Olfactory Groove Meningiomas: Clinical Outcome and Recurrence Rates after Tumor Removal Through the Frontolateral and Bifrontal Approach

Transfrontal-Sinus-Subcranial Approach to Olfactory Groove Meningiomas: Surgical Results and Clinical and Functional Outcome in a Consecutive Series of 21 Patients

BACKGROUND

The transfrontal-sinus-subcranial approach (TFSSA) allows for direct exposure and removal of olfactory groove meningiomas (OGMs), without any brain retraction. Compared with other skull base approaches (e.g., fronto-orbitobasal, transbasal, subcranial, fronto-orbitozygomatic, and one-and-half approach), it could offer the same advantages but is less invasive.

OBJECTIVE

We report the results in a series of 21 consecutive patients with OGMs and operated on through TFSSA, to propose a viable alternative approach.

METHODS

Mean maximum tumor diameter was 45.9 ± 3.4 mm (range, 25-70 mm). The aim of surgery was Simpson grade I removal. Surgical, clinical, and functional outcomes were reported. Mean follow-up was 87 ± 7 months (range, 36-176 months).

RESULTS

In all patients, magnetic resonance imaging after surgery confirmed complete tumor removal. The recurrence-free survival rate was 100% and 85.7% at 5 and 10 years, respectively. Surgery-related mortality and major morbidity were 0% and 4.8%, respectively. Risk of anosmia significantly correlates with meningioma size (P < 0.001) and smell sense was preserved only in patients with tumors less than 4 cm in maximum diameter (4/7; 57.1%). A significant improvement of Mini Mental Standard Examination score was recorded at follow-up (P < 0.001) and no patients worsened their cognitive profile. Visual function improved in 7/8 (87.5%). Karnofsky Performance Scale score after surgery significantly increased (P < 0.001). According to the Glasgow Outcome Score, good outcome was achieved in 20 patients (95.2%).

CONCLUSIONS

Based on reported results, TFSSA allows complete tumor removal with good outcome and low complication rate. It may be proposed as a safe and effective approach to treat large and giant OGMs.

Surgical Resectability of Skull Base Meningiomas

With recent advances in surgical technology such as preoperative imaging, neuro-monitoring, and surgical instruments, the surgical resectability of intracranial meningiomas has increased over the last two decades. This study reviewed clinical articles regarding the surgical treatment of meningiomas to clarify the role of surgical excision, with a focus on skull base meningiomas. We sub-classified clinical articles about skull base meningiomas into two categories (anterior and middle fossa meningiomas; and posterior fossa meningiomas) and reviewed papers in each category. In cases with anterior and middle fossa meningiomas, surgical resectability has reached a sufficient level to maximize functional preservation. In cases of posterior fossa meningioma, however, surgical respectability remains insufficient even with full use of recent surgical modalities. Continuous refining of operative procedures is required to obtain more satisfactory outcomes, especially for posterior fossa meningioma. In addition, recent long-term outcomes of stereotactic radiosurgery (SRS) were acceptable for controlling the skull base meningiomas. Therefore, combination with surgical excision and SRS should be considered in complicated skull base meningiomas.

Olfactory Groove Meningiomas: Comparison of Extent of Frontal Lobe Changes After Lateral and Bifrontal Approaches

OBJECTIVE

Olfactory groove meningiomas often are behaviorally silent. Numerous surgical approaches have been described in the literature for the successful removal of these meningiomas. Lateral (pterional/frontolateral) and anterior (bifrontal/fronto-orbito-basal) approaches with their various modifications remain the 2 major corridors in resecting them. In this study, we discuss our experience in microsurgical treatment of these tumors at our institution and assess the extent of frontal lobe damage after the resection of tumor.

METHODS

We reviewed the medical records of patients who underwent surgical excision of olfactory groove meningiomas from 1990 to 2014. To measure the extent of frontal lobe damage via lateral and anterior approaches, we measured the volume of porencephalic cave in the postoperative magnetic resonance imaging by using Brainlab software. The ratio of volume of porencephalic cave to tumor was measured between 2 sides and 2 approaches.

RESULTS

Fifty-seven patients with olfactory groove meningiomas, who underwent 62 microsurgical resection procedures in 1990-2014 were included in the study (74% were more than 5 cm at presentation). Pterional and bifrontal craniotomies were the most commonly used approaches. At follow-up, the volume of porencephalic cave after lateral approach was significantly less in the side contralateral to craniotomy irrespective of tumor size. The difference between ratio of volume of porencephalic cave and initial tumor was significantly less after lateral approaches, when compared to anterior approaches.

CONCLUSIONS

Lateral approaches (pterional/frontolateral) resulted in less frontal lobe change and better olfactory preservation in comparison to anterior approaches in present series.

Evaluation of anterior third of superior sagittal sinus in normal population: Identifying the subgroup with dominant drainage

BACKGROUND/OBJECT

The ligation and transection of anterior third of superior sagittal sinus (AT-SSS) is an important step to approach anterior skull base lesions. Some clinical studies have shown frontal lobe venous infarct following such surgical procedures questioning the safety of its ligation. We have studied the variations in venous drainage patterns to AT-SSS in the normal population using postcontrast magnetic resonance venogram (MRV). A novel scoring system to recognize the subgroup with dominant venous drainage from frontal lobes has been described.

MATERIALS AND METHODS

In this study, 60 three-dimensional contrast-enhanced (CE) MRVs were obtained from those cases being evaluated for a headache not harboring any intracranial mass lesion. The AT-SSS with all its draining veins was studied in detail. Morphology of individual veins such as length, caliber, tributaries, and angulation with AT-SSS was studied, and a numerical value of 0 or 1 was assigned for each of the above parameters. Summing up these scores derived from the individual cortical veins quantified the drainage of AT-SSS.

RESULTS

There are 3-4 veins on either side draining to AT-SSS. Barely, 3% of the veins had > 3 tributaries. Only 6.6% of veins had a caliber >3 mm, and 16.5% drained at acute angles to AT-SSS. About 26% of the veins did cross at least half of the lateral frontal lobe. We found in 26 individuals the AT-SSS score was 0-2, in 22 it was 3-5 and, in only in 12 (20%) the score was 6 or more (dominant drainage).

CONCLUSION

There are anatomical variations in venous drainage of frontal lobes into AT-SSS. Those with dominant drainage are likely to develop venous congestion and complications if sacrificed. It is possible to identify these individuals on the basis of venous drainage pattern as shown in CE-MRV.

Endoscopic Endonasal Approach for Olfactory Groove Meningiomas: Operative Technique and Nuances

Olfactory groove meningiomas represent approximately 10% of all intracranial meningiomas. Because these tumors originate at the ventral skull base, the endonasal route provides direct access to the tumor blood supply for early devascularization and removal of the underlying hyperostotic bone at the cranial base. In carefully selected patients, these tumors can be totally removed without additional brain retraction or manipulation. In this report, we describe the surgical technique and operative nuances for removal of olfactory groove meningiomas using the endoscopic endonasal approach, and also discuss the indications, limitations, complication avoidance and management, and postoperative care.

Frontobasal Midline Meningiomas: Is It Right To Shed Doubt on the Transcranial Approaches? Updates and Review of the Literature

BACKGROUND

Traditionally, the surgical removal of tuberculum sellae meningioma (TSM) and olfactory groove meningioma (OGM) requires transcranial approaches and microsurgical techniques, but in the last decade endoscopic expanded endonasal approaches have been introduced: transcribriform for OGMs and transtuberculum-transplanum for TSM. A comparative analysis of the literature concerning the two types of surgical treatment of OGMs and TSM is, however, difficult.

METHODS

We conducted a literature search using the PubMed database to compare data for endoscopic and microsurgical techniques in the literature. We also conducted a retrospective analysis of selected cases from our series presenting favorable characteristics for an endoscopic approach, based on the criteria of operability of these lesions as generally accepted in the literature, and we compared the results obtained in these patients with those in the endoscopic literature.

RESULTS

We believe that making the sample more homogeneous, the difference between microsurgical technique and endoscopic technique is no longer so striking. A greater radical removal rate, a reduced incidence of cerebrospinal fluid fistula and, especially, the possibility of removing lesions of any size are advantages of transcranial surgery; a higher percentage of improvement in visual outcome and a lower risk of a worsening of a pre-existing deficit or onset of a new deficit are advantages of the endoscopic technique.

CONCLUSION

At present, the microsurgical technique is still the gold standard for the removal of the anterior cranial fossa meningiomas of all sizes, and the endoscopic technique remains a second option in certain cases.

Magnetic resonance imaging fluid-attenuated inversion recovery sequence signal reduction after endoscopic endonasal transcribiform total resection of olfactory groove meningiomas

BACKGROUND

Olfactory groove meningiomas grow insidiously and compress adjacent cerebral structures. Achieving complete removal without further damage to frontal lobes can be difficult. Microsurgical removal of large lesions is a challenging procedure and usually involves some brain retraction. The endoscopic endonasal approaches (EEAs) for tumors arising from the anterior fossa have been well described; however, their effect on the adjacent brain tissue has not. Herein, the authors utilized the magnetic resonance imaging fluid attenuated inversion recovery (FLAIR) sequence signal as a marker for edema and gliosis on pre- and post-operative images of olfactory groove meningiomas, thus presenting an objective parameter for brain injury after surgical manipulation.

METHODS

Imaging of 18 olfactory groove meningiomas removed through EEAs was reviewed. Tumor and pre/postoperative FLAIR signal volumes were assessed utilizing the DICOM image viewer OsiriX(®). Inclusion criteria were: (1) No previous treatment; (2) EEA gross total removal; (3) no further treatment.

RESULTS

There were 14 females and 4 males; the average age was 53.8 years (±8.85 years). Average tumor volume was 24.75 cm(3) (±23.26 cm(3), range 2.8-75.7 cm(3)), average preoperative FLAIR volume 31.17 cm(3) (±39.38 cm(3), range 0-127.5 cm(3)) and average postoperative change volume, 4.16 cm(3) (±6.18 cm(3), range 0-22.2 cm(3)). Average time of postoperative scanning was 6 months (range 0.14-20 months). In all cases (100%) gross total tumor removal was achieved. Nine patients (50%) had no postoperative FLAIR changes. In 2 patients (9%) there was minimal increase of changes postoperatively (2.2 cm(3) and 6 cm(3) respectively); all others demonstrated image improvement. The most common complication was postoperative cerebrospinal fluid leakage (27.8%); 1 patient (5.5%) died due to systemic complications and pulmonary sepsis.

CONCLUSIONS

FLAIR signal changes tend to resolve after endonasal tumor resection and do not seem to worsen with this operative technique.

Lateral supracerebellar infratentorial approach for microsurgical resection of large midline pineal region tumors: techniques to expand the operative corridor

Pineal region tumors pose certain challenges in regard to their resection: a deep surgical field, associated critical surrounding neurovascular structures, and narrow operative working corridor due to obstruction by the apex of the culmen. The authors describe a lateral supracerebellar infratentorial approach that was successfully used in the treatment of 10 large (> 3 cm) midline pineal region tumors. The patients were placed in a modified lateral decubitus position. A small lateral suboccipital craniotomy exposed the transverse sinus. Tentorial retraction sutures were used to gently rotate and elevate the transverse sinus to expand the lateral supracerebellar operative corridor. This approach placed only unilateral normal structures at risk and minimized vermian venous sacrifice. The surgeon achieved generous exposure of the caudal midline mesencephalon through a "cross-court" oblique trajectory, while avoiding excessive retraction on the culmen. All patients underwent the lateral approach with no approach-related complication. The final pathological diagnoses were consistent with meningioma in 3 cases, pilocytic astrocytoma in 3 cases, intermediate grade pineal region tumor in 2 cases, and pineoblastoma in 2 cases. The entire extent of these tumors was readily reachable through the lateral supracerebellar route. Gross-total resection was achieved in 8 (80%) of the 10 cases; in 2 cases (20%) near-total resection was performed due to adherence of these tumors to deep diencephalic veins. Large midline pineal region tumors can be removed through a unilateral paramedian suboccipital craniotomy. This approach is simple, may spare some of the midline vermian bridging veins, and may be potentially less invasive and more efficient.

Endoscope-assisted endonasal versus supraorbital keyhole resection of olfactory groove meningiomas: comparison and combination of 2 minimally invasive approaches

OBJECTIVE

Although the endonasal endoscopic approach has been applied to remove olfactory groove meningiomas, controversy exists regarding the efficacy and safety of this approach compared with more traditional transcranial approaches. The endonasal endoscopic approach was compared with the supraorbital (eyebrow) keyhole technique, as well as a combined "above-and-below" approach, to evaluate the relative merits of each approach in different situations.

METHODS

Nineteen cases were reviewed and divided according to operative technique into 3 different groups: purely endonasal (6 cases); supraorbital eyebrow (microscopic with endoscopic assistance; 7 cases); and combined endonasal endoscopic with either the bicoronal or eyebrow microscopic approach (6 cases). Resection was judged on postoperative MRI using volumetric analysis. Tumors were assessed based on the Mohr radiological classification and the presence of the lion's mane sign.

RESULTS

The mean age at surgery was 61.4 years. The mean tumor volume was 19.6 cm(3) in the endonasal group, 33.5 cm(3) in the supraorbital group, and 37.8 cm(3) in the combined group. Significant frontal lobe edema was identified in 10 cases (52.6%). The majority of tumors were either Mohr Grade II (moderate) (42.1%) or Grade III (large) (47.4%). Gross-total resection was achieved in 50% of the endonasal cases, 100% of the supraorbital eyebrow cases with endoscopic assistance, and 66.7% of the combined cases. The extent of resection was 87.8% for the endonasal cases, 100% for the supraorbital eyebrow cases, and 98.9% for the combined cases. Postoperative anosmia occurred in 100% of the endonasal and combined cases and only 57.1% of the supraorbital eyebrow cases. Excluding anosmia, permanent complications occurred in 83.3% of the cases in the endoscopic group, 0% of the cases in the supraorbital eyebrow group, and 16.7% of cases in the combined group (p = 0.017). There were 3 tumor recurrences: 2 in the endonasal group and 1 in the combined group.

CONCLUSIONS

The supraorbital eyebrow approach, with endoscopic assistance, leads to a higher extent of resection and lower rate of complications than the purely endonasal endoscopic approach. The endonasal endoscopic approach by itself may be suitable for a small percentage of cases. The combined above-and-below approaches are useful for large tumors with invasion of the ethmoid sinuses.

Resection of olfactory groove meningioma - a review of complications and prognostic factors

INTRODUCTION

High complication rates have been cited following olfactory groove meningioma (OGM) resection but data are lacking on attendant risk factors. We aimed to review the complications following OGM resection and identify prognostic factors.

METHODS

A retrospective review was performed on 34 consecutive patients who underwent primary OGM resection at a single London institution between March 2008 and February 2013. Collected data included patient comorbidities, pre-operative corticosteroid use, tumour characteristics, imaging features, operative details, extent of resection, histology, use of elective post-operative ventilation, complications, recurrence and mortality.

RESULTS

Complication rate was 39%. 58% of complications required intensive care or re-operation. Higher complication rates occurred with OGM > 40 mm diameter versus ≤ 40 mm (53 vs. 28%; p = 0.16); OGM with versus without severe perilesional oedema (59 vs. 19%; p = 0.26), more evident when corrected for tumour size; and patients receiving 1-2 days versus 3-5 days of pre-operative dexamethasone (75 vs. 19%; p = 0.016). Patients who were electively ventilated post-operatively versus those who were not had higher risk tumours but a lower complication rate (17 vs. 44%; p = 0.36) and a higher proportion making a good recovery (83 vs. 55%; p = 0.20). Complete versus incomplete resection had a higher complication rate (50 vs. 23%; p = 0.16) but no recurrence (0 vs. 25%; p = 0.07).

CONCLUSION

Risk of morbidity with OGM resection is high. Higher complication risk is associated with larger tumours and greater perilesional oedema. Pre-operative dexamethasone for 3-5 days versus shorter periods may reduce the risk of complications. We describe a characteristic pattern of perilesional oedema termed 'sabre-tooth' sign, whose presence is associated with a higher complication rate and may represent an important radiological prognostic sign. Elective post-operative ventilation for patients with high-risk tumours may reduce the risk of complications.

Unilateral Tailored Fronto-Orbital Approach for Giant Olfactory Groove Meningiomas: Technical Nuances

OBJECTIVE

Giant olfactory groove meningiomas (maximum diameter ≥6 cm) remain a surgical challenge. Historically, extensive anterior and antero-lateral approaches have been the primary approaches for removal of such large tumors with limitations and morbidity pertaining to each approach. Herein, the authors describe a minimally invasive, unilateral, tailored fronto-orbital approach for resection of these complex lesions with an emphasis on preservation of the anterior cerebral arteries and olfactory nerves.

METHODS

A 4-stage approach using neuronavigation is performed: 1) predefined corridor, 2) identification of the ipsilateral anterior cerebral artery, 3) postdefined corridor, and 4) tumor base. The details of this approach are described below in a stepwise fashion and supplemented by a sample of 3 cases utilizing this technique.

RESULTS

In the 3 representative cases in which this technique was used, gross total resection was achieved without injury to any of the adjacent neurovascular structures. Significant sellar extension can be resected through a second stage endoscopic endonasal approach.

CONCLUSION

Giant olfactory groove meningiomas (≥6 cm) can be safely and completely resected with this 4-stage, unilateral fronto-orbital technique. Furthermore, early identification and preservation of the adjacent critical neurovascular structures can be achieved. This technique avoids the inherent limitations and morbidity associated with the more classic pterional and bifrontal approaches respectively while minimizing normal tissue disruption.

Open Transcranial Resection of Small (<35 mm) Meningiomas of the Anterior Midline Skull Base in Current Microsurgical Practice

OBJECTIVE

Despite technical surgical advance, the ultimate management of midline anterior skull base meningiomas remains to be defined. Open transcranial surgery is usually the first treatment option for large meningiomas, while less invasive techniques such as endoscopic surgery or radiosurgery might represent an alternative to open microsurgery for smaller lesions. The aim of our study is to investigate the outcome of open transcranial microsurgery in the resection of small (<35 mm) meningiomas of the midline anterior cranial base.

METHODS

Clinical and surgical data from 43 patients affected by small midline anterior skull base meningiomas operated via an open transcranial approach were retrospectively reviewed.

RESULTS

The tumor diameter on its major axis ranged from 12 to 35 mm, with a mean diameter of 28 mm. Gross total resection (Simpson grades I-II) was achieved in 100% of cases through a pterional approach. Postoperative overall morbidity was 9%. It was 3% among patients <70 years. No mortality was reported. Postoperative visual outcome was significantly associated with preoperative visual performance (P = 0.02), but not with preoperative optic nerve compression as detected by magnetic resonance imaging (P = 0.116). Age >70 years was associated with postoperative visual impairment, although not significantly (P = 0.06). Visual function was preserved or improved in 95% of cases, in 100% of patients <70 years, and in 71% of patients with preoperative visual impairment.

CONCLUSIONS

In our experience, open transcranial surgery proved safe and effective for midline anterior skull base meningiomas smaller than 35 mm in all patients <70 years and in patients >70 years without preoperative visual deficit. Our data are consistent with the literature. Conversely, the standard of treatment for the subgroup of patients >70 years with preoperative visual deficit has not yet been defined. This specific subgroup of patients offers a topic for further investigation.

Indications and limitations of the endoscopic endonasal approach for anterior cranial base meningiomas

OBJECTIVE

To describe the decision-making and the surgical strategy in the resection of anterior skullbase meningiomas.

METHODS

Details of the microsurgical and endoscopic approach to anterior skullbase meningiomas are presented.

RESULTS

Small and midsize olfactory groove, planum sphenoidale, and tuberculum sellae meningiomas can be removed via an endonasal endoscopic approach, an alternative option to the transcranial microsurgical approach. The choice of approach depends on tumor size and location, involvement of important neurovascular structures, and, most importantly, the surgeon's preference and experience. In my opinion, in most meningiomas, the endonasal approach has no advantage compared with the transcranial approach. Disadvantages of the endonasal approach are the discomfort after surgery and the prolonged recovery phase because of the nasal morbidity, which requires intensive nasal care. Compared with the eyebrow approach, the trauma to the nasal cavity, paranasal sinuses, and skull base is greater, and the risk of cerebrospinal fluid leak is higher.

CONCLUSION

For most skull base meningiomas, I usually prefer the endoscope-assisted microsurgical transcranial approach which combines the advantages of the operating microscope with the advantages of the endoscope. The endonasal approach is beneficial for small tumors located below or behind the chiasm.

The anterior interhemispheric approach: a safe and effective approach to anterior skull base lesions

BACKGROUND

Many approaches to the anterior skull base have been reported. Frequently used are the pterional, the unilateral or bilateral frontobasal, the supraorbital and the frontolateral approach. Recently, endoscopic transnasal approaches have become more popular. The benefits of each approach has to be weighted against its complications and limitations. The aim of this study was to investigate if the anterior interhemispheric approach (AIA) could be a safe and effective alternative approach to tumorous and non-tumorous lesions of the anterior skull base.

METHODS

We screened the operative records of all patients with an anterior skull base lesion undergoing transcranial surgery. We have used the AIA in 61 patients. These were exclusively patients with either olfactory groove meningioma (OGM) (n = 43), ethmoidal dural arteriovenous fistula (dAVF) ( n = 6) or frontobasal fractures of the anterior midline with cerebrospinal fluid (CSF) leakage ( n = 12). Patient records were evaluated concerning accessibility of the lesion, realization of surgical aims (complete tumor removal, dAVF obliteration, closure of the dural tear), and approach related complications.

RESULTS

The use of the AIA exclusively in OGMs, ethmoidal dAVFs and midline frontobasal fractures indicated that we considered lateralized frontobasal lesions not suitable to be treated successfully. If restricted to these three pathologies, the AIA is highly effective and safe. The surgical aim (complete tumor removal, complete dAVF occlusion, no rhinorrhea) was achieved in all patients. The complication rate was 11.5 % (wound infection (n = 2; 3.2 %), contusion of the genu of the corpus callosum, subdural hygroma, epileptic seizure, anosmia and asymptomatic bleed into the tumor cavity (n = 1 each). Only the contusion of the corpus callosum was directly related to the approach (1.6 %). Olfaction, if present before surgery, was preserved in all patients, except one (1.6 %).

CONCLUSIONS

The AIA is an effective and a safe approach to tumorous, vascular and traumatic pathologies of the midline anterior skull base. This approach should be part of the armamentarium of skull base surgeons.

The lion's mane sign: surgical results using the bilateral fronto-orbito-nasal approach in large and giant anterior skull base meningiomas

OBJECT

Concerns about extreme peritumoral edema and its ensuing surgical and perioperative complications led the authors to use the bilateral fronto-orbito-nasal approach to remove midline anterior skull base meningiomas that were larger than 4 cm. The authors hypothesize that extreme vasogenic edema exemplified by finger-like hyperintensities extending into the bifrontal white matter and external capsule and/or the extreme capsule, coined the lion's mane sign (LMS), would help identify patients with a challenging postoperative course. They hypothesize that the LMS would better predict symptomatic postoperative cerebral edema than the edema index (EI).

METHODS

This is an observational case series of 9 patients. The authors noted the grade, pathology, tumor volume, EI, and the presence or absence of the LMS in all tumors. They used the intensive unit care (ICU) length of stay as a nonspecific measure reflecting postoperative symptomatic cerebral edema. Comparisons of edema-related postoperative complications and the EI were made between patients with and without an LMS.

RESULTS

Bifrontal hyperintensities, extending into at least three-eighths of the length of the external capsules on T2-weighted MRI, seen in 4 of 9 patients, portended a longer postoperative ICU stay. The presence of an LMS better predicted postoperative complications related to cerebral edema than tumor grade, pathology, volume, or EI.

CONCLUSIONS

The LMS predicts an increased duration of stay in the ICU after a bilateral fronto-orbito-nasal approach for resection of large and giant anterior skull base meningiomas. Furthermore, the LMS better predicted increased length of stay in the ICU than did the EI.

Patterns in neurosurgical adverse events: intracranial neoplasm surgery

Object

Neurosurgery is a high-risk specialty currently undertaking the pursuit of systematic approaches to measuring and improving outcomes. As part of a project to devise evidence-based safety interventions for specialty surgery, the authors sought to review current evidence in cranial tumor resection concerning the frequency of adverse events in practice, their patterns, and current methods of reducing the occurrence of these events. This review represents part of a series of papers written to consolidate information about these events and preventive measures as part of an ongoing effort to ascertain the utility of devising system-wide policies and safety tools to improve neurosurgical practice.

Methods

The authors performed a PubMed search using search terms “intracranial neoplasm,” “cerebral tumor,” “cerebral meningioma,” “glioma,” and “complications” or “adverse events.” Only papers that specifically discussed the relevant complication rates were included. Papers were chosen to maximize the range of rates of occurrence for the reported adverse events.

Results

Review of the tumor neurosurgery literature showed that documented overall complication rates ranged from 9% to 40%, with overall mortality rates of 1.5%–16%. There was a wide range of types of adverse events overall. Deep venous thromboembolism (DVT) was the most common adverse event, with a reported incidence of 3%–26%. The presence of new or worsened neurological deficit was the second most common adverse event found in this review, with reported rates ranging from 0% for the series of meningioma cases with the lowest reported rate to 20% as the highest reported rate for treatment of eloquent glioma. Benign tumor recurrence was found to be a commonly reported adverse event following surgery for intracranial neoplasms. Rates varied depending on tumor type, tumor location, patient demographics, surgical technique, the surgeon's level of experience, degree of specialization, and changes in technology, but these effects remain unmeasured. The incidence on our review ranged from 2% for convexity meningiomas to 36% for basal meningiomas. Other relatively common complications were dural closure–related complications (1%–24%), postoperative peritumoral edema (2%–10%), early postoperative seizure (1%–12%), medical complications (6%–7%), wound infection (0%–4%), surgery-related hematoma (1%–2%), and wrong-site surgery.

Strategies to minimize risk of these events were evaluated. Prophylactic techniques for DVT have been widely demonstrated and confirmed, but adherence remains unstudied. The use of image guidance, intraoperative functional mapping, and real-time intraoperative MRI guidance can allow surgeons to maximize resection while preserving neurological function. Whether the extent of resection significantly correlates with improved overall outcomes remains controversial.

Discussion

A significant proportion of adverse events in intracranial neoplasm surgery may be avoidable by use of practices to encourage use of standardized protocols for DVT, seizure, and infection prophylaxis; intraoperative navigation among other steps; improved teamwork and communication; and concentrated volume and specialization. Systematic efforts to bundle such strategies may significantly improve patient outcomes.

Bilateral visual loss due to a giant olfactory meningioma

Olfactory groove meningiomas can present as large and insidious masses in the anterior cranial base. Due to their location and minimal clinical symptoms, these tumors can go undetected until they have grown extremely large. We present a clinical case and discuss the surgical management of a 63-year-old man who presented for an initial eye examination with bilateral visual loss for over 2 years due to a giant olfactory meningioma encompassing his entire frontal lobe and compressing on his optic nerves.

Endoscopic skull base surgery: a comprehensive comparison with open transcranial approaches

Little data exists comparing endoscopic endonasal approaches to pathology of the anterior skull base with more traditional transcranial and transsphenoidal microscopic approaches. In order to more fully characterize the role of endoscopy in the management of pathology of the anterior cranial base, we conducted a systematic review of case series and case reports documenting surgical and clinical outcomes. We found that for craniopharyngiomas, clival chordomas, esthesioneuroblastomas and giant pituitary adenomas, the endonasal endoscopic approach can result in equivalent or higher rates of gross total resection than open approaches. For meningiomas, however, open transcranial approaches are still able to achieve higher rates of total resection. CSF leak rates are higher for patients undergoing endoscopic surgery for meningiomas and craniopharyngiomas, but not for chordomas, esthesioneuroblastomas or giant pituitary adenomas. In certain patients, the endonasal endoscopic approach may be a safe and effective alternative for the treatment of a wide variety of skull base pathology, particularly those with small midline tumours.

Giant olfactory groove meningiomas: extent of frontal lobes damage and long-term outcome after the pterional approach

OBJECTIVE

The treatment of giant olfactory groove meningiomas (OGMs; maximum diameter ≥ 6 cm) poses special problems and represents a surgical challenge. We discuss the long-term results in a series of 18 patients with giant OGMs and report our experience on a global strategy encompassing the pterional approach to manage the lesion and an extended transbasal approach to treat recurrences.

METHODS

Between February 1991 and December 2007, 18 patients with giant OGMs were surgically managed via a pterional craniotomy. Postoperative follow-up imaging was obtained at one, six, and 12 months and then yearly. In preoperative images, data from tumor volume were assessed. The volume of the residual right frontal porencephalic cave (ipsilateral to the operative side) was compared with the volume of the porencephalic cave measured in the left frontal lobe (internal control) in each case. Comparison between porencephalic cave and the original tumor volume for each side was also performed.

RESULTS

At the first operation in 17 of 18 patients (94.4%), the tumor resection was accomplished by a complete macroscopic lesion removal and coagulation of its dural attachment (Simpson grade II). In one patient, a Simpson grade V resection was obtained. The mean follow-up was 93.5 months, ranging from 12 to 214 months. Recurrences were observed in three patients (16.7%) at 103, 102, and 128 months, respectively, from the time of the first operation. These patients were operated on via an extended subfrontal transbasal approach accomplishing a complete (Simpson grade I) resection. No death occurred. The visual deficit improved in seven of 13 patients (53.8%), remained stable in five (38.5%), and worsened in one patient (7.7%). Overall, 17 of 18 patients (94.4%) had a good outcome and returned to their previous occupations. All the tumors presented with a symmetrical growth pattern. The mean meningioma volume was 23.51 ± 1.62 cm(3) for the right portion of the tumor and 23.04 ± 1.35 cm(3) for the left portion. The mean residual porencephalic volume was significantly smaller in the left frontal lobe (mean value 5.7 mL) than in the right frontal lobe (mean value 16.6 mL; P < 0.05). The mean residual porencephalic volume was significantly smaller than the tumor volume both in the left (P < 0.01) and in the right side (P < 0.05).

CONCLUSION

The pterional-transsylvian approach provides two major advantages: first, it minimizes morbidity and mortality through an early neurovascular control and by limiting parenchymal damage as demonstrated by a quantitative analysis; second it is associated with low recurrence rate at a long-term follow-up.

Endoscopic endonasal versus open transcranial resection of anterior midline skull base meningiomas

OBJECTIVE

To assess the advantages and limitations of the endoscopic endonasal approach to anterior skull base meningiomas, a minimally invasive approach that avoids extensive bone drilling, brain retraction, and manipulation of nerves and critical vessels, versus open transcranial surgery.

METHODS

A MEDLINE (2000-2010) search was performed to identify series for either olfactory groove meningiomas or tuberculum sellae (TS) or planum sphenoidale meningiomas. Statistical analyses of categorical variables such as extent of resection, morbidity, and visual outcome were performed using χ(2) and Fisher exact tests.

RESULTS

The literature review included 60 studies, involving 1426 patients. Open surgery achieved a higher rate of gross total resection (GTR) for both olfactory groove (P < 0.001) and TS and planum (P < 0.001) meningiomas. Postoperative cerebrospinal fluid (CSF) leak occurred more frequently in the endoscopic cohort (P < 0.001). Other postoperative complications occurred more frequently in the open cohort, although this difference was not statistically significant. There were no significant differences in postoperative visual outcome between the groups.

CONCLUSIONS

Based on the current literature, open transcranial approaches for olfactory groove and TS and planum sphenoidale meningiomas still result in higher rates of total resection with lower postoperative CSF leak rates. The endoscopic endonasal approach may be safe and effective for certain skull base meningiomas; careful patient selection and multilayer closure techniques are essential.

Olfactory groove meningioma: discussion of clinical presentation and surgical outcomes following excision via the subcranial approach

OBJECTIVES/HYPOTHESIS

To describe surgical outcomes and radiographic features of olfactory groove meningiomas treated by excision through the subcranial approach. Special emphasis is placed on paranasal sinus and orbit involvement.

STUDY DESIGN

Retrospective review of a series of patients.

METHODS

Nineteen patients underwent excision of olfactory groove meningioma (OGM) via the transglabellar/subcranial approach between December 1995 and November 2009. Nine patients had previously undergone prior resection at outside institutions, and four had prior radiotherapy in addition to a prior excision. Transglabellar/subcranial surgical approach to the anterior skull base was performed.

RESULTS

Tumor histology included three World Health Organization (WHO) grade III lesions, one WHO grade II lesion, and 15 WHO grade I lesions. Fourteen patients had evidence of extension into the paranasal sinuses, with the ethmoid sinus being most commonly involved. Kaplan-Meier estimates of mean overall and disease-free survival were 121.45 months and 93.03 months, respectively. The mean follow-up interval was 41.0 months, and at the time of data analysis three patients had recurrent tumors. Seven (36.8%) patients experienced a major complication in the perioperative period; there were no perioperative mortalities. Orbit invasion was observed in four patients, with optic nerve impingement in 11 patients. Of these, three patients had long-term diplopia. No patients experienced worsening of preoperative visual acuity.

CONCLUSIONS

Olfactory groove meningiomas demonstrate a propensity to spread into the paranasal sinuses, particularly in recurrent cases. Given a tendency for infiltrative recurrence along the skull base, this disease represents an important area of collaboration between neurosurgery and otolaryngology. The subcranial approach offers excellent surgical access for excision, particularly for recurrences that involve the paranasal sinuses and optic apparatus.

Surgical nuances for removal of olfactory groove meningiomas using the endoscopic endonasal transcribriform approach

Olfactory groove meningiomas represent 10% of intracranial meningiomas and arise in the midline of the anterior cranial fossa along the dura of the cribriform plate and planum sphenoidale. Hyperostosis of the adjacent underlying bone is common, and further extension into ethmoid sinuses and nasal cavity can occur in 15%-25% of cases. Radical tumor resection including the involved dural attachment and underlying hyperostotic bone offers the best chance of a Simpson Grade I resection to minimize recurrence. Incomplete removal of involved hyperostotic bone can result in tumor recurrence at the cribriform plate with extension into the paranasal sinuses. Resection has traditionally been performed using a bifrontal or pterional approach, both of which require some degree of brain retraction or manipulation to expose the tumor. The endoscopic endonasal transcribriform approach offers the most direct and immediate exposure to the tumor without brain retraction and manipulation of neurovascular structures. An endonasal "keyhole craniectomy" is performed in the ventral skull base directly over the basal dural attachment, extending from the posterior wall of the frontal sinus to the planum sphenoidale and tuberculum sellae in the anteroposterior plane, and from one medial orbit to the other in the coronal plane. Excellent panoramic visualization of the keyhole skull base defect can be obtained with a 30° endoscope after performing a modified Lothrop procedure. Because the dural attachment is adjacent to the paranasal sinuses, early devascularization and total Simpson Grade I removal of the tumor including the dural attachment and underlying hyperostotic bone can be achieved in properly selected patients. This approach is also very suitable for meningiomas that have recurred or extended into the paranasal sinuses. Extracapsular, extraarachnoid dissection of the tumor from the frontal lobes and neurovascular structures can be performed using conventional bimanual microsurgical techniques. In this report, we review the surgical technique and describe our operative nuances for removal of olfactory groove meningiomas, including recurrent tumors with extension into the nasal cavity, using a purely endoscopic endonasal transcribriform approach. In addition, we discuss the advantages, limitations, patient selection, and complications of this approach. We specifically highlight our technique for multilayer reconstruction of large anterior skull base dural defects using fascia lata and acellular dermal allograft supplemented by bilateral vascularized pedicled nasoseptal flaps. Three new cases of endoscopically resected olfactory groove meningiomas are also presented.

Endoscope-assisted microsurgical resection of skull base meningiomas

This study aims to determine the value of endoscope assistance in the microsurgical resection of skull base meningiomas. Fourty-six patients harboring a skull base meningioma underwent an endoscope-assisted microsurgical resection. In 30 patients (65%), tumor parts which could not be visualized under the microscope were detected with the endoscope. In 26 patients (56%), these tumor remnants were removed under endoscopic view. Gross total resection was achieved in 35 patients (76%) and near-total resection in 11 (24%). There was no surgical mortality. The major complication was new cranial nerve deficit. The application of endoscopes was most useful in the small supraorbital craniotomies to look under the ipsilateral optic nerve and internal carotid artery as well as to visualize the diaphragm sellae and olfactory groove. In the retrosigmoid craniotomies, the endoscope was beneficial to inspect the internal auditory canal, to look into Meckel's cave, or to inspect areas hidden behind the jugular tubercle and tentorial edge. There was no obvious complication related to the application of the endoscope. Endoscope assistance is particularly of value when skull base meningiomas are to be removed via small craniotomies to inspect blind corners which cannot be visualized in a straight line with the microscope. In addition, there is a benefit of using endoscopes with various angles of view in standard craniotomies and skull base approaches to look around bony and dural corners or to look behind neurovascular structures, by which the amount of skull base drilling and retraction to expose the tumor can be reduced.

Supra-orbital keyhole removal of anterior fossa and parasellar meningiomas

The improvement of surgical techniques as well as the introduction of new surgical instruments promoted the use of keyhole craniotomies in neurosurgery. We evaluated the technical aspects of the supra-orbital keyhole approach considering the indications, limitations, and complications of this approach to treat anterior cranial fossa and parasellar meningiomas. Twenty-four patients (21 females; mean age, 53 + or - 8.6 years) operated on between 2002 and 2006 through a supra-orbital eyebrow approach were studied. Maximal tumor diameter ranged from 1.6 to 6 cm. Gross total resection was done in 20 (83.3%). All tumors were histologically benign. Two patients (8%) experienced CSF rinorhea and another two patients suffered transitory diabetes insipidus (8%). One patient experienced transitory hemiparesis. There was one case of meningitis and one mortality. Follow-up ranged between 6 to 66 months (mean 31.5 + or - 20.1 months), with no recurrence. The supra-orbital keyhole craniotomy is a useful minimally invasive approach to treat selected anterior fossa and parasellar meningiomas.

Endoscopic endonasal transethmoidal transcribriform transfovea ethmoidalis approach to the anterior cranial fossa and skull base

OBJECTIVE

The anterior skull base, in front of the sphenoid sinus, can be approached using a variety of techniques including extended subfrontal, transfacial, and craniofacial approaches. These methods include risks of brain retraction, contusion, cerebrospinal fluid leak, meningitis, and cosmetic deformity. An alternate and more direct approach is the endonasal, transethmoidal, transcribriform, transfovea ethmoidalis approach.

METHODS

An endoscopic, endonasal approach was used to treat a variety of conditions of the anterior skull base arising in front of the sphenoid sinus and between the orbits in a series of 44 patients. A prospective database was used to detail the corridor of approach, closure technique, use of intraoperative lumbar drainage, operative time, and postoperative complications. Extent of resection was determined by a radiologist using volumetric analysis.

RESULTS

Pathology included meningo/encephaloceles (19), benign tumors (14), malignant tumors (9), and infectious lesions (2). Lumbar drains were placed intraoperatively in 20 patients. The CSF leak rate was 6.8% for the whole series and 9% for intradural cases. Leaks were effectively managed with lumbar drainage. Early reoperation for cerebrospinal fluid (CSF) leak occurred in 1 patient (2.2%). There were no intracranial infections. Greater than 98% resection was achieved in 12 of 14 benign and 5 of 9 malignant tumors.

CONCLUSION

The endoscopic, endonasal, transethmoidal, transcribriform, transfovea ethmoidalis approach is versatile and suitable for managing a variety of pathological entities. This minimal access surgery is a feasible alternative to transcranial, transfacial, or combined craniofacial approaches to the anterior skull base and anterior cranial fossa in front of the sphenoid sinus. The risk of CSF leak and infection are reasonably low and decrease with experience. Longer follow-up and larger series of patients will be required to validate the long-term efficacy of this minimally invasive approach.

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.

Validity of the frontolateral approach as a minimally invasive corridor for olfactory groove meningiomas

BACKGROUND

Several approaches are described for olfactory groove meningiomas (OGMs) varying from a very wide bifrontal craniotomy to minimally invasive endoscopic techniques. The goal of this study was to evaluate the results of the frontolateral approach for olfactory groove meningioma. Pitfalls related to this corridor will be described. The impact of tumor size and encasement of the anterior cerebral artery complex on the degree of tumor removal will be described on the basis of experience with 18 cases.

METHODS

Eighteen patients with OGM underwent microsurgical removal using the frontolateral approach. A retrospective study was conducted by analyzing clinical data, neuroimaging studies, operative findings, clinical outcome, and degree of tumor removal.

FINDINGS

The patients were classified into group A with tumor size less than 4 cm in diameter (7 out of 18 cases, 38.9%) and group B with tumor size more than 4 cm in diameter (11 out of 18 cases, 61.1%). CSF rhinorrhea was observed in three patients (16.7%). Postoperative left frontal intracerebral hematoma occurred in one patient (5.6%) belonging to group A. In another patient (5.6%) belonging to group B, marked right frontal lobe swelling was evident after dural opening, which necessitated partial right frontal pole resection. Total tumor removal (Simpson grade 1 and 2) was achieved in 14 out of 18 patients (77.8%), while subtotal removal (Simpson grade 3 and 4) was achieved in 4 patients (22.2%). In the 14 patients in whom total removal was achieved, 7 belonged to group A (all 7 patients of group A with 100% removal), while the remaining 7 patients belonged to group B (7 out of 11 patients, 63.6% removal; one of them had anterior cerebral artery complex encasement). The four patients in whom subtotal removal was achieved belonged to group B; three of them showed anterior cerebral artery complex encasement, and one elderly patient had non-extensive paranasal sinus involvement. One patient (5.6%) in group B died from cerebral infarction after subtotal tumor removal with anterior cerebral artery injury during its dissection from the tumor capsule.

CONCLUSION

The frontolateral approach has the advantages of both the pterional and conventional bifrontal approaches. The frontolateral approach allows quick and minimally invasive access to OGMs less than 4 cm in diameter, and also to tumors more than 4 cm in diameter without encasement of the anterior cerebral artery complex. Tumor size more than 4 cm in diameter and encasement of the anterior cerebral artery complex are limiting factors for the frontolateral approach if radical tumor removal is considered.

Endoscopic transnasal resection of anterior cranial fossa meningiomas

OBJECT

The extended transnasal approach, a recent surgical advancements for the ventral skull base, allows excellent midline access to and visibility of the anterior cranial fossa, which was previously thought to be approachable only via a transcranial route. The extended transnasal approach allows early decompression of the optic canals, obviates the need for brain retraction, and reduces neurovascular manipulation.

METHODS

Between 2004 and 2007, 11 consecutive patients underwent transnasal resection of anterior cranial fossa meningiomas--4 olfactory groove (OGM) and 7 tuberculum sellae (TSM) meningiomas. Age at surgery, sex, symptoms, and imaging studies were reviewed. Tumor size and tumor extension were estimated, and the anteroposterior, vertical, and horizontal diameters were measred on MR images. Medical records, surgical complications, and outcomes of the patients were collected.

RESULTS

A gross-total removal of the lesion was achieved in 10 patients (91%), and in 1 patient with a TSM only a near-total (> 90%) resection was possible. Four patients with preoperative visual function defect had a complete recovery, whereas 3 patients experienced a transient worsening of vision, fully recovered within few days. In 3 patients (2 with TSMs and 1 with an OGM), a postoperative CSF leak occurred, requiring a endoscopic surgery for skull base defect repair. Another patient (a case involving a TSM) developed transient diabetes insipidus. The operative time ranged from 6 to 10 hours in the OGM group and from 4.5 to 9 hours in the TSM group. The mean duration of the hospital stay was 13.5 and 10 days in the OGM and TSM groups, respectively. Six patients (3 with OGMs and 3 with TSMs) required a blood transfusion. Surgery-related death occurred in 1 patient with TSM, in whom the tumor was successfully removed.

CONCLUSIONS

The technique offers a minimally invasive route to the midline anterior skull base, allowing the surgeon to avoid using brain retraction and reducing manipulation of the large vessels and optic apparatus; hastens postoperative recovery; and improves patient compliance. Further assessment and refinement are required, particularly because of the potential risk of CSF leakage. Other studies and longer follow-up periods are necessary to ascertain the benefits of the technique.

LATERAL SUPRAORBITAL APPROACH APPLIED TO OLFACTORY GROOVE MENINGIOMAS

OBJECTIVE

The lateral supraorbital approach for safely and completely removing olfactory groove meningiomas was assessed.

METHODS

Between September 1997 and June 2008, a total of 656 meningiomas were operated on by the senior author (JH) at the Department of Neurosurgery, Helsinki University Central Hospital; 66 were olfactory meningiomas. We retrospectively analyze the clinical data, radiological findings, surgical treatment, histology, and outcome of all the olfactory groove meningioma patients and discuss the operative techniques used.

RESULTS

Sixty-six patients were operated on by the lateral supraorbital approach. The median preoperative Karnofsky Performance Scale score was 80 (range, 40–100). Three patients were redo cases in which the primary operation had been performed elsewhere. Seemingly complete tumor removal was achieved in 60 patients (91%); there was no surgical mortality. Postoperatively, 6 patients (9%) had cerebrospinal fluid leakage, 5 (8%) had new visual deficits, 4 (6%) had wound infections, 4 (6%) had cotton granulomas, and 1 (2%) had a postoperative hematoma. The median Karnofsky score at discharge was 80 (range, 40–100). Six patients had recurrent tumors; 3 underwent reoperations after an average of 21 months (range, 1–41 months); 1 was treated with radiosurgery, and 2 were only followed. During the median follow-up time of 45 months (range, 2–128 months), there were 4 recurrences (6%) diagnosed on average 32 months (range, 17–59 months) after surgery.

CONCLUSION

The lateral supraorbital approach can be used safely for olfactory groove meningiomas of all sizes with no mortality and relatively low morbidity. Surgical results and tumor recurrence with this fast and simple approach are similar to those obtained with more extensive, complex, and time-consuming approaches.

Gamma Knife surgery of large meningiomas: early response to treatment

PURPOSE

Gamma Knife treatment is traditionally limited to tumours with a diameter not exceeding 3-3.5 cm. The current paper presents 97 patients with meningiomas with a minimum volume of 10 cm(3), treated with a prescription dose of 12 Gy (or sometimes less to protect neighbouring structures). The post-treatment assessment of these patients, the early response to treatment and the complications of treatment are presented.

METHODS

There were 97 patients, 70 females and 27 males. The mean age was 48.1 years (range 20.4-87.2 years). The mean follow-up was 54 months (range 25-86 months). All tumours had a volume of 10 cm(3) or more. The mean volume was 15.9 cm(3) (range 10.0-43.2 cm(3)). Post-treatment follow-up used quantitative and qualitative assessments, which are described.

RESULTS

No tumour continued to grow. Twenty-seven were smaller and 72 unchanged in volume. Three patients suffered adverse radiation effects (defined as a new post-treatment oedema detected on the magnetic resonance image with or without contrast leakage). In one case this was silent. In two cases the clinical and radiological effects were temporary and resolved completely.

CONCLUSIONS

It is suggested on the basis of this material that the dosimetry used here permits the safe Gamma Knife treatment of larger meningiomas within the range reported. The early radiological response is encouraging, but further follow-up is needed to check long term tumour control. A qualitative method of tumour volume assessment is presented. It seems to be a simpler and more reliable way of assessing tumour volume changes than other methods currently in routine use.

Giant olfactory groove meningioma: ophthalmological and cognitive outcome after bifrontal microsurgical approach

OBJECT

Olfactory groove meningiomas arise in the midline along the dura of the cribriform plate and may reach a large size before producing symptoms. We conducted a retrospective study of patients with these lesions focused on pre- and post-operative investigations for ophthalmological, personality and cognitive disturbances.

METHODS

The authors reviewed 36 patients with giant olfactory groove meningiomas surgically treated via a bifrontal approach. Ophthalmological evaluation included visual acuity, fundoscopy and visual fields while psychological evaluation included a Mini-Mental State Examination. Data was collected before, 1 and 12 months after surgery. Formal pre- and post-operative ophthalmological examinations discovered visual deficits in 55.5% of the patients. Within the first month after surgery, improvement of visual acuity and of visual field deficits was observed. In post-operative neuropsychological testing, higher mental functions showed improvement. The most frequent post-operative complication was persistent rhinorrhoea in two patients.

CONCLUSIONS

Results at longest follow up indicate that cognitive changes and visual deficits will improve in patients with giant olfactory groove meningiomas after a bifrontal approach, without additional neurological deficits.

Surgery of extra-axial tumors of the cerebral base

Because of the complex structure of the cranial base and its close proximity to cranial nerves and vessels, surgery in this area is associated with considerable risk of morbidity and mortality. Multiple approaches to each part of the cranial base have been developed over the past few decades, ranging from small modifications of more traditional approaches to complex and sophisticated new techniques. However, experience has shown that optimal outcome is achieved if the selected approach is not associated with significant approach-related morbidity. Furthermore, not all cranial base tumors can be cured by surgery. The selection of operative approach and the goal of surgery should be part of the whole treatment strategy. The attempt to achieve complete resection can, therefore, be justified only if the associated long-term morbidity is minimal. Refinements of the traditional retrosigmoid suboccipital approach have made it the most effective and safe approach, the "gold standard" for lesions in the cerebellopontine angle. On the other hand, in some basal tumors, e.g., chordomas and chondrosarcomas, the approach has to be selected individually and must always be tailored to the characteristics of the particular tumor, its location, and the patient's expectations. The expertise of the surgeon is not reflected in his or her ability to perform the most complex approaches but in the ability to select the approach that affords both removal of the tumor and preservation of patient's neurological function and quality of life.