Extent of resection and survival outcomes in World Health Organization grade II meningiomas.

PURPOSE: WHO grade II meningiomas behave aggressively, with recurrence rates as high as 60%. Although complete resection in low-grade meningiomas is associated with a relatively low recurrence rate, the impact of complete resection for WHO grade II meningiomas is less clear. We studied the association of extent of resection with overall and progression-free survivals in patients with WHO grade II meningiomas. METHODS: A retrospective database review was performed to identify all patients who underwent surgical resection for intracranial WHO grade II meningiomas at our institution between 1995 and 2019. Kaplan-Meier analysis was used to compare overall and progression-free survivals between patients who underwent gross total resection (GTR) and those who underwent subtotal resection (STR). Multivariable Cox proportional-hazards analysis was used to identify independent predictors of tumor recurrence and mortality. RESULTS: Of 214 patients who underwent surgical resection for WHO grade II meningiomas (median follow-up 53.4 months), 158 had GTR and 56 had STR. In Kaplan-Meier analysis, patients who underwent GTR had significantly longer progression-free (p = 0.002) and overall (p = 0.006) survivals than those who underwent STR. In multivariable Cox proportional-hazards analysis, GTR independently predicted prolonged progression-free (HR 0.57, p = 0.038) and overall (HR 0.44, p = 0.017) survivals when controlling for age, tumor location, and adjuvant radiation. CONCLUSIONS: Extent of resection independently predicts progression-free and overall survivals in patients with WHO grade II meningiomas. In an era of increasing support for adjuvant treatment modalities in the management of meningiomas, our data support maximal safe resection as the primary goal in treatment of these patients.

Dominant Occipital Sinus Complicating Surgery of a Fourth Ventricular Mass.

BACKGROUND: We describe a case of a fourth ventricular mass requiring a modified approach to its management owing to a rare variation of the occipital sinus (OS). CASE DESCRIPTION: A 32-year-old female presented with persistent headache and nausea. Magnetic resonance imaging revealed a fourth ventricular mass and hydrocephalus. Venous sinus anatomy appeared unusual, and thus magnetic resonance venography was performed, which identified the OS as the main drainage pathway for the entire brain, providing the sole drainage between the superior sagittal sinus and the jugular veins through the marginal sinus. Both the transverse and sigmoid sinuses were hypoplastic, and flow through the straight sinus was diminished. Thus, endoscopic third ventriculostomy and biopsy were performed as the first step. Postoperatively, the patient's nausea persisted and biopsy results were inconclusive, and thus a second surgery was planned. The dural opening was tailored so as not to damage the OS and marginal sinus, and the tumor was resected subtotally through the limited dural opening. Histopathological analysis identified a low-grade glioma. CONCLUSIONS: Rare variations of the venous/sinus anatomy may fundamentally change the surgical management plan, and recognizing such variations is crucial to minimizing the risk of potentially fatal complications.

Evaluation of Non-Watertight Dural Reconstruction with Collagen Matrix Onlay Graft in Posterior Fossa Surgery.

OBJECTIVE: Many surgeons advocate for watertight dural reconstruction after posterior fossa surgery given the significant risk of cerebrospinal fluid (CSF) leak. Little evidence exists for posterior fossa dural reconstruction utilizing monolayer collagen matrix onlay graft in a non-watertight fashion. Our objective was to report the results of using collagen matrix in a non-watertight fashion for posterior fossa dural reconstruction. METHODS: We conducted a retrospective review of operations performed by the senior author from 2004-2011 identified collagen matrix (DuraGen) use in 84 posterior fossa operations. Wound complications such as CSF leak, infection, pseudomeningocele, and aseptic meningitis were noted. Fisher's exact test was performed to assess risk factor association with specific complications. RESULTS: Incisional CSF leak rate was 8.3% and non-incisional CSF leak rate was 3.6%. Incidence of aseptic meningitis was 7.1% and all cases resolved with steroids alone. Incidence of palpable and symptomatic pseudomeningocele in follow-up was 10.7% and 3.6% respectively. Postoperative infection rate was 4.8%. Previous surgery was associated with pseudomeningocele development (p<0.05). CONCLUSION: When primary dural closure after posterior fossa surgery is undesirable or not feasible, non-watertight dural reconstruction with collagen matrix resulted in incisional CSF leak in 8.3%. Incidence of pseudomeningocele, aseptic meningitis, and wound infection were within acceptable range. Data from this study may be used to compare alternative methods of dural reconstruction in posterior fossa surgery.

Microvascular decompression for trigeminal neuralgia.

The microvascular decompression procedure has proven to be a safe and effective option in the surgical management of neurovascular compression syndromes in general and trigeminal neuralgia in particular. This article aims to serve as an overview of the decision-making process, application of the surgical technique, and clinical outcome pertaining to this procedure.

The influence of age on the histological grading of meningiomas.

This study was undertaken to assess the relationship between the age of patients at the time of their surgery and histological grading of meningiomas. A retrospective review was conducted for 1,083 consecutive patients with meningiomas who had surgical removal between January 1991 and December 2006. Histological grading for each tumor was done utilizing the WHO classification for meningiomas. The incidence of WHO grade II or III tumors between the elderly and the non-elderly groups was compared. The mean age at diagnosis for the WHO grade I, II, and III tumors was 55.1 (±14.79), 59.0 (±15.54), and 64.3 years (±13.28) (p value = 0.007), respectively. We found that 11.9 % of meningiomas diagnosed after the age of 60 years was WHO grade II or III, while this value was only 6.9 % for patients 60 years or younger (p = 0.0006). Our study showed that the combined incidence of WHO grade II and III meningiomas increases as age advances. We believe that this constitutes an important piece of information requiring neurosurgeons to carefully and continuously observe the elderly patients harboring meningiomas.

Surgical outcomes of trigeminal neuralgia in patients with multiple sclerosis.

BACKGROUND: Trigeminal neuralgia (TN) is relatively frequent in multiple sclerosis (MS) patients and can be extremely disabling. Surgical interventions are less effective for the treatment of MS-related TN compared with classic TN, and higher recurrence rates are observed. OBJECTIVE: To evaluate initial pain-free response (IPFR), duration of pain-free intervals (PFIs), and factors predictive of outcome in different surgical modalities used to treat MS-related TN. METHODS: A total of 96 MS patients underwent 277 procedures (range, 1-11 procedures per patient) to treat TN at our institution from 1995 to 2011. Of these, 89 percutaneous retrogasserian glycerol rhizotomies, 82 balloon compressions, 52 stereotactic radiosurgeries, 28 peripheral neurectomies, 15 percutaneous radiofrequency rhizotomies, and 10 microvascular decompressions were performed as upfront or repeat treatments. RESULTS: Bilateral pain was observed in 10% of patients during the course of disease. During the follow-up period (median, 5.7 years), recurrence of symptoms was seen in 66% of patients, and 181 procedures were performed for symptom recurrence. As an initial procedure, balloon compression had the highest IPFR (95%; P = .006) and median PFI (28 months; P = .05), followed by percutaneous retrogasserian glycerol rhizotomy (IPFR, 74%, P = .04; median PFI, 9 months; P = .05). In general, repeat procedures had lower effectiveness compared with initial procedures, with no statistically significant difference seen across the various treatment modalities. CONCLUSION: Treatment failure occurs in most of the MS-related TN patients independently of the type of treatment. However, balloon compression had the highest rate of IPFR and PFI compared with other modalities in the initial treatment of MS-related TN.

The Dorello canal: historical development, controversies in microsurgical anatomy, and clinical implications.

Interest in studying the anatomy of the abducent nerve arose from early clinical experience with abducent palsy seen in middle ear infection. Primo Dorello, an Italian anatomist working in Rome in the early 1900s, studied the anatomy of the petroclival region to formulate his own explanation of this pathological entity. His work led to his being credited with the discovery of the canal that bears his name, although this structure had been described 50 years previously by Wenzel Leopold Gruber. Renewed interest in the anatomy of this region arose due to advances in surgical approaches to tumors of the petroclival region and the need to explain the abducent palsies seen in trauma, intracranial hypotension, and aneurysms. The advent of the surgical microscope has allowed more detailed anatomical studies, and numerous articles have been published in the last 2 decades. The current article highlights the historical development of the study of the Dorello canal. A review of the anatomical studies of this structure is provided, followed by a brief overview of clinical considerations.

Minimally invasive endoscopic endonasal management of skull base cholesterol granulomas.

BACKGROUND: Skull base cholesterol granulomas (SBCGs) are rare lesions that have traditionally been managed via middle fossa or transtemporal approaches. Despite the relative paucity in the literature, the endoscopic endonasal approach may serve as a potential alternative surgical route. In this study, we report our experience with the management of SBCG using this minimally invasive approach. METHODS: The charts and imaging studies of three patients were reviewed retrospectively. The mean age was 36 years (range 30-42). The male/female ratio was 2:1. The epicenter of the lesion was petrous apex in two patients and clivus in one. One patient had undergone surgery via a middle fossa approach 3 years before the endoscopic procedure. The SBCG was drained using an endoscopic endonasal approach in all patients. A stent was left in place in 2 cases. RESULTS: All patients presented with headaches and ipsilateral retroorbital pain. One patient also had diplopia, ipsilateral blepharospasm, and hearing loss. Average lesion size was 31 mm (22-37 mm). Pain and associated neurologic symptoms completely resolved in one patient, and the headache significantly improved in the other two. These two patients underwent revision surgeries for symptomatic reaccumulation and stenosis of cavity opening at 5 and 7 months, respectively. Both patients improved subsequently, and have been stable since that time. One patient developed chronic sphenoid sinusitis. Average hospital stay was 1 day per procedure. All patients had functional patency of the SBCG with average follow-up of 25 months (10-36 months). CONCLUSIONS: Endoscopic endonasal approach may serve as a technically feasible and minimally invasive alternative to traditional surgical approaches for the management of SBCG in carefully selected patients.

A tentorial venous hemangioma presenting as an extra-axial mass in the ambient cistern: a case report.

Although venous hemangiomas are one of the most common soft-tissue tumors, venous hemangiomas in the central nervous system are extremely rare. We present an unusual case of venous hemangioma originating from the interdural space of the tentorium. A 32-year-old woman was incidentally found to have extra-axial mass occupying the left ambient cistern. This tumor was observed for the first 4 years as it was completely asymptomatic. Surgical resection was later recommended when the tumor grew. The mass originated from between the two layers of the anteromedial tentorial incisura. There were no findings indicative of previous hemorrhage inside the mass. The matrix of the mass was firm and vascular, resembling a fibrous meningioma. Gross total resection was achieved without any neurological deficit. Pathological examination revealed a dense fibrous connective tissue with a proliferation of vessels marked by thickened walls. A spindle cell proliferation in the vessel walls did not stain with the antibody to S-100 protein. Movat stain demonstrated the venous character of the vessels. These results were histologically compatible with a venous hemangioma. Albeit extremely rare, a venous hemangioma, a distinct clinical and pathological entity from a venous angioma, can present an intracranial mass lesion.

Benefits and limitations of diameter measurement in the conservative management of meningiomas.

BACKGROUND: Meningiomas are the most common benign brain tumors that are frequently followed-up by neurologists, general practitioners, and neurosurgeons. Some recent studies advocate the accurate volumetric method (VM) over measuring the linear maximum diameter although its clinical significance still remains unknown. The aim of this study is to directly compare the linear method (LM) and VM to delineate the characteristics of both measurements. METHODS: Between 2003 and 2010, growth analysis using magnetic resonance imaging DICOM files was performed for 189 meningiomas in 161 patients at the Cleveland Clinic. In LM, a minimum increase of 2 mm in maximum diameter was defined as tumor growth. The absolute volume growth (VG, in cm(3)) was calculated for each tumor. RESULTS: Linear growth (LG) was seen in 71 tumors (37.6%) within the median follow-up of 2.0 years. These tumors with LG showed a mean VG of 2.80 cm(3). Some large LG-positive tumors can be larger than estimated from LG. In addition, the skull base location was correlated to greater VG. On the other hand, 118 tumors without LG demonstrated the minimal actual volume increase, i.e., mean VG of 0.16 cm(3). Although a small subset of these LG-negative tumors might have slightly high VG when they were large, the location of tumor had no correlation to VG. CONCLUSIONS: Our data demonstrated some important precautions in measuring the tumor growth. We believe that it is mandatory in the conservative management of meningiomas to correctly understand benefits and potential limitations of different measurement methods utilized.

The natural history of intracranial meningiomas.

OBJECT: Despite the increased detection of incidental or small meningiomas, the lesion's natural history is largely unknown. METHODS: One year or longer of follow-up was conducted in 244 patients with 273 meningiomas managed conservatively by a single surgeon between 2003 and 2008. Data were stratified according to age, sex, tumor location, symptoms, initial tumor diameter, calcification, MR imaging intensity, and edema. Linear tumor growth was defined as a 2-mm or larger increase in the maximum diameter in any direction of the tumor. Volumetric analysis (ImageJ version 1.43) was also conducted in 154 of 273 meningiomas for which complete radiological data were available in the form of DICOM files throughout the follow-up period. A volume increase greater than 8.2% was regarded as significant because the preliminary volumetry based on 20 randomly selected meningiomas showed that the average SD was 4.1%. RESULTS: Linear growth was observed in 120 tumors (44.0%) with a mean follow-up of 3.8 years. Factors related to tumor growth were age of 60 or younger (p = 0.0004), absence of calcification (p = 0.027), MR imaging T2 signal hyperintensity (p = 0.021), and edema (p = 0.018). Kaplan-Meier analysis and Cox proportional hazards regression analysis revealed that age 60 or younger (hazard ratio [HR] 1.54, 95% CI 1.05-2.30, p = 0.026), initial tumor diameter greater than 25 mm (HR 2.23, 95% CI 1.44-3.38, p = 0.0004), and the absence of calcification (HR 4.57, 95% CI 2.69-8.20, p < 0.0001) were factors associated with a short time to progression. Volumetric growth was seen in 74.0% of the cases. Factors associated with a higher annual growth rate were male sex (p = 0.0002), initial tumor diameter greater than 25 mm (p < 0.0001), MR imaging T2 signal hyperintensity (p = 0.0001), presence of symptoms (p = 0.037), and edema (p < 0.0001). CONCLUSIONS: Although the authors could obtain variable results depending on the measurement method, the data demonstrate patients younger than 60 years of age and those with meningiomas characterized by hyperintensity on T2-weighted MR imaging, no calcification, diameter greater than 25 mm, and edema need to be observed more closely. Volumetry was more sensitive to detecting tumor growth than measuring the linear diameter.

Sphenoorbital meningioma: surgical technique and outcome.

OBJECT: The aim of this study was to describe the surgical technique used for removal of sphenoorbital meningiomas in the authors' practice and to review the operative outcome. METHODS: Review of the senior author's practice between 1994 and 2009 revealed 39 patients (mean age 48 years) eligible for this study. Clinical presentation, surgical technique, postoperative outcome, and follow-up data are presented. Surgical technique is detailed, with an emphasis on aggressive removal consisting of drilling of the hypertrophied sphenoid bone, orbital wall, and anterior clinoid process, followed by tumor removal and a wide resection of the involved dura. A simple dural closure without reconstruction of the orbital roof or the lateral wall of the orbit is also described. RESULTS: Gross-total resection was achieved in 15 cases (38.5%), near-total resection with small residual in the cavernous sinus or periorbita in 20 cases (51.3%), and subtotal resection in 4 cases (10.3%). Postoperative complications included trigeminal hypesthesia in 9 patients [corrected], oculomotor palsy in 3 patients [corrected], and seizure in 2 patients. Seven patients had recurrence within the mean follow-up period of 40.7 months [corrected]. Preoperative visual deficits were present in 21 patients (53.8%). Of these, 14 (66.7%) experienced visual recovery to normal levels postoperatively.Statistical analyses revealed preoperative severe visual deficit and sphenoid bone hypertrophy as an independent risk factor and an independent favorable factor, respectively, for a favorable visual outcome. Proptosis was resolved (≤ 2 mm) in 73.5% of the authors' patients. No patient had postoperative enophthalmos. CONCLUSIONS: In the authors' practice, surgery for sphenoorbital meningiomas consists of resection of the orbital/sphenoid intraosseous, intraorbital, and intradural tumor components. The authors believe that aggressive removal of the orbital/sphenoid intraosseous tumor is critical for a favorable visual outcome and tumor control. Furthermore, satisfactory cosmetic results can be achieved with simple reconstruction techniques as described.

Spontaneous cerebrospinal fluid rhinorrhea as the initial presentation of growth hormone-secreting pituitary adenoma.

Patients with acromegaly usually present with characteristic clinical features or comorbidities associated with excess insulinlike growth factor 1 (IGF-1)/growth hormone (GH) or may come to medical attention secondary to mass effects causing visual field distortions. Herein, we report a case of spontaneous cerebrospinal fluid (CSF) rhinorrhea as the presenting symptom of acromegaly. A 68-year-old man presented to an outside facility with a 2-day history of headache associated with nausea, vomiting, dizziness, and clear nasal discharge and underwent 2 attempted repairs of a sphenoid sinus CSF leak. Examination on admission to our hospital was significant for fluctuating level of consciousness. Subsequently, subtle coarse facial features were appreciated. Pituitary function testing showed thyrotropin and gonadotropin deficiencies along with an elevated age- and sex-matched IGF-1 of 285 (normal level, 59-225 ng/mL). Nadir GH during oral glucose tolerance test was 5.5 ng/mL and confirmed the diagnosis of acromegaly. Magnetic resonance imaging showed pneumocephalus, an enlarged sella with an elongated pituitary stalk, and partial erosion of the anterior wall of the sphenoid sinus. A distinct adenoma could not be identified. An endoscopic, transnasal, transsphenoidal exploration and biopsy with multilayered skull base reconstruction were performed. Histologic examination of the biopsy contents was consistent with a GH-producing adenoma. Postoperatively, the patient's fluctuating level of consciousness improved and returned to baseline after his successful skull base repair. During the follow-up period, he had an IGF-1 of 713 ng/mL and started treatment with a somatostatin analogue. To our knowledge, this is the first reported case of a GH-producing pituitary adenoma presenting with spontaneous CSF rhinorrhea. Pituitary adenomas should be considered in the differential diagnosis of patients presenting with spontaneous CSF rhinorrhea with abnormal sellar image, and these patients should undergo a thorough hormonal evaluation.

Non-watertight dural reconstruction in meningioma surgery: results in 439 consecutive patients and a review of the literature. Clinical article.

OBJECT: There are various schools of thought when it comes to dural reconstruction following meningioma surgery, which are largely based on the personal experience of the individual surgeons. The authors' aim in this study was to review different dural reconstruction techniques, with an emphasis on their experience with the synthetic onlay dural graft technique. METHODS: The medical records of 439 consecutive patients who were surgically treated for an intracranial meningioma over a period of 7 years, and for whom dural reconstruction was performed using the onlay dural graft DuraGen (Integra Neurosciences) were reviewed retrospectively. The most common tumor location was the convexity (27.6%), and 12% of the patients had undergone previous surgery. Complications related to the closure technique and/or closure material, such as CSF leakage from the incision, rhinorrhea, or infectious or chemical meningitis were reviewed. RESULTS: A CSF leak was encountered in 2 patients (0.4%), and 10 patients (2.3%) experienced graft-related complications in the form of chemical meningitis, cerebritis, and accumulation of extraaxial fluid. Infectious complications were seen in 4 patients (0.9%; bacterial meningitis, osteomyelitis, epidural abscess). None of the patients had pseudomeningocele that required a second intervention. CONCLUSIONS: In the authors' experience, the incidence of CSF leakage following non-watertight reconstruction of the dura mater in meningioma surgery performed using dural onlay graft was 0.4%. Graft-related complications occurred in 2.3%. These figures compare favorably to the majority of the series in which watertight dural closure is described and emphasized.

Intraosseous cavernous angioma of the petrous bone.

OBJECTIVE: Intraosseous cavernous angioma (CA) of the petrous bone is rare and preoperative diagnosis can be challenging, especially when its epicenter is outside the internal auditory canal (IAC) or geniculate ganglion. METHODS: A 45-year-old man presented to our clinic with right-sided hearing loss, tinnitus, and unsteadiness. Neuroimaging revealed a right posterior petrous mass. Aggressive subtotal resection with decompression of the IAC was achieved through a right suboccipital craniotomy. Histopathological findings were consistent with CA. CONCLUSION: As was the case with this patient, we believe that CA should be included in the differential diagnosis of petrous region pathology with bony involvement. Surgery is warranted due to its expansive nature and to decompress the adjacent neural structures.

Ventral petrous meningiomas: unique tumors.

INTRODUCTION: This study aims to analyze our experience with petrous meningiomas (PM), testing the hypothesis that these tumors have different histologic subtypes and operative outcome depending on the site of origin in reference to the internal auditory canal (IAC). METHODS: Fifty-eight patients with PM were reviewed retrospectively. Tumors were classified as posterior (PPM; n = 29), superior (SPM; n = 8), and ventral petrous (VPM; n = 19), in reference to the IAC. Two patients had multiple meningiomas arising from different parts of the petrous bone. Petroclival, clival, and jugular tubercle meningiomas were excluded. All patients were operated through a suboccipital retrosigmoid approach. Clinical presentation, tumor size, involvement of IAC, extent of resection, outcome, and tumor histology were analyzed. RESULTS: Simpson grade I and II resection was achieved in 84.5%: 96.6% in PPM, 100% in SPM, and 57.9% in VPM. Fibrous histology accounted for 69% in PPM, 62% in SPM, and only 10.5% in VPM, whereas meningothelial histology was seen 27.6%, 25%, and 68.4%, respectively. Postoperative hearing loss was the most frequent operative complication, and was seen in 31.6% of VPM, as compared to none in PPM or SPM. CONCLUSIONS: Ventral petrous meningiomas are clearly different tumors in their histology and operative outcome. The predominance of meningothelial histology in this location may imply a different tumorigenesis as compared to other PM. Ventral petrous meningiomas should be viewed as a distinct group of tumors.

High incidence of optic canal involvement in tuberculum sellae meningiomas: rationale for aggressive skull base approach.

BACKGROUND: Current literature on TSMs underemphasizes the significance of OCI by the tumor. In this study, we aimed to document the incidence of OCI, its management using a SBT, and its significance with relation to the visual outcome. METHODS: Thirty-one patients with TSM were retrospectively analyzed. In 28 patients, SBT consisting of extradural anterior clinoidectomy with falciform ligament and optic nerve sheath opening was performed. Pre- and postoperative visual status was analyzed with respect to OCI. RESULTS: The incidences of OCI and preoperative visual deficit (VD) were 77.4% and 83.8%, respectively. With regard to preoperative visual status, OCI incidence was 84.6% in 26 patients with VD compared to 40% in 5 patients without (P = .016). Among the 23 patients with VD and detailed postoperative neuroopthalmologic evaluation, 78.3% had visual improvement; and in 21.7%, vision was unchanged on the operated side. In one patient (3.2% in the whole series), vision deteriorated on the side contralateral to the side of surgery. In the presence of OCI in 20 patients, vision improved in 80% and remained unchanged in 20%, whereas 1 of the 3 patients without OCI improved and the other 2 remained unchanged. Simpson grade I or II resection was achieved in 83.8%. CONCLUSION: Optic canal involvement is very common in TSM (77.4%), and it correlates well with preoperative visual status. With the use of SBT, without which the tumor in the optic canal could not have been removed completely and safely, visual improvement of 78.3% and stability of 21.7% were achieved on the operated side.

High incidence of optic canal involvement in clinoidal meningiomas: rationale for aggressive skull base approach.

INTRODUCTION: Literature specifically focusing on clinoidal meningiomas is scant, particularly with regards to the postoperative visual outcome. In this study, we aimed to document the incidence of optic canal involvement (OCI) by the tumor, its management using a skull base technique, and its significance with relation to the visual outcome. MATERIALS AND METHODS: Fifty-two patients with clinoidal meningiomas were retrospectively analyzed. In 47 patients, skull base technique consisting of extradural anterior clinoidectomy with falciform ligament and optic nerve sheath opening was performed. Pre-operative visual status and post-operative outcome were analyzed with respect to OCI. RESULTS: The incidences of OCI was present in 19 (36%) and pre-operative visual deficit (VD) in 24 (46%) patients. With regard to pre-operative visual status, OCI was seen in 14 (58%) of 24 patients with VD, as compared to five (18%) in 28 patients without (p = 0.004). Among the 22 patients with VD and detailed postoperative neuro-ophthalmological evaluation, 17 (77%) had visual improvement, and in five patients (23%), vision was unchanged. In the presence of OCI in 11 patients, vision improved in seven (64%), and remained unchanged in four patients (36%), whereas all but one of the 11 patients (91%) without OCI improved and in the remaining one (9%), remained unchanged. Simpson Grade I and II resection was achieved in 71%. CONCLUSION: OCI is observed in 36% of clinoidal meningiomas, and it correlates well with pre-operative visual status. With the use of the skull base technique, without which the tumor in the optic canal could not have been removed completely and safely, visual improvement of 77% and stability of 23% was achieved.

New prospects for management and treatment of inoperable and recurrent skull base meningiomas.

Skull base, including optic nerve, cavernous sinus, clival and foramen magnum tumors represent a major challenge for neurosurgeons and neuro-oncologists. Growth regulatory signaling pathways for these tumors are of increasing interest as potential targets for new chemotherapy. Those differentially activated in various grades of meningiomas are currently being identified as well. This article reviews some recent findings pathways that appear to regulate meningioma growth. Potential targets for novel therapies are also discussed.

World Health Organization Grades II and III meningiomas are rare in the cranial base and spine.

OBJECTIVE: This study was undertaken to assess a possible relationship between the tumor location and the incidence of World Health Organization (WHO) Grades II and III meningiomas. METHODS: A retrospective review of 794 consecutive patients who underwent meningioma resection between January 1991 and March 2004 was conducted. Among these, 47 patients (5.9%) with WHO Grade II meningiomas and 16 patients (2%) with Grade III meningiomas were further analyzed. Tumor location was assessed using preoperative magnetic resonance imaging scans and/or operative reports. Histological grading was done according to the WHO 2000 Classification scheme. RESULTS: WHO Grade II tumors were found in eight out of 289 (2.8%) cranial base meningiomas and in zero spinal meningiomas, compared with 39 out of 429 (9.1%) non-cranial base meningiomas. Grade III histology was encountered in two (0.7%) cranial base tumors and in one out of 76 (1.3%) spinal tumors, compared with 13 (3%) non-cranial base tumors. The combined incidence of Grades II and III meningiomas was significantly lower in the cranial base (3.5%) and spinal (1.3%) locations compared with non-cranial base locations (12.1%) (P < 0.001). CONCLUSION: WHO Grades II and III meningiomas occur far less frequently in the cranial base and spinal locations. Tumors arising from these locations may have different mechanisms of tumorigenesis and/or progression compared with meningiomas arising from other (non-cranial base) regions.