Neurosurgery Blog

Neurosurg Rev (2012) 35:53–66. DOI 10.1007/s10143-011-0333-6

Meningiomas of the posterior fossa represent a heterogeneous group of tumors regarding difficulty of resection and functional outcome.

The aim of this review was to focus on tumors located mainly on the posterior surface of the petrous bone and threatening hearing and facial functions.

An anatomical classification was used to evaluate surgical outcome depending on the relationship of the tumor to the internal auditory meatus. The authors performed a retrospective chart review of 53 consecutive patients operated on for a posterior petrous bone meningioma in a tertiary referral center and a literature review. Tumors were classified in four groups according to the modified Desgeorges and Sterkers classification: posterior petrous (P; 17 tumors), meatus and internal auditory canal (M; 12 tumors), petrous apex without invasion of the internal auditory canal (A; 9 tumors), and cerebellopontine angle with invasion of the internal auditory canal (AMP; 15 tumors).

The facial function was preserved in 100% of P and A tumors, 75% of group M tumors, and 53% of AMP tumors. Hearing preservation was attempted only in P, A, and M groups where rates of serviceable hearing preservation were 82%, 80%, and 66%, respectively. The cumulative rate of hearing preservation for AMP tumors was 45% in our literature review. The increased facial morbidity associated with AMP tumors compared with other groups was also confirmed by the review of the literature.

In conclusion, this study shows that among posterior petrous bone meningiomas, tumors invading the internal auditory canal present with increased postoperative functional morbidity in spite of a tailored approach regarding dural insertion.

J Neurosurg 115:802–810, 2011.DOI: 10.3171/2011.5.JNS101812

Various surgical approaches, such as uni- and bifrontal, frontolateral, and pterional approaches, havebeen advocated for tuberculum sellae meningiomas. The authors retrospectively reviewed the effectiveness of a bilateralsubfrontal approach for tuberculum sellae meningiomas with special attention to ophthalmological outcomesand complications.

Methods. Between 1993 and 2009, 34 patients underwent surgery for removal of tuberculum sellae meningiomasat Osaka City University. Tumor size ranged from 14 to 45 mm. Thirty-two of 34 patients presented with visualdisturbances before the surgery. The visual functions in all patients were assessed using a visual impairment score(VIS) before and after surgery. Postoperative visual examination was performed 2 weeks after surgery. Long-termfollow-up examinations were conducted 1 year after surgery.

Results. Radical resection (Simpson Grades I and II) was accomplished in 27 patients, and subtotal or partialresection (Simpson Grades III and IV) was achieved in 7. There was no deterioration in postoperative visual outcome.Twenty-nine (90.6%) of 32 patients showed improved VIS compared with preoperative VIS. The average VIS was38.1 preoperatively, 23.5 in the short-term postoperative period, and 21.8 in the long-term postoperative period. Inthe short-term postoperative period, the visual function in 6 patients normalized, and visual problems persisted in theremaining 26. Six (23%) of 26 patients showed further improvement in VIS during the long-term follow-up period,and no patient exhibited a worsened VIS during this time. One patient complained of hyposmia after surgery, butthere was no indication of related complications such as CSF leakage or frontal brain contusion.

Conclusions. The bilateral subfrontal approach was previously avoided because of the relatively high rate ofcomplications in earlier surgical series of tuberculum sellae meningiomas. However, after developments in microsurgicaltechniques in recent years, the bilateral subfrontal approach can now provide satisfactory visual outcomes withminimal postoperative complications. Careful preservation of the blood supply to optic apparatus and early unroofingof the optic canal using a bilateral subfrontal approach led to further improvement in long-term postoperative visual outcome.

Neurosurg Rev. DOI 10.1007/s10143-011-0340-7

The paper describes a retrospective study of a consecutive series of 20 midline anterior cranial fossa meningiomas (five of the olfactory groove, 14 of the tuberculum sellae, and one clinoidal), which were operated on via a supraorbital keyhole approach between 2002 and 2008.

The series includes three males and 17 females (mean age 57 years, mean size of the tumors 3.5×3 cm, and mean follow-up 48 months). Gross total excision was achieved in 18 cases and subtotal resection in two. Out of 14 patients with visual deficits, nine patients improved, one remained stable, and three deteriorated. Two patients presented a recurrence 3 years after surgery. One peri-operative death was recorded.

The subgroup of patients with tuberculum sellae meningiomas was analyzed in details. A meta-analysis of the major series of such meningiomas in the last 20 years has been performed in order to compare results of different surgical techniques. With regard to primary outcomes of these tumors, gross total removal, restoration of visual function, morbidity, mortality, and recurrence rates, the supraorbital approach, for selected cases, seems to offer valuable results, comparable with those reported in conventional and endoscopic approaches and with very low surgical aggressiveness. However, statistical data available from the literature, particularly on visual function, are still too limited to draw definitive conclusions.

The best surgical option for the individual patient cannot yet be standardized and should be chosen on the basis of tumor anatomy, pre-operative clinical symptoms, and surgeon’s experience.

J Neurosurg 115:49–54, 2011. DOI: 10.3171/2011.2.JNS101759

The retrosigmoid intradural suprameatal approach with the patient in a semisitting position is an effective alternative to transpetrosal approaches for the treatment of petroclival meningiomas. The authors have made a simple modification to the retrosigmoid intradural suprameatal approach by using the lateral oblique position and preferentially dividing the tentorium with limited drilling of the suprameatal bone, which is termed the “lateral su- pracerebellar transtentorial approach.”

Methods. Twenty-six patients with petroclival meningiomas surgically treated via the lateral supracerebellar transtentorial approach were analyzed. All tumors had most of their bulk in the posterior fossa with some degree of extension into the middle fossa and/or Meckel cave. The patient is placed in the lateral oblique position, and a standard retrosigmoid craniotomy is performed. The tentorium medial to the trigeminal nerve is incised toward the free edge, which improves exposure to the petroclival region without extensive resection of the suprameatal petrous bone.

Results. Gross-total resection was achieved in 11 patients (42%). Ten patients (38%) underwent subtotal resection, and 5 patients (19%) underwent partial resection. There was no incidence of operative death, and the postoperative permanent morbidity rate was 15%. All patients except one did well postoperatively and were independent at the time of their last follow-up examinations.

Conclusions. The lateral supracerebellar transtentorial approach provides the simplest and safest access to the petroclival region. It offers an advantageous approach to petroclival meningiomas exclusively located in the posterior fossa with minimal extension into the Meckel cave and middle fossa.

Neurosurg Rev (2011) 34:327–335. DOI 10.1007/s10143-011-0308-7

Aggressive tumor removal is not always the best treatment for petroclival meningioma (PCM). However, radical removal actually provides the cure with minimal morbidity.

We evaluated the relation of surgical results and tumor size in the PCM removal to clarify the treatment policy for PCM. This study comprised 32 consecutive patients with newly-diagnosed PCM who underwent tumor removal; tumor size was small (< 3 cm) in 12 patients and large (≥3 cm) in 20. Tumor removal was classified into radical (Simpson’s grade I/II) and non-radical (Simpson’s grade III/IV). Removal of small PCM was 11 radical and one non-radical; no surgical morbidity/mortality occurred and postoperative regular follow-up using magnetic resonance imaging showed no recurrence in the period of 66± 45 months. Removal of large PCM was eight radical and 12 non-radical; despite no mortality, the incidence of permanent cranial nerve deficits and major neurological deficits newly developed postoperatively was 35% and 25%, respectively. Radical removal was significantly more frequent in small PCMs than in large PCMs. Permanent cranial nerve deficits newly developed postoperatively and poor outcome (Karnofsky score ≤80) were significantly more frequent in large PCMs than in small PCMs. Radical removal of small PCM is achieved with minimal morbidity and results in the cure. Notwithstanding high morbidity, aggressive removal of large PCM does not achieve a high rate of radical removal.

To find and remove PCM radically while it is small is the only way to cure the disease with minimal morbidity.

Neurosurgery 68[ONS Suppl 2]:ons282–ons290, 2011. DOI: 10.1227/NEU.0b013e318212464e

The ability to diagnose brain tumors intraoperatively and identify tumor margins during resection could maximize resection and minimize morbidity. Advances in optical imaging enabled production of a handheld intraoperative confocal microscope.

OBJECTIVE: To present a feasibility analysis of the intraoperative confocal microscope for brain tumor resection.

METHODS: Thirty-three patients with brain tumor treated at Barrow Neurological Institute were examined. All patients received an intravenous bolus of sodium fluorescein before confocal imaging with the Optiscan FIVE 1 system probe. Optical biopsies were obtained within each tumor and along the tumor-brain interfaces. Corresponding pathologic specimens were then excised and processed. These data was compared by a neuropathologist to identify the concordance for tumor histology, grade, and margins.

RESULTS: Thirty-one of 33 lesions were tumors (93.9%) and 2 cases were identified as radiation necrosis (6.1%). Of the former, 25 (80.6%) were intra-axial and 6 (19.4%) were extra-axial. Intra-axial tumors were most commonly gliomas and metastases, while all extra-axial tumors were meningiomas. Among high-grade gliomas, vascular neoproliferation, as well as tumor margins, were identifiable using confocal imaging. Meningothelial and fibrous meningiomas were distinct on confocal microcopy—the latter featured spindle-shaped cells distinguishable from adjacent parenchyma. Other tumor histologies correlated well with standard neuropathology tissue preparations.

CONCLUSION: Intraoperative confocal microscopy is a practicable technology for the resection of human brain tumors. Preliminary analysis demonstrates reliability for a variety of lesions in identifying tumor cells and the tumor-brain interface. Further refinement of this technology depends upon the approval of tumor-specific fluorescent contrast agents for human use.

Acta Neurochir (2011) 153:1161–1167. DOI 10.1007/s00701-011-1010-9

Among the potential approaches to access the petroclival area, epidural anterior petrosectomy (EAP) appears to be the most direct and conservative transpetrous route.

In this article, we aim to detail the relevant surgical steps necessary to perform EAP in a reproducible and safe manner.

Method The temporo-pterional bone flap is tailored to access the floor of the middle fossa and expose the foramen ovale and foramen spinosum. Elevation of the dura covering the upper surface of the petrous apex is conducted medially toward the level of the petrous ridge. Identification of the landmarks of the rhomboid fossa delineates the limits of the drilling zone (necessary for removal of the petrous apex)—beneath Meckel’s cave and just anterior to the anterior margin of the internal auditory meatus. The tentorium is divided at its free edge and is followed by opening of the posterior fossa dura.

Conclusion Epidural anterior petrosectomy is a conservative trans-petrous approach that offers an excellent direct surgical corridor for exposure of disease processes involving Meckel’s cave, the petroclival area and the ventrolateral pons

J Neurosurg 114:1250–1256, 2011. DOI: 10.3171/2010.12.JNS101623

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.

J Neurosurg 114:1399–1409, 2011. DOI: 10.3171/2010.11.JNS101193

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.

J Neurosurg 114:1241–1249, 2011.DOI: 10.3171/2010.10.JNS101128

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, oculomotor palsy in 3 patients, and seizure in 2 patients. Seven patients had recurrence within the mean follow-up period of 40.7 months. 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.

Acta Neurochir (2011) 153:1–9. DOI 10.1007/s00701-010-0788-1

Removal of tuberculum sella (TS) meningiomas is traditionally performed through transcranial approaches. Wide use of the endoscope in transphenoidal pituitary surgery is recently accessible through the tuberculum sellae with an endoscope-assisted or purely endoscopic technique. Extended endoscopic approach is an important and alternative route for meningiomas, which are located on the midline originating from the tuberculum sella. However, cerebrospinal fluid (CSF) leakage is an important problem in extended endoscopic approaches. In this report, we discuss surgical limitations and nuances of endoscopic transphenoidal approach from a retrospective analysis of nine patients with TS meningiomas.

Methods: Endoscopic transphenoidal approach was performed for seven women and two men (mean age, 51.1 years; age range, 32–78 years) with TS meningiomas between July 2007 and March 2010 in the Department of Neurosurgery, Kocaeli, Turkey.

Results: Total removal was achieved in six of nine patients. An improvement of the preoperative visual deficits was observed in six of the nine patients. Multilayer closure was performed for reconstruction, and lumbar external drainage was used for all patients for 3–5 days. CSF leakage was not seen in any of the patients after the operation and removal of the drainage.

Conclusion: Endoscopic extended transphenoidal approach is still not a standardized procedure for TS meningiomas, but it may be considered as an alternative procedure in selected cases.

Neurosurgery 67:1703–1708, 2010 DOI: 10.1227/NEU.0b013e3181fb801b

Peritumoral brain edema (PTBE) may be crucial in the clinical outcome of meningioma patients. The underlying pathogenetic key mechanism has so far not been determined. Sex, age, tumor size, location, involvement of other structures, or the histological appearance was not found to sufficiently explain PTBE formation in meningiomas.

OBJECTIVE: As PTBE formation is widely accepted to be vasogenic, we investigated the role of vascular endothelial growth factor (VEGF) and pial supplying vessels in a series of World Health Organization (WHO) grade I meningiomas.

METHODS: A total of 79 patients with WHO grade I meningiomas were immunohistochemically studied for VEGF and MIB-1. Pre- and postoperative magnetic resonance imaging including 3-dimensional reconstruction of 1.3-mm thick layers, with calculation of tumor and edema volume, was performed. Intraoperatively, the vascular supply and arachnoidal state were noted by the neurosurgeon.

RESULTS: VEGF was found to be exclusively confined to meningioma tumor cells. We identified 4 different patterns. VEGF and supplying pial vessels were found in 14 meningioma patients, pial vascular supply only in 3, VEGF expression only in 46, and neither VEGF expression nor supplying pial vessels in 16. Only the occurrence of both pial vascular supply and tumor VEGF expression was found to be correlated with PTBE formation (P , .002).

CONCLUSION: Our data suggest that VEGF may be crucial in angiogenesis and therefore indirectly in PTBE formation in World Health Organization grade I meningiomas

J Neurosurg 113:1087–1092, 2010. (DOI: 10.3171/2010.3.JNS091807)

Although there is a considerable volume of literature available on the treatment of patients with cavernous sinus meningiomas (CSMs), most of the data regarding tumor control and survival come from case studies or single-institution series. The authors performed a meta-analysis of reported tumor control and survival rates of patients described in the published literature, with an emphasis on specific prognostic factors.

Methods. The authors systematically analyzed the published literature and found more than 3000 patients treated for CSMs. Separate meta-analyses were performed to calculate pooled rates of recurrence and cranial neuropathy after 1) gross-total resection, 2) subtotal resection without adjuvant postoperative radiotherapy or radiosurgery, and 3) stereotactic radiosurgery (SRS) alone. Results were expressed as pooled proportions, and random-effects models were used to incorporate any heterogeneity present to generate a pooled proportion. Individual studies were weighted using the inverse variance method, and 95% CIs for each group were calculated from the pooled proportions.

Results. A total of 2065 nonduplicated patients treated for CSM met inclusion criteria for the analysis. Comparisons of the 95% CIs for recurrence of these 3 cohorts revealed that SRS-treated patients experienced improved rates of recurrence (3.2% [95% CI 1.9–4.5%]) compared with either gross-total resection (11.8% [95% CI 7.4–16.1%]) or subtotal resection alone (11.1% [95% CI 6.6–15.7%]) (p < 0.01). The authors found that the pooled mixed-effects rate of cranial neuropathy was markedly higher in patients undergoing resection (59.6% [95% CI 50.3–67.5%]) than for those undergoing SRS alone (25.7% [95% CI 11.5–38.9%]) (p < 0.05).

Conclusions. Radiosurgery provided improved rates of tumor control compared with surgery alone, regardless of the subjective extent of resection.

J Neurosurg 113:1036–1042, 2010, DOI: 10.3171/2010.3.JNS091966

Definitive data allowing clinicians to predict which meningioma patients will fail to respond to conservative management are lacking. To address this need, the authors systematically reviewed the published literature regarding the natural history of small, untreated meningiomas.

Methods. The authors performed a systematic review of the existing literature on untreated meningiomas that were followed with serial MR imaging. They summarize the published linear rates of tumor growth, and the risk factors for development of new or worsened symptoms during follow-up by using a stratified chi-square test.

Results. The search methods identified 22 published studies reporting on 675 patients with untreated meningiomas followed by serial MR imaging. Linear growth rates varied significantly: no growth was the most common rate, although reports of more aggressive tumors noted growth rates of up to a 93% linear increase in size per year. The authors found that few patients with initial tumor diameters < 2 cm went on to develop new or worsened symptoms over a median follow-up period of 4.6 years. Patients with initial tumor diameters of 2–2.5 cm demonstrated a marked difference in the rate of symptom progression if their tumors grew > 10% per year, compared with those tumors growing ≤ 10% per year (42% vs 0%; p < 0.001, chi-square test). Patients with tumors between > 2.5 and 3 cm in initial size went on to develop new or worsened symptoms 17% of the time.

Conclusions. This systematic review of the literature regarding the clinical behavior of untreated meningiomas suggests that most meningiomas ≤ 2.5 cm in diameter do not proceed to cause symptoms in the approximately 5-year period following their discovery. Those that do cause symptoms can usually be predicted with close radiographic follow-up. Based on these findings, the authors suggest the importance of observation in the early course of treatment for small asymptomatic meningiomas, especially those with an initial diameter < 2 cm.

Neuroradiology (2010) 52:1003–1010. DOI 10.1007/s00234-010-0671-z

“Brain surface motion imaging” (BSMI) is the subtraction of pulse-gated, 3D, heavily T2-weighted image of two different phases of cerebrospinal fluid (CSF) pulsation, which enables the assessment of the dynamics of brain surface pulsatile motion. The purpose of this study was to evaluate the feasibility of this imaging method for providing presurgical information about adhesions between meningiomas and the brain surface.

Methods Eighteen cases with surgically resected meningioma in whom BSMI was presurgically obtained were studied. BSMI consisted of two sets of pulse-gated, 3D, heavily T2-weighted, fast spin echo scans. Images of the systolic phase and the diastolic phase were obtained, and subtraction was performed with 3D motion correction. We analyzed the presence of band-like texture surrounding the tumor and judged the degree of motion discrepancy as “total,” “partial,” or “none.” The correlation between BSMI and surgical findings was evaluated. For cases with partial adhesions, agreements in the locations of the adhesions were also evaluated.

Results On presurgical BSMI, no motion discrepancy was seen in eight cases, partial in six cases, and total in four cases. These presurgical predictions about adhesions and surgical findings agreed in 13 cases (72.2%). The locations of adhesions agreed in five of six cases with partial adhesions.

Conclusion In the current study, BSMI could predict brain and meningioma adhesions correctly in 72.2% of cases, and adhesion location could also be predicted. This imaging method appears to provide presurgical information about brain/meningioma adhesions.

Acta Neurochir (2010) 152:1711–1719. DOI 10.1007/s00701-010-0708-4

5-aminolevulinic acid (5-ALA) has gained importance as an intraoperative photodynamic diagnostic agent for the extirpation of malignant gliomas. The application of this technique for resection of meningiomas has barely been explored. The aim of this study was to evaluate the utility of 5-ALA-induced fluorescence as a visual tool in meningioma resection and its correlation with histological findings.

Methods A total of 33 consecutive patients undergoing resection of intracranial meningiomas from December 2007 to August 2009 were included in this study. After confirmation of normal liver function, 5-ALA was administered orally (20 mg/kg) within 3–5 h prior to skin incision. All cases were operated on using standard microsurgical and neuronavigation-guided techniques. Intraoperative 440 nm fluorescence was applied periodically during and at the end of resection in order to detect tumor-infiltrated sites. The fluorescence of the tumor was evaluated intraoperatively by the surgeon and confirmed by subsequent video analysis.

Results A total of 32 (97%) patients presented with benign meningiomas (WHO I–II). In 1 (3%) patient, histological anaplastic signs (WHO III) could be demonstrated. 5-ALAinduced fluorescence of the tumor was confirmed in a total of 31 (94%) patients. The fluorescence did not correlate with the histological findings (n=30 WHO I–II, n=1 WHO grade III) or with preoperative brain edema and administration of steroids. A total resection could be postoperatively demonstrated in 25 (76%) patients. No adverse effects attributable to 5-ALA occurred.

Conclusions 5-ALA-induced fluorescence is a useful and promising intraoperative tool for the visualization of meningioma tissue. The novel findings demonstrated in this study in terms of high fluorescence and poor correlation with histological findings highlight the usefulness of this technique as a routine visual tool to achieve optimal resection of meningiomas.

Neurosurgery 67:80-86, 2010. DOI: 10.1227/01.NEU.0000370938.46353.77

Little is known regarding meningiomas that primarily arise from the floor of the middle fossa as opposed to the sphenoid wing, the cavernous sinus, the anterior petrous ridge, or the lateral convexity dura.

OBJECTIVE: Given the relative paucity of literature addressing this disease entity, we review the University of California at San Francisco (UCSF) experience with these tumors.

METHODS: Between 1991 and 2006, 1228 patients were seen by neurosurgeons at UCSF for meningiomas of which 17 (1.1%) patients met our criteria for a “middle fossa floor” meningioma, of which 15 underwent first-time surgery and were included in this series. The most common presenting symptoms were headache (9 patients), seizures (6 patients), trigeminal nerve dysfunction (5 patients), hearing loss (5 patients), gait disturbance (5 patients), and cognitive decline (3 patients). All patients underwent surgical resection via frontotemporal craniotomy, with or without orbitozygomatic osteotomy.

RESULTS:We were able to achieve a Simpson grade 1 or 2 resection in 10 of 15 patients (67%). The operative morbidity was clustered in 5 patients, as 10 of 15 patients (67%) experienced no operative morbidity. There were 4 known clinical recurrences in this group at 5 years median follow-up. All patients had either higher grade tumors, or received a Simpson grade 3 or higher resection.

CONCLUSION:We present the clinical characteristics and surgical outcome of a series of patients presenting with meningiomas primarily arising from the concave floor of the middle cranial fossa. Given the relatively uncommon nature of these lesions, more investigation into the clinical behavior of this entity is warranted.

J Neurosurg 112:951–956, 2010. DOI: 10.3171/2009.8.JNS09703

Stereotactic radiosurgery (SRS) has proven to be a safe and effective treatment for many patients with intracranial meningiomas. Nevertheless, the morbidity associated with radiosurgery of larger meningiomas is poorly understood.

Methods. The authors performed a retrospective review of 116 patients who underwent SRS for meningiomas (WHO Grade I) > 10 cm3 between 1990 and 2007, with a minimum follow-up of 12 months. Patients with atypical or malignant meningiomas and those who received prior radiotherapy were excluded. The average tumor volume was 17.5 cm3 (range 10.1–48.6 cm3); the average tumor margin dose was 15.1 Gy (range 12–18 Gy); and the mean follow-up duration was 70.1 months (range 12–199 months).

Results. Tumor control was 99% at 3 years and 92% at 7 years after radiosurgery. Thirty complications after radiosurgery were noted in 27 patients (23%), including 7 cases of seizures, 6 cases of hemiparesis, 5 cases of trigeminal injury, 4 cases of headaches, 3 cases of diplopia, 2 cases each of cerebral infarction and ataxia, and 1 case of hearing loss. Patients with supratentorial tumors experienced a higher complication rate compared with patients with skull base tumors (44% compared with 18%) (hazard ratio 2.9, 95% CI 1.3–6.7, p = 0.01).

Conclusions. The morbidity associated with SRS for patients with benign meningiomas > 10 cm3 is greater for supratentorial tumors compared with skull base tumors. Whereas radiosurgery is relatively safe for patients with large-volume skull base meningiomas, resection should remain the primary disease management for the majority of patients with large-volume supratentorial meningiomas.

J Neurosurg 112:907–912, 2010. DOI: 10.3171/2009.6.JNS09120

Resecting large meningiomas along the posterior fossa convexity or cerebellopontine angle (CPA) through a suboccipital approach can be challenging. Limitations include a restricted angle of view, high venous pressures, and suboptimal brain relaxation. While a far-lateral craniotomy is a viable alternative, the risks associated with condylar resection are undesirable.

Methods. The authors retrospectively evaluated a modified far-lateral approach in a consecutive series of 12 patients with large or giant posterior fossa convexity and CPA meningiomas. This approach incorporates transversesigmoid sinus exposure and C-1 laminectomy, but there is no condylar resection.

Results. Between January 2006 and February 2008, 12 patients (mean age 52 years) presented with large or giant meningiomas of the posterior fossa convexity or CPA. The mean tumor volume was 72.6 cm3 (range 8–131 cm3). Signs and symptoms at presentation included headache (in 8 patients), cranial neuropathy (in 4), and progressive hemiparesis (in 4). There were no operative complications, and the majority of patients (9) had Simpson Grade I or II resections. There were no new permanent neurological deficits following resection, although 2 patients (17%) had transient deficits. The mean modified Rankin score decreased from 2.2 preoperatively to 0.6 postoperatively.

Conclusions. A modified far-lateral approach to the posterior fossa and CPA allows for safe, and often total, resection of large meningiomas with minimal morbidity. While avoiding the risks of condylar resection, this microsurgical strategy allows for greater field of view, minimal venous bleeding, and immediate access to the spinal subarachnoid space.

Neurosurgery 66:661-669, 2010.DOI: 10.1227/01. NEU.0000366112.04015.E2

Resection of meningiomas involving the cavernous sinus often is incomplete and associated with considerable morbidity. As a result, an increasing number of patients with such tumors have been treated with gamma knife surgery (GKS). However, few studies have investigated the long-term outcome for this group of patients.

METHODS: 100 patients (23 male/77 female) with meningiomas involving the cavernous sinus received GKS at the Department of Neurosurgery at Haukeland University Hospital, Bergen, Norway, between November 1988 and July 2006. They were followed for a mean of 82.0 (range, 0–243) months. Only 2 patients were lost to long-term follow-up. Sixty patients underwent craniotomy before radiosurgery, whereas radiosurgery was the primary treatment for 40 patients.

RESULTS: Tumor growth control was achieved in 84.0% of patients. Twelve patients required re-treatment: craniotomy (7), radiosurgery (1), or both (4). Three out of 5 patients with repeated radiosurgery demonstrated secondary tumor growth control. Excluding atypical meningiomas, the growth control rate was 90.4%. The 1-, 5-, and 10-year actuarial tumor growth control rates are 98.9%, 94.2%, and 91.6%, respectively. Treatment failure was preceded by clinical symptoms in 14 of 15 patients. Most tumor growths appeared within 2.5 years. Only one third grew later (range, 6–20 yr). The complication rate was 6.0%: optic neuropathy (2), pituitary dysfunction (3), worsening of diplopia (1), and radiation edema (1). Mortality was 0. At last follow-up, 88.0% were able to live independent lives.

CONCLUSION: GKS gives long-term growth control and has a low complication rate. Most tumor growths manifest within 3 years following treatment. However, some appear late, emphasizing the need for long-term follow-up.