What's New in Skull Base Medicine and Surgery? Skull Base Committee Report

Endoscopic Endonasal Internal Carotid Artery Transposition Technique in Tumor With Parasellar Extension: A Single-Center Experience

BACKGROUND AND OBJECTIVES

Lateralization or mobilization of the internal carotid artery (ICA) during a midline approach is required to expose lesions behind or lateral to the ICA. However, there have been no published data regarding the surgical outcomes of the endoscopic endonasal internal carotid transposition technique (EEITT). This study aimed to analyze the relevant surgical anatomy around the ICA and propose a grading scheme of EEITT.

METHODS

A retrospective review of patients who underwent EEITT at a single institution was performed. Based on structures that limited the ICA and intraoperative findings, an anatomically surgical grading scheme of EEITT was proposed.

RESULTS

Forty-two patients (mean age 45.6 years, 57.1% female patients) were included. Of them, 29 cases (69.0%) were Knosp grade 4 pituitary adenoma, 6 cases (14.3%) were chordoma, 6 cases (14.3%) were meningioma, and a single case (2.4%) was meningeal IgG4-related disease. The EEITT was categorized into Grades 1, 2 and 3, which was used in 24 (57.1%), 12 (28.6%), and 6 (14.3%) cases, respectively. The most common symptom was visual disturbance (45.2%). The gross total resection rate in Grade 1 (79.2%) and Grade 2 (83.3%) was much higher than that in Grade 3 (66.6%). The overall rate of visual function improvement, preoperative cranial nerve (CN) palsy improvement, and postoperative hormonal remission was 89.4%, 85.7%, and 88.9%, respectively. The rate for the following morbidities was cerebrospinal fluid leakage, 2.4%; permanent diabetes insipidus, 4.8%; new transient CN palsy, 9.5%; permanent CN palsy, 4.7%; panhypopituitarism, 7.1%; and ICA injury, 2.4%.

CONCLUSION

The EEITT is technically feasible and could be graded according to the extent of disconnection of limiting structures. For complex tumor with parasellar extensions, the distinction into Grades 1, 2, and 3 will be of benefit to clinicians in predicting risks, avoiding complications, and generating tailored individualized surgical strategies.

Transsphenoidal resection for pituitary adenoma in elderly versus younger patients: a systematic review and meta-analysis

INTRODUCTION

Pituitary adenomas (PA) are common intracranial tumors. In the context of the aging of the population, the question is whether postsurgical outcomes are comparable to the younger ones. The primary objective of the present study was to review published resection and recurrence rates after transsphenoidal resection. The secondary aim was to evaluate visual improvement and complication rates.

METHODS

The authors searched PubMed and Medline databases, of published English series, with no time frame limit, evaluating outcomes of transsphenoidal resection in populations aged more or less than 65, 70, and 80 years. We performed a systematic review and meta-analysis.

RESULTS

Median overall resection rates for younger population was 70.7% (range 54-76.8) and for elderly one was 65.7% (range 16.6-78.2) (two-sample t test, p = 0.35). The only statistically significant difference for gross total resection rates (GTR) favored patients aged less than 80 (p = 0.01). There was no statistically significant difference among recurrence rates. There was a statistically significant difference for visual improvement favoring patients aged more than 80 (p = 0.03). For the age groups of less versus more than 70, there was a statistically significant difference for overall complication rate favoring younger groups (p < 0.05).

CONCLUSION

Present data shows GTR rates favoring younger patients. Recurrence rates remain similar over the mean follow-up period. Moreover, visual improvement favors patients aged more than 80. Overall complication rates favor patients younger than 70, which might be also related to additional comorbidities, frequently present in seniors. Transsphenoidal surgery is safe and effective even for older patients.

A novel drainage approach in patients with cholesterol granuloma: From petrous apex to mastoid air cell

Background:

Cholesterol granulomas (CG) of the petrous apex (CGPA) are benign lesions that have high recurrence rates after surgical intervention. We describe the use of a robust silicon drain between the petrous apex and mastoid air cells to allow constant aeration of the lesion for preventing recurrence.

Case Description:

A retrospective analysis was performed using the data of four patients treated at the Maastricht University Medical Centre between 2014 and 2016. Using the middle fossa approach, the petrous apex was reached, the cyst was opened, and the content aspirated. Subsequently, a robust silicon drain was placed between the cyst and mastoid air cell system. The outcome measures were clinical improvement of the symptoms and radiological parameters. The patients were female (n = 2) and male (n = 2) with an age range between 33 and 53 years at the time of the operation. Computed tomography and magnetic resonance imaging scans were used to confirm CG diagnosis. The most common presenting symptoms in our population were diplopia and headaches. The symptoms improved after surgery and there were no complications. Thus far, no recurrence has been observed and imaging shows aeration in the lesion area.

Conclusion:

The use of a robust drain seems to be an effective, safe, and feasible option to prevent recurrences in patients with CG.

Advantages and limitations of endoscopic endonasal approaches to the skull base

BACKGROUND

The anatomy of the skull base is extremely complex with an abundance of critical neurovascular bundles and their corresponding foramina as well as the insertions and origins of multiple masticatory and craniocervical muscles. These anatomic intricacies increase the difficulty of surgery within this area.

METHODS

Advantages and disadvantages of endoscopic endonasal approaches (EEAs) based on the authors' sequential learning and experience are described.

RESULTS

EEAs offer the advantages of using preexistent air spaces that enable accessing various areas of the skull base, while avoiding external incisions or scars and obviating the need for the translocation of the maxillofacial skeleton. In addition, EEAs are well suited to preserve neurologic, visual, and masticatory functions as well as cosmesis. However, the sinonasal corridor must be expanded and optimized to access the skull base adequately, facilitate the reconstruction of the surgical defect, avoid sinonasal complications, and minimize sequelae. Important considerations can limit or indicate the approach, such as the nature of the pathology, including location, diagnosis, and vascularity; patient characteristics, including age and medical comorbidities; surgeon attributes, including training, experience, and expertise; the resultant need to reconstruct large skull base defects and feasible alternatives to do so; and institutional resources, including adjunctive services, an intensive care unit, and operating room equipment.

CONCLUSIONS

EEAs are important techniques in contemporary skull base surgery. Understanding the indications for and limitations of these approaches help to maximize outcomes.

Surgical approaches to resection of anterior skull base and paranasal sinuses tumors

Malignant tumours of the sinonasal tract comprise approximately 3% of the malignancies that arise in the upper aerodigestive tract. Approximately 10% of tumours that arise in the sinonasal tract originate in the ethmoid and/or frontal sinuses, and are likely to involve the anterior cranial base. The route of spread of tumours originating in the anterior skull base and paranasal sinuses is determined by the complex anatomy of the craniomaxillofacial compartments. These tumours may invade laterally into the orbit and middle fossa, inferiorly into the maxillary antrum and palate, posteriorly into the nasopharynx and pterygopalatine fossa, and superiorly into the cavernous sinus and brain. Recent improvements in endoscopic technology now allow the resection of the majority of benign neoplasms and some early malignant tumours with minor dural involvement. For advanced-stage malignant tumours and benign tumours with frontal bone involvement, the classical open approaches remain viable surgical techniques. In this paper, we review the open surgical resection approaches used for resections in the craniomaxillofacial area.

A Vascular Catastrophe during Endonasal Surgery: An Endoscopic Sheep Model

Internal carotid artery (ICA) injury is a dramatic complication of endonasal skull base approaches with massive bleeding. This study aims to design an animal model of ICA injury during endonasal skull base surgery. Eight sheep underwent ICA isolation followed by arterial pressure monitoring and placement of a rapid infuser. The Sinus Model Otorhino Neuro Trainer (Pro Delphus, Pernambuco, Brazil) nasal model was then modified. A novel posterior sphenoid wall was created, allowing the artery to be placed within and fixed to the model in a watertight fashion. A diamond-tipped bur allowed surgical exposure of the carotid artery. A standardized injury was created endoscopically. The "two-surgeon technique" allowed local packing measures to be performed. Outcome measures were mean arterial pressure (MAP) following injury, resuscitation fluid volume, survival time, and total blood loss. Mean preinjury weight was 51.8 ± 4.59 kg. All baseline hematologic parameters fell within normal limits. The mean preinjury and postinjury MAP was 65.7 ± 9.3 mm Hg versus 39.1 ± 6.9 mm Hg, respectively. The mean survival time was 50.25 ± 17.89 minutes, with mean resuscitation fluid volume of 10.89 ± 2.40 L and mean blood loss of 4943 ± 1089 mL. This model replicates the endoscopic surgical field of an ICA injury, with the potential to train endoscopic skull base teams in the skills require to manage an ICA injury.

Endoscopic craniofacial resection. Indications and technical aspects

INTRODUCTION

Anterior craniofacial resection (CFR) is a standardised procedure for the treatment of tumours involving the anterior skull base. We present our experience in the endoscopic treatment of these tumours.

MATERIAL AND METHOD

A retrospective analysis was performed of patients treated by endoscopic anterior CFR in our Department from 2004 until 2011.

RESULTS

Thirty-two patients were analysed. Mean follow-up was 28 months (range: 6-84 months). The most frequent pathological entity was adenocarcinoma (60%), followed by undifferentiated carcinoma (13%). According to TNM classification, malignant epithelial tumour staging was T3 in 9%, T4a in 53% and T4b in 19% of the malignant epithelial tumours. The complication rate was 6% and the resection was complete in 91% of cases. During follow-up, 9% of patients developed recurrence. The 5-year overall survival rate was 70% and the 5-year disease-free survival rate was 85%

CONCLUSION

These results seem to indicate that properly planned endoscopic CFR may be a valid alternative to traditional open approaches for the management of malignancies of the anterior skull base.

Indications and limitations of endoscopic skull base surgery

A wealth of critical neurovascular structures within a relatively small surface area adds to the already intricate nature of skull base surgery. Surgical approaches to the area are difficult and often associated with significant morbidity and mortality. During the past two decades, endoscopic endonasal approaches (EEAs) have evolved to access the ventral skull base for the resection of tumors (benign and malignant), the decompression of neural structures including the cervicomedullary junction (pannus from rheumatoid arthritis or congenital anomalies, such as platybasia) and the reconstruction of skull base defects (cerebrospinal leaks, meningoencephalocele). These minimal access approaches obviate the need for external incisions, translocation of maxillofacial bones and retraction of the brain. Furthermore, EEAs yield improved visualization, which may reduce complications, and improve quality of life outcomes. Anatomical difficulties (e.g., vascular encasement or extension beyond the plane of a major vessel or cranial nerve), various special conditions (e.g., pediatric patients and vascular tumor) and limitation of institutional resources and technical difficulties may limit the use of EEAs. Thus, one should understand the indications and limitations of EEAs to optimize patient selection, which, in turn, may lead to superior surgical outcomes and reduced morbidity.

Pituitary surgery: legacies from the past

Pituitary surgery is a recent development in neurosurgery and most of the surgical techniques concerned have been described within the last century. We provide a historical perspective by reviewing the major steps in the development of this neurosurgical subspecialty through the ages. We concentrate on the most important figures whose advances in the study of the physiology and anatomy of the pituitary are most significant. This journey into the past will demonstrate that our current knowledge is the summation of a long road of investigation.

Utility of a three-dimensional endoscopic system in skull base surgery

We evaluated the utility of a three-dimensional (3-D) endoscopic system for skull base surgery. We performed a retrospective case series in a tertiary care medical center. Thirty-six patients underwent skull base (nonpituitary) resections via 3-D endoscopic system. Fifteen patients (42%) were operated for excision of malignant tumors, 19 (53%) for excision of benign lesions, and 3 (8.3%) for skull base reconstruction. The tumors involved the cribriform plate (n = 13), sphenoid sinus and planum (n = 17), clivus (n = 7), and sella (n = 7). Complete tumor resection was achieved in 31 patients and subtotal resection in two. Five patients (14%) had postoperative complications. There was one case of meningitis, and there were no cases of cerebrospinal fluid leak. The surgeon's ability to recognize anatomic structures at the skull base was evaluated using the 3-D and two-dimensional systems. The 3-D technique was superior to the conventional technique for identification of the sella, carotid prominence, optic prominence, cribriform plate, sphenoid, and fovea ethmoidalis. The two systems were equal for detection of the turbinates, clivus, maxillary, ethmoids, and frontal sinuses. Endoscopic skull base surgery with stereoscopic viewing is feasible and safe. Further studies are required to evaluate the advantage of binocular vision in skull base surgery.

Endoscopic anatomy of the oculomotor nerve: defining the blind spot during endoscopic skull base surgery

OBJECTIVE

The objective of this study is to define the endoscopic anatomy of the oculomotor nerve (CN III) and its neurovascular relations in order to facilitate surgical procedures and avoid injury to this nerve during endoscopic endonasal approach to the skull base.

MATERIALS AND METHODS

Endoscopic anatomy of the cavernous sinus was studied in seven fresh adult cadavers bilaterally and the basal cisterns in five fresh adult cadavers. Extended endoscopic endonasal suprasellar approach was performed to expose the oculomotor nerve in the interpeduncular cistern and the endoscopic endonasal transethmoidopterygoidosphenoidal approach to expose the oculomotor nerve within the cavernous sinus.

RESULTS

The extraorbital part of the oculomotor nerve can be divided into three segments in regard to the cisterns and venous spaces that are being transected: the interpeduncular segment, the cisternal segment, and the intercavernous segment. Of these segments, only the cisternal segment could not be exposed since this segment was located at the initial part of the roof of the cavernous sinus, anterolateral to the posterior clinoid, and posteroinferior to the anterior clinoid processes. Thus, cisternal segment of the oculomotor nerve was considered a blind spot during endoscopic approaches to the skull base.

CONCLUSION

We defined the endoscopic anatomy of the CN III and the related neurovascular structures and proposed a new segmental classification of extraorbital oculomotor nerve. Awareness of the endoscopic anatomy and the new segmental classification of the CN III may prove helpful in avoiding the risk of nerve injury during endoscopic endonasal surgery for skull base pathologies.

What are the limits of endoscopic sinus surgery?: the expanded endonasal approach to the skull base

The advent of endoscopic technologies and techniques has expanded the limits of conventional endoscopic sinus surgery. The expanded endonasal approach describes a series of surgical modules in the sagittal and coronal planes that allow surgical access to the entire ventral skull base. The sagittal plane extends from the frontal sinus to the second cervical vertebra. The coronal plane extends from the midline to the roof of the orbit, the floor of the middle cranial fossa, and the jugular foramen. Key principles of endonasal skull base surgery are choosing a surgical corridor that minimizes the need for neural and vascular manipulation, team surgery, use of the endoscope to enhance visualization, and bimanual tumor dissection under direct visualization. Particular challenges of the expanded endonasal approach are identification of anatomical structures using unfamiliar landmarks, hemostasis, and dural reconstruction. Over the last decade with more than 1000 completely endonasal skull base surgeries, we have demonstrated that endoscopic endonasal surgery of the skull base can be performed with minimal morbidity and mortality. The introduction of the septal mucosal flap for dural reconstruction has decreased the incidence of postoperative cerebrospinal fluid leaks to less than 5%. Early data suggests that oncological outcomes for malignant sinonasal tumors with skull base involvement are comparable to conventional techniques. Proper training in endonasal surgical techniques is essential to prevent unnecessary morbidity and achieve good outcomes.

Closure of large skull base defects after endoscopic transnasal craniotomy

Object

The authors describe the utility of and outcomes after endoscopic transnasal craniotomy and skull reconstruction in the management of skull base pathologies.

Methods

The authors conducted a observational study of patients undergoing totally endoscopic, transnasal, transdural surgery. The patients included in the study underwent treatment over a 12-month period at 2 tertiary medical centers. The pathological entity, region of the ventral skull base resected, and size of the dural defect were recorded. Approach-related complications were documented, as well as CSF leaks, infections, bleeding-related complications, and any minor complications.

Results

Thirty consecutive patients were assessed during the study period. The patients had a mean age of 45.5 ± 20.2 years and a mean follow-up period of 182.4 ± 97.5 days. The dural defects reconstructed were as large as 5.5 cm (mean 2.49 ± 1.36 cm). One patient (3.3%) had a CSF leak that was managed endoscopically. Two patients had epistaxis that required further care, but there were no complications related to intracranial infections or bleeding. Some minor sinonasal complications occurred.

Conclusions

Skull base endoscopic reconstructive techniques have significantly advanced in the past decade. The use of pedicled mucosal flaps in the reconstruction of large dural defects resulting from an endoscopic transnasal craniotomy permits a robust repair. The CSF leak rate in this study is comparable to that achieved in open approaches. The ability to manage the skull base defects successfully with this approach greatly increases the utility of transnasal endoscopic surgery.

Outcome of craniofacial surgery in children and adolescents with malignant tumors involving the skull base: an international collaborative study

BACKGROUND

The aim of the study was to characterize the distribution of anterior skull base (ASB) cancers in the pediatric population and to identify predictors of outcome.

METHODS

This was an international study of 1307 patients undergoing craniofacial surgery for malignant tumors; 6.4% (n = 84) among these were <or=21 years old.

RESULTS

The most common histologic type was sarcoma (40%), followed by squamous cell carcinoma (14%). Higher incidence of tumors was found in older children (7.5-21 years) compared to younger children. The 5-year disease-specific and overall survival rates were 61% and 55%, respectively (median follow-up of 30 months). The best prognosis was associated with low-grade sarcomas and the worst with salivary and squamous cell carcinomas. High-grade sarcoma represented an intermediate risk group. On multivariate analysis, prior radiotherapy and histology were independent predictors of survival.

CONCLUSION

Surgery for malignant tumors involving the ASB is feasible and safe in children. Histology is significant determinant of poor outcome in this population.

Intracranial complications before and after endoscopic skull base reconstruction

BACKGROUND

Endoscopic skull base reconstruction (ESBR) has been widely accepted in the management of cerebrospinal fluid (CSF) leaks. However, it is not the CSF leak itself but the potential for life-threatening intracranial complications (ICCs) that is of primary clinical concern. The risk of developing complications, such as meningitis, in a skull base defect is unknown. Many ESBR are multilayered soft tissue repairs, and long-term prevention of ICCs is not well described.

METHODS

Retrospective chart review and telephone consultation was used to assess patients who had an ESBR from 2002 to 2008. The incidence of an ICCs (meningitis, cerebral abscess, and pneumocephalus) and associated risk factors were assessed before and after surgery.

RESULTS

One hundred six patients underwent ESBR (mean age (+/-SD), 47.7 +/- 18.5 years; range, 2-78 years) with 95.3% long-term follow-up (mean, 19.9 +/- 16.3 months). ICCs occurred in 21.7% of patients at presentation, in 2.8% of patients during the perioperative period (<2 weeks), and in one patient (0.9%) during the postoperative period. Risk factors for presenting with an ICC and meningitis were revision cases performed elsewhere (chi(2) = 9.10; p = 0.007) and leaking encephaloceles (chi(2) = 5.98; p = 0.014). Factors not associated with increased ICC were an active CSF leak at presentation (chi(2) = 3.03; p = 0.082) and previous radiotherapy.

CONCLUSION

ESBR offers an excellent long-term option in preventing subsequent ICC with low perioperative complications. ESBR is robust with delayed (>2weeks) CSF leakage occurring in only 1.9% regardless of etiology. The presence of identifiable risk factors for ICC may guide the surgeon in determining the urgency of ESBR.

Head and neck cancer: an evolving treatment paradigm

Since the inception of this journal in 1948, the understanding of etiologic factors that contribute to and the treatment of head and neck cancer has evolved dramatically. Advances in surgery, radiation therapy, and chemotherapy have improved locoregional control, survival, and quality of life. The outcomes of these treatment modalities have shifted the focus of curative efforts from radical ablation to preservation and restoration of function. This evolution has been documented in the pages of Cancer for the past 6 decades. This review focuses on the evolution of treatment approaches for head and neck cancer and future directions while recognizing the historic contributions recorded within this journal.

Algorithm for Reconstruction After Endoscopic Pituitary and Skull Base Surgery

INTRODUCTION

The expanding role of endoscopic skull base surgery necessitates a thorough understanding of the indications, techniques, and limitations of the various approaches to reconstruction. The technique and outcomes of endoscopic skull base reconstruction remain incompletely described in the literature.

STUDY DESIGN AND METHODS

Patients undergoing endoscopic skull base surgery underwent an algorithmic approach to reconstruction based on tumor location, defect size, and presence of intraoperative cerebrospinal fluid (CSF) leak. A prospective database was reviewed to determine the overall efficacy of reconstruction and to identify risk factors for postoperative CSF leak.

RESULTS

The diagnosis in the 127 patients in this series included pituitary tumor in 70 (55%) patients, encephalocele in 16 (12.6%) patients, meningioma in 11 (8.7%) patients, craniopharyngioma in 9 (7.1%) patients, and chordoma in 6 (4.7%) patients. Successful reconstruction was initially achieved in 91.3% of patients. Eleven (8.7%) patients experienced postoperative CSF leak, 10 of which resolved with lumbar drainage alone. One (0.8%) patient required revision surgery. Correlation between postoperative CSF leak and study variables revealed a statistically significant longer duration of surgery (243 vs. 178 min, P = .008) and hospitalization (12.1 vs. 4.5 days, P < .0001) and a trend toward larger tumors (mean, 3.2 vs. 2.3 cm; P = .058) in patients experiencing postoperative CSF leak.

CONCLUSION

The algorithm for reconstruction after endoscopic surgery presented in this study is associated with excellent overall efficacy. A greater understanding of risk factors for postoperative CSF leak is imperative to achieve optimal results.

Acquisition of surgical skills for endonasal skull base surgery: a training program

INTRODUCTION

Endonasal surgery represents a radical change in the practice of cranial base surgery and requires the acquisition of new knowledge and surgical skills. The optimal training program for surgeons has not been established.

METHODS

We reviewed our experience with endonasal cranial base surgery from 1998 to 2006 to develop a training plan for the acquisition of surgical skills. It consists of a modular and incremental approach to endonasal skull base surgery that is designed to train surgeons to function as a team, learn endoscopic skull base anatomy, and develop fundamental endoscopic skills.

RESULTS

Stages of training are established for the otolaryngologist-head and neck surgeon and the neurosurgeon that are based on level of technical difficulty, potential risk of vascular and neural injury, and unfamiliar endoscopic anatomy. Mastery of each level is recommended before attempting procedures at a higher level.

CONCLUSIONS

Standardization of training and the adoption of a modular, incremental training program are expected to facilitate the training of endonasal surgeons in both surgical specialties. Adherence to such a program during the growth phase of endoscopic skull base surgery may decrease the risk of complications as the surgeon's knowledge and surgical expertise develop.