Meningiomas of the cranial base

Skull Base Meningiomas in Patients with Neurofibromatosis Type 2: An International Multicenter Study Evaluating Stereotactic Radiosurgery

Objective  Meningiomas are the second most common tumors in neurofibromatosis type 2 (NF-2). Microsurgery is challenging in NF-2 patients presenting with skull base meningiomas due to the intrinsic risks and need for multiple interventions over time. We analyzed treatment outcomes and complications after primary Gamma Knife radiosurgery (GKRS) to delineate its role in the management of these tumors. Methods  An international multicenter retrospective study approved by the International Radiosurgery Research Foundation was performed. NF-2 patients with at least one growing and/or symptomatic skull base meningioma and 6-month follow-up after primary GKRS were included. Clinical and radiosurgical parameters were recorded for analysis. Results  In total, 22 NF-2 patients with 54 skull base meningiomas receiving GKRS as primary treatment met inclusion criteria. Median age at GKRS was 38 years (10-79 years). Most lesions were located in the posterior fossa (55.6%). Actuarial progression free survival (PFS) rates were 98.1% at 2 years and 90.0% at 5 and 10 years. The median follow-up time after initial GKRS was 5.0 years (0.6-25.5 years). Tumor volume at GKRS was a predictor of tumor control. Lesions >5.5 cc presented higher chances to progress after radiosurgery ( p  = 0.043). Three patients (13.64%) developed adverse radiation effects. No malignant transformation or death due to meningioma or radiosurgery was reported. Conclusions  GKRS is effective and safe in the management of skull base meningiomas in NF-2 patients. Tumor volume deserve greater relevance during clinical decision-making regarding the most appropriate time to treat. GKRS offers a minimally invasive approach of particular interest in this specific group of patients.

Long-term evaluation of the effect of hypofractionated high-energy proton treatment of benign meningiomas by means of (11)C-L-methionine positron emission tomography

PURPOSE

To determine if (11)C-L-methionine PET is a useful tool in the evaluation of the long-term effect of proton beam treatment in patients with meningioma remnant.

METHODS

Included in the study were 19 patients (4 men, 15 women) with intracranial meningioma remnants who received hypofractionated high-energy proton beam treatment. Patients were examined with (11)C-L-methionine PET and MRI prior to treatment and after 6 months, and 1, 2, 3, 5, 7 and 10 years. Temporal changes in methionine uptake ratio, meningioma volume, meningioma regrowth and clinical symptoms throughout the follow-up period were evaluated.

RESULTS

In 17 patients the tumour volume was unchanged throughout the follow-up. The methionine uptake ratio on PET decreased over the years in most patients. In two patients the tumour remnant showed progression on MRI. In these patients, prior to the volume increase on MRI, the methionine uptake ratio increased. One patient experienced transient clinical symptoms and showed radiological evidence of a radiation-induced reaction close to the irradiated field.

CONCLUSION

Proton beam treatment is a safe and effective treatment for achieving long-term growth arrest in meningioma remnants. Follow-up with (11)C-L-methionine PET may be a valuable adjunct to, but not a replacement for, standard radiological follow-up.

Advances in radiotherapy of brain tumors: radiobiology versus reality

Radiotherapy still remains the most effective adjunctive therapy for malignant gliomas following surgery and provides useful local control for some benign tumors. Research efforts have been directed towards several aspects of the radiation therapy of tumors. The results of clinical trials undertaken in the last decade offer some basis for optimism in the management of patients with malignant brain tumors, although cure is still not a realistic objective. This review focuses on the rationale and radiobiological basis for recent developments in the radiotherapy of adult brain tumors. The salient issues are discussed from a neurosurgeon's perspective.

Magnetic resonance imaging, computed tomography, and 68Ga-DOTATOC positron emission tomography for imaging skull base meningiomas with infracranial extension treated with stereotactic radiotherapy--a case series

Introduction

Magnetic resonance imaging (MRI) and computed tomography (CT) with ⁶⁸Ga-DOTATOC positron emission tomography (⁶⁸Ga-DOTATOC-PET) were compared retrospectively for their ability to delineate infracranial extension of skull base (SB) meningiomas treated with fractionated stereotactic radiotherapy.

Methods

Fifty patients with 56 meningiomas of the SB underwent MRI, CT, and ⁶⁸Ga-DOTATOC PET/CT prior to fractionated stereotactic radiotherapy. The study group consisted of 16 patients who had infracranial meningioma extension, visible on MRI ± CT (MRI/CT) or PET, and were evaluated further. The respective findings were reviewed independently, analyzed with respect to correlations, and compared with each other.

Results

Within the study group, SB transgression was associated with bony changes visible by CT in 14 patients (81%). Tumorous changes of the foramen ovale and rotundum were evident in 13 and 8 cases, respectively, which were accompanied by skeletal muscular invasion in 8 lesions. We analysed six designated anatomical sites of the SB in each of the 16 patients. Of the 96 sites, 42 had infiltration that was delineable by MRI/CT and PET in 35 cases and by PET only in 7 cases. The mean infracranial volume that was delineable in PET was 10.1 ± 10.6 cm³, which was somewhat larger than the volume detectable in MRI/CT (8.4 ± 7.9 cm³).

Conclusions

⁶⁸Ga-DOTATOC-PET allows detection and assessment of the extent of infracranial meningioma invasion. This method seems to be useful for planning fractionated stereotactic radiation when used in addition to conventional imaging modalities that are often inconclusive in the SB region.

Different microsurgical approaches to meningiomas of the anterior cranial base

INTRODUCTION

Meningiomas of the anterior skull base show specific characteristics, which render them difficult to handle. These tumors include olfactory groove, supra- and parasellar, anterior sphenoid ridge, cavernous sinus, and spheno-orbital meningiomas. Tumor localization and size, encasement of important structures as well as the extent of dural attachment may influence the decision for an adequate approach.

DISCUSSION

Various approaches to the anterior cranial fossa exist, each with corresponding advantages and disadvantages. Recently, endoscopic approaches have increasingly been used. In this review, the different approaches to meningiomas of the anterior cranial fossa in respect of anatomical issues, indications, and associated risks are discussed.

The role of radical microsurgical resection in multimodal treatment for skull base meningioma

OBJECT

Because resection followed by timely stereotactic radiosurgery (SRS) is becoming a standard strategy for skull base meningiomas, the role of initial surgical tumor reduction in this combined treatment should be clarified.

METHODS

This study examined 161 patients with benign skull base meningiomas surgically treated at Osaka City University between January 1985 and December 2005. The mean follow-up period was 95.3 months. Patients were categorized into 3 groups based on the operative period and into 4 groups based on tumor location. Maximal resection was performed as first therapy throughout all periods. In the early period (1985-1994), in the absence of SRS, total excision of the tumor was intentionally performed for surgical cure of the disease. In the mid and late periods (1995-2000 and 2001-2005), small parts of the tumor invading critical neurovascular structures were left untouched to obtain good functional results. Residual tumors with high proliferation potential (Ki 67 index > 4%) or with progressive tendencies were treated with SRS. The extent of initial tumor resection, recurrence rate, Karnofsky Performance Scale score, and complication rate were investigated in each group.

RESULTS

The mean tumor equivalent diameter of residual tumors was 3.67 mm in the no-recurrence group and 11.7 mm in the recurrence group. The mean tumor resection rate (TRR) was 98.5% in the no-recurrence group and 90.1% in the recurrence group. A significant relationship was seen between postoperative tumor size, TRR, and recurrence rate (p < 0.001), but the recurrence rate showed no significant relationship with any other factors such as operative period (p = 0.48), tumor location (p = 0.76), or preoperative tumor size (p = 0.067). The mean TRR was maintained throughout all operative periods, but the complication rate was lowest and postoperative Karnofsky Performance Scale score was best in the late period (p < 0.001 each). Late-period results were as follows: mean TRR, 97.9%; mortality rate, 0%; and severe morbidity rate, 0%. Stereotactic radiosurgery procedures were added in 27 cases (16.8%) across all periods. Throughout all follow-up periods, 158 tumors were satisfactorily controlled by maximal possible excision alone or in combination with adequate SRS.

CONCLUSIONS

The combination of maximal possible resection and additional SRS improves functional outcomes in patients with skull base meningioma. A TRR greater than 97% in volume can be achieved with satisfactory functional preservation and will lead to excellent tumor control in combined treatment of skull base meningioma.

Levine-Sekhar grading system for prediction of the extent of resection of cranial base meningiomas revisited: study of 124 cases

INTRODUCTION

Skull base meningiomas comprise an intricate kingdom in neurological surgery. Due to their proximity to critical neurovascular structures, these tumours impose a cumbersome burden on the surgeon regarding surgical intervention and the clinical outcome. Preoperative prediction of the meningioma resectability will help the surgeon seek a rational result from surgery. This study tries to re-examine and promote the Levine-Sekhar (LS) grading system proposed to predict the resectability of basal meningiomas.

PATIENTS AND METHODS

A retrospective study was performed on 124 eligible patients (90 female and 34 male) suffering from cranial base meningioma that had been operated on between April 1996 and February 2003. The patients were classified according to LS and our modified grading systems. The modified grading system deploys six groups of variables: optic apparatus involvement, cavernous sinus neural involvement, facial-auditory involvement, caudal cranial nerve dysfunction, data derived from imaging studies (multiple fossa involvement and/or vessel encasement), and history of previous radiosurgery. Each criterion scores 1 if present and the total score is the sum of scores obtained from the aforementioned criteria.

RESULTS

Amongst 124 patients, 66 (52%) underwent gross total removal of the tumour. Regression and correlation analysis were performed for both LS (r(2) = 0.9683) and our modified grading systems (r(2) = 0.990) to evaluate the relationship of tumour grade versus the proportion of total resection. The correlations were significantly different (P < 0.01).

CONCLUSION

Although the LS grading system is reported to be a good predictor of the extent of tumour resection, we believe that application of the six aforementioned variables will enhance the accuracy of this system, while preserving simplicity and communicability.

Vascular Lesions of the Skull Base: Endovascular Prospective for the Otolaryngologist

With continual advances being made in endovascular equipment and techniques, the role that these image-guided, minimally invasive therapies play in the multidisciplinary management of vascular lesions of the skull base will probably continue to expand. The introduction of emerging technologies, including the development and implementation of implantable bioactive devices such as drug-eluting stents, bioactive embolic coils, and bioactive particulate embolic materials, will provide an increasing array of options for these patients. This article has reviewed the basic concepts of embolization and revascularization for vascular lesions of the skull base encountered by the practicing otolaryngologist. These concepts can provide a framework for collaboration between the otolaryngologist and neuroendovascular operator in a cooperative approach to these patients. The importance of detailed knowledge of the vascular anatomy of the skull base when dealing with these lesions, the concept of dangerous anastomoses, several clinically useful classification schemes for these lesions, and basic endovascular techniques of embolization and revascularization have been highlighted.

Meningiomas of the basal posterior fossa. Surgical experience in 80 cases

INTRODUCTION

Despite recent improvements in microsurgical and radiotherapy techniques, treatment of basal posterior fossa meningiomas still carries an elevated risk of morbidity. We present our results in a series of patients with this type of tumor and review the recent literature looking for the results obtained with different approaches and the new tendencies and algorithms proposed for managing these challenging lesions.

MATERIAL AND METHODS

We analyzed retrospectively the clinical presentation and outcome of 80 patients consecutively operated between 1979 and 2003 for basal posterior fossa meningioma (foramen magnum tumors excluded). All patients had preoperative CT scans and the majority MRI studies. A total of 114 operations were performed including two-stage operations, reoperation for recurrence, CSF diversion, and XII-VII anastomosis. The most commonly used approaches were lateral suboccipital retrosigmoid, subtemporal-transtentorial, frontotemporal pterional and supra-infratentorial presigmoid. Thirteen patients received postoperative radiotherapy.

RESULTS

There were 59 (73.7%) women and 21 men (mean age = 51.5 years; range = 18-78 yrs). Most common presenting symptoms were cranial nerve dysfunction, gait disturbances and intracranial hypertension. The mean duration of symptoms was 2.9 years. 70% of the tumors were over 3 cm in size. Fifty patients (62.5%) had a complete resection, 22 (27.5%) subtotal resection (> 90% tumor volume removed), and 8 (10%) only partial resection. Postoperative complications included hematoma, CSF leak, and infection. Fifty four (67.5%) patients developed new or increased cranial nerve deficits and 12.5% somatomotor, somatosensory or cerebellar deficits immediately after surgery with subsequent improvement in most cases. Following initial surgery 67 patients made a good recovery, 10 developed variable degrees of disability and 3 died. Eleven patients died later in the course for tumor recurrence with or without reoperation, malignant meningioma or unrelated causes. There were 9 recurrences in the subgroup of patients having complete resection initially (mean follow-up = 8.6 years). The majority of patients having initial subtotal or partial resections have been managed without reoperation during a mean follow-up period of 6.5 years (radiosurgery and/or observation).

DISCUSSION AND CONCLUSION

Current microsurgical and radiotherapy techniques allow either a cure or an acceptable control of basal posterior fossa meningiomas. In patients with tumor invasion of the cavernous sinus, extracranial extension, violation of the arachnoidal membranes in front of the brainstem, or encasement and infiltration of major arteries, a subtotal excision seems preferable followed by observation and/ or radiosurgical treatment. Apart from the patients age and the clinical presentation (symptomatic or not), the size and secondary extensions of the tumor must be taken into account for planning treatment in the individual patient.

Treatment of meningioma: an update

Aggressive surgical resection continues to be the mainstay of current meningioma management, with advances in microsurgical techniques facilitating the safety and effectiveness of this approach. Complete surgical removal of meningiomas provides the optimal opportunity for long-term remission. Advances in skull base surgical approaches have greatly improved patient outcomes for tumors in precarious locations once thought to be inoperable. For tumors that recur or are unresectable, stereotactic radiosurgery and conformal fractionated radiation therapy can provide safe, palliative treatment with favorable long-term outcomes. Additionally, advances in the understanding of molecular biologic and biochemical mechanisms underlying meningioma growth offer unique opportunities for potential treatment adjuncts for atypical and malignant tumors. This review discusses current understanding of meningioma pathology and accepted meningioma treatment paradigms. The technologic advances and experimental strategies for the future treatment of complex intracranial meningiomas are also discussed.

Two-staged gamma knife radiosurgery for the treatment of large petroclival and cavernous sinus meningiomas

BACKGROUND

In this study, we report on the effectiveness and usefulness of two-staged gamma knife radiosurgery (GKS) for large petroclival and cavernous sinus meningiomas that have a high rate of surgical morbidity.

METHODS

We have treated 7 patients suffering from large petroclival and cavernous sinus meningiomas using two-staged radiosurgery since March 1995. The tumors were located in the petroclival region in 4 patients, the cavernous sinus region in 2 patients, and in the petrocavernous region in the remaining patient. Three of the patients had been surgically treated and 4 patients (57%) were only followed with MR imaging. The volume of the tumors ranged between 34.5 to 101 cm(3) (mean 53.5 cm(3)). The treatment volume was between 6.8 to 29.6 cm(3) (mean 18.6 cm(3)). The treatment interval between the first GKS and second GKS was 6 months. The marginal doses for the tumors were 8 to 12 Gy (mean, 9 Gy).

RESULTS

Six patients demonstrated tumor growth control during the follow-up period after the first radiosurgery (mean 39 months). Tumor regression was observed in 3 patients (43%). Three patients (43%) had improved clinically by the time of the follow-up examinations. No patient suffered from symptomatic radiation injury.

CONCLUSION

Although we have treated only 7 patients using two-staged GKS, we believe this treatment may be a very useful option for large petroclival and cavernous sinus meningiomas in selected patients.

The treatment of skull base meningiomas--combining surgery and radiosurgery

While the operative results for treating skull base meningiomas have improved due to modern microsurgical techniques, surgery is still accompanied by a high morbidity rate. Over the last 6 years, we operated on 50 patients with intracranial meningiomas, 23 of which were skull-based lesions. Among these patients with skull base meningiomas, seven (30%) were treated with both surgery and radiosurgery. All patients received standard operative procedures. Five patients received subtotal resections and two patients received partial resections. No mortalities occurred in our series. Following the operations, the clinical status improved in six patients, while only one patient (with a tuberculum sellae meningioma) experienced deterioration of a preexisting visual disturbance. Radiosurgery was performed at a mean of 4.3 months after the operations. One patient was treated by a two-staged radiosurgery regimen in light of the patient's large tumour volume (57.5 cm(3)). The treatment volume of the series ranged from 0.3 to 29.6 cm(3)(mean 11.6 cm(3)), and the minimum dose for the tumours was from 8 Gy to 12 Gy (mean, 11.6 Gy). Tumour regression was observed in three patients (43%) during the follow up period for radiosurgery (mean: 28 months). No patients revealed tumour growth in the follow up period or suffered symptomatic radiation injury. The clinical status remained unchanged in each of the seven patients after radiosurgery. Although we treated only seven patients with skull base meningiomas using surgery combined with radiosurgery, and the follow up period has been short, we believe that such combination treatment may be a very useful option in selected patients.

[Role of radiotherapy in the treatment of cerebral meningiomas]

Cerebral meningiomas account for 15-20% of all cerebral tumours. Although seldom malignant, they frequently recur in spite of complete surgery, which remains the cornerstone of the treatment. In order to decrease the probability of local recurrence, radiotherapy has often been recommended in atypical or malignant meningioma as well as in benign meningioma which was incompletely resected. However, this treatment never was the subject of prospective studies, randomized or not. The purpose of this review of the literature was to give a progress report on the results of different published series in the field of methodology as well as in the techniques of radiotherapy. Proposals for a therapeutic choice are made according to this analysis. For grade I or grade II-III meningiomas, limits of gross tumor volume (GTV) include the tumour in place or the residual tumour after surgery; clinical target volume (CTV) limits include gross tumour volume before surgery with a GTV-CTV distance of 1 and 2 cm respectively. Delivered doses are 55 Gy into CTV and 55-60 Gy and 70 Gy into GTV for grade I and grade II-III meningiomas respectively.

Progress in the diagnosis and treatment of patients with meningiomas. Part I: diagnostic imaging, preoperative embolization

BACKGROUND

The clinical management of patients with meningiomas has changed over the past decade. Change has occurred because of a variety of factors including improved diagnostic imaging, better results with surgery and interventional neuroradiology, and the advent of radiosurgery. Recent clinical studies from several disciplines have provided new information on topics germane to the management of patients with meningiomas. Collecting this information into a series of review articles would have significant value, primarily for neurosurgeons.

OBJECTIVE

The purpose of this first paper is to bring together and evaluate the available data on: 1) noninvasive diagnostic imaging of meningiomas, including magnetic resonance imaging (MRI), computed tomography (CT) scanning, and MR angiography, venography and spectroscopy; 2) the present role of cerebral angiography in patients with meningiomas; and 3) the current status of preoperative embolization for these tumors.

RESULTS

With the advent of MR technology, the quality of diagnostic imaging for meningiomas has improved dramatically, and this is reflected in more sophisticated preoperative planning. MR imaging provides improved delineation of dura and sinus involvement, and even information about a tumor's consistency. Meningiomas have characteristic neuroimaging features, yet other lesions can still mimic a meningioma. MR venography can be used to demonstrate sinus patency, but intra-arterial cerebral angiography gives the most precise information concerning the degree of tumor involvement of critical vascular structures, and the anatomy of arterial feeders. In trained hands, superselective catheterization for preoperative embolization of meningiomas is feasible, and seems to be reasonably safe.

CONCLUSIONS

MR imaging, CT scans, and cerebral angiography can currently be used in a complementary fashion to diagnose, evaluate, and treat patients with meningiomas, with a high degree of clinical certainty. Angiography is used to determine the sites of blood supply to the tumor, which can then be attacked first intraoperatively, making tumor removal easier. Preoperative embolization continues to have value in selected patients, including those in whom the blood supply to the tumor is difficult to access at the time of surgery.

Treatment of cranial base meningiomas with linear accelerator radiosurgery

OBJECTIVE

Radiosurgery is increasingly being used to treat cranial base tumors. Since 1989, 55 patients with cranial base meningiomas were treated at Stanford University Medical Center with linear accelerator radiosurgery. An analysis of the clinical and radiographic results of this patient population was the focus of this study.

METHODS

The mean patient age was 55.1 years (range, 28-82 yr). The mean tumor volume was 7.33 cm3 (range, 0.45-27.65 cm3). The radiation dose averaged 18.3 Gy (range, 12-25 Gy), delivered with an average of 2.2 isocenters (range, 1-5). Patients were evaluated retrospectively through clinic notes from follow-up examinations, and residual tumor volume was measured during follow-up imaging studies. The length of follow-up averaged 48.4 months (range, 17-81 mo).

RESULTS

Tumor stabilization after radiosurgery was noted in 38 patients (69%), shrinkage in 16 patients (29%), and enlargement in only 1 patient (2%). The results of follow-up magnetic resonance imaging demonstrated decreased central contrast uptake in 11 meningiomas (20%), possibly indicating evidence of central tumor necrosis or tumor vessel obliteration. Neurological status was improved in 15 patients in the series (27%) and unchanged in 34 patients (62%). Three patients (5%) died during the follow-up period, all as a result of causes other than tumor progression. Three patients (5%) developed new permanent symptoms (one patient with seizures, one patient with mild right hemiparesis, and one patient with both vagal and hypoglossal nerve palsy). All other complications were transient, including partial trigeminal nerve palsy in seven patients and diplopia in three patients. The 2-year actuarial tumor control rate was 98%.

CONCLUSIONS

Although our follow-up period is short, this experience corroborates previous reports that radiosurgery can be used to ablate selected small cranial base meningiomas, with good clinical results and modest morbidity.