Anterior Skull Base Tumors Research Articles

The Draf III Mucosal Grafting Technique

The Draf III procedure is an advanced surgical option for frontal sinus disease refractory to endoscopic frontal sinusotomy and is used to expose the anterior limit of resection of the skull base during endoscopic management of anterior skull base tumors. Our objective was to evaluate outcomes of a strategy using mucosal grafts to decrease postoperative closure. Prospective cohort. Tertiary care facility. Patients requiring a Draf III procedure were prospectively enrolled in the study. Demographics, reason for the procedure, percentage graft viability, and complications were recorded. The primary outcome measure was anterior-posterior (AP) diameter at 3 months. Mucosal grafting was performed during 29 Draf III procedures from 2008 to 2011. Twenty-seven patients (average age, 58 years) were available for measurement at 3 months (average postoperative follow-up, 15.4 months; range, 3-30 months). Reasons for the procedure included tumor (n = 14), chronic rhinosinusitis (CRS) with frontal ostium stenosis (n = 12), and trauma (n = 1). Average intraoperative AP diameter was 11.7 mm. All patients met the definition of success (<50% reduction in diameter), maintaining a patent combined frontal sinus ostium for the duration of follow-up (average diameter 10.8 mm at 3 months). Nine patients with CRS and frontal ostium stenosis had openings similar to the entire cohort (>1-year follow-up; average, 19.3 months) with significant symptom reduction (SNOT-22 preop 62.3 ± 20.8 vs 3 months 27.8 ± 14.8 and 1 year 21.4 ± 13.6; P < .0001). Cicatricial stenosis and osteoneogenesis are common following the Draf III procedure. This study indicates that the use of mucosal grafts may assist with postoperative stenosis and should be considered a routine strategy for preventing closure.

Expanded endoscopic endonasal transcribriform approach for resection of anterior skull base olfactory schwannoma.

Anterior skull base (ASB) schwannomas are extremely rare and can often mimic other pathologies involving the ASB such as olfactory groove meningiomas, hemangiopericytomas, esthesioneuroblastomas, and other malignant ASB tumors. The mainstay of treatment for these lesions is gross-total resection. Traditionally, resection for tumors in this location is performed through a bifrontal transbasal approach that can involve some degree of brain retraction or manipulation for tumor exposure. With the recent advances in endoscopic skull base surgery, various ASB tumors can be resected successfully using an expanded endoscopic endonasal transcribriform approach through a "keyhole craniectomy" in the ventral skull base. This approach represents the most direct route to the anterior cranial base without any brain retraction. Tumor involving the paranasal sinuses, medial orbits, and cribriform plate can be readily resected. In this video atlas report, the authors demonstrate their step-by-step techniques for resection of an ASB olfactory schwannoma using a purely endoscopic endonasal transcribriform approach. They describe and illustrate the operative nuances and surgical pearls to safely and efficiently perform the approach, tumor resection, and multilayered reconstruction of the cranial base defect. The video can be found here: http://youtu.be/NLtOGfKWC6U .

Global and Disease-Specific Health-Related Quality of Life after Complete Endoscopic Resection of Anterior Skull Base Neoplasms

Minimally invasive surgery for neoplasms of the anterior skull base has revolutionized the treatment of these diseases. The relative effect of endoscopic procedures, however, has not been described in terms of disease-specific and global health-related quality of life (QoL). A single-center longitudinal study was performed of patients undergoing complete endoscopic resection of anterior skull base neoplasms. Patients presenting between October 2009 and September 2010 were enrolled. QoL assessments were based on the 22-question Sinonasal Outcomes Test (SNOT-22), Health Utilities Index Mark II (HUI-2), and Short-Form 12 (SF-12) and were completed preoperatively and at 3, 6, and 12 months postoperatively. Comparisons over time were made within subjects. Fourteen patients were enrolled; 11 completed preoperative and postoperative assessments (79%). Our cohort consisted of five men and six women; mean age was 55 years. Six patients had malignant tumors; four required adjuvant therapy. SNOT-22 scores were stable or improved in 10 cases (91%), with a significant difference for the cohort (mean, -33 points; p < 0.01). Ten (91%) patients had stable or improved HUI-2 scores (mean utility change, +0.13). SF-12 scores were stable for both mental (p = 0.17) and physical (p = 0.26) components. Mean quality-adjusted life year gain over the study period was 0.07. Complete endoscopic resection of anterior skull base neoplasms is oncologically sound with anecdotal QoL improvements relative to open craniofacial resection. We show positive, quantifiable QoL results with validated global and disease-specific instruments. Additional work will help to improve outcomes in this population and will be used in formal cost-effectiveness analysis.

Intraoperative monitoring of visual function

Due to the excellent functional outcomes reported in thestudy published in this issue of Acta Neurochirurgica byBenedicic et al. [1], Intraoperative monitoring of the visualfunction using cortical potentials after electrical epiduralstimulation of the optic nerve, the authors have first of allto be congratulated.Indeed, they recorded the intraoperative visualevoked potential after electrical epidural stimulationof the optic nerve in 11 patients who underwentsurgical resection for a skull base meningioma. Theyobserved that P20 and N30 amplitude changes wererelated to the manipulation of ON during anterior skullbase tumor removal. Interestingly, there was noimmediate postoperative visual worsening, althoughthe rate of postsurgical visual deterioration is usuallyhigher in the literature, up to 10% in patients with nopresurgical deficit. It is nonetheless worth noting thatBenedicic et al. have already reported the stability andreproducibility of cortical potentials after electricalepidural stimulation of the ON. In addition, severalother authors have previously performed intraoperativemonitoring of visual function in patients with tumorsalong the visual pathways (from ON to optic radia-tion), using different techniques such as flash visualevoked potentials [2] or direct subcortical electrostimu-lation of the optic radiation in awake patients [3].Therefore, from a methodological point of view, no newdata are described here. The results presented byBenedicic et al. using cortical potentials should now bereproduced and validated by other teams.Furthermore, it is not really surprising to observe P20and N30 amplitude changes during manipulation of ON.Using the recording of ON-evoked potentials, Kikuchi et al.already noted attenuation of amplitude as a response to ONmanipulation [4]. Thus, the actual contribution of thepresent series would have been to demonstrate that thenew technique introduced by the authors was able to predictpostoperative deterioration. Unfortunately, the authorsfailed to identify any correlation between intrasurgicalchanges of cortical potentials and newly acquired postop-erative visual worsening. It would have been helpful tofocus more on this point. Indeed, the aim of oncologicalsurgery is to optimize the benefit-to-risk ratio of the surgicalprocedure, that is, to increase the extent of resection whilepreserving the quality of life. In the present study, nooncological considerations have been detailed: the extent oftumor removal and the long-term follow-up were notdescribed. Thus, because P20 and N30 amplitude changeswere related to the manipulation of ON or chiasma duringanterior skull base tumor removal, one could think that theauthors stopped the resection earlier. As a consequence, thequestion is to know whether it was justified to interrupt themeningiomal removal according to the results provided bythese online cortical potentials or whether the patientswould have been able to recover even if the authors hadpursued the resection in spite of the electrophysiologicalchanges.In summary, despite the rigorous methodology andthe favorable functional outcomes here described, on thebasis of this small series reporting a negative result (i.e.,no correlation between intrasurgical modifications ofcortical potentials and newly acquired postoperative

Intraoperative monitoring of the visual function using cortical potentials after electrical epidural stimulation of the optic nerve

Central skull base meningiomas commonly present with visual deficit, and their removal often leads to improvement of visual function. However, the incidence of postoperative visual deterioration has been reported to be up to 10%. Intraoperative monitoring using flash visual evoked potential has only recently been used with success. Cortical potentials (CP) after electrical epidural stimulation of the optic nerve (ON) were correlated with ON manipulation due to central skull base tumor removal to contribute to improvement of the intraoperative monitoring of the visual function. Blunt needle stimulating electrodes were attached epidurally alongside ON in an unroofed optic canal and used for delivering a rectangular current pulse (intensity 0.2-5.0mA; duration 0.1-0.3ms; rate 2Hz). CPs after electrical epidural stimulation of ON were recorded with corkscrew electrodes at O(z) with the reference electrode at F(z). P20 and N30 amplitudes were significantly lower (p < 0.05) during tumor removal associated with ON manipulation than in other phases of surgery; the amplitude reductions were reversible in all cases. There were no significant changes in P20, N30 and P40 latencies during the surgery. Immediate postoperative visual function was unchanged in all patients. P20 and N30 amplitude changes seem to reliably correspond with the manipulation of ON during anterior skull base tumor removal. Reversible reduction of P20 and N30 amplitude was associated with unchanged immediate postoperative visual function. No correlation between intraoperative variation of CP and newly acquired postoperative visual deficit can presently be made.

Placement of NP Airways after Skull Base Tumor Resection

Objective: 1) Assess the efficacy of nasopharyngeal (NP) airways in lieu of tracheotomy to prevent tension pneumocephalus after open resection of anterior skull base (ASB) tumors. 2) Determine predictors of tension pneumocephalus in patients undergoing NP airway placement after open resection of ASB tumors. Method: A total of 121 ASB resections (mean age, 48.5 years; M:F 73:47) performed between 1994 to 2009 with documented NP airway placement were identified and charts retrospectively reviewed. Main outcome measures were presence of tension pneumocephalus, while controlling for other clinical parameters (presence of CSF leak, placement of lumbar drain, type of reconstruction). Results: All patients were extubated on the day of surgery and NP airways remained in place for 3 days; no complications from NP airways were seen (eg, nasal septal pressure necrosis, displacement of the tubes). A total of 3 (2.5%) cases of tension pneumocephalus occurred. There were 34 (28%) lumbar drains placed and 14 (12%) CSF leaks. Although only 3 events were recorded, there was a statistically significant difference in the rate of tension pneumocephalus stratified by lumbar drain placement ( P = .02), presence of CSF leak ( P = .04), and both together ( P = .004). Type of reconstruction did not affect rate of tension pneumocephalus ( P = 1.0). Conclusion: Resection of anterior skull base tumors does not necessitate prophylactic tracheotomy and use of a nasopharyngeal airway to divert airflow is well tolerated and highly successful. Lumbar drainage, the presence of a CSF leak, or both together may increase the risk of tension pneumocephalus.

Endoscopic Removal of Massive Sinonasal and Skull Base Osteoblastoma

Objective: Osteoblastomas are uncommon bone neoplasms, accounting for 1% of all newly diagnosed primary bone tumors. Sinonasal and skull base osteoblastomas are exceedingly rare. We describe an endoscopic resection of a massive sinonasal/skullbase osteoblastoma, which was misdiagnosed as an ossifying fibroma. We discuss the histopathologic diagnosis of these sinonasal bony lesions. Method: Case report and current literature review. Results: A 14-year-old female presented with progressive right-sided proptosis and nasal obstruction. CT and MRI scanning demonstrated a massive sinonasal lesion with orbital and skull base involvement. An endoscopic biopsy performed by another otolaryngologist revealed a fibrous and highly vascular lesion. Histopathologic diagnosis was consistent with an ossifying fibroma. Endoscopic endonasal extended approach of this anterior skull base tumor was successfully performed with complete resection. Final histopathologic diagnosis revealed an osteoblastoma. The patient did well postoperatively without complication. Conclusion: This case aims to increase awareness of this infrequently encountered disease of the nasal cavity and paranasal sinuses and offers insight into the diagnosis and treatment of this rare entity.

Esthesioneuroblastomas in an Asian Population: Similarities and Differences

Objective: Esthesioneuroblastomas is an uncommon malignant tumor of the olfactory neuroepithelium in the white population. However, in our series with predominantly Asian patients, it is the most common anterior skull base malignancy requiring a craniofacial resection. Method: Twenty-four patients who underwent craniofacial resections for malignant anterior skull base tumors and were diagnosed with esthesioneuroblastomas were recruited in this prospective study over a 10-year period. All patients were operated on by the same surgeon with the same technique. Results: Twenty-four out of 48 patients with anterior skull base malignancies had esthesioneuroblastomas. The mean age of patients with esthesioneuroblastomas was 53 years old with no bimodal distribution. Most patients were Chinese (92%) with a male predominance (62%). Major complication rate was 13% and we had 1 unrelated perioperative mortality. Fifty percent of our patients had either local or regional recurrence. Three patients passed away in our series from tumor-unrelated reasons. Two-thirds of the patients in our series are alive more than 5 years after the initial diagnosis. The overall 5 year survival rate was 86%. Conclusion: The predominant malignant anterior skull base tumor requiring a craniofacial resection was an esthesioneuroblastoma (50%). This is much more common than described in other series. There is a good curability with this tumor, with most patients surviving well beyond 5 years.

Transciliary Supraorbital Approach

To the Editor: We read with interest the comments by Dr Balasubramanian.1 The pros and cons that Dr Balasubramanian mentioned are important aspects when neurosurgeons consider these transciliary methods. However, we think it is prudent to stress that the transciliary incision could be used not only for the supraorbital craniotomy but also for the mini-orbitozygomatic craniotomy. With the orbital rim removed, the latter provides increased space for instrument use, minimizes brain retraction, and improves the vertical angle of the corridor to common sites in the anterior circulation aneurysms and anterior skull base lesions (especially in frontobasal or suprasellar tumors).2,3 We find this mini-orbitozygomatic craniotomy especially useful when the endoscope-assisted method is considered (because the increased angle provides a better space to insert the endoscope, which avoids “sword fighting” with the other instruments). In our experience, the prominent frontal sinus is not a contraindication to these approaches. In our patients, the pericranial flap could be harvested and used for reconstruction of the frontal sinus, similar to traditional anterior skull base procedure. In our experience, the initial saline injection to the space above the periosteum is very critical (Figure, A). Immediately after the junction of the orbicularis and frontalis muscle is split, the underlying pericranial (periosteal) flap is harvested (Figure, B; the supraorbital nerve was isolated with a silk). The harvested flap is usually about 3.5 cm in height and 4.5 cm in width, depending on the length of transciliary incision (Figure, C, showing the bony exposure for supraorbital craniotomy [arrow indicates pericranial flap]). If a longer flap is needed (judging from preoperative sagittal imaging), the traction endoscopic method could be used to harvest the flap up to 10 cm. With this traction endoscopic method, the supraorbital nerve (Figure, D) could be preserved after it was isolated up to 5 cm and lateralized to the nasal side during surgery. In our experience, this technique minimizes the postoperative scalp numbness (in both the supraorbital and temporoparietal regions). A similar method is reported by Patel et al4 for repair of the dural defect from an extended endonasal approach. However, they used a median nasion incision and an additional incision behind the hairline to harvest the flap. During surgery, the frontal sinus was entered and the mucosa removed. After irrigation with gentamicin water, the frontal sinus was packed with beta-iodine-soaked gel foam, and the roof was covered with the pericranial flap. With such a method, none of the 23 supraorbital or mini-orbitozygomatic craniotomies that traverse the frontal sinus had postoperative central nervous system or wound infection. Therefore, we do not consider a prominent frontal sinus to be a contraindication to these approaches.FIGURE: The steps and technique used to harvest the pericranial flap in the transciliary approach.When a ventriculostomy is needed, mostly in aneurysm cases, the entry point could be created at the frontal basal region directly under the keyhole. The ventriculostomy catheter was directed at a 45° angle to the midline and a 20° angle up from an imaginary line parallel to the orbitomeatal line.5 The catheter will usually be inserted into the frontal horn at a point 5 cm from the pial surface and may be inserted to 6.5 cm. A subcutaneous tunnel is then created, and the catheter is pulled through another small incision near the pterion behind the hairline. We could not agree more with Dr Balasubramanian that patient selection is the most important step in choosing these minimally invasive techniques. In terms of aneurysmal surgery, traditional craniotomy or even hemicraniectomy was needed in patients with poor-grade subarachnoid hemorrhage or significant brain edema. These cases are apparently poor candidates for supraciliary approach. The approach selection for an anterior skull base tumor is further complicated by the additional option of the extended endonasal approach.6 The tumor size, relationship to optic nerve, surgical experience, and confidence in a watertight reconstruction of dural defect are all important factors to consider. In summary, when minimally invasive approaches are considered, the exposure and angle provided by these approaches are equally important.7 As most experts have mentioned, the most important point is to use the most suitable approach for a particular patient rather than using a one-size-fits-all approach for all patients. Abel Po-Hao Huang Chien-Lian Chen Taipei, Taiwan

Solitary extra-skeletal sinonasal metastasis from a primary skeletal Ewing's sarcoma

Ewing's sarcoma is a rare, malignant tumour predominantly affecting young adolescent males. We describe a unique case of an isolated extra-skeletal metastasis from a skeletal Ewing's sarcoma primary, arising in the right sinonasal cavity of a young man who presented with severe epistaxis and periorbital cellulitis. Histologically, the lesion comprised closely packed, slightly diffuse, atypical cells with round, hyperchromatic nuclei, scant cytoplasm and occasional mitotic figures, arranged in a sheet-like pattern. Immunohistochemical analysis showed positive staining only for cluster of differentiation 99 glycoprotein. Fluorescent in situ hybridisation identified the Ewing's sarcoma gene, confirming the diagnosis. Complete surgical resection was achieved via a minimally invasive endoscopic transnasal approach; post-operative radiotherapy. Ten months post-operatively, there were no endoscopic or radiological signs of disease. Metastatic Ewing's sarcoma within the head and neck is incredibly rare and can pose significant diagnostic and therapeutic challenges. An awareness of different clinical presentations and distinct histopathological features is important to enable early diagnosis. This case illustrates one potential management strategy, and reinforces the evolving role of endoscopic transnasal approaches in managing sinonasal cavity and anterior skull base tumours.

Utility of novel 3‐dimensional stereoscopic vision system for endoscopic sinonasal and skull‐base surgery

The objective of this pilot study was to evaluate the utility of novel 3-dimensional (3D) endoscopy during endoscopic sinonasal and skull base surgery. Eight surgeries were performed in 7 patients between August 2009 and March 2010 at a tertiary care academic medical center. A high-definition 2-dimensional (2D) endoscopy system was employed in all cases. The Visionsense stereoscopic system (Orangeburg, NY) was incorporated during key portions of the procedures. Two independent surgeons assessed utility of the technology for the following 2 variables: (1) ability to facilitate orientation and depth perception; and (2) impact on completeness of surgery and potential complications. The mean age was 50.4 years and the male:female ratio was 6:1. Indications included anterior skull base (ASB) tumor resection (5), directed skull base biopsies (2), and ethmoid dissection adjacent to dehiscent skull base/optic nerve in allergic fungal rhinosinusitis (1). Endoscopic orientation and depth perception was aided using the 3D endoscope in all cases. Additional interventions were performed in 3 cases (37.5%), including tumor resection (1) and removal of remnant ethmoid partitions (2). Limitations posed included inability to visualize a type III frontal cell (1) and loss of orientation during ASB reconstruction due to overmagnification (1). No complications were observed in this patient series. This preliminary study demonstrated the effectiveness of binocular 3D endoscopy during sinonasal and skull-base surgery. The technology facilitated depth perception and completeness of surgery without increase in complications. Additional experience is warranted to define its role in the endoscopic surgical paradigm.

The Extended Endoscopic Endonasal Approach for Orbital Apex Tumor Resection

Introduction: Endoscopic approaches for resection of anterior skull base tumors have recently gained popularity. The extended endoscopic endonasal approach to the midline skull base has been used to treat a variety of midline tumors including craniopharyngiomas, pituitary adenomas, meningiomas, and chordomas. Intraorbital tumors have traditionally been resected through transcranial approaches or through lateral orbitotomies. We describe a modification of the extended endoscopic endonasal approach to the medial orbit and orbital apex for tumor resection.

Endoscopic-assisted Craniofacial Resection

ABSTRACTManagement of anterior skull base tumors has progressed steadily since AS Ketcham popularized the craniofacial surgical technique in the seventies with good results. In the past two decades, endoscopic sinonasal tumor resection has been established as an additional treatment option. For tumors that cross the anterior skull base, a cranial access is vital to encompass the tumor all around. For a select group of these transcranial lesions, the sinonasal component is suitable for an endoscopic endonasal oncologically safe resection along with a traditional transcranial access to complete the resection. This article endeavors to describe the endoscopicassisted craniofacial combining the advantages of a transnasal minimal access to reduce facial morbidity and the transcranial access for superior control of tumors with adequate margins.

Combined craniofacial resection of anterior skull base tumors: long-term results and experience of single institution

In this article, the authors are presenting their experience and the results with combined craniofacial resection of anterior skull base tumors based on a review of 27 constitutive cases. Our data are evaluated in comparison to other major centers in other parts of the world, and possible factors that might influence surgical outcome and survival are discussed. Twenty-seven patients diagnosed with anterior skull base tumors between 1999 and 2009 were treated by combined craniofacial resection. Of these patients, there were 19 males (70, 3%) and eight females (29, 7%). The age ranged between 11 and 75years (mean = 45.9 ± 17.6years). The follow-up period ranged between 14 and 123months (avarage = 74months). The most common presenting symptoms were nasal obstruction and vision disturbance (11 patients for each -40.7%). Total resection was achieved in 24 patients (89%), while subtotal resection was done in three patients (11%). The most common complication was CSF fistule with rhinorrhea, which occurred in five patients (18.5%). Eight patients had recurrences at the time of this long-term follow-up. There were two mortalities in the early postoperative period and seven deaths in the long-term follow-up (overall mortality, 33.3%). The overall 5-year overall survival for all patients in our series was 70.4%. The 5-year overall survival was 62% for patients with malignant tumors and 100% for patients with benign tumors. Combined craniofacial resection of tumors of the anterior skull base is an effective approach for the management of these pathologies. The effectiveness is clearly demonstrated by the clinical results and outcomes of these patients' groups. The favorable prognosis is enhanced by significantly by total resection with negative tumor margins.

Defining the “edge of the envelope”: patient selection in treating complex sellar-based neoplasms via transsphenoidal versus open craniotomy

Endonasal approaches have become the gold standard intervention for many anterior and middle skull base tumors. The authors aimed to define some of the existing limitations of these approaches by reviewing their experience with complex sellar region tumors that were initially considered for both transsphenoidal and open skull base approaches and were thus deemed tumors at "the edge of the envelope." Between April 2008 and April 2010, 250 transsphenoidal operations were performed at Brigham and Women's Hospital. All cases were retrospectively reviewed to identify patients with complex sellar region tumors that were initially considered for, or soon thereafter required, an open craniotomy as the definitive treatment. The anatomical tumor characteristics that posed limitations to performing safe and effective endonasal skull base operations were reviewed. Thirteen cases exemplifying some of the existing limitations to achieving optimal surgical outcomes via transsphenoidal-based approaches are presented. The following 8 factors are separately discussed that repeatedly limited the extent of resection, increased the risk of the operation, and contributed to perioperative complications: significant suprasellar extension, lateral extension, retrosellar extension, brain invasion with edema, firm tumor consistency, involvement or vasospasm of the arteries of the circle of Willis, and encasement of the optic apparatus or invasion of the optic foramina. Although the ability to approach and resect complex tumors using endonasal skull base techniques has evolved dramatically in recent years, several inherent tumor characteristics mandate extensive preoperative consideration. In selected cases these characteristics may lend support to selecting an open craniotomy as the initial operation.

Endoscopic Anterior Skull Base Surgery: Intraoperative Considerations of the Crista Galli

We sought to measure the anatomic dimensions of the crista galli in a consecutive series of patients undergoing the endoscopic transcribriform approach for anterior skull base tumors at a tertiary academic university hospital. We performed a retrospective chart review of patients undergoing purely endoscopic transcribriform surgery for sinonasal and skull base lesions. Main outcome measures included radiological dimensions of the crista galli. A total of 12 patients were identified and treated by the senior authors at the University of Pennsylvania. The average crista galli dimensions were 12.7 ± 2.4 mm (anterior-posterior) and 12.9 ± 2.5 mm (cranial-caudal dimension). Knowledge of the dimensions of the crista galli is important in preoperative planning for both instrumentation and access.

Anterior craniofacial resection — for paranasal sinus tumors involving anterior skull base

Management of anterior skull base tumors is complex due to the anatomic detail of the region and the variety of tumors that occur in this area. Currently, the "gold standard" for surgery is the anterior craniofacial approach. Craniofacial resection represents a major advance in the surgical treatment of tumors of the paranasal sinuses involving anterior skull base. It allows wide exposure of the complex anatomical structures at the base of skull permitting monobloc tumor resection. This study presents a series of 18 patients with anterior skull base tumors, treated by a team of head-neck surgeons and neurosurgeons. The series included 15 malignant tumors of the nose and paranasal sinuses and 3 extensive benign lesions. All tumors were resected by a combined bi-frontal craniotomy and rhinotomy. The skull base was closed with a pediculated pericranial flap and a split-thickness free skin graft underneath. There were no postoperative problems of wound infection, cerebrospinal fluid-leakage or meningitis. Recurrent tumor growth or systemic metastasis occurred in 3 out of 15 patients with malignant tumors, 6 months to 2 years postoperatively. Craniofacial resection was thus found to give excellent results with low morbidity in malignant lesions and can also be adapted for benign tumors of anterior skull base.

Anterior skull base surgery

The basic principle of anterior skull base surgery is to provide adequate exposure to enable three dimensional resection of skull base tumors. Negative surgical margins, which is within the control of surgeon, is the principle prognostic factor in anterior skull base tumors. Open skull base approaches is the standard of care for malignant anterior skull base tumors. Benign lesions may be resected by alternate minimally invasive approaches. Advances in anterior skull base surgery, in particular the facial translocation approaches allows wide exposure of the tumors with minimal retraction of the brain. The outcome of anterior skull base tumors have steadily increased over the years with disease free survival comparable to other malignant neoplasm of the head and neck region. This review described various surgical approaches and pertaining anatomy and pathology of anterior skull base tumors.

Endoscopic v/s conventional approach to sino-nasal tumours — What’s the debate?

In the past two decades nasal endoscopy has advanced technologically to offer us magnified vision and better illumination along with better instrumentation. Surgery has traditionally been via the transfacial approaches such as lateral rhinotomy or the Weber Fergueson incision. For disease extension into the skull base traditional approach is a transfrontal craniotomy via either the bicoronal incision or the subcranial Raveh's approach. A combined access via the cranium from above and the transfacial access from below aids in encompassing the tumour all around. Transnasal access is a natural trajectory which leads us directly onto the tumour. The endoscope alone or with the microscope has been utilised to improve the magnification and illumination to aid in tumour removal. Minimal access to the Sinonasal and anterior skull base tumours is proven to be possible and feasible. We now have an additional armamentarium to our existing approaches in management of these tumours. We have to be judicious and see which approach can remove the disease completely maintaining the quality of life of the patient.

High-viscosity polymethylmethacrylate cement for endoscopic anterior cranial base reconstruction

Endoscopic endonasal transsphenoidal surgery (ETSS) is an effective, minimally invasive approach for the resection of anterior skull base tumors. Cerebrospinal leakage is a common complication, and repair of the anterior skull base defect with alloplastic materials has been used to minimize the risk of postoperative CSF rhinorrhea and meningitis. Injectable cements, such as low-viscosity polymethylmethacrylate (PMMA), are useful for cranial base reconstruction because they are easy to shape to the contour of the defect. These low-viscosity materials, however, are more susceptible to leakage into the nasal cavity prohibiting their use and are prone to cracking upon hardening. Cement extravasation not only obstructs the operator's view during placement, but it is also associated with significant local and systemic complications. High-viscosity (HV) PMMA-based cement and its specialized delivery system have recently been shown to be safe and effective in human applications. Moreover, its constant high viscosity significantly reduces cement leakage and its associated complications. The authors hypothesized that this type of cement would therefore be ideal for ETSS to repair anterior skull base defects. The authors report their experience using HV-PMMA to reconstruct the anterior skull base in 12 patients following ETSS. The unique puttylike consistency of this material is easy to work, malleable, does not leak into the nasal cavity, does not aspirate into suction tubing, and hardens without cracks in less than 10 minutes. None of the 12 patients suffered postoperative CSF leaks or infections more than 8 months, on average, after surgery. Although not necessary in all cases of ETSS, the authors conclude that HV-PMMA, if needed, may be an excellent choice for reconstructing the anterior skull base after ETSS. Further studies are needed to better assess the long-term outcomes of HV-PMMA cement and its use in repairing skull base defects after extended ETSS.