Operative management of skull base malignancies: choosing the appropriate approach

Transfacial Exposures of the Anterior Skull Base and Cervical Spine: Straightforward "Line-of-Sight" Algorithm for Selection of Approach

ABSTRACT

Surgical treatment for tumors of the skull base remains gross total resection with microscopic negative margins. Sufficient surgical access is paramount to adequate treatment but must be balanced with patient morbidity and protection of vital neurovascular structures. While endoscopic surgery has made transfacial access less common, there are still indications for open transfacial exposure including tumors that involve facial soft tissues, the palate, anterolateral frontal sinus, dural involvement lateral to the mid-pupillary line, tumor recurrence/repeat resection, and/or lack of access to endoscopic equipment or expertise. The authors present a "line-of-sight" algorithm for selection of approach, discuss pre-operative planning, review selected clinical experiences, and discuss the role of microsurgery and prevention of complications.

The Manufacturing of 3D Printed models for the Neurotraumatological Education of Military Surgeons

Introduction

When deployed abroad, military surgeons frequently have to deal with casualties involving head trauma. The emergency treatments, as well as craniotomies, are often performed by non-neurosurgeons qualified with basic neurotraumatological skills. Previous neurotrauma courses for education of non-neurosurgeons in Germany teach surgical emergency skills but do not include the training of skills needed to successfully utilize imaging in surgical planning, which is of importance for the safety and success of the treatment. To overcome these limitations, 3D printed models of neurotrauma cases were fabricated for application in the training of non-neurosurgeons.

Materials and Methods

Five models of actual neurotrauma cases from our neurosurgical department were segmented from CT scans and 3D printed using multi-part fused deposition modeling. Model quality was assessed with respect to the representation of pre-defined anatomical landmarks. The models were then fixed to a wooden mount with a central light source and covered by a latex mask for skin simulation. Surgical planning by means of craniometric measurements on the basis of available CT scans of the corresponding patients was then applied to the model.

Results

The 3D printed models precisely represented the cranium, the lesion, and anatomical landmarks, which are taken into consideration during surgical planning. Surface covering with washable latex masks ensured sufficient masking of the now non-noticeable lesion within the semi-translucent skull. Surgical planning was performed using washable marker drawings. When lighted, the otherwise non-visible lesion within the semi-translucent 3D printed craniums became visible and facilitated immediate success control for the course participants.

Conclusion

The presented method provided a way to fabricate precise 3D models of neurotrauma cases, which are suitable to teach the application of medical imaging in surgical planning. For further benefit analysis, the application of the presented education tool needs to be investigated within a neurotrauma course.

Cavernous sinus meningioma

Cavernous sinus meningioma (CSM) presents a management challenge to present-day neurosurgeons. Lack of adequate understanding of the natural history of these lesions, the early involvement of vital neurovascular structures, the absence of clear tissue planes with normal surrounding structures, and a high rate of aggressive surgery-related morbidity each pose management dilemmas for neurosurgeons. Over the past few decades, the enthusiasm of the neurosurgical community has shifted from aggressive microsurgical resection to maximal safe resection and institution of adjuvant radiotherapy, if necessary. This paradigm shift has ensured better functional outcome in treated patients. This chapter has been designed to discuss the current treatment algorithm and the importance of multimodality management for optimal outcome in patients with CSM. The technical aspects of this approach to management are presented, and the various treatment options are compared.

Anterolateral thigh versus pectoralis major flaps in reconstruction of the lateral temporal bone defect

BACKGROUND

Free tissue reconstruction is reliable in suitable patients but patient selection remains a challenge for the reconstructive surgeon. The anterolateral thigh (ALT) free flap and pedicled pectoralis major myocutaneous flap (PMMF) are two common reconstructive options for a lateral temporal bone resection defect. The threshold at which free tissue reconstruction should be considered over locoregional reconstruction is not defined. We sought to define reconstructive flap choice in the setting of medical comorbidities that may dissuade free tissue transfer.

METHODS

A retrospective analysis of lateral temporal bone defects at a single institution was undertaken. The primary outcomes were flap survival, surgical complications and durations of surgery and stay. Data regarding medical comorbidities and potential confounders were examined.

RESULTS

Sixty patients with lateral temporal bone defects were identified. Twenty-four (40%) patients underwent PMMF reconstruction and 36 (60%) were reconstructed with ALT. The former were significantly older (73 versus 62 years), though with similar Anesthesiologists Risk Classification System status. Free-flap reconstruction resulted in significantly less flap loss (two versus six) but a longer operating time (790 versus 671 min).

CONCLUSION

Patients suffering head and neck cancer with medical comorbidities can make selection of a suitable reconstruction difficult. We found that while patients undergoing ALT reconstruction were typically younger, the comorbidity profile of those patients was similar to patients undergoing PMMF reconstruction. ALT flaps were more reliable than the PMMF, lending credence to the view that free tissue transfer should be the preferred reconstructive option in suitable candidates and defects.

Access to the Skull Base - Maxillary Swing Procedure - Long Term Analysis

Background:

Skull base is difficult to approach surgically due to its complex anatomy. A number of procedures that is endoscopic, microscopic, and open approaches have been used. The maxillary swing approach provides a wide exposure to the surgeon for better oncological clearance.

Patients and Methods:

A total of 62 patients with varied etiologies involving the skull base region were operated with maxillary swing procedure over a period of 15 years from 2001 to 2016 in plastic surgery department at a single institution.

Results:

There was no recurrence in the follow-up period. One patient had palatal fistula and one patient had mild nasal mucosal atrophy. None of the patients had malocclusion in the postoperative period. The minimum follow-up period was 24 months.

Conclusion:

Maxillary swing procedure provides excellent exposure to skull base, and most of the tumors involving this region can be effectively excised with minimal morbidity to the patient.

Management of Cavernous Sinus Involvement in Sinonasal and Ventral Skull Base Malignancies

Cavernous sinus (CS) involvement by sinonasal and ventral skull base malignancies is infrequently encountered in neurosurgical practice. Despite advancements in skull base microneurosurgery and endoscopic techniques, detailed knowledge and experience of the surgical management of these lesions are limited. This article elaborates on surgical strategies and approaches for CS involvement of malignant ventral skull base tumors. The article discusses the indications, techniques, nuances, advantages, limitations, and complications of minimally invasive CS biopsy, transcranial microscopic, and transfacial endoscopic approaches to the CS using illustrative diagrams and operative videos. The principles and nuances of a high-flow cerebral revascularization procedure are mentioned.

[Choosing an anterior midline approach to skull base tumors]

The purpose of this review is to analyze used anterior midline approaches to the skull base, identify their advantages and disadvantages, and, after reviewing the literature data, submit a developed algorithm for choosing an optimal approach to the approval of colleagues. We provide brief information on approach techniques, indications and contraindications, and advantages and disadvantages as well as analyze international experience of using the discussed approaches. On the basis of literature data, we have developed a prototype algorithm for choosing an optimal approach to medial tumors of the anterior skull base. The situation of choosing an optimal approach reveals the absence of a clear understanding of the boundaries between capabilities and limitations of approaches. To solve this problem, an original prospective study is required.

The palatal overlap flap: a modification of the maxillary swing procedure to prevent ascending infection

The maxillary swing procedure provides an excellent approach to the anterior skull base region and to the clivus. The osteotomy should not be standard; it should vary with the size and position of the central skull base tumor being resected. The main reason for publishing this article is to draw attention to a method of preventing ascending infection from the oral cavity to the intracranial area using the palatal overlap flap. Examples of this approach are provided.

Malignant peripheral nerve sheath tumors of the lateral skull base

Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive spindle cell tumors that develop from peripheral nerve sheath cells and account for 5% of all soft tissue sarcomas. MPNSTs involving the lateral skull base are an extremely rare subgroup of these lesions. The article deals with the case of a 51-year-old man with a huge primary MPNST: the disease involved the left frontozygomatic and retroauricolar regions of the scalp with erosion of the outer table of the calvaria and diffuse infiltration of the temporal, infratemporal, and pterygoid fossae. Radical surgery via left transfacial- transparotid approach and reconstruction with microvascular flap were performed. Intraoperative radiotherapy and postoperative radiotherapy were also delivered. Twenty-two months postoperatively, the patient is alive despite recurrence of the tumor in the neck and lung metastases. The article reviews the few series of patients and the small number of case reports of MPNSTs involving the lateral skull base that are available in the English literature describing current concept of pathophysiology, diagnosis, and management of the disease. Although MPNSTs of the lateral skull base have an adverse prognosis, an acceptable survival time and a good quality of life are possible; however, they require an early and correct diagnosis as well as an adequate and aggressive combination therapy.

Transnasal endoscopy-assisted skull base surgery

Skull base surgery (SBS), which originated in the 19th century, became refined in the 20th century in parallel with technological advancements and is now in the midst of further refinements largely driven by advances in endoscopic sinus surgery. With the development of modern SBS, lesions that were once inoperable and potentially fatal can now be eradicated successfully by means of endoscopy-assisted procedures that reduce or completely eliminate intracranial trauma, minimize postsurgical morbidity, and make full recovery possible. It is absolutely mandatory to have the appropriate instrumentation for endoscopy-assisted SBS. Among the new technologies available are advanced endoscopes, high-speed suction irrigation drills, digital video cameras, computed tomography and magnetic resonance imaging, and systems for 3-dimensional computer-assisted image-guided surgical navigation. An experienced endoscopic surgeon working with multidisciplinary teams, and using new instrumentation and techniques, can bring SBS to new levels of success in the 21st century.

Skull Base Tumors: A Comprehensive Review of Transfacial Swing Osteotomy Approaches

Numerous techniques have been proposed for the resection of skull base tumors, each one unique with regard to the region exposed and degree of technical complexity. This study describes the use of transfacial swing osteotomies in accessing lesions located at various levels of the cranial base. Eight patients who underwent transfacial swings for exposure and resection of cranial base lesions between 1996 and 2002 were studied. The mandible was the choice when wide exposure of nasopharyngeal and midline skull base tumors was necessary, especially when they involved the infratemporal fossa. The midfacial swing osteotomy was an option when access to the entire clivus was necessary. An orbital swing approach was used to access large orbital tumors lying inferior to the optic nerve and posterior to the globe, a region that is often difficult to visualize. Gross total tumor excision was possible in all patients. Six patients achieved disease control and two had recurrences. The complications of cerebrospinal fluid leak, infection, hematoma, or cranial nerve damage did not occur. After surgery, some patients experienced temporary symptoms caused by local swelling. The aesthetic result was considered good. Transfacial swing osteotomies provide a wide exposure to tumors that occur in the central skull base area. Excellent knowledge of the detailed anatomy of this region is paramount to the success of this surgery. The team concept is essential; it is built around the craniofacial surgeon and an experienced skull base neurosurgeon.

Surgical strategies in the removal of malignant tumors and benign lesions of the anterior skull base

The choice of surgical approaches to the tumors of the anterior skull base is determined by the location, dimensions of such lesions and their relations to the surrounding structures. Furthermore, the need for the reconstruction of the dura and skull base structures has an important influence on the decision about the surgical procedure. Transfacial approaches provide limited exposure, especially when tumors damage the floor of the anterior cranial fossa and involve the frontobasal dura and brain. Transcranial, craniofacial and subcranial approaches in particular may aid a surgeon in the removal of such lesions, and often these surgical procedures are the only beneficial methods. Our study comprised 15 patients. Transcranial approaches were used in ten cases. In five further cases, we adopted craniofacial or subcranial approaches. Total removal of these lesions was possible in 13 cases. Neither important complications nor death after surgery was observed except for two cases (craniofacial/subcranial approach) where the CSF leak and CNS infection were reported. We deem that the transcranial approach creates a good possibility for total removal of anterior skull base tumors, particularly of the benign lesions, and permits reconstruction of the skull base damaged by the tumor. However, in patients with large malignant tumors, the en bloc resection via the combined craniofacial/subcranial approach achieved better outcome.