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PubMed2001

Surgical approaches and strategies for skull base chordomas.

OBJECT: The management of chordomas involving the skull base continues to present a number of treatment-related problems. Recently, both radical resection and charged-particle irradiation or stereotactic radiosurgery have reportedly been found effective for tumor control and for promoting a better quality of life in patients. In this article the authors analyzed the outcomes in 17 patients with skull base chordomas who were surgically treated at Kobe University Hospital between 1972 and 2000. METHODS: Preoperative radiological examinations included magnetic resonance imaging, computerized tomography, angiography, and balloon occlusion test of the internal carotid artery. Among the various surgical approaches used to remove the tumor were the frontoorbitozygomatic, transmaxillary, transcondylar, transsphenoidal, and the transbasal. Total removal was achieved in two (12%), near-total removal in three (18%), subtotal removal in nine (52%), and partial removal in three patients (18%). Since 1990, chordomas have been radically resected via various skull base approaches; the combined total or near-total removal rate has been 80% in this period. Radical removal of the tumors has not led to an increased risk. At the final follow-up review (mean 59.5 month), 75% of the patients were still alive, and 25% had died of chordoma recurrence. The overall recurrence-free survival rate was 82% at 3 years and 51% at 5 years. The 5-year recurrence-free survival rate in the five patients who underwent the operation during the past decade was 77% (mean follow up of 5.2 years). In two patients with recurrent tumors who underwent radiosurgery, no evidence of tumor regrowth was demonstrated at 3 years posttreatment. CONCLUSIONS: The authors suggest that for the treatment of skull base chordomas radical resection is a key factor for longer survival and improved quality of life. Patients with sufficiently small tumors, which show a favorable configuration and location, can be suitable candidates for stereotactic radiosurgery.

Adolescent↗
PubMed2004

Linear accelerator-based radiosurgery in the management of skull base meningiomas.

From May 1994 to December 1999, 43 patients with meningiomas in the base of the skull underwent linear accelerator (LINAC)-based stereotactic radiosurgery (SRS) at Chung Gung Memorial Hospital. SRS was performed as a primary treatment in 14 patients, and after resection in 29 patients. The mean tumor volume was 5.68 cc, and the mean target surface dose was 16 Gy, delivered with an average of three isocenters. The median follow-up was 74.5 months. The 7-year local control rate and 7-year overall survival rate were 89.7% and 80.2%, respectively. The 7-year local control was 100% and 84.4% in SRS alone group and surgical excision with SRS group (p = 0.21), respectively. A stationary tumor following SRS was seen in 23 (53.5%) patients, partial shrinkage was seen in 16 (37.2%) patients, and complete disappearance in one patient was seen (2.3%). Furthermore, disease progression was noted in three (7%) patients, one of whom died of disease. The median time to tumor response was 15.4 months (range 5.8-52.8 months). Cases remained stable or had improved neurological statuses without any deterioration in 37.9% and 78.7% of the groups treated with surgery and SRS and SRS alone, retrospectively. In summary, LINAC-based SRS is an effective and safe modality of treating unresectable or partially resected meningiomas in the base of the skull. For tumors with diameters of 3 cm or less, particularly in patients without or with minimal clinical neurological symptom, SRS alone can provide a good local control without causing cranial neuropathy.

Adult↗
PubMed2003

The natural history of untreated skull base meningiomas.

BACKGROUND: This study was undertaken to determine the natural history of untreated skull base meningiomas. Although there are reports on the natural history of meningiomas, most series contain only a few cases of meningiomas involving the skull base. Natural history information is important when recommending treatment and evaluating results. METHODS: The case records and imaging studies of 40 patients with skull base meningiomas from a single practice were reviewed. These patients either did not receive treatment or there was a long delay from the onset of symptoms to the initiation of treatment. RESULTS: Skull base meningiomas may be very indolent tumors. Patients with these tumors have lived long, comfortable, and relatively productive lives without treatment or with delayed treatment. Impairment may be much less than imaging studies would suggest. CONCLUSION: The authors are not advocating that skull base meningiomas not receive treatment. However, their unique experience with this group of patients provides convincing evidence that the indolent behavior of some skull base meningiomas must be considered when recommending various surgical and radiation procedures and interpreting their results in relationship to the functional outcome of the patient.

Adult↗
PubMed2005

Diagnostic and surgical challenges in the pediatric skull base.

Advances in management of adult skull base pathologies are increasingly being applied in children. Pediatric patients present special challenges because of their smaller anatomy, but potential gains in reduced morbidity make improvements in skull base approaches well worth pursuing.

Angiofibroma↗
PubMed2000

Preservation of olfaction in anterior skull base surgery.

OBJECTIVES/HYPOTHESIS: In selected unilateral tumors and defects of the anterior skull base, the preservation of contralateral olfaction is achievable through a localized subcranial approach without compromising surgical objectives of resection or repair. STUDY DESIGN: Description of a functional adaptation of anterior skull base surgical techniques through a retrospective patient series. METHODS: Nine patients underwent anterior skull base surgery for unilateral cribriform plate disease including four malignant and two benign tumors, two encephaloceles, and one iatrogenic cribriform injury with cerebrospinal rhinorrhea. All nine patients consented to a localized subcranial approach to the anterior skull base to preserve the contralateral olfactory nerves. In four patients with benign disease a portion of the ipsilateral nerves was additionally conserved. Postoperative olfaction was assessed objectively with a commercially available smell test. Indications, technique, results, and complications are reported and discussed. RESULTS: All patients had eradication of disease with preservation of functional olfaction CONCLUSIONS: Conservation of olfaction is possible in selected cases of anterior skull base surgery when the lesion is unilaterally confined.

Adenocarcinoma↗
PubMed2003

Radiation therapy for chordoma and chondrosarcoma of the skull base and the cervical spine. Prognostic factors and patterns of failure.

BACKGROUND: Prospective analysis of local tumor control, survival and treatment complications in 67 consecutive patients treated with fractionated photon and proton radiation for chordoma or chondrosarcoma of the base of the skull and the cervical spine. PATIENTS AND METHODS: Between December 1995 and January 2000, 67 patients with a median age of 52 years (range: 14-85 years), were treated at the Centre de Protonthérapie d'Orsay (CPO), France, using the 201-MeV proton beam, 49 for chordoma and 18 for chondrosarcoma. Irradiation combined high-energy photons and protons. Photons represented two thirds of the total dose and protons one third. The median total dose delivered within gross tumor volume (GTV) was 67 Cobalt Gray Equivalents (CGE; range: 60-70 CGE). RESULTS: Within a median follow-up of 29 months (range: 4-71 months), the 3-year local control rates were 71% and 85% for chordomas and chondrosarcomas, respectively, and the 3-year overall survival rates 88% and 75%, respectively. 14 tumors (21.5%) failed locally (eight within the GTV, four within the clinical target volume [CTV], and two without further assessment). Seven patients died from their tumor and another one from a nonrelated condition (pulmonary embolism). The maximum tumor diameter and, similarly, the GTV were larger in relapsing patients, compared with the rest of the population: 56 mm vs 44 mm (p = 0.024) and 50 ml vs 22 ml (p = 0.0083), respectively. In univariate analysis, age < or = 52 years at the time of radiotherapy (p = 0.002), maximum diameter < 45 mm (p = 0.02), and GTV < 28 ml (p = 0.02) impacted positively on local control. On multivariate analysis, only age was an independent prognostic factor of local control. CONCLUSION: In chordomas and chondrosarcomas of the skull base and cervical spine, combined photon and proton radiation therapy offers excellent chances of cure. In two thirds of the cases, relapses are located in the GTV. Maximum diameter, GTV, and age are prognostic indicators of local control. These results should be confirmed during a longer follow-up.

Adolescent↗
PubMed2002

[Surgical approaches to the skull and near skull base neoplasms].

OBJECTIVE: To seek for the best surgical approaches to the skull and near-skull base neoplasms. METHOD: 161 patients with skull or near-skull base tumors were surgically treated. The surgical approaches were craniofacial approach in 6 cases, total maxillectomy or/with orbital exenteration in 5 cases, lateral rhinotomy in 7 cases, frontorbital approach in 1 cases, maxillary swing or extended maxillary swing approach in 21 cases, mandibular swing approach in 30 cases, cervical approach in 48 cases, postaurical large C incision approach in 19 cases, transparotid approach in 8 cases, transoral approach in 6 cases, temporofrontal approach in 8 cases, subtemporal preauricular approach in 2 cases. RESULT: Of the 98 benign tumors cases, 2 recurred postoperatively. Of the 63 malignant tumors, 1 case had cerebrospinal fluid leakage and died of intracranial infection 1.5 months postoperatively. In the follow up period, the longest one survival was over 8 years, and 10 over 5 years, 19 over 3 years, 16 over 2 years, 16 over 1 year. Survival rates of 3 and 5 years were 59.18% and 38.46% respectively. CONCLUSION: According to the site, range and pathology of the skull base neoplasmas, surgical approaches were designed and selected rationally and the effects better.

Adolescent↗
PubMed2003

Intensity-modulated stereotactic radiotherapy vs. stereotactic conformal radiotherapy for the treatment of meningioma located predominantly in the skull base.

PURPOSE: This study evaluates a possible advantage of intensity-modulated stereotactic radiotherapy (IMSRT) over stereotactic conformal radiotherapy (SCRT) in the treatment of lesions in the base of the skull. METHODS AND MATERIALS: Ten patients (7 with a skull base meningioma) planned for routine SCRT were replanned for IMSRT. The criteria for comparison were the same for both methods: optimal dose to the planning target volume (PTV) and optimal sparing of the organs at risk (OAR). For SCRT, sparing of OAR was achieved by conformal avoidance using 5-6 fields. The IMSRT inverse planning process used optimized OAR sparing through user-defined dose constraints. Dose to the PTV and OAR were assessed by dose-volume histograms, maximum dose, 2 conformity indices, and volumes of relevant isodoses. RESULTS: The conformity index is consistently higher for IMSRT, the largest improvement being for the multifocal and irregular cases. Volumes of the 90% and 80% isodoses were smaller for IMSRT, whereas the volume of the 30% isodose was larger for IMSRT in 6 cases. The maximum dose was consistently higher for IMSRT (mean values 102% and 108% for SCRT and IMSRT, respectively). Sparing of OAR was better with IMSRT, especially for those OARs situated in or near a concave PTV. CONCLUSIONS: In terms of PTV coverage, there is an advantage in using IMSRT for all target shapes, but especially for irregular and concave targets. The dose to OAR is lower with IMSRT, although the volume of normal tissue receiving a low dose can be larger than for SCRT.

Aged↗
PubMed1989

Management of neurovascular complications in extended skull base surgery.

Combined oncologic approaches to the skull base now permit resection of extensive basicranial neoplasms. Despite advances in microsurgical techniques, disabling or life-threatening complications are still encountered in such surgery. Successful management of these sequelae is dependent upon meticulous intraoperative care and compulsive postoperative clinical assessment. Perioperative neurovascular complications were recorded in 154 consecutive skull base procedures. The most frequent severe complication was cerebral edema, which occasionally required surgical intervention. Dysphagia was the most common complication noted in the late postoperative period. Based upon this review, the management and methods found to minimize the incidence of various perioperative neurovascular complications related to extended skull base surgery are described.

Brain Edema↗
PubMed2006

Hypofractionated stereotactic radiation therapy for skull base and upper cervical chordoma and chondrosarcoma: preliminary results.

INTRODUCTION: Chordoma and chondrosarcoma are rare tumors of the base of the skull and are difficult candidates for surgical treatment. They are also usually resistant to conventional radiation therapy. We report preliminary results of hypofractionated stereotactic radiation therapy (SRT) using the Cyberknife system (Accuray Inc., Sunnyvale, Calif., USA) for primary and recurrent chordomas and chondrosarcomas of the skull base and upper cervical region. MATERIAL AND METHODS: Nine pathologically proven chordoma/chondrosarcoma patients underwent Cyberknife treatment, and in 4 patients Cyberknife was performed as a primary adjuvant treatment after operation. Remainder of the patients had previously received conventional radiotherapy except 1 who had received Gamma Knife treatment. The prescribed tumor dose ranged from 21 to 43.6 Gy in three to five fractions. The dosimetric characteristics were evaluated for conformity and coverage indices. Dose volume histograms of both the tumor and the critical structure were obtained, and the dose delivered to a specific volume (25, 50 and 100%) of the critical structure was calculated in each case. Mass response was measured on follow-up MRI scans. Total tumor doses of different fractionation numbers were converted into single session equivalent doses and linear quadratic equivalent doses of conventional radiation for comparison among patient groups. RESULT: No significant complications were observed during the treatment and early follow-up periods except one instance of transient esophagitis and one instance of otitis. All treatment plans met the criteria for standard protocol of radiosurgery suggested by the Radiation Therapy Oncology Group, specifically in terms of conformity index, which ranged from 1.01 to 1.83. Three plans had a coverage index that was rated as a minor acceptable deviation. All patients were followed from 11 to 30 (median 24) months following the treatment with regular magnetic resonance images, and 4 patients showed mass reduction. Disease progression was not noted in any patient during the above follow-up period except 1 patient who showed asymptomatic recurrence on 27-month follow-up MRI. Dose volume histograms revealed that the relative dose to volume percent of critical structure, measured at 25, 50 and 100%, was apparently lower in the pretreatment surgical decompression group than in the nondecompression group. Two patients developed radiation-induced myelopathy. The delivered radiation dose to the critical structure calculated using the linear-quadratic formula was within the acceptable range in one case and exceeded 70 Gy at 50% volume of the spinal cord in the other. CONCLUSION: The hypofractionated Cyberknife SRT is effective in generating therapeutic response in these radioresistant tumors, with minimal toxicity during the procedure and early follow-up period. Repeated radiosurgical treatment may also be feasible for tumor recurrences but deserves great caution with respect to the biological effects of the accumulated dose on the adjacent critical structures. Cyberknife SRT may be a potentially valuable treatment option once the long-term results and appropriate dose calculators are optimally defined.

Adult↗
PubMed2002

Tumors of the skull base in children: review of tumor types and management strategies.

Although many treatment strategies for skull base tumors in adults have been reported, relatively little has been reported regarding such therapies in the pediatric population. Skull base tumors in children present a therapeutic challenge because of their unique pathological composition, the constraints of the maturing skull and brain, and the small size of the patients. In this review, the authors examine the pediatric skull base lesions that occur in the anterior, middle, and posterior cranial base, focusing on unique pediatric tumors such as encepahalocele, fibrous dysplasia, esthesioneuroblastoma, craniopharyngioma, juvenile nasopharyngeal angiofibroma, cholesteatoma, chordoma, chondrosarcoma, and Ewing sarcoma. They review management strategies that include radio- and chemotherapy, as well as surgical approaches with emphasis on the modifications and complications associated with the procedures as they apply in children. Evidence for the advantages and limitations of radiotherapy, chemotherapy, and surgery as it pertains to the pediatric population will be examined. With a working knowledge of skull base anatomy and special considerations of the developing craniofacial skeleton, neurosurgeons can treat skull base lesions in children with acceptable morbidity and mortality rates. Outcomes in this population may be better than those in adults, in part because of the benign histopathology that frequently affects the pediatric skull base, as well as the plasticity of the maturing nervous system.

Adolescent↗
PubMed1993

Role of bone graft in reconstruction of skull base defect: is a bone graft necessary.

Ten patients underwent reconstruction of skull base defects between 1989 and 1992. In this series, the maximum size of the skull base defect was 6 x 5 cm. Three patients underwent bone grafts to reinforce the skull base. The postoperative course of seven patients without bone grafts was uneventful. There was no cerebrospinal fluid leakage, meningitis, extradural abscess, on brain herniation. On the other hand, two of the three patients with bone grafts developed extradural abseesses requiring the bone grafts to be removed. Although the number of patients in this series is not large, this study demonstrates that the use of bone grafts in reconstruction of skull base detects could be one of the factors in increasing the chances of infectious complications. We think that a bone graft is not necessary to reconstruct moderate-sized skull base defects.

Journal Article↗
PubMed1997

Lateral skull base surgery: the otology group experience.

Lateral skull base surgery has remained the surgical frontier of new developments in the treatment of lesions heretofore difficult to access. Examination of surgical results stimulates technical innovation and provides an intervention risk-benefit ratio assessment for particular lesions useful in management planning. With this in mind, we report the updated collective experience with lateral skull base surgery at the Otology Group over the past 20 years. Two hundred ninety-eight patients underwent surgical intervention for lateral skull base lesions. In 81 patients these lesions were malignant; in 217, benign. Of the benign lesions, 165 were glomus tumors: 139 glomus jugulare, 19 glomus vagale, and 7 glomus tympanicum. The remainder comprised 21 menigniomas, 14 neuromas, two neurofibromas, and a small group of much rarer entities. The philosophy of surgical approach, results, and follow-up are discussed.

Journal Article↗
PubMed2004

Three-dimensional computational reconstruction of lateral skull base with plastinated slices.

The goals of this study were to build the 3D reconstructed model of lateral skull base and to explore the spatial relationships of the important structures for providing the morphological basis for lateral skull base surgery and clinical image diagnosis. Blocks with edges of about 80 mm containing the lateral skull base region and adjacent structures were sawn out from both sides of the heads and sectioned on transverse plane at a thickness of 700 microm using a plastination technique. On an SGI workstation, a Contours-Marching cubes algorithm was selected to reconstruct the 3D model of the lateral skull base. Accurate alignment of the structures in the serial macroscopic sections was obtained by the employment of the plastination technique. The quality of the reconstructed images was distinct and perfect, specifically, the spatial positions and complicated adjacent relationships of various structures of the lateral skull base can be shown in direct viewing when they are displayed in background of the cranial bony substance. The time spent in displaying or rotating one image including 50 sections was 1.5 sec; all reconstructed structures can be represented individually or jointly and rotated in any plane. The plastination technique and computer-aided 3D reconstruction have an obvious advantage in the study of the complex anatomy of the lateral skull base. Plastination technique provides cross-section images of a higher resolution than those obtained from CT scanning. The computerized 3D reconstruction is important in studying the spatial anatomy of the lateral skull base and can serve as a standard for models created with other techniques.

Epoxy Resins↗
PubMed2000

Osteomyelitis of the skull base with atypical onset and evolution.

Skull base osteomyelitis arises as a complication of malignant external otitis, but it can be also due to middle ear and/or mastoid infection. Other causes can be infections of the paranasal sinuses or of the mandible or maxilla due to odontic caries. Generally, osteomyelitis involves elderly patients affected by diabetic immunodeficiency or microvascular disease. In this paper, we present 3 new cases of skull base osteomyelitis with atypical onset and evolution. The difficulties of diagnosis and details of the management are discussed.

Adult↗
PubMed2000

The role of chemotherapy for skull base carcinomas and sarcomas.

The rarity of most primary skull base carcinomas and sarcomas has prevented a careful examination of the role of chemotherapy in these diseases. For advanced nasopharyngeal cancer, however, convincing data have now been generated supporting the role of systemic chemotherapy in conjunction with definitive locoregional treatment. Chemotherapy also seems to have a role in the management of other squamous cell head and neck cancers, and its use concurrently with radiation may be appropriate when extension to the base of the skull is identified. The role of chemotherapy in the management of the other skull base neoplasms remains less well established. Existing evidence is little more than anecdotal, and the use of systemic chemotherapy should generally be restricted to the palliative treatment setting. The ultimate role of this intervention in the aggressive sinonasal undifferentiated carcinomas and primary neuroendocrine carcinomas is unknown, but for these diseases, chemotherapy is a reasonable addition to locoregional treatment.

Antineoplastic Agents↗
PubMed2002

Reconstruction of the skull base after tumor resection: an overview of methods.

Successful surgical management of malignant skull base tumors depends on both tumor resection and reconstruction of the cranial base defect. The primary goals of skull base reconstruction are to repair dural defects, to prevent the development of cerebrospinal fluid fistulas, and to provide a protective barrier that isolates the intracranial contents from the nasopharynx and paranasal sinuses. Failure to do so can result in potentially life-threatening infectious complications. With modern skull base and reconstructive techniques, malignant tumors in this region, which were once deemed inoperable, can now be safely removed. The authors review the different modalities available for skull base reconstruction following tumor resection.

Bone Transplantation↗
PubMed2002

Perioperative management of complex skull base surgery: the anesthesiologist's point of view.

The anesthetic management of complex skull base surgical procedures provides unique problems and concerns for the neuroanesthesiologist. Positioning to access the skull base could put the patient at risk for peripheral nerve injury and some of the positions may increase the risk for air emboli. In addition, tumor pathology and involvement with vital structures could increase the chances for substantive blood loss, destruction of associated nerves or vessels, and may require temporary occlusion of the carotid artery necessitating intraoperative neuroprotection. Neurophysiological monitors may also be used to safeguard nerve function and anesthetic techniques must be adjusted to accommodate their use. Finally, postoperative morbidity may be affected by surgical approach to the skull base and the anesthesiologist should be aware of which approach may produce a greater incidence of pain, nausea, and vomiting in the postoperative period. The authors discuss the anesthetic concerns and management for complex cranial base surgery. Different approaches will be discussed and comparisons of perioperative parameters between these approaches will be made with data provided by retrospective chart review of more than 600 skull base procedures performed at the authors' institution over the last 10 years. This information should help guide decision making concerning anesthetic management for these skull base procedures.

Anesthesia, General↗