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At least 163 records · Page 9Linked to original sources
PubMed2006

CyberKnife radiosurgery in the treatment of complex skull base tumors: analysis of treatment planning parameters.

BACKGROUND: Tumors of the skull base pose unique challenges to radiosurgical treatment because of their irregular shapes, proximity to critical structures and variable tumor volumes. In this study, we investigate whether acceptable treatment plans with excellent conformity and homogeneity can be generated for complex skull base tumors using the Cyberknife radiosurgical system. METHODS: At Georgetown University Hospital from March 2002 through May 2005, the CyberKnife was used to treat 80 patients with 82 base of skull lesions. Tumors were classified as simple or complex based on their proximity to adjacent critical structures. All planning and treatments were performed by the same radiosurgery team with the goal of minimizing dosage to adjacent critical structures and maximizing target coverage. Treatments were fractionated to allow for safer delivery of radiation to both large tumors and tumors in close proximity to critical structures. RESULTS: The CyberKnife treatment planning system was capable of generating highly conformal and homogeneous plans for complex skull base tumors. The treatment planning parameters did not significantly vary between spherical and non-spherical target volumes. The treatment parameters obtained from the plans of the complex base of skull group, including new conformity index, homogeneity index and percentage tumor coverage, were not significantly different from those of the simple group. CONCLUSION: Our data indicate that CyberKnife treatment plans with excellent homogeneity, conformity and percent target coverage can be obtained for complex skull base tumors. Longer follow-up will be required to determine the safety and efficacy of fractionated treatment of these lesions with this radiosurgical system.

Adolescent↗
PubMed2000

Central skull base invasion of maxillofacial tumors: computed tomography appearance.

OBJECTIVE: The aim of this study was to demonstrate computed tomography (CT) features of maxillofacial tumors invading the central skull base and to offer information in aiding diagnosis. METHODS: Fifty-eight maxillofacial tumors with central skull base invasion shown on axial and coronal CT images were divided into benign (13 cases) and malignant (45 cases) groups, based on their pathologic outcomes as proven by biopsy and surgery. RESULTS: Four manifestations of the skull base abnormality were observed on CT images: (1) resorption of central skull base (53 cases, 11 benign and 42 malignant tumors); (2) enlargement of the foramen and canal in the central skull base (20 cases, 4 benign and 16 malignant tumors); (3) thinning of the central skull base (11 cases, 8 benign and 3 malignant tumors); and (4) displacement of the central skull base (5 cases, all benign tumors). The following structures of the central skull base were involved: the roof of the pterygoid process of the sphenoid bone (49 cases), the sphenoid greater wing (37 cases), the sphenoid body and sinus (33 cases), the petrous apex (12 cases), the clivus (4 cases), and the articular surface of the temporal squama (3 cases). Of 58 patients, 30 (7 benign and 23 malignant) had tumors with central skull base erosion that infiltrated into the cranial cavity. CONCLUSION: Benign maxillofacial tumors with center skull base erosion tended to lead to the displacement and thinning of the base of the middle skull fossa in contrast with tumors with malignant maxillofacial tumors. It is believed that these CT manifestations might be valuable in making a differential diagnosis.

Adolescent↗
PubMed1996

Three-dimensional helical CT angiography of skull base meningiomas.

PURPOSE: To describe the findings of skull base meningiomas on three-dimensional CT angiograms obtained with helical scanning and to evaluate the usefulness of this method. METHODS: Fifteen patients who had a meningioma near the skull base were examined with helical CT after receiving an intravenous bolus injection of contrast material. RESULTS: All meningiomas had either a honeycomb (12 patients) or solid (3 patients) pattern of enhancement. Bony structures of the skull base and adjacent major arteries that were displaced or surrounded by tumor were also evident. CONCLUSION: Three-dimensional CT angiography depicts the relationship between skull base meningiomas and neighboring bony and vascular structures clearly, quickly, and with minimal risk to the patient.

Adult↗
PubMed2007

Expanded endonasal approach: a fully endoscopic completely transnasal resection of a skull base arteriovenous malformation.

OBJECTIVE AND IMPORTANCE: Vascular lesions with an intraosseus nidus involving the skull base are uncommon and challenging [Gianoli GJ, Amedee RG Vascular malformation of the sphenoid sinus. Ear Nose Throat J. 70:373-375;(1991), Malik GM, Mahmood A, Mehta BA Dural arteriovenous malformation of the skull base with intraosseous vascular nidus. Report of two cases. J. Neurosurg 81:620-623;(1994)]. We present a pediatric patient, with a life-threatening arteriovenous malformation (AVM) of the sphenoid sinus, clivus, and ventral skull base, who failed routine multimodality management of AVMs. An entirely transsphenoidal fully endoscopic resection was used to resect this ventral cranial base AVM with an intraosseus nidus located in the clivus. CLINICAL PRESENTATION: A 4-year-old female presented with recurrent, life-threatening hemorrhages from a clival and ventral skull base AVM of the entire clivus and ventral skull base. The patient had been temporized from the age of 2-4 years with multiple internal and external carotid arterial particulate and alcohol embolizations, including both external and internal carotid artery embolizations, intracranial ligation of the right internal carotid artery, and gamma knife irradiation. Despite these multiple interventions, the patient had persistent, life-threatening hemorrhages from arterial recanalization and recruitment requiring intubation, tracheostomy, and nasopharyngeal packing. INTERVENTION: The patient underwent a three-stage surgical intervention to resect the AVM. An open subfrontal approach, as the first procedure, provided minimal access to the feeding vessels and was therefore aborted. A two-stage image-guided fully endoscopic approach via a sublabial midface approach without external incisions was performed. Postoperative angiography revealed minimal residual shunting in the pharynx and cavernous sinus. The patient has been free of significant hemorrhages over the past three years. CONCLUSION: Technological advances in endoscopic surgery and image guidance are now allowing for purely endoscopic surgical treatment of previously unresectable lesions with acceptable morbidity. We report the successful and safe resection of a ventral cranial base AVM via a fully endoscopic approach. This paper reports the first AVM with a purely intraosseus nidus of the ventral skull base and demonstrates the ability to deal with complex ventral skull base lesions using a fully endoscopic transsphenoidal technique.

Cerebral Angiography↗
PubMed2003

Experimental robotic milling in skull-base surgery.

OBJECTIVE: In the field of otorhinolaryngology, a variety of skull implants have been developed to assist hearing-impaired or even deaf patients. The first step in the implantation procedure, and also in lateral skull-base surgery, is to drill the calvarian or mastoid bone. We intended to investigate the hitherto unknown parameters for performing this procedure and to establish the first set-up for robotic milling of the lateral skull base. MATERIALS AND METHODS: Experimental milling of the skull base was conducted on two human specimens using a hexapod robot. RESULTS: Optimized parameters were determined with a drill speed of 30,000 revolutions/min and a form feed rate of 5 mm/s for the calvarium and 1 mm/s for mastoid bone, respectively, in a spiral-path fashion. While using a cutting burr, mean force levels were 4.81 N for calvarian bone and 6.12 N for mastoid bone, respectively--well below our empirical limit of 10 N. However, maximum levels easily surpassed these limits, reaching 27.7 N. CONCLUSION: The prerequisites for robotic skull-base surgery were fulfilled. With further work to implement feedback of sensory input, robots may increase precision for various tasks in skull-base surgery.

Humans↗
PubMed2006

Meningothelioma as the predominant histological subtype of midline skull base and spinal meningioma.

OBJECT: This study was undertaken to test a hypothesis that meningiomas of the midline skull base and spine are predominantly of the meningothelial histological subtype. METHODS: The cases of 794 consecutive patients who underwent resection for meningioma at the Cleveland Clinic between January 1991 and March 2004 were reviewed retrospectively. The authors analyzed the relationship between the tumors' histological subtypes and sites of origin in the 731 patients from this group who harbored tumors that were determined to be benign histologically (World Health Organization Grade I). Meningothelial meningiomas (MMs) accounted for 63.5% (464/731) of the Grade I tumors. The incidence of MM according to the site of origin was as follows: 84.9% (186/219) in the midline skull base, 58.3% (35/60) in the lateral skull base, 48.5% (183/377) in a non-skull base location, and 80% (60/75) in spinal locations. The incidence of MM in the midline skull base and spinal locations were significantly higher than in non-skull base or lateral skull base locations. CONCLUSIONS: Meningiomas of the midline neuraxis are predominantly meningotheliomas. Analysis of the increasingly available data on genetic and topographic characteristics of MMs suggests that they may represent a unique entity, contrary to the prevailing belief that all benign meningiomas are identical tumors.

Humans↗
PubMed1998

An experimental approach to image guided skull base surgery employing a microscope-based neuronavigation system.

INTRODUCTION: A cadaveric study was undertaken to investigate the usefulness and reliability of a microscope based navigation system (NS) for skull base surgery. MATERIAL AND METHODS: CT-scans (1 mm slices) were performed in 10 fixed cadaver heads after implantation of fiducials. There upon, various skull base dissections were undertaken: transethmoidal-transsphenoidal approach to sella and clivus, retrosigmoidal approach to the internal auditory canal (IAC) and to the posterior semicircular canal (PSCC). The navigated dissections were performed with the MKM, a microscope based navigation system of Carl Zeiss (Oberkochen, Germany). RESULTS: The registration assessment by the NS yielded a mean deviation of 0.23 mm +/- 0.03 mm (mean +/- SD, n = 7, range 0.19 to 0.27 mm). The real anatomical deviation during dissection was 0.67 mm +/- 0.2 mm for navigation to the IAC and 0.71 mm +/- 0.37 mm to the PSCC. This accuracy was achieved with three fiducials (4 x 1 mm titanium screws) arranged as a triangle (side length 4-6 cm) nearby the surgical field. Navigation data on current position, direction and distance to a target structure were helpful in the transethmoidal-transsphenoidal approach to the clivus, as well as for accessing deep seated structures (C1-C2 junction, petrous bone tip). The contouring feature was beneficial for identifying structures embedded in the bone. However, due to inaccurate 3-D modelling this feature has a restricted reliability. DISCUSSION: Our cadaveric skull base study has shown that the MKM is a reliable tool with high anatomical accuracy and usefulness of most navigation features. However, in order to effectively and reliably use any NS the surgeon must be familiar with its potential features and limitations as is demonstrated in this study.

Equipment Design↗
PubMed2005

[Management of occult malformations at the lateral skull base].

BACKGROUND: Occult malformations of the lateral skull base are rare anomalies, but can cause severe complications such as recurrent meningitis. Therefore, they need to be precisely delineated and sufficient surgical closure is mandatory. PATIENTS AND METHODS: Between 1986 and 2004 twenty patients (10 children and 10 adults) with occult malformations at the lateral skull base were treated surgically at the ENT-Department of the Hospital Fulda gAG. Of these 3 Mondini-malformations, 11 defects of the tegmen tympani or the mastoidal roof, 2 dural lesions to the posterior fossa and 4 malformations within the pyramidal apex have been found. Four patients have had multiple anomalies. Routing symptom was in all cases at least one previous meningitis. Radiological diagnostics included high-resolution computed tomography (CT) and magnetic resonance imaging (MRI) as well as CT- or MR-cisternography. Depending on type and localisation of the defect the following surgical algorithm was carried out: The trans-mastoidal approach was used in all cases of Mondini-malformation (including obliteration of the ear), in case of lesions to the posterior fossa as well as partly in anomalies at the tegmen tympani and mastoidal roof, respectively. Defects of the pyramidal apex should be explored via the trans-mastoidal way if the lesion is located caudally to the inner auditory canal (IAC), whereas the trans-temporal approach should be used if the lesion is situated ventral to the IAC and dorso-medially to the internal carotid artery (ICA). The trans-temporal approach was also performed in large defects of the tegmen tympani and mastoidal roof as well as in recurrences. CONCLUSIONS: In all cases of recurrent meningitis caused by agents of the upper airway tract the basic principle should be to search for occult skull base malformations radiologically as well as by sodium fluorescein endoscopy as long as the anomaly is detected.

Adolescent↗
PubMed1996

Internal carotid artery sacrifice for radical resection of skull base tumors.

When dealing with skull base tumors that encase the internal carotid artery (ICA), the surgeon must decide between ICA preservation and incomplete tumor resection, or radical resection with ICA sacrifice. In our experience with more than 300 anterior skull base tumors, the ICA was sacrificed in only 10 patients. These tumors were malignant, except for one meningioma that occluded the ICA and produced translent ischemic symptoms. All patients had the ICA resected with the tumor, and all patients underwent revascularization (cervical ICA-MCA saphenous bypass, n = 4; cervical-to-supraclinoid bypass, n = 1; petrous-to-supraclinoid bypass, n = 3; bonnet bypass, n = 2). This small patient series reflects our practice of preserving the ICA whenever possible. We recommend preserving the ICA with benign tumors because they do not invade the artery, or do so only to a limited extent. In addition, similar rates of tumor recurrence are seen after aggressive resection with or without ICA sacrifice. In contrast, we recommend radical tumor resection and sacrifice of the ICA with malignant tumors because they directly threaten the integrity of the ICA and the patient's survival. The ICA should not be considered a limitation to radical tumor resection because the ICA can be reconstructed safely with an appropriate bypass procedure.

Journal Article↗
PubMed1984

The role of digital subtraction angiography in diagnosis of skull-base lesions.

Advances in radiographic diagnosis of skull-base lesions have made it possible to approach lesions formerly considered unresectable. The most important of these are the high-resolution computerized tomographic (CT) scanners with bone algorithms. In conjunction with their evaluations it is important to know in detail the vascular structures involved with the skull base. These include not only the jugular vein and bulb and lateral sinus associated with glomus tumor surgery but often the carotid artery associated with lesions of the jugular foramen and petrous apex. Conventional arteriograms have been the best way to evaluate the vascular system but were occasionally associated with some risk and much patient discomfort. New digital subtraction techniques (digital subtraction angiography [DSA] using an intravenous bolus injection of dye) are now yielding x-ray studies equal to or better than conventional arteriography. DSA will be described and the results of these studies of various lesions of the skull base will be presented in conjunction with the results of high-resolution CT scanning to show the complete workup of the skull-base lesion possible for an outpatient.

Aged↗
PubMed2000

Surgical treatment of a massive chondrosarcoma in the skull base associated with Maffucci's syndrome: a case report.

BACKGROUND: A successfully treated massive chondrosarcoma in the skull base associated with Maffucci's syndrome is presented. The purpose of this report is to discuss the surgical approach to the tumor and reconstruction of the skull base. CASE DESCRIPTION: A 36-year-old woman who had a history of multiple enchondromas and subcutaneous hemangiomas presented with decreased right visual acuity and left papilledema. Computed tomography (CT) and magnetic resonance imaging (MRI) demonstrated a mass in the skull base. The tumor occupied the nasal and paranasal cavities, and extended to the anterior, middle, and posterior intracranial spaces. The midline skull base structures and the left middle cranial base were destroyed. Using a combined anterior craniofacial and left orbitozygomatic approach, the tumor was totally resected. The large skull base defect was reconstructed with a vascularized outer table parietal bone graft attached to a bipedicled temporoparietal galeal flap. The postoperative course was uneventful except for decreased left visual acuity, and temporary diplopia and facial hypesthesia. In 40 months of follow-up there was no recurrence. CONCLUSIONSA skull base approach should be selected to perform total resection of an extensive skull base tumor. The bipedicled temporoparietal galeal flap and vascularized calvarial bone was useful for simultaneous reconstruction.

Adult↗
PubMed2002

3-D-conformal radiation therapy for pediatric giant cell tumors of the skull base.

BACKGROUND: Giant cell tumors (GCT) of the base of skull are rare neoplasms. This report reviews the treatment of four pediatric patients presenting with aggressive giant cell tumor, using fractionated and combined, conformal proton and photon radiation therapy at Massachusetts General Hospital and Harvard Cyclotron Laboratory. PATIENTS AND METHODS: Three female patients and one adolescent male, ages 10-15 years, had undergone prior, extensive surgical resection(s) and were treated for either primary (two patients) or recurrent (two patients) disease. Gross residual tumor was evident in three patients and microscopic disease suspected in one patient. Combined proton and photon radiation therapy was based on three-dimensional (3-D) planning, consisting of fractionated treatment, one fraction per day at 1.8 CGE (cobalt-gray equivalent) to total target doses of 57.6, 57.6, 59.4, and 61.2 Gy/CGE. RESULTS: With observation times of 3.1 years, 3.3, 5.3, and 5.8 years, all four patients were alive and well and remained locally controlled without evidence of recurrent disease. Except for one patient with partial pituitary insufficiency following radiotherapy for sellar recurrent disease, thus far no late effects attributable to radiation therapy have been observed. CONCLUSIONS: 3-D-conformal radiation therapy offers a realistic chance of tumor control for aggressive giant cell tumor in the skull base, either postoperatively or at time of recurrence. Conformal treatment techniques allow the safe delivery of relatively high radiation doses in the pediatric patient without apparent increase of side effects.

Adolescent↗
PubMed1993

[Skull base surgery using the degloving technique--an approach without facial scarring].

Skull base surgery has been performed in 16 cases for en bloc resection of the nasal cavity and paranasal sinus carcinoma invading the anterior and middle skull base in our department. The surgical approach to skull base surgery is mainly a combined craniofacial approach, which includes craniotomy via a coronal incision intracranially and a transfacial or transoral approach extracranially. The direct transfacial approaches, such as lateral rhinotomy, Weber-Furguson incision, and midfacial split, resultin facial scarring. The midface degloving procedure was reported by Casson in 1974. This method can expose the midfacial skeleton by lifting the soft tissue from the face through an intraoral approach without external scarring. The authors have modified Casson's facial degloving technique and applied it to skull base surgery. The entire cranium and facial skeleton can be extensively degloved by using coronal, gingival and conjunctival incisions. Then, en bloc resection of the craniofacial compound segment can be accomplished through this degloving approach without external scarring of the face in anterior and middle skull base surgery. The authors have performed this procedure in 2 cases, and proved it to be an extremely valuable technique, displaying excellent cosmetic and functional results with minimal complications.

Esthetics↗
PubMed1992

Association of skull base and facial fractures.

A retrospective analysis of 268 trauma patients with facial fractures who received computed tomography of the head was undertaken to assess an association with skull base fractures. The incidence of skull base fracture was compared to facial fractures of various anatomic locations. Skull base fractures were significantly increased in orbital wall/rim fractures (36.0%, P = .0823). In contrast, skull base fractures related to orbital floor (27.3%, P = .6191) and maxillary/zygomatic (29.4%, P = .1148) fractures were not significantly greater and were infrequently seen with mandible (4.0%, P = .0454) and nasal (7.7%, P = .0345) fractures. The incidence of skull base fracture was directly associated with the number of facial fractures per patient; one facial fracture (21.0%), two facial fractures (30.4%), and three or more facial fractures (33.3%) (P < .05). The incidence of skull base fractures was related to the location of facial fractures and the number of facial fractures per patient. The results provide additional clinical information to facilitate the prompt detection and diagnoses of skull base fracture.

Adult↗
PubMed1999

[Unusual intra-extracranial extension of meningioma of the lateral skull base].

Extracranial meningiomas are rare tumors of the lateral skull base. A 37-year-old woman presented with tinnitus und progressive hearing loss of her right ear. A painful mass lesion was also palpable in her mandibular angle. CT and MRI scans revealed an intracranial mass with extension to the lateral skull base. These findings suggested the occurrence of a paraganglioma or meningioma. In a two-stage surgical procedure tumor was extirpated without functional impairment to the patient. Histology of the excised lesion demonstrated an endotheliomatous meningioma. Since an extracranial meningioma can present as a mass lesion of the lateral skull base, CT and MRI scans are essential in preoperative surgical planning.

Adult↗
PubMed2004

[Clinical analysis of 430 cases of skull base lesions].

OBJECTIVE: Through analysis of surgical treatment and repair methods for the skull base lesions, to summarize the type, sites, characters of the lesions and the methods of surgical treatment and repair, and to provide the beneficial experience for the surgeons. METHODS: Four hundred and thirty patients were hospitalized and treated surgically between Feb. 1982 and Dec, 2002, and their clinical data were analyzed. RESULTS: Of 430 patients, 265 (61.6%) were male, 165 (38.4%) female. The mean age was 36. 1 years old (range from 2.5 to 76.0). In 173 cases (40.2%), the lesions were on the left side of the skull base, 178 cases (41.4%) on the right, 79 cases (18.4%) involving the central and both side of the skull base. In 116 cases (27.0%), the lesions were located in anterior skull base, 57 (13.3%) in central, 174 (40.5%) in lateral and posterior, and the remainder 83 cases (19.5%) in two or more regions. Of 430 cases, 283 (65.8%) were tumors, among them, 154 (35.8%) were benign, 129 (30.0%) malignant, 76 (17.7%) trauma, 42 (9.8%) congenital, 18 (4.2%) infection, 11 (2.6%) unknown. All patients were surgically treated. Of them, 43 cases were treated for 2 times, 5 cases for 3 times, 4 for 4 times, 1 for 5 times, 3 for 6 times. The total were 514 times. The bone defect was reconstructed in 95 cases (22.1%). The dura mater was repaired in 117 cases (27.2%). The postoperative complications occurred in 27 cases. Two cases died in 2 and 3 days after operation because of brain hernia with the ligation of common carotid artery and internal carotid artery for artery rupture. No death occurred during operation. CONCLUSIONS: The majority of the skull base lesions were tumors. The male patients were more than female. Appropriate surgical approach and better perioperative treatment could harvest the satisfactory effect.

Adolescent↗
PubMed2002

Imaging of the nasopharynx and skull base.

The prerequisite for the correct diagnosis and accurate delineation of skull base lesions is familiarity with the complex anatomy of the skull base. Imaging plays a central role in the management of skull base disease because this region is often difficult to evaluate clinically. CT and MR imaging are complementary; they are often used together to demonstrate the full disease extent. This article focuses on the critical anatomy of theskull base and how this knowledge contributes to accurate disease assessment.

Cranial Fossa, Anterior↗
PubMed1993

[Opening of the carotid canal in the skull base surgery: drilling of the carotid canal triangle].

With the recent advance in skull base surgery, approaches to the cavernous sinus and frontal skull base have been established and introduced positively. The author has applied extensive transbasal approach to lesions in the frontal skull base, and transzygomatic approach to those in the middle skull base, but since the fact that the internal carotid artery runs inside the temporal bone restricts surgical procedure for lesions extending not only to the middle skull base but to the infratemporal fossa, preservation of the internal carotid artery during surgery is demanded. Radical surgery was performed for 5 patients with malignant tumor occupying the infratemporal fossa, resulting in successful en-bloc resection of the tumor by securing a substantial operative space during surgery after early opening of the carotid canal for preservation of the internal carotid artery. In opening the carotid canal, the carotid canal triangle is first identified, then its bone is shaved and cut as far as the spine of the sphenoid, allowing a look at the inside of the tumor, or a view of the internal carotid artery, that permits en-bloc resection of the tumor. Representative cases are reported here and microanatomical information for surgical procedure in opening the carotid canal is also presented with the relevant literature.

Adult↗