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Neil L. Dorward, Olaf Alberti, Binti Velani, Frans A. Gerritsen, William F. J. Harkness, Neil D. Kitchen and David G. T. Thomas

This prospective study was conducted to quantify brain shifts during open cranial surgery, to determine correlations between these shifts and image characteristics, and to assess the impact of postimaging brain distortion on neuronavigation.

During 48 operations, movements of the cortex on opening, the deep tumor margin, and the cortex at completion were measured relative to the preoperative image position with the aid of an image-guidance system. Bone surface offset was used to assess system accuracy and correct for registration errors. Preoperative images were examined for the presence of edema and to determine tumor volume, midline shift, and depth of the lesion below the skin surface. Results were analyzed for all cases together and separately for four tumor groups: 13 meningiomas, 18 gliomas, 11 nonglial intraaxial lesions, and six skull base lesions.

For all 48 cases the mean shift of the cortex after dural opening was 4.6 mm, shift of the deep tumor margin was 5.1 mm, and shift of the cortex at completion was 6.7 mm. Each tumor group displayed unique patterns of shift, with significantly greater shift at depth in meningiomas than gliomas (p = 0.007) and significantly less shift in skull base cases than other groups (p < 0.003). Whereas the preoperative image characteristics correlating with shift of the cortex on opening were the presence of edema and depth of the tumor below skin surface, predictors of shift at depth were the presence of edema, the lesion volume, midline shift, and magnitude of shift of the cortex on opening.

This study quantified intraoperative brain distortion, determined the different behavior of tumors in four pathological groups, and identified preoperative predictors of shift with which the reliability of neuronavigation may be estimated.

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James T. Kryzanski, Donald J. Annino Jr. and Carl B. Heilman

The treatment of malignant skull base tumors has improved with the development of skull base surgical approaches that allow en bloc resection of a lesion and increase the efficacy of adjuvant therapies. The anatomical complexity of these lesions and their surroundings has led to a relatively high complication rate. Infection and cerebrospinal fluid fistulas are the most common serious procedure-related complications. They result from the frequent necessity of working in a contaminated space such as the paranasal sinuses as well as from the creation of large dural and skull base defects. The authors have reviewed the literature regarding complications of surgery for malignant skull base lesions and present several techniques and strategies for minimizing their incidence by performing the craniofacial approach to anterior skull base lesions.

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Eve C. Tsai, Stephen Santoreneos and James T. Rutka

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.

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Rodrigo Couto Torres, Leonardo Frighetto, Antonio A. F. De Salles, Brian Goss, Paul Medin, Timothy Solberg, Judith Marianne Ford and Michael Selch

Object

The authors report the evolution of linear accelerator (LINAC)–based radiosurgery in the treatment of patients with intracranial meningiomas. They describe the technical aspects as well as clinical and radiological outcomes.

Methods

The authors performed a retrospective review of 161 patients harboring 194 intracranial meningiomas treated with various types of stereotactic irradiation at their institution between May 1991 and July 2002. Clinical and radiological follow-up data (mean follow-up period 32.5 months, range 6–125 months) were obtained in 128 patients (79.5%) with 156 meningiomas (80.4%). There were 88 women and 40 men whose mean age was 57.2 years (range 18–87 years). Stereotactic irradiation was the primary treatment in 44 patients, and 84 patients underwent resection prior to radiosurgery. Stereotactic radiosurgery (SRS) was used to treat 79 lesions and fractionated stereotactic radiotherapy (SRT) was used to treat 77. The mean dose for SRS was 1567 cGy (range 1200–2285 cGy) prescribed to a mean isodose line of 66.6% (range 50–90%). Stereotactic radiotherapy was delivered using a mean dose of 4839 cGy (range 2380–5400 cGy), prescribed to a mean isodose line of 89% (range 50–90%).

The mean follow-up periods were 40 and 24 months in SRS- and SRT-treated patients, respectively. Tumor control was achieved in 58 SRT-treated benign meningiomas (90%) and in 70 SRT-treated lesions (97.2%). In patients with atypical meningiomas a considerably poorer prognosis was seen. Clinical improvement or stabilization of symptoms was observed in the majority of patients. Symptomatic complications were limited to four patients (5%) treated with SRS and four (5.2%) treated with SRT.

Conclusions

Stereotactic irradiation techniques have changed the neurosurgical approach to intracranial meningiomas. Either SRS or SRT delivered as a primary treatment in selected cases of skull base lesions or as an adjuvant after conservative resection has improved the management of these complex intracranial tumors.

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Ricardo Ramina, Joao Jarney Maniglia, Yvens Barbosa Fernandes, Jorge Rizzato Paschoal, Leopoldo Nizan Pfeilsticker, Maurício Coelho Neto and Guilherme Borges

Object

Jugular foramen tumors are rare skull base lesions that present diagnostic and complex management problems. The purpose of this study was to evaluate a series of patients with jugular foramen tumors who were surgically treated in the past 16 years, and to analyze the surgical technique, complications, and outcomes.

Methods

The authors retrospectively studied 102 patients with jugular foramen tumors treated between January 1987 and May 2004. All patients underwent surgery with a multidisciplinary method combining neurosurgical and ear, nose, and throat techniques. Preoperative embolization was performed for paragangliomas and other highly vascularized lesions. To avoid postoperative cerebrospinal fluid (CSF) leakage and to improve cosmetic results, the surgical defect was reconstructed with specially developed vascularized flaps (temporalis fascia, cervical fascia, sternocleidomastoid muscle, and temporalis muscle). A saphenous graft bypass was used in two patients with tumor infiltrating the internal carotid artery (ICA). Facial nerve reconstruction was performed with grafts of the great auricular nerve or with 12th/seventh cranial nerve anastomosis. Residual malignant and invasive tumors were irradiated after partial removal.

The most common tumor was paraganglioma (58 cases), followed by schwannomas (17 cases) and meningiomas (10 cases). Complete excision was possible in 45 patients (77.5%) with paragangliomas and in all patients with schwannomas. The most frequent and also the most dangerous surgical complication was lower cranial nerve deficit. This deficit occurred in 10 patients (10%), but it was transient in four cases. Postoperative facial and cochlear nerve paralysis occurred in eight patients (8%); spontaneous recovery occurred in three of them. In the remaining five patients the facial nerve was reconstructed using great auricular nerve grafts (three cases), sural nerve graft (one case), and hypoglossal/facial nerve anastomosis (one case). Four patients (4%) experienced postoperative CSF leakage, and four (4.2%) died after surgery. Two of them died of aspiration pneumonia complicated with septicemia. Of the remaining two, one died of pulmonary embolism and the other of cerebral hypoxia caused by a large cervical hematoma that led to tracheal deviation.

Conclusions

Paragangliomas are the most common tumors of the jugular foramen region. Surgical management of jugular foramen tumors is complex and difficult. Radical removal of benign jugular foramen tumors is the treatment of choice, may be curative, and is achieved with low mortality and morbidity rates. Larger lesions can be radically excised in one surgical procedure by using a multidisciplinary approach. Reconstruction of the skull base with vascularized myofascial flaps reduces postoperative CSF leaks. Postoperative lower cranial nerves deficits are the most dangerous complication.

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Amin Kassam, Carl H. Snyderman, Ricardo L. Carrau, Paul Gardner and Arlan Mintz

The increasing popularity of minimally invasive neurosurgery has led to the development of transnasal expanded approaches for the treatment of skull base lesions. One of the greatest challenges in safely accomplishing resection of tumors, particularly intradural lesions, is effective hemostasis. Over the past 7 years the authors have progressively developed an organized approach to address this challenge. This has required the development of new instrumentation as well as variations on standard techniques. In this report they present the technique that has evolved at their institution for endoneurosurgical hemostasis.

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Amin Kassam, Carl H. Snyderman, Arlan Mintz, Paul Gardner and Ricardo L. Carrau

Object

Transsphenoidal approaches have been used for a century for the resection of pituitary and other sellar tumors. More recently, the standard endonasal approach has been expanded to provide access to other, parasellar lesions. With the addition of the endoscope, this expansion carries significant potential for the resection of skull base lesions.

Methods

The anatomical landmarks and surgical techniques used in expanded (extended) endoscopic approaches to the rostral, anterior skull base are reviewed and presented, accompanied by case illustrations of each segment (or module) of approach. The rostral half of the anterior skull base is divided into modules of approach: sellar/parasellar, transplanum/transtuberculum, and transcribriform. Case illustrations of successful resections of lesions with each module are presented and discussed.

Conclusions

Endoscopic, expanded endonasal approaches to rostral anterior skull base lesions are feasible and hold great potential for decreased morbidity. The effectiveness and appropriate use of these techniques must be evaluated by close examination of outcomes as case series expand.

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Amin Kassam, Carl H. Snyderman, Arlan Mintz, Paul Gardner and Ricardo L. Carrau

Object

Transsphenoidal approaches have been used for a century for the resection of pituitary and other sellar tumors. Recently, however, the standard endonasal approach has been expanded to provide access to other parasellar lesions. With the addition of the endoscope, this expansion has significant potential for the resection of skull base lesions.

Methods

The anatomical landmarks and surgical techniques used in expanded (extended) endoscopic approaches to the clivus and cervicomedullary junction are reviewed and presented, accompanied by case illustrations of each segment (or module) of approach.

The caudal portion of the midline anterior skull base and the cervicomedullary junction is divided into modules of approach: the middle third of the clivus, its lower third, and the cervicomedullary junction. Case illustrations of successful resections of lesions via each module of the approach are presented and discussed.

Conclusions

Endoscopic expanded endonasal approaches to caudally located midline anterior skull base and cervicomedullary lesions are feasible and hold great potential for decreased morbidity. The effectiveness and appropriate use of these techniques must be evaluated by close examination of outcomes as case series expand.

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Laurence Davidson, Dawn Fishback, Jonathan J. Russin, Martin H. Weiss, Cheng Yu, Paul G. Pagnini, Vladimir Zelman, Michael L. J. Apuzzo and Steven L. Giannotta

removal impossible. 17 , 29 To that end, the authors of several reports have emphasized the use of subtotal resection for improved functional outcome over complete resection of skull base lesions to minimize the risk of permanent postoperative cranial nerve deficits. 3 , 5 , 24 , 25 , 27 Unfortunately, long-term outcome after subtotal resection of cranial base meningiomas is associated with an unacceptably high symptomatic recurrence rate. 20 It is clear that the optimal management of complex skull base meningiomas is not always achievable with surgery alone. As a

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James B. Elder, Roscoe Atkinson, Chi-Shing Zee and Thomas C. Chen

reconstruction should occur as part of the same procedure. 33 Total resection of skull base lesions may not be possible, in which case decompression of vital neural structures is performed. The use of neuronavigation for preoperative planning and intraoperative surgical navigation may facilitate maximal resection of the tumor. Additionally, preoperative assessment of potential defect geometry, for example with three-dimensional CT, may allow implantation of a custom-made cranioplasty at the time of resection. 36 Use of angiography to rule out vascular involvement has been