Preoperative and intraoperative imaging for endoscopic endonasal approaches to the skull base

The Displacement Patterns of Petrous Internal Carotid Artery and Its Morphometric Relations with Vidian Canal in Petroclival Chondrosarcomas Relevant to Extended Endoscopic Endonasal Approaches: A Radiological Study

BACKGROUND

Extended endoscopic endonasal approaches (EEAs) to petroclival chondrosarcomas (PCs) require a thorough understanding of skullbase anatomy, especially the anatomy of petrous internal carotid artery (pICA), as ICA injury is the most dreaded complication of extended EEAs. We conducted this study to determine the displacement patterns of pICA in patients with PCs.

METHODS

Contrast enhanced computed tomography scan and angiography images of patients with PCs were analyzed for following parameters-antero-posterior, cranio-caudal, medio-lateral, and direct distances between anterior genu of petrous internal carotid artery (AGpICA) and posterior end of Vidian canal (pVC). pICA encasement/narrowing by tumor was noted on magnetic resonance imaging.

RESULTS

We studied 11 patients with histopathologically proven PCs. pICA encasement/narrowing and pVC destruction were observed in one patient each. The mean antero-posterior and cranio-caudal distances on tumor side/normal side were 7.7 ± 1.9/6.4 ± 1.0 mm & 4.5 ± 1.5/3.4 ± 0.9 mm, respectively. The overall displacement was posterior & superior. Medio-lateral displacement was seen in 4 patients (lateral in 3 and medial in 1). In rest, AGpICA was centered on pVC. The mean direct distance was 9.4 ± 2.5 mm. In 3 patients with displacement seen in all three axes, direct distance was measured by the "cuboid method." Overall, posterior-superior-lateral, posterior-superior, and anterior-inferior were the common displacement patterns of AGpICA relative to pVC.

CONCLUSIONS

The displacement patterns of AGpICA in PCs are variable. An individualized approach with meticulous analysis of preoperative imaging can help in determining the relation between AGpICA and pVC. This detailed morphometric information can facilitate better orientation to altered anatomy, which can be helpful in preventing pICA injury during extended EEAs.

Management of squamous cell carcinomas of the skull-base

PURPOSE

The purpose of this review is to assess the recent evidence regarding the management of squamous cell carcinoma of the skull-base and to discuss the implications of these findings on clinical practice.

METHOD

Free text Medline and MeSH term search of publications relating to Squamous Cell Carcinoma & Skull-base and Skull base, Neoplasm respectively. Multidisciplinary clinical guidelines were also reviewed.

RESULTS

The primary search yielded a total of 271 papers which following initial review was reduced to 28. Secondary search yielded 56 papers. There were no randomised controlled trials relating to squamous cell carcinoma of the skull-base and as such this review is based on cohort studies, case series and expert opinion.

CONCLUSION

Squamous cell carcinoma (SCC) is the most common cancer occurring in the Head and Neck. Squamous cell carcinoma is also the most common cancer arising within the nose and sinuses of which skull-base squamous cell carcinoma is a rare subgroup. Evidence relating to the management and survival of skull-base SCC is based on expert opinion and. retrospective analyses Clinical examination and biopsy, imaging and a broad multidisciplinary team are key to the management of skull-base SCC. The information gathered should be used to guide informed discussion by suitably trained experts with patients regarding surgical approach, post-operative recovery and adjuvant or neoadjuvant treatments. The standard of care is currently to perform skull base resection with or without additional craniotomy, pedicled or free flap reconstruction in multiple layers and post-operative radiation (usually photons or protons). Open approaches have traditionally been the mainstay, however in certain cases endoscopic approaches can yield equivalent results and offer many advantages. Despite advances in care survival remains poor with a nearly one in five risk of nodal recurrence within two years.

The pterygoclival ligament: a novel landmark for localization of the internal carotid artery during the endoscopic endonasal approach

OBJECTIVE

The transpterygoid extension of the endoscopic endonasal approach provides exposure of the petrous apex, Meckel's cave, paraclival area, and the infratemporal fossa. Safe and efficient localization of the lacerum segment of the internal carotid artery (ICA) is a crucial part of such exposure. The aim of this study is to introduce a novel landmark for localization of the lacerum ICA.

METHODS

Ten cadaveric heads were prepared for transnasal endoscopic dissection. The floor of the sphenoid sinus was drilled to expose an extension of the pharyngobasilar fascia between the sphenoid floor and the pterygoid process (the pterygoclival ligament). Several features of the pterygoclival ligament were assessed. In addition, 31 dry skulls were studied to assess features of the bony groove harboring the pterygoclival ligament.

RESULTS

The pterygoclival ligament was identified bilaterally during drilling of the sphenoid floor in all specimens. The ligament started a few millimeters posterior to the posterior end of the vomer alae and invariably extended posterolaterally and superiorly to blend into the fibrous tissue around the lacerum ICA. The mean length of the ligament was 10.5 ± 1.7 mm. The mean distance between the anterior end of the ligament and midline was 5.2 ± 1.2 mm. The mean distance between the posterior end of the ligament and midline was 12.3 ± 1.4 mm. The bony pterygoclival groove was identified at the confluence of the vomer, pterygoid process of the sphenoid, and basilar part of the occipital bone, running from posterolateral to anteromedial. The mean length of the groove was 7.7 ± 1.8 mm. Its posterolateral end faced the anteromedial aspect of the foramen lacerum medial to the posterior end of the vidian canal. A clinical case illustration is also provided.

CONCLUSIONS

The pterygoclival ligament is a consistent landmark for localization of the lacerum ICA. It may be used as an adjunct or alternative to the vidian nerve to localize the ICA during endoscopic endonasal surgery.

A small 3D-printing model of macroadenomas for endoscopic endonasal surgery

PURPOSE

This paper examines the application of 3D printing technology in the endoscopic endonasal approach for the treatment of macroadenomas.

METHODS

We have retrospectively analysed 20 patients who diagnosed with macroadenoma underwent endoscopic transsphenoidal surgery in Wuhan Union hospital from January 2017 to May 2017. Among the 20 patients, 10 patients received the service of 3D printing technology preoperatively. The data of 3D processing and clinical result were recorded for further evaluation.

RESULTS

The 10 patients who received the service had a successful 3D printed model of their tumors, it shows the anatomy of sphenoid sinus, tumor location which were in good agreement with our intraoperative observations. The 10 patients who received the service had a less operation time (127.0 ± 15.53 vs. 143.40 ± 17.89), blood loss (159.90 ± 12.31 vs. 170.00 ± 29.06) and less postoperative complication rate (20% vs. 40%). the design time of the 3D images varies 2 h 10 min to 4 h 32 min. the printing time of the 3D models varies 10 h 12 min to 22 h 34 min.

CONCLUSIONS

The use of 3D printing technology has unquestionable potential applications to endoscopic endonasal approach for macroadenomas, in particular reflecting the complicated anatomy of sphenoid sinus and tumor location. Owing to the advantages of 3D printing technology, it may help the patients get a good prognosis.

Radiographic Analysis of the Vidian Canal and Its Utility in Petrous Internal Carotid Artery Localization

BACKGROUND

Endoscopic endonasal surgery of the skull base requires expert knowledge of the anatomy and a systematic approach. The vidian canal is regarded as a reliable landmark to localize the petrous internal carotid artery (pICA) near the second genu, which can be used for orientation in deep skull base approaches. There is controversy about the relationship between the vidian canal and the pICA.

OBJECTIVE

To further establish the vertical relationship between the vidian canal and the pICA to aid in surgical approaches to the skull base.

METHODS

We utilized a collection of institutional review board-approved computed tomographic (CT) angiograms (CTAs). Fifty CTAs were studied bilaterally for 100 total sides. The vidian canal was visualized radiographically to determine whether it terminates below, at, or above the level of the pICA.

RESULTS

Sixty-six of 100 vidian canals terminated inferior to the pICA (66%), which was the most common relationship observed. The average distance inferior to the pICA was 1.01 mm on the right, 1.18 mm on the left, and 1.09 mm of the total 66 sides. Less commonly, the vidian canal terminated at the level of the pICA canal in 34 sides (34%). The vidian canal was not observed to terminate superior to the pICA in any of the 50 CTAs studied.

CONCLUSION

The vidian canal terminates inferior to the pICA most commonly, but often terminates at the level of the pICA. Careful drilling clockwise inferior to superior around the vidian canal should allow for safe pICA localization in most cases.

Usefulness of Oblique Coronal Computed Tomography and Magnetic Resonance Imaging in the Endoscopic Endonasal Approach to Treat Skull Base Lesions

OBJECTIVE

This report examines the usefulness of the preoperative image to orient the surgeon in the sphenoid sinus during endoscopic endonasal transsphenoidal surgery (ETSS).

METHODS

ETSS was performed in 100 cases of sellar lesion and used to classify the sphenoid sinus septum shape. Preoperative computed tomography and magnetic resonance imaging were performed for 2 types of coronal imaging: conventional and oblique. Expected sphenoid sinus septum shape was compared with those from ETSS to estimate concordance. The confirmation rate of anatomic landmarks in the sphenoid sinus by endoscopic observation was compared in various types of septum and the identification rate in oblique coronal imaging was also examined.

RESULTS

The most common septum shape was single type (31%), followed by branched (26%), parallel (18%), none (12%), cross (9%), and bridge (4%) types. In oblique coronal images, preoperative evaluation and endoscopic findings were consistent in 93%-100% of cases. However, with conventional coronal images, the concordance rate was 22.2%-83.9%, and in the none, branched, and cross types, the concordance rate was significantly lower than that for oblique coronal images. Although confirmation of the midline through estimation of landmarks by endoscopic observation was difficult in 33 cases, preoperative computed tomography and magnetic resonance imaging showed landmarks in all cases and oblique coronal images best indicated the midline.

CONCLUSIONS

Use of oblique coronal images in addition to conventional images provided good orientation of anatomic structures in the sphenoid sinus. The combination of preoperative imaging and endoscopic observation could allow safer surgery in ETSS.

Endoscopic endonasal resection of the odontoid process: clinical outcomes in 34 adults

OBJECTIVE Treatment of odontoid disease from a ventral corridor has consisted of a transoral approach. More recently, the endoscopic endonasal approach (EEA) has been used to access odontoid pathology. METHODS A retrospective review was conducted of patients who underwent an EEA for odontoid pathology from 2004 to 2013. During our analysis, the mean follow-up duration was 42.6 months (range 1-80 months). Patient outcomes, complications, and postoperative swallowing function were assessed either by clinic visit or phone contact. RESULTS Thirty-four patients underwent an EEA for symptomatic odontoid pathology. The most common pathology treated was basilar invagination (n = 17). Other pathologies included odontoid fractures, os odontoideum, and metastatic carcinoma. The mean patient age was 71.5 years. Thirty-one patients underwent a posterior fusion. All 34 patients experienced stability or improvement in symptoms and all had successful radiographic decompression. The overall complication rate was 76%. Nearly all of these complications were transient (86%) and the overall complication rate excluding mild transient dysphagia was only 44%. Twenty-one patients (62%) suffered from transient postoperative dysphagia: 15 cases were mild, transient subjective dysphagia (6 of whom had documented preoperative dysphagia), whereas 6 other patients required tube feedings for decreased oral intake, malnutrition, and dysphagia in the perioperative setting (5 of these patients had documented preoperative dysphagia). Sixteen patients had documented preoperative dysphagia and 6 of these had lower cranial nerve dysfunction. Postoperatively, 6 (37.5%) of 16 patients with preoperative dysphagia and 4 (67%) of 6 with lower cranial nerve dysfunction had significant dysphagia/respiratory complications. Eighteen patients had no documented preoperative dysphagia and only 2 had significant postoperative dysphagia/respiratory complications (11%). The rates of these complications in patients without preoperative dysphagia were lower than in those with any preoperative dysphagia (p = 0.07) and especially those with preexisting lower cranial neuropathies (p = 0.007). Dysphagia was also significantly more common in patients who underwent occipitocervical fixation (19/26, 73%) than in patients who underwent cervical fusion alone or no fusion (2/8, 25%; p = 0.02). All patients with perioperative dysphagia had improved at follow-up and all patients were tolerating oral diets. No patient suffered from velopalatal insufficiency. Two patients had intraoperative CSF leaks. One of these patients underwent a negative exploratory surgery for a questionable postoperative CSF leak. One patient developed infection in the resection bed requiring debridement and antibiotics. One patient died 8 days following surgery from an unknown cause. The 90-day perioperative mortality rate was 2.9%. CONCLUSIONS A completely EEA can be performed for compressive odontoid disease in all cases of neoplastic, degenerative, or invaginative atlantoaxial disease with satisfactory outcomes and low morbidity. Transient perioperative dysphagia and respiratory complications are common, usually as an exacerbation and reflection of underlying disease or occipitocervical fusion rather than the EEA, emphasizing the importance of avoiding transoral surgery.

Endoscopic Resection of Sinonasal and Ventral Skull Base Malignancies

The transnasal endoscopic resection of ventral skull base lesions represents a safe and effective method for the surgical management of sinonasal and ventral skull base malignancies in carefully selected cases. The goal of surgery is complete removal of all tumor with negative resection margins while maintaining the key oncological principles. Careful selection of cases along with the presence of an experienced surgeon and a fully involved multidisciplinary skull base team trained in the management of ventral skull base neoplasm are essential for excellent outcomes.

Role of targeted magnetic resonance imaging sequences in the surgical management of anterior skull base pathology

BACKGROUND

The skull base is a highly complex anatomical region that provides passage for important nerves and vessels as they course into and out of the cranial cavity. Key to the management of pathology in this region is a thorough understanding of the anatomy, with its variations, and the relationship of various neurovascular structures to the pathology in question. Targeted high-resolution magnetic resonance imaging on high field strength magnets can enable the skull base surgeon to understand this intricate relationship and deal with the pathology from a position of relative advantage.

OBJECTIVE

With the help of case studies, this paper illustrates the application of specialised magnetic resonance techniques to study pathology of the orbital apex in particular.

CONCLUSION

The fine anatomical detail provided gives surgeons the ability to design an endonasal endoscopic procedure appropriate to the anatomy of the pathology.

Imaging in Endoscopic Cranial Skull Base and Pituitary Surgery

Endoscopic endonasal approaches have widely accepted techniques for managing benign and malignant processes along the entire ventral skull base with similar or better results compared with open procedures, but with lower rates of complication. Managing pathology affecting the skull base can be challenging because of complex anatomy and the proximity of critical neurovascular structures. Postoperative imaging can be challenging, because of surgical alterations of normal anatomy and the now common use of complex reconstruction techniques. Understanding the normal imaging appearance of skull base reconstruction is important for accurate postoperative interpretation and delineation between normal reconstructive tissue and recurrent neoplasm.

Minimally invasive surgery of the anterior skull base: transorbital approaches

Minimally invasive approaches are becoming increasingly popular to access the anterior skull base. With interdisciplinary cooperation, in particular endonasal endoscopic approaches have seen an impressive expansion of indications over the past decades. The more recently described transorbital approaches represent minimally invasive alternatives with a differing spectrum of access corridors. The purpose of the present paper is to discuss transorbital approaches to the anterior skull base in the light of the current literature. The transorbital approaches allow excellent exposure of areas that are difficult to reach like the anterior and posterior wall of the frontal sinus; working angles may be more favorable and the paranasal sinus system can be preserved while exposing the skull base. Because of their minimal morbidity and the cosmetically excellent results, the transorbital approaches represent an important addition to established endonasal endoscopic and open approaches to the anterior skull base. Their execution requires an interdisciplinary team approach.

Postoperative otorhinolaryngologic complications in transnasal endoscopic surgery to access the skull base

Introduction

The large increase in the number of transnasal endoscopic skull base surgeries is a consequence of greater knowledge of the anatomic region, the development of specific materials and instruments, and especially the use of the nasoseptal flap as a barrier between the sinus tract (contaminated cavity) and the subarachnoid space (sterile area), reducing the high risk of contamination.

Objective

To assess the otorhinolaryngologic complications in patients undergoing endoscopic surgery of the skull base, in which a nasoseptal flap was used.

Methods

This was a retrospective study that included patients who underwent endoscopic skull base surgery with creation of a nasoseptal flap, assessing for the presence of the following post-surgical complications: cerebrospinal fluid leak, meningitis, mucocele formation, nasal synechia, septal perforation (prior to posterior septectomy), internal nasal valve failure, epistaxis, and olfactory alterations.

Results

The study assessed 41 patients undergoing surgery. Of these, 35 had pituitary adenomas (macro- or micro-adenomas; sellar and suprasellar extension), three had meningiomas (two tuberculum sellae and one olfactory groove), two had craniopharyngiomas, and one had an intracranial abscess. The complications were cerebrospinal fluid leak (three patients; 7.3%), meningitis (three patients; 7.3%), nasal fossa synechia (eight patients; 19.5%), internal nasal valve failure (six patients; 14.6%), and complaints of worsening of the sense of smell (16 patients; 39%). The olfactory test showed anosmia or hyposmia in ten patients (24.3%). No patient had mucocele, epistaxis, or septal perforation.

Conclusion

The use of the nasoseptal flap has revolutionized endoscopic skull base surgery, making the procedures more effective and with lower morbidity compared to the traditional route. However, although mainly transient nasal morbidities were observed, in some cases, permanent hyposmia and anosmia resulted. An improvement in this technique is therefore necessary to provide a better quality of life for the patient, reducing potential complications.

Severe hyperthermia, hypernatremia, and early postoperative death after transethmoidal cavitron ultrasonic surgical aspirator (CUSA)-assisted diencephalic mass removal in 4 dogs and 2 cats

OBJECTIVE

To report clinical findings including severe hyperthermia and hypernatremia after transethmoidal Cavitron ultrasonic surgical aspirator (CUSA)-assisted diencephalic mass removal.

STUDY DESIGN

Retrospective case series.

ANIMALS

Dogs (n = 4) and 2 cats.

METHODS

Medical records (1997-2003) of dogs and cats that had transethmoidal CUSA-assisted diencephalic mass removal were reviewed. Retrieved data were: history, signalment, blood work, neurologic examination findings, MRI results, histopathology, postoperative complications, pre- and postoperative medical therapy, and outcome.

RESULTS

Tumor types included: meningioma (n = 3), choroid plexus papilloma (1), astrocytoma (1), and pituitary macroadenoma (1). Median onset of hyperthermia was 3.5 hours (range: 1-6 hours) after extubation; median high temperature at onset was 40.3°C, (range: 39.6-41.7°C). Median onset of hypernatremia (median, 172 mmol/L; range: 168-196 mmol/L) was 4.5 hours (range: 1-9 hours) after extubation. Median time of death after hyperthermia was 10.5 hours (range: 6-13 hours) and after extubation was 13.5 hours (range: 11-15 hours).

CONCLUSIONS

Transethmoidal CUSA-assisted diencephalic mass removal is associated with early postoperative hyperthermia, hypernatremia, and death, and cannot be recommended.

[Shifting paradigm in skull base surgery: Roots, current state of the art and future trends of endonasal endoscopic approaches]

During the last two decades, endoscopic endonasal approach has completed the minimally invasive skull base surgery armamentarium. Endoscopic endonasal skull base surgery (EESBS) was initially developed in the field of pituitary adenomas, and gained an increasing place for the treatment of a wide variety of skull base pathologies, extending on the midline from crista galli process to the occipitocervical junction and laterally to the parasellar areas and petroclival apex. Until now, most studies are retrospective and lack sufficient methodological quality to confirm whether the endoscopic endonasal pituitary surgery has better results than the microsurgical trans-sphenoidal classical approach. The impressions of the expert teams show a trend toward better results for some pituitary adenomas with the endoscopic endonasal route, in terms of gross total resection rate and probably more comfortable postoperative course for the patient. Excepting intra- and suprasellar pituitary adenomas, EESBS seems useful for selected lesions extending onto the cavernous sinus and Meckel's cave but also for clival pathologies. Nevertheless, this infatuation toward endoscopic endonasal approaches has to be balanced with the critical issue of cerebrospinal fluid leaks, which constitutes actually the main limit of this approach. Through their experience and a review of the literature, the authors aim to present the state of the art of this approach as well as its limits.

Challenging reconstructive techniques for skull base defect following endoscopic endonasal approaches

OBJECTIVE

We assessed the outcomes of various reconstructive methods for skull base defect after endoscopic endonasal approaches (EEA) depending on the degree of intraoperative cerebrospinal fluid (CSF) leaks.

METHODS

Between Jan. 2008 and Sep. 2009, 122 consecutive patients underwent 124 EEA for sellar and extra-sellar lesions. Intraoperative CSF leaks were classified as grade 0, no intraoperative CSF leak; grade 1, low output; and grade 2, high-output based on the degree of CSF leakage and size of opening in the arachnoid membrane (<5 or ≥5 mm).

RESULTS

Postoperative CSF leaks or meningitis occurred in 13 of 124 cases (10.5%). In 77 patients with grade 0, there was no postoperative CSF leak. Among 20 patients with grade 1 CSF leaks, four patients developed meningitis or postoperative CSF leak. Postoperative CSF leaks occurred in nine of 26 patients (34.6%) with grade 2 leaks. Comparison of reconstructive methods revealed that gasket-seal method provided better control of CSF leaks than free-fat graft in patients with grade 2 leaks (11.8% vs. 66.7%, p = 0.028). However, in grades 0 and 1, we found no difference among the various reconstructive methods.

CONCLUSION

The selection of reconstructive methods for skull base defects should be determined by the degree of CSF leaks. Although grade 0 or 1 leak requires relatively conservative management such as simple closure or free-tissue grafting, a more aggressive reconstructive technique is required to prevent postoperative complication in grade 2 CSF leak.

Middle turbinectomy for exposure in endoscopic endonasal transsphenoidal surgery: when is it necessary?

OBJECTIVES

To evaluate the benefits of middle turbinectomy on the exposure of the skull base structures.

DESIGN

An anatomical study on 20 fresh cadaver heads.

METHODS

The extent of the exposure of the skull base structures during endoscopic endonasal approach has not been addressed specifically in respect to the whether or not the middle turbinectomy is performed. We compared the extent of exposure obtained by endonasal transsphenoidal approaches without middle turbinectomy (NMT), with unilateral turbinectomy (UMT), and with bilateral turbinectomy (BMT). Our preselected target points in the skull base consisted of sella turcica, tuberculum sella, planum sphenoidale, clivus (upper and middle third), and ipsilateral sphenopalatine artery (SPA).

RESULTS

Of our preselected anatomic target points, only the middle third of the clivus and ipsilateral SPA had enhanced exposure in UMT (100% for both structures) compared to NMT (45% and 20%, respectively). The addition of a BMT did not provide added exposure to any target compared with a UMT.

CONCLUSIONS

Middle turbinectomy may not be necessary for endonasal transsphenoidal approach to the lesions of the sella, planum sphenoidale, and upper third of the clivus. However, gaining access to the middle clival region is facilitated by resection of middle turbinate.

Prevention and management of vascular injuries in endoscopic surgery of the sinonasal tract and skull base

In the past 2 decades, endoscopic sinus surgery has been widely used as a safe and effective treatment for disorders of the paranasal sinuses that are refractory to medical therapy. Advances in surgical technique, including powered instrumentation and stereotactic image-guided surgery, have improved the efficiency and safety of this procedure. These techniques have been further expanded to manage skull base pathologies. This expansion has been facilitated by a better understanding of the endonasal skull base anatomy. Despite these advances, complications are still encountered. Vascular injuries are particularly troublesome. Interior ethmoid artery injuries during sinus surgery that led to orbital hematoma were discussed extensively in a recent issue of this journal. Therefore, this article focuses mainly on inadvertent carotid artery injuries during routine sinus surgery and vascular injuries during endoscopic skull base surgery.

Level of complete dissection of the ethmoid sinuses with a computed tomographic image guidance system

OBJECTIVES

We sought to determine the adequacy of endoscopic total ethmoidectomy with the use of a computed tomographic (CT) image guidance system.

METHODS

Endoscopic ethmoid sinus dissections were performed on cadavers by otolaryngologists. All cadavers were scanned before dissection. On each side of the cadaver, the ethmoid sinuses were examined independently. A complete endoscopic ethmoidectomy was performed with a CT image guidance system. After the endoscopic ethmoidectomy, the cadaver underwent a postdissection CT scan. The postdissection CT images were then evaluated for the level of complete dissection of the anterior and posterior ethmoid sinuses.

RESULTS

There were 18 ethmoid sinuses in the study. One specimen underwent a complete total ethmoidectomy with no residual cells. There were 4 complete anterior ethmoidectomies and 5 complete posterior ethmoidectomies. Overall, the average numbers of residual anterior ethmoid and posterior ethmoid air cells were 1.39 and 1.22, respectively. This difference was not statistically significant. The skull base was dissected more completely than the lamina papyracea, with a significant difference (p = 0.03). There was no difference in terms of residual cells between the left and right ethmoid sinuses (p > 0.05).

CONCLUSIONS

Even with the use of a CT image guidance system, a complete ethmoidectomy was still difficult to achieve. Residual ethmoid sinus cells were more commonly found along the lamina papyracea than along the skull base.

Endoscopic endonasal skull base surgery: past, present and future

Endoscopic techniques have undergone tremendous advancement in the past years. From the management of phlogistic pathologies, we have learned to manage skull base lesions and even selected intracranial diseases. Current anatomical knowledge plus computer-aided surgery has enabled surgeons to remove large lesions in the paranasal sinuses extending beyond the boundaries of the sinuses themselves. In this sense, management of benign diseases via endoscopic routes is nowadays well accepted whilst the role of endoscopic techniques in sinonasal malignancies is still under investigation. Nowadays, it is possible to tackle different pathologies placed not only in the ventral skull base, but also extended laterally (infratemporal fossa and petrous apex) and even, in really selected cases, within the orbit. The ability to resect and reconstruct has improved significantly. At the moment, the improvement in surgical techniques, like the four-handed technique, has rendered endoscopic procedures capable of managing complex pathologies, according the same surgical principles of the open approaches. From now onwards, frameless neuronavigation, modular approaches, intraoperative imaging systems and robotic surgery are and will be an increasingly important part of endonasal surgery, and they will be overtaken by further evolution.

Endoscopic endonasal odontoidectomy in a patient affected by Down syndrome: technical case report

OBJECTIVE

Atlantoaxial instability and odontoid invagination may occur in Down syndrome. The treatment of this lesion may require an odontoidectomy. In similar circumstances, a transoral procedure may be hampered by a macroglossia which is part of Down syndrome. In a situation occurring in an 11-year-old child affected by atloaxial instability and os odontoideum, the persistence of ventral compression after a previous atloaxial fixation induced us to perform an endoscopic endonasal odontoidectomy. We feel that this is an elective indication for endoscopic endonasal odontoidectomy.

CLINICAL PRESENTATION

An 11-year-old child, affected by Down syndrome, presented with progressive tetraparesis with severe superior diplegia. He was wheelchair-bound. Recently, respiratory disturbances had appeared.

INTERVENTION

The patient underwent an endoscopic endonasal odontoidectomy. The postoperative course was uneventful, and the patient experienced improvement of the preoperative symptoms.

CONCLUSION

An endonasal technique is indicated for patients presenting with narrowness of the oral cavity, such as in the case reported, where the narrowness due to pediatric age and the macroglossia characteristic of Down syndrome hamper the transoral approach.

Endoscopic skull base surgery

Endoscopic skull base surgery has undergone rapid advancement in the past decade moving from pituitary surgery to suprasellar lesions and now to a myriad of lesions extending from the cribriform plate to C2 and laterally out to the infratemporal fossa and petrous apex. Evolution of several technological advances as well as advances in understanding of endoscopic anatomy and the development of surgical techniques both in resection and reconstruction have fostered this capability. Management of benign disease via endoscopic methods is largely accepted now but more data is needed before the controversy on the role of endoscopic management of malignant disease is decided. Continued advances in surgical technique, navigation systems, endoscopic imaging technology, and robotics assure continued brisk evolution in this expanding field.