pictures of key positions as appropriate. We then employed this approach in a single overweight patient with a short neck who was suffering from large ventral FMMs and cerebellar tonsillar herniation. Results  Through cadaver studies, we were able to confirm that this transmastoid Trautman's triangle combined with low retrosigmoid approach achieves satisfactory cranial nerve and vasculature visualization while also offering a wide view of the whole of the ventrolateral medulla oblongata. We, additionally, have successfully employed this approach to treat a single patient suffering from large ventral FMMs with cerebellar tonsillar herniation. Conclusion  This transmastoid Trautman's triangle combined low retrosigmoid approach may represent a complement to treatment strategies for ventral and ventrolateral FMMs, particularly in patients with the potential for limited surgical positioning due to their being overweight, having a short neck and suffering from cerebellar tonsillar herniation.

Foramen magnum meningioma: Series of 20 cases. Complications, risk factors for relapse, and follow-up

Introduction:

Meningiomas account for 2.2% to 2.5% of all cerebral tumors, of which only 2% are located in the foramen magnum. Foramen magnum meningiomas (FMMs) are commonly found in women, with a mean age at onset of 52 years old. They generally behave more aggressively than other meningiomas.

Materials and Methods:

We performed epidemiological, anatomical and surgical analyses of 20 patients diagnosed with FMMs who underwent surgical treatment from 1999 to 2019 at Santa Paula Hospital in Sao Paulo. This case series was compared with previously published ones to better understand this relatively rare disease.

Results:

Twenty patients were included, with a mean follow-up of 110 months. Their mean age was 37.8 years old. The mean preoperative Karnofsky performance status scale (KPS) was 84%. We found a female (65%) and left hemisphere predominance (50%). Involvement of both hemispheres was found in 25% of patients. FMM locations were anterior, anterolateral, lateral and posterior, in 45%, 35%, 10%, and 10%, respectively. Simpson resection grades I, II, and III were achieved in 25%, 60%, and 15% of cases, respectively. Mean postoperative KPS was 79%. Three patients with anterior and bilateral located meningiomas had a worse postoperative KPS in comparison to the preoperative one.

Conclusion:

Anterior and bilateral FMMs seem to be related to a worse prognosis. A gross total resection can reduce the recurrence rates. The KPS is worse in patients with recurrence.

Foramen magnum meningiomas: a systematic review and meta-analysis

Foramen magnum meningiomas (FMMs) account for 1.8–3.2% of all meningiomas. With this systematic review and meta-analysis, our goal is to detail epidemiology, clinical features, surgical aspects, and outcomes of this rare pathology. Using PRISMA 2015 guidelines, we reviewed case series, mixed series, or retrospective observational cohorts with description of surgical technique, patient and lesion characteristics, and pre- and postoperative clinical status. A meta-analysis was performed to search for correlations between meningioma characteristics and rate of gross total resection (GTR). We considered 33 retrospective studies or case series, including 1053 patients, mostly females (53.8%), with a mean age of 52 years. The mean follow-up was of 51 months (range 0–258 months). 65.6% of meningiomas were anterior, and the mean diameter was of 29 mm, treated with different surgical approaches. Postoperatively, 17.2% suffered complications (both surgery- and non-surgery-related) and 2.5% had a recurrence. The Karnofsky performance score improved in average after surgical treatment (75 vs. 81, p < 0.001). Our meta-analysis shows significant rates of GTR in cohorts with a majority of posterior and laterally located FMM (p = 0.025) and with a mean tumor less than 25 mm (p < 0.05). FMM is a rare and challenging pathology whose treatment should be multidisciplinary, focusing on quality of life. Surgery still remains the gold standard and aim at maximal resection with neurological function preservation. Adjuvant therapies are needed in case of subtotal removal, non-grade I lesions, or recurrence. Specific risk factors for recurrence, other than Simpson grading, need further research.

Natural history of intracranial meningiomas

We know that the extent of resection is the greatest predictor of long-term survival. However, the potential tradeoff for gross total resection in difficult locations is diminished quality of life. Benign subtotally resected or small incidentally discovered meningiomas may be followed clinically especially in the elderly. In addition, radiosurgery plays a role in the treatment of meningiomas as a primary treatment modality, or as a salvage therapy. Decisions regarding management should be made with an understanding of the natural history and rate of growth. In this chapter we review the known meningioma epidemiology as well as the growth patterns of meningiomas based upon location.

Mirror meningioma at foramen magnum: Enigma in management of a very rare case

Background:

We report a very rare case of bilateral foramen magnum mirror meningioma and discuss difficulties in managing the surgical challenge. To the best of our knowledge, mirror foramen magnum meningioma (FMM) has been reported only once in literature. FMMs are rare and also a great challenge for neurosurgeons due to the complex anatomy of this area. The purpose of this article is to illustrate the rare occurrence of bilateral meningioma in the foramen magnum and the difficulties in managing the surgical challenge.

Case Description:

A case of a 45-year-old female presented with neck pain, paresthesia in all four limbs, and difficulty in walking for 1 year duration. Magnetic resonance imaging revealed well-defined lobulated dural based mass lesion at foramen magnum on both sides. The left vertebral artery (VA) was encased within the lesion while the right VA was seen abutting it. Tumor was resected gross totally on the right side. However, during the resection of the medial part of the left side tumor, it was found to be adhered to the VA. Since the mass was adherent to the left VA, subtotal resection was done.

Conclusion:

There is no single best surgical approach for FMMs and the optimal approach should be defined according to the localization and the extent of the tumor to minimize the extent of resultant morbidity. Although complete excision of the tumor is the aim of surgery, it is safer to leave portions of tumor that is adherent to critical structures which can be managed by Gamma Knife radiosurgery.

Endoscopic Endonasal and Transcranial Surgery for Microsurgical Resection of Ventral Foramen Magnum Meningiomas: A Preliminary Experience

BACKGROUND

Purely ventral foramen magnum meningiomas are challenging tumors to treat given their location, and proximity and relationship to vital neurovascular structures.

OBJECTIVE

To present endoscopic endonasal surgery (EES) as a complementary approach to the far-lateral suboccipital approach (FLA) for ventral midline tumors.

METHODS

From May 2008 to October 2013, 5 patients underwent EES and 5 FLA for primary ventral foramen magnum meningiomas. We retrospectively reviewed their records to evaluate outcomes.

RESULTS

Nine of 10 patients presented with long-tract and lower cranial nerve deficits. All patients who presented with deficits preoperatively completely normalized after tumor resection regardless of approach. Gross total resection was achieved in 2 cases in the EES group and 4 cases in the FLA group (the rest were near total). Vascular encasement was a limitation to gross total resection with both approaches. Preoperative median Karnofsky Performance Scale score was 80 and improved to 100 in both groups. Following EES, 1 patient developed cerebrospinal fluid leak with resultant meningitis. Two patients developed hydrocephalus, one of which developed an epidural abscess following necrosis of the nasoseptal flap, requiring debridement. In the FLA group, 1 patient developed a pseudomeningocele associated with hydrocephalus. One patient developed an abdominal fat graft site hematoma.

CONCLUSION

Both approaches provide excellent results for resection of ventral foramen magnum meningiomas, with reconstruction and hydrocephalus as the main sources of complication. In our practice, EES is a preferred technique in ventral, purely midline tumors with limited inferior extension and reduced lower cranial nerve manipulation, whereas FLA is preferred in tumors with lateral and caudal extension below the tip of the dens.

Our surgical experience in foramen magnum meningiomas: clinical series of 11 cases

INTRODUCTION

We aimed to discuss surgical approaches and results that we applied foramen magnum meningiomas.

METHODS

We retrospectively investigated 11 foramen magnum meningioma cases, who had been operated between the dates of February 2012 and March 2017.

RESULTS

Eight of the patients were females and 3 of the patients were males, the age range was 32-75 and the age average was 60.8. 5 of the tumors were anatomically localized as posterolateral, 2 of them were localized as anterolateral, 2 of them were localized as lateral and 2 of them were localized as anterior according to the brain stem or spinal cord. Posterior far lateral (4 patients) approach including C1 laminoplasty (7 patients) and 1/3 condyle resection was surgically applied to the patients with median suboccipital craniotomy. Gross total excision was applied to 82% of the patients (9 patients) and subtotal mass excision was applied to 18% (2 patients) of the patients. The most frequent post-operative complications were temporary lower cranial nerve (CN IX and X ) palsy in our 2 anterior localized cases (18%) and also cerebrospinal fluid (CSF) fistula in our 1 anterior localized case with difficulty in swallowing (dysphagia). Karnofsky scores of the patients, who were followed for 18 months in post-operative 12 and 48 months of average, in the last follow-up were 80 and no post-operative mortality occurred.

CONCLUSION

Posterior midline suboccipital and far lateral approaches that we apply in our own series were appropriate approaches for foramen magnum meningiomas.

Stereotactic radiosurgery for WHO grade I posterior fossa meningiomas: long-term outcomes with volumetric evaluation

OBJECTIVEResearch over the past 2 decades has been characterizing the role of stereotactic radiosurgery (SRS) in the treatment of benign intracranial tumors, including meningiomas. However, few studies have examined the long-term outcomes of SRS treatment for posterior fossa meningiomas (PFMs). Furthermore, previous studies have typically used single diameter measurements when reporting outcomes, which can yield misleading results. The authors describe the use of SRS in the treatment of benign WHO grade I PFMs and correlate volumetric analysis with long-term outcomes.METHODSThis study is a retrospective analysis of a prospectively maintained IRB-approved database. Inclusion criteria were a diagnosis of WHO grade I PFM with subsequent treatment via single-session SRS and a minimum of 3 follow-up MRI studies available. Volumetric analysis was performed on the radiosurgical scan and each subsequently available follow-up scan by using slice-by-slice area calculations of the meningioma and numerical integration with the trapezoid rule.RESULTSThe final cohort consisted of 120 patients, 76.6% (92) of whom were female, with a median age of 61 years (12-88 years). Stereotactic radiosurgery was the primary treatment for 65% (78) of the patients, whereas 28.3% (34) had 1 resection before SRS treatment and 6.7% (8) had 2 or more resections before SRS. One patient had prior radiotherapy. Tumor characteristics included a median volume of 4.0 cm3 (0.4-40.9 cm3) at treatment with a median margin dose of 15 Gy (8-20 Gy). The median clinical and imaging follow-ups were 79.5 (15-224) and 72 (6-213) months, respectively. For patients treated with a margin dose ≥ 16 Gy, actuarial progression-free survival rates during the period 2-10 years post-SRS were 100%. In patients treated with a margin dose of 13-15 Gy, the actuarial progression-free survival rates at 2, 4, 6, 8, and 10 years were 97.5%, 97.5%, 93.4%, 93.4%, and 93.4%, respectively. Those who were treated with ≤ 12 Gy had actuarial progression-free survival rates of 95.8%, 82.9%, 73.2%, 56.9%, and 56.9% at 2, 4, 6, 8, and 10 years, respectively. The overall tumor control rate was 89.2% (107 patients). Post-SRS improvement in neurological symptoms occurred in 23.3% (28 patients), whereas symptoms were stable in 70.8% (85 patients) and worsened in 5.8% (7 patients). Volumetric analysis demonstrated that a change in tumor volume at 3 years after SRS reliably predicted a volumetric change and tumor control at 5 years (R2 = 0.756) with a p < 0.001 and at 10 years (R2 = 0.421) with a p = 0.001. The authors also noted that the 1- to 5-year tumor response is predictive of the 5- to 10-year tumor response (R2 = 0.636, p < 0.001).CONCLUSIONSStereotactic radiosurgery, as an either upfront or adjuvant treatment, is a durable therapeutic option for WHO grade I PFMs, with high tumor control and a low incidence of post-SRS neurological deficits compared with those obtained using alternate treatment modalities. Lesion volumetric response at the short-term follow-up of 3 years is predictive of the long-term response at 5 and 10 years.

A case report of surgical management of hemangiopericytoma at the foramen magnum

Background:

Hemangiopericytoma (HPC) is a highly vascularized mesenchymal tumor known for its high rates of recurrence and metastasis. The extent of tumor removal is known to be the most trustful prognostic factor. Skull base HPCs are challenging to treat because of the difficulty of the surgical approach and proximity to vital vascular and neuronal structures. We successfully treated a case of HPC at the ventral foramen magnum through surgical gross tumor removal via a far-lateral transcondylar approach.

Case Description:

A 38-year-old male complained of neck pain and bilateral paresthesia of his shoulders for 2 months, for which he was referred to our hospital. A magnetic resonance image (MRI) showed a 20 mm diameter mass at the ventral foramen magnum, which compressed his medulla oblongata. The tumor was gross totally removed via a far-lateral transcondylar approach. During the surgery, marked bleeding disturbed the surgical field until the main feeding artery from the direction of the dura mater was coagulated and cut. A relatively wide surgical field and a transcondylar approach were helpful to control the bleeding. The pathological examination revealed the tumor to be a HPC. After an uneventful recovery period of 9 days, the patient was discharged without neurological sequelae.

Conclusion:

We successfully and completely removed an HPC near the foramen magnum, employing a wide surgical field and a transcondylar approach to help control bleeding. When the tumor is suspected preoperatively to be a hemangiocytoma or vascular-rich tumor, a surgical approach that can secure a wide surgical field should be selected.

Foramen magnum meningioma's management: the experience of the department of neurosurgery in Marrakesh

Our study is a retrospective analysis of the clinical data, surgical outcomes, histological finding and prognosis of foramen magnum meningiomas through a serie of 8 cases operated at the department of neurosurgery at Mohammed VI medical university hospital, Marrakesh. From January 2002 to December 2015. There were 3 male and 5 female patients (mean age, 46.75 years). Cervico-occipital pain (100%) and motor deficit (100%) were the most common presenting symptoms. MRI was the most appropriate diagnostic tool in visualizing tumors of this region. All operations were performed by the posterior approach and gross total resection was achieved in 7 cases. Surgical mortality was 20%. 3 other patients had complications like CSF leak (25%), meningitis (12,5%) and transient worsening of neurological deficit (12.5%) but made neurological recovery later. Foramen magnum meningiomas have long been regarded as difficult lesions both in terms of diagnosis and management. However, with the availability of MR imaging, newer surgical techniques and skull base exposures, the excision of these lesions is becoming easier and safer.

[Phase contrast MRI-based evaluation of cerebrospinal fluid circulation parameters in patients with foramen magnum meningiomas]

BACKGROUND

Meningiomas of the foramen magnum (FMR) region account for 1.8 to 3.2% of all meningiomas. The international literature has insufficient data describing the state of cerebrospinal fluid (CSF) circulation in these patients.

MATERIAL AND METHODS

We studied 38 patients with FM meningiomas, aged from 35 to 79 years (mean age, 56.7 years). The mean meningioma size was 30 mm (10-60 mm). Meningiomas had the anterolateral localization in 29 patients, ventral localization in 5 patients, and dorsal localization in 4 patients. Twenty nine patients underwent surgery. All operated patients were examined before and after surgery. The CSF circulation was studied using phase contrast MRI (PC-MRI).

RESULTS

The size and localization of FM meningiomas do not significantly affect the CFS circulation parameters. Pyramidal symptoms, sensory disorders, and XIth cranial nerve dysfunction are correlated with the CFS circulation parameters. According to the preoperative PC-MRI data, the CFS circulation parameters in all FM meningioma patients were significantly higher than their normal values. Surgery was followed by a reduction in the peak positive velocity, negative peak velocity, and range of the maximum linear velocity amplitude. Positive and negative volumes and the stroke volume did not change. Recovery dynamics of the CFS circulation parameters was similar, regardless of surgery completeness. According to the PC-MRI data, the CFS circulation parameters did not reach normal values in all groups of operated patients.

CONCLUSION

The results of investigation of the CFS circulation in patients with FM meningiomas support the use of palliative surgery (partial resection, dural plasty, craniovertebral junction decompression) in the case of inoperable meningiomas.

Prognostic factors affecting the surgical outcome of anterolateral benign tumors in the foramen magnum region

INTRODUCTION

Anterior and anterolateral tumors in foramen magnum region are rare and surgically challenging although most of them are benign. The optimal approach is debatable and prognostic factors affecting surgical outcome remains unclear. We aimed to identify factors including surgical approach determining postoperative outcome.

METHODS

The data of 49 patients diagnosed benign tumors involving the anterior and anterolateral foramen magnum were retrospectively analyzed in our institution from January 2009 to January 2015. The demographic, clinicoradiological, surgical and follow-up information were collected. Primary surgical outcome was new neurological deficits. A multivariate analysis was performed to determine predictors of postoperative neurological deficits.

RESULTS

Patients were operated on either via suboccipital (31 cases, 63.3%) or far lateral (18 cases, 36.7%) approach. Newly developed neurological deficits occurred in 11 (22.4%) patients, improved over time in 6 (12.2%) patients. 2 (4.1%) patients died within 3 month after operation and 2 (4.1%) suffered tumor recurrence. 44 (93.6%) out of 47 survivors had good functional outcome (postoperative Karnofsky performance score ≥80) at last follow-up period. Patients with postoperative new neurodeficits harbored tumors which tended to more frequently involve lower third clivus (p = 0.083), to be meningiomas (p = 0.059), were more likely to be removed through far lateral approach (p = 0.010) and have extradural extension (p = 0.024). Multivariate analysis showed that the far lateral approach was the sole predictor independently related to postoperative neurological deficits (p = 0.029).

CONCLUSIONS

The far lateral approach to benign tumors anterolateral to foramen magnum experienced higher rate of immediate new neurological deficits compared to suboccipital approach. The role of the suboccipital approach may be underestimated and should be further evaluated.

Foramen magnum meningiomas: surgical results and risks predicting poor outcomes based on a modified classification

OBJECTIVE This study aimed to evaluate neurological function and progression/recurrence (P/R) outcome of foramen magnum meningioma (FMM) based on a modified classification. METHODS This study included 185 consecutive patients harboring FMMs (mean age 49.4 years; 124 females). The authors classified the FMMs into 4 types according to the previous classification of Bruneau and George as follows: Type A (n = 49, 26.5%), the dural attachment of the lesion grows below the vertebral artery (VA); Type B (n = 39, 21.1%), the dural attachment of the lesion grows above the VA; Type C1 (n = 84, 45.4%), the VA courses across the lesion with or without VA encasement or large lesions grow both above and below the bilateral VA; and Type C2 (n = 13, 7.0%), Type C1 plus partial/total encasement of the VA and extradural growth. RESULTS The median preoperative Karnofsky Performance Scale (KPS) score was 80. Gross-total resection (GTR) was achieved in 154 patients (83.2%). Lower cranial nerve morbidity was lowest in Type A lesions (16.3%). Type C2 lesions were inherently larger (p = 0.001), had a greater percentage of ventrolateral location (p = 0.009) and VA encasement (p < 0.001), lower GTR rate (p < 0.001), longer surgical duration (p = 0.015), higher morbidity (38.5%), higher P/R rate (30.8%, p = 0.009), and poorer recent KPS score compared with other types. After a mean follow-up duration of 110.3 months, the most recent follow-up data were obtained in 163 patients (88.1%). P/R was observed in 13 patients (7.2%). The median follow-up KPS score was 90. Compared with preoperative status, recent neurological status was improved in 91 (49.2%), stabilized in 76 (41.1%), and worsened in 18 (9.7%) patients. The multivariate Cox proportional hazard regression model demonstrated Type C2 (HR 3.94, 95% CI 1.04-15.0, p = 0.044), nontotal resection (HR 6.30, 95% CI 1.91-20.8, p = 0.003), and pathological mitosis (HR 7.11, 95% CI 1.96-25.8, p = 0.003) as independent adverse predictors for tumor P/R. Multivariate logistic regression analysis identified nontotal resection (OR 4.06, 95% CI 1.16-14.2, p = 0.029) and pathological mitosis (OR 6.29, 95% CI 1.47-27.0, p = 0.013) as independent risks for poor outcome (KPS score < 80). CONCLUSIONS The modified classification helped to predict surgical outcome and P/R in addition to the position of the lower cranial nerves. Preoperative imaging studies and neurological function should be reviewed carefully to establish an individualized management strategy to improve long-term outcome.

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

BACKGROUND

Anterior 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.

METHODS

All 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.

RESULTS

All 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.

CONCLUSION

Based on these results, the posterolateral approach was a simple, effective and safe procedure for anterior and anterolateral intradural lesion of the foramen magnum.

Gamma Knife radiosurgery for posterior fossa meningiomas: a multicenter study

OBJECT

Posterior fossa meningiomas represent a common yet challenging clinical entity. They are often associated with neurovascular structures and adjacent to the brainstem. Resection can be undertaken for posterior fossa meningiomas, but residual or recurrent tumor is frequent. Stereotactic radiosurgery (SRS) has been used to treat meningiomas, and this study evaluates the outcome of this approach for those located in the posterior fossa.

METHODS

At 7 medical centers participating in the North American Gamma Knife Consortium, 675 patients undergoing SRS for a posterior fossa meningioma were identified, and clinical and radiological data were obtained for these cases. Females outnumbered males at a ratio of 3.8 to 1, and the median patient age was 57.6 years (range 12-89 years). Prior resection was performed in 43.3% of the patient sample. The mean tumor volume was 6.5 cm(3), and a median margin dose of 13.6 Gy (range 8-40 Gy) was delivered to the tumor.

RESULTS

At a mean follow-up of 60.1 months, tumor control was achieved in 91.2% of cases. Actuarial tumor control was 95%, 92%, and 81% at 3, 5, and 10 years after radiosurgery. Factors predictive of tumor progression included age greater than 65 years (hazard ratio [HR] 2.36, 95% CI 1.30-4.29, p = 0.005), prior history of radiotherapy (HR 5.19, 95% CI 1.69-15.94, p = 0.004), and increasing tumor volume (HR 1.05, 95% CI 1.01-1.08, p = 0.005). Clinical stability or improvement was achieved in 92.3% of patients. Increasing tumor volume (odds ratio [OR] 1.06, 95% CI 1.01-1.10, p = 0.009) and clival, petrous, or cerebellopontine angle location as compared with petroclival, tentorial, and foramen magnum location (OR 1.95, 95% CI 1.05-3.65, p = 0.036) were predictive of neurological decline after radiosurgery. After radiosurgery, ventriculoperitoneal shunt placement, resection, and radiation therapy were performed in 1.6%, 3.6%, and 1.5%, respectively.

CONCLUSIONS

Stereotactic radiosurgery affords a high rate of tumor control and neurological preservation for patients with posterior fossa meningiomas. Those with a smaller tumor volume and no prior radiation therapy were more likely to have a favorable response after radiosurgery. Rarely, additional procedures may be required for hydrocephalus or tumor progression.

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.

Foramen magnum meningiomas: surgical treatment in a single public institution in a developing country

Objective: To analyze the clinical outcome of patients with foramen magnum (FM) meningiomas. Method: Thirteen patients (11 Feminine / 2 Masculine with FM meningiomas operated on through lateral suboccipital approach were studied. Clinical outcome were analyzed using survival (SC) and recurrence-free survival curves (RFSC). Results: All tumors were World Health Organization grade I. Total, subtotal and partial resections were acchieved in 69.2%, 23.1% and 7.7%, respectively, and SC was better for males and RFSC for females. Tumor location, extent of resection and involvement of vertebral artery/lower cranial nerves did not influence SC and RFSC. Recurrence rate was 7.7%. Operative mortality was 0. Main complications were transient (38.5%) and permanent (7.7%) lower cranial nerve deficits, cerebrospinal fluid fistula (30.8%), and transient and permanent respiratory difficulties in 7.7% each. Conclusions: FM meningiomas can be adequately treated in public hospitals in developing countries if a multidisciplinary team is available for managing postoperative lower cranial nerve deficits.

Surgical outcomes of craniocervial junction meningiomas: a series of 22 consecutive patients

OBJECTIVE

We present our experience in managing craniocervical junction meningiomas and discuss various surgical approaches and outcomes.

METHODS

We retrospectively reviewed 22 consecutive cases of craniocervical junction meningiomas operated on between August 1995 and May 2012.

RESULTS

There were 15 female and 7 male patients (mean age: 54 years). Meningiomas were classified based on origin as spinocranial (7 cases) or craniospinal (15 cases). Additionally, the tumors were divided into anatomical location relative to the brainstem or spinal cord: there were 2 anterior tumors, 7 anterolateral, 12 lateral, and 1 posterolateral. Surgical approaches included the posterior midline suboccipital approach (9 cases), the far lateral approach (12 cases) and the lateral retrosigmoid approach (1 case). Gross-total resection was achieved in 45% of patients and subtotal in 55%. The most common post-operative complications were cranial nerve (CN) IX and X deficits. The mortality rate was 4.5%. There have been no recurrences to date with a mean follow-up was 46.5 months and the mean Karnofsky score at the last follow-up of 82.3. In this series, spinocranial tumors were detected at a smaller size (p=0.0724) and treated earlier (p=0.1398) than craniospinal tumors. They were associated with a higher rate of total resection (p=0.0007), fewer post-operative CN IX or X deficits (p=0.0053), and shorter hospitalizations (p=0.08).

CONCLUSION

Our experience suggests that posterior midline suboccipital or far-lateral approaches with minimal condylar drilling and vertebral artery mobilization were suitable for most cases in this series.

The far-lateral approach for foramen magnum meningiomas

Foramen magnum meningiomas (FMMs) are slow growing, most often intradural and extramedullary tumors that pose significant challenges to the skull base neurosurgeon. The indolent clinical course of FMMs and their insidious onset of symptoms are important factors that contribute to delayed diagnosis and relative large size at the time of presentation. Symptoms are often produced by compression of surrounding structures (such as the medulla oblongata, upper cervical spinal cord, lower cranial nerves, and vertebral artery) within a critically confined space. Since the initial pathological description of a FMM in 1872, various surgical approaches have been described with the aim of achieving radical tumor resection. The surgical treatment of FMMs has evolved considerably over the last 4 decades due to the progress in microsurgical techniques and development of a multitude of skull base approaches. Posterior and posterolateral FMMs can be safely resected via a standard midline suboccipital approach. However, controversy still exits regarding the optimal management of anterior or anterolateral lesions. Independently of technical variations and the degree of bone removal, all modern surgical approaches to the lower clivus and anterior foramen magnum derive from the posterolateral (or far-lateral) craniotomy originally described by Roberto Heros and Bernard George. This paper is a review of the surgical management of FMMs, with emphasis on the far-lateral approach and its variations. Clinical presentation, imaging findings, important neuroanatomical correlations, recurrence rates, and outcomes are discussed.

Conventional Posterior Approach without Far Lateral Approach for Ventral Foramen Magnum Meningiomas

Objective

We present our experience of conventional posterior approach without fat lateral approach for ventral foramen magnum (FM) meningioma (FM meningioma) and tried to evaluate the approach is applicable to ventral FM meningioma.

Methods

From January 1999 to March 2011, 11 patients with a ventral FM meningioma underwent a conventional posterior approach without further extension of lateral bony window. The tumor was removed through a working space between the dura and arachnoid membrane at the cervicomedullary junction with minimal retraction of medulla, spinal cord or cerebellum. Care should be taken not to violate arachnoid membrane.

Results

Preoperatively, six patients were of Nurick grade 1, three were of grade 2, and two were of grade 3. Median follow-up period was 55 months (range, 20-163 months). The extent of resection was Simpson grade I in one case and Simpson grade II in remaining 10 cases. Clinical symptoms improved in eight patients and stable in three patients. There were no recurrences during the follow-up period. Postoperative morbidities included one pseudomeningocele and one transient dysphagia with dysarthria.

Conclusion

Ventral FM meningiomas can be removed gross totally using a posterior approach without fat lateral approach. The arachnoid membrane can then be exploited as an anatomical barrier. However, this approach should be taken with a thorough understanding of its anatomical limitation.

Gamma Knife surgery in the treatment paradigm for foramen magnum meningiomas

Object

Microsurgical management of foramen magnum meningiomas (FMMs) can be associated with significant morbidity and mortality. Stereotactic radiosurgery may be an efficient and safe alternative treatment modality for such tumors. The object of this study was to increase the documented experience with Gamma Knife surgery (GKS) for FMMs and to delineate its role in an overall management paradigm.

Methods

The authors report on their experience with 24 patients harboring FMMs managed with GKS. Twelve patients had primary symptomatic tumors, 5 had asymptomatic but enlarging primary tumors, and 7 had recurrent or residual tumors after a prior surgery.

Results

Follow-up clinical and imaging data were available in 21 patients at a median follow-up of 47 months (range 3–128 months). Ten patients had measurable tumor regression, which was defined as an overall volume reduction > 25%. Eleven patients had no further tumor growth. Two patients died as a result of advanced comorbidities before follow-up imaging. One patient was living 8 years after GKS but had no clinical evaluation. Ten of 17 symptomatic patients with at least 6 months of follow-up had symptom improvement, and 7 remained clinically stable. Smaller tumors were more likely to regress. No patient suffered an adverse radiation effect after radiosurgery.

Conclusions

Gamma Knife surgery was a safe management strategy for small, minimally symptomatic, or growing FMMs as well as for residual tumors following conservative microsurgical removal.

Gamma knife radiosurgery of meningiomas involving the foramen magnum

Background:

Foramen magnum meningiomas represent a challenging clinical entity. Although resection is performed for those with a mass effect, complete resection is not always feasible. For some patients, stereotactic radiosurgery may be used as the primary treatment modality. We evaluatedthe long-term outcome of Gamma Knife radiosurgery (GKRS) for the treatment of patientswith a foramen magnum meningioma.

Materials and Methods:

Between 1991 and 2005, 222 patients with a meningioma in the posterior fossa were treated with GKRS at the University of Virginia. Of these patients, 5 had meningiomas involving the foramen magnum. At the time of GKRS, the median age of the patients was 60 years (range, 51–78). Three patients were treated with radiosurgery following an initial resection and 2 were treated with upfront radiosurgery. The patients were assessed clinically and radiologically at routine intervals following GKRS.

Results:

The median tumor volume was 6.8 cc (range 1.9–17 cc). The GKRS tumor received a marginal dose of 12 Gy (range 10–15), and the median number of isocenters was 5 (range 3–19). The mean follow-up was 6 years (range 4–13). One lesion increased in size following GKRS requiring a second treatment, resulting in size stabilization. At the time of the last follow-up, all meningiomas had either demonstrated no growth (n = 4) or reduction in size (n = 1). No patients experienced post-radiotherapy complications.

Conclusions:

GKRS affords a high rate of tumor control and preservation of neurologic function for patients with foramen magnum meningiomas. Further study of its role in the neurosurgical management of such patients seems warranted.

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.

Contemporary surgical outcome for skull base meningiomas

Although surgical excision of meningioma and its dural base is the most common primary management, skull base meningiomas are quite different, and contemporary management usually consists of multimodal treatment with the aim of achieving the best possible functional outcome and quality of life (QOL) for these patients. As surgery plays an important role in the treatment of skull base meningiomas, it is crucial for neurosurgeons to appreciate the surgical outcome and QOL after meningioma surgery. Outcome is usually measured for meningiomas in terms of morbidity, mortality, time to recurrence, and QOL. The extent of resection, tumor grade, proliferative markers, and tumor location are significant factors in predicting the surgical outcome. Therefore, we address each of these factors in detail in this review. Advances in recent decades in microsurgical techniques, neuroimaging modalities, neuroanesthesia, and perioperative intensive care have substantially improved the surgical outcome; therefore, most surgical outcomes discussed in this review are cited from contemporary literature (2000 to the present) in order to depict the surgical outcome of contemporary microsurgery.

Gamma Knife surgery of meningiomas located in the posterior fossa: factors predictive of outcome and remission

Object

Although numerous studies have analyzed the role of stereotactic radiosurgery for intracranial meningiomas, few studies have assessed outcomes of posterior fossa meningiomas after stereotactic radiosurgery. In this study, the authors evaluate the outcomes of posterior fossa meningiomas treated with Gamma Knife surgery (GKS). The authors also assess factors predictive of new postoperative neurological deficits and tumor progression.

Methods

A retrospective review was performed of a prospectively compiled database documenting the outcomes of 152 patients with posterior fossa meningiomas treated at the University of Virginia from 1990 to 2006. All patients had a minimum follow-up of 24 months. There were 30 males and 122 females, with a median age of 58 years (range 12–82 years). Seventy-five patients were treated with radiosurgery initially, and 77 patients were treated with GKS after resection. Patients were assessed clinically and radiographically at routine intervals following GKS. Factors predictive of new neurological deficit following GKS were assessed via univariate and multivariate analysis, and Kaplan-Meier analysis and Cox multivariate regression analysis were used to assess factors predictive of tumor progression.

Results

Patients had meningiomas centered over the tentorium (35 patients, 23%), cerebellopontine angle (43 patients, 28%), petroclival region (28 patients, 18%), petrous region (6 patients, 4%), and clivus (40 patients, 26%). The median follow-up was 7 years (range 2–16 years). The mean preradiosurgical tumor volume was 5.7 cm3 (range 0.3–33 cm3), and mean postradiosurgical tumor volume was 4.9 cm3 (range 0.1–33 cm3). At last follow-up, 55 patients (36%) displayed no change in tumor volume, 78 (51%) displayed a decrease in volume, and 19 (13%) displayed an increase in volume. Kaplan-Meier analysis demonstrated radiographic progression-free survival at 3, 5, and 10 years to be 98%, 96%, and 78%, respectively. In Cox multivariable analysis, pre-GKS covariates associated with tumor progression included age greater than 65 years (hazard ratio [HR] 3.24, 95% CI 1.12–9.37; p = 0.03) and a low dose to the tumor margin (HR 0.76, 95% CI 0.60–0.97; p = 0.03), and post-GKS covariates included shunt-dependent hydrocephalus (HR 25.0, 95% CI 3.72–100.0; p = 0.001). At last clinical follow-up, 139 patients (91%) demonstrated no change or improvement in their neurological condition, and 13 patients showed symptom deterioration (9%). In multivariate analysis, the only factors predictive of new or worsening symptoms were clival or petrous location (OR 4.0, 95% CI 1.1–13.7; p = 0.03).

Conclusions

Gamma Knife surgery offers an acceptable rate of tumor control for posterior fossa meningiomas and accomplishes this with a low incidence of neurological deficits. In patients selected for GKS, tumor progression is associated with age greater than 65 years and decreasing dose to the tumor margin. Clival- or petrous-based locations are predictive of an increased risk of new or worsening neurological deficit following GKS.

Dorsal approaches to intradural extramedullary tumors of the craniovertebral junction

Tumors of the craniovertebral junction (CVJ) pose significant challenges to cranial and spine surgeons. Familiarity with the complex anatomy and avoidance of injury to neurologic and vascular structures are essential to success. Multiple surgical approaches to address lesions at the CVJ have been promoted, including ventral and dorsal-based trajectories. However, optimal selection of the surgical vector to manage the pathology requires a firm understanding of the limitations and advantages of each approach. The selection of the best surgical trajectory must include several factors, such as obtaining the optimal exposure of the region of interest, avoiding injury to critical neurologic or vascular structures, identification of normal anatomical landmarks, the familiarity and comfort level of the surgeon to the approach, and the need for fixation. This review article focuses on dorsal approaches to the CVJ and the advantages and limitations in managing intradural extramedullary tumors.