Foramen magnum meningiomas

Novel classification of foramen magnum meningiomas predicted by topographic position relative to neurovascular bundle

PURPOSE

Proximity to critical neurovascular structures can create significant obstacles during surgical resection of foramen magnum meningiomas (FMMs) to the detriment of treatment outcomes. We propose a new classification that defines the tumor's relationship to neurovascular structures and assess correlation with postoperative outcomes.

METHODS

In this retrospective review, 41 consecutive patients underwent primary resection of FMMs through a far lateral approach. Groups defined based on tumor-neurovascular bundle configuration included Type 1, bundle ventral to tumor; Type 2a-c, bundle superior, inferior, or splayed, respectively; Type 3, bundle dorsal; and Type 4, nerves and/or vertebral artery encased by tumor.

RESULTS

The 41 patients (range 29-81 years old) had maximal tumor diameter averaging 30.1 mm (range 12.7-56 mm). Preoperatively, 17 (41%) patients had cranial nerve (CN) dysfunction, 12 (29%) had motor weakness and/or myelopathy, and 9 (22%) had sensory deficits. Tumor type was relevant to surgical outcomes: specifically, Type 4 demonstrated lower rates of gross total resection (65%) and worse immediate postoperative CN outcomes. Long-term findings showed Types 2, 3, and 4 demonstrated higher rates of permanent cranial neuropathy. Although patients with Type 4 tumors had overall higher ICU and hospital length of stay, there was no difference in tumor configuration and rates of postoperative complications or 30-day readmission.

CONCLUSION

The four main types of FMMs in this proposed classification reflected a gradual increase in surgical difficulty and worse outcomes. Further studies are warranted in larger cohorts to confirm its reliability in predicting postoperative outcomes and possibly directing management decisions.

Surgical corridors to foramen magnum meningiomas: a mini-review

Gross-total resection of foramen magnum meningiomas remains the gold standard of treatment and should be performed whenever possible. The transcondylar approach (and its variations) represents the most used approach for meningiomas located in the lateral or anterior borders of the foramen magnum. Endoscopic transclivus approaches represent a useful option in selected cases of anterior midline foramen magnum meningiomas, to be performed in centers with advanced experience in endoscopic skull base surgery, with the caveats of increased risk of postoperative cerebrospinal fluid leak. Alternatively, radiosurgery remains an option for well-selected cases, especially for the management of asymptomatic patients with small enlarging tumors. Advances in molecular profiling, as well as genetic analysis, may guide adjuvant treatment.

Anaesthetic Management of a Foramen Magnum Meningioma Resection Surgery: A Case Report

The foramen magnum meningioma (FMM) is one of the most threatening tumours among the meningiomas because of its specific location, clinical course, subtle onset, and relatively big dimensions at presentation. Tumour size may mandate careful airway management to avoid further brainstem compression. The surgical management of these complex tumours in the posterior fossa can be performed with the patient in several positions. A lot of surgeons believe the sitting position provides important advantages, yet this remains controversial. We report a successful approach to a large FMM resection surgery performed in the sitting position.

Outcomes following stereotactic radiosurgery for foramen magnum meningiomas: a single-center experience and systematic review of the literature

OBJECTIVE

Foramen magnum meningiomas (FMMs) pose a unique challenge given their intimate anatomical relationship with the craniovertebral junction. While resection has been studied extensively, much less has been reported about the use of stereotactic radiosurgery (SRS) for FMMs. This study includes what is to the authors’ knowledge the first systematic review in the literature that summarizes patient and treatment characteristics and synthesizes outcomes following SRS for FMMs.

METHODS

A retrospective chart review was conducted at a single major academic institution, and a systematic review was performed according to PRISMA guidelines. The initial search on the PubMed and Scopus databases yielded 530 results. Key data extracted from both databases included Karnofsky Performance Status (KPS) score and neurological deficits at presentation, tumor location, treatment indication, target volume, single versus multiple fractions, marginal and maximum doses, isodose line, clinical and radiographic follow-up times, and primary (clinical stability and local control at last follow-up) and secondary (mortality, adverse radiation events, time to regression, progression-free survival) outcomes.

RESULTS

The study patients included 9 patients from the authors’ institution and 165 patients across 4 studies who received SRS for FMMs. The weighted median age at treatment was 60.2 years, and 73.9% of patients were female. Common presenting symptoms included headache (33.9%), dizziness/ataxia (29.7%), cranial nerve deficit(s) (27.9%), numbness (22.4%), weakness (15.2%), and hydrocephalus (4.2%). Lateral/ventrolateral (64.2%) was the most common tumor location. SRS was utilized as the primary therapy in 63.6% of patients and as salvage (21.8%) or adjuvant (14.5%) therapy for the rest of the patients. Most patients (91.5%) were treated with a single fraction. A tumor with a weighted median target volume of 2.9 cm3 was treated with a weighted median marginal dose, maximum dose, and isodose line of 12.9 Gy, 22.8 Gy, and 58%, respectively. Clinical stability and local control at last follow-up were achieved in 98.8% and 97.0% of patients, respectively. Only one possible adverse radiation event occurred, and no mortality directly related to the tumor or SRS was reported.

CONCLUSIONS

In this retrospective analysis and systematic review, the authors demonstrate SRS to be an effective and safe treatment option for carefully selected patients with FMMs.

The Role of Stereotactic Radiosurgery in the Management of Foramen Magnum Meningiomas-A Multicenter Analysis and Review of the Literature

Simple Summary

Meningiomas represent the most common central nervous system (CNS) tumor. Despite their often benign nature, a tumor location in direct proximity to vital brain structures may lead to significant morbidity. This is the case for foramen magnum meningiomas (FMMs) as they grow at the skull base, next to the brain stem and foramen magnum. Surgical resection represents the mainstay of FMM treatments. In patients unsuitable for surgery, with tumor recurrences or tumor remnants after surgery, non-invasive treatment modalities may play a crucial role in patient management. Reports and studies on stereotactic radiosurgery (SRS) for the treatment of FMMs are scarce. This multicenter analysis reported the outcome data of 62 patients with FMMs. SRS achieved a high local tumor control and demonstrated a favorable safety profile. These results are in agreement with previous findings. SRS should be considered for selected FMM patients.

Abstract

Background: Foramen magnum meningiomas (FMMs) represent a considerable neurosurgical challenge given their location and potential morbidity. Stereotactic radiosurgery (SRS) is an established non-invasive treatment modality for various benign and malignant brain tumors. However, reports on single-session or multisession SRS for the management and treatment of FMMs are exceedingly rare. We report the largest FMM SRS series to date and describe our multicenter treatment experience utilizing robotic radiosurgery. Methods: Patients who underwent SRS between 2005 and 2020 as a treatment for a FMM at six different centers were eligible for analysis. Results: Sixty-two patients met the inclusion criteria. The median follow-up was 28.9 months. The median prescription dose and isodose line were 14 Gy and 70%, respectively. Single-session SRS accounted for 81% of treatments. The remaining patients received three to five fractions, with doses ranging from 19.5 to 25 Gy. Ten (16%) patients were treated for a tumor recurrence after surgery, and thirteen (21%) underwent adjuvant treatment. The remaining 39 FMMs (63%) received SRS as their primary treatment. For patients with an upfront surgical resection, histopathological examination revealed 22 World Health Organization grade I tumors and one grade II FMM. The median tumor volume was 2.6 cubic centimeters. No local failures were observed throughout the available follow-up, including patients with a follow-up ≥ five years (16 patients), leading to an overall local control of 100%. Tumor volume significantly decreased after treatment, with a median volume reduction of 21% at the last available follow-up (p < 0.01). The one-, three-, and five-year progression-free survival were 100%, 96.6%, and 93.0%, respectively. Most patients showed stable (47%) or improved (21%) neurological deficits at the last follow-up. No high-grade adverse events were observed. Conclusions: SRS is an effective and safe treatment modality for FMMs. Despite the paucity of available data and previous reports, SRS should be considered for selected patients, especially those with subtotal tumor resections, recurrences, and patients not suitable for surgery.

Consensus core clinical data elements for meningiomas

BACKGROUND

With increasing molecular analyses of meningiomas, there is a need to harmonize language used to capture clinical data across centers to ensure that molecular alterations are appropriately linked to clinical variables of interest. Here the International Consortium on Meningiomas presents a set of core and supplemental meningioma-specific Common Data Elements (CDEs) to facilitate comparative and pooled analyses.

METHODS

The generation of CDEs followed the four-phase process similar to other National Institute of Neurological Disorders and Stroke (NINDS) CDE projects: discovery, internal validation, external validation, and distribution.

RESULTS

The CDEs were organized into patient- and tumor-level modules. In total, 17 core CDEs (10 patient-level and 7-tumour-level) as well as 14 supplemental CDEs (7 patient-level and 7 tumour-level) were defined and described. These CDEs are now made publicly available for dissemination and adoption.

CONCLUSIONS

CDEs provide a framework for discussion in the neuro-oncology community that will facilitate data sharing for collaborative research projects and aid in developing a common language for comparative and pooled analyses. The meningioma-specific CDEs presented here are intended to be dynamic parameters that evolve with time and The Consortium welcomes international feedback for further refinement and implementation of these CDEs.

Clinical Presentation of Foramen Magnum Meningioma Masqueraded by Carpal Tunnel Syndrome: A Report of 2 Cases

CASE

Meningioma is the second most common intracranial tumor. We present 2 cases of foramen magnum meningioma (FMM) that was first operated on with the diagnosis of carpal tunnel syndrome (CTS).

CONCLUSION

During the diagnostic assessment of CTS and recalcitrant CTS, a more proximal etiology of nerve compression should be considered, including FMM. If a more proximal cause of nerve dysfunction is suspected, cervical spine magnetic resonance imaging may be beneficial to evaluate a patient for spinal etiology.

Foramen magnum meningioma with excessive calcification and no dura tail sign: A case report

RATIONALE

Foramen magnum meningiomas are very rare lesions. They frequently originate from the arachnoid cells at the dura matter of the craniocervical junction. Foramen magnum meningiomas are challenging for neurosurgeons because of the complex anatomy of foramen magnum. We present a rare case of FMM with excessive calcification and without the dura tail sign which made the lesion mimic a teratoma.

PATIENTS CONCERNS

A 63 years old woman presented with progressive numbness and hyperesthesia of the shoulders and upper limbs for 2 and half years. She also experienced occasional headaches and dizziness with no nausea, vomiting or fever.

DIAGNOSES

Computed tomography scan, and magnetic resonance imaging revealed a calcified mass at occipital cistern. The lesion did not show the usual "dura tail sign" which made it mimic a teratoma on magnetic resonance imaging. Histopathology established meningioma.

INTERVENTION

The tumor was completely resected via suboccipital approach.

OUTCOMES

Two years follow-up revealed no recurrence of the lesion and no neurological deficits.

LESSONS

We advocate the use of electromyographic and auditory brainstem responses to monitor the inferior cranial nerves because the tumor often adheres to these nerves.