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Vol 10 No 1 Archive

Presentation Abstracts: Presenting Authors R-S

TRAUMATIC CRANIAL INJURY SUSTAINED FROM A FALL ON THE RIGID EXTERNAL DISTRACTION DEVICE

James Rieger, MD (presenter), Ian T. Jackson, MD, Jeffrey S. Topf, DDS, Blaise Audet, MD (Southfield, USA)

Distraction osteogenesis has become a popular treatment of congenital maxillo-craniofacial anomalies. Many ingenious internal and external devices have been developed and used. The rigid external distraction (RED) system based on systems previously used in correction of maxillary retrusion offers postoperative adjustment in two dimensions. Figueroa and Polley [1] reported the use of this device with minimal morbidity in children as young as 5 years of age. They reported no problems with infection, bleeding, pain, loosening of the intraoral splint, dental injury or wear problems in a series of 14 consecutive cleft patients.

Recent modification of the system, RED II, has allowed it to be applied to more complex craniofacial deformities which require a LeFort III osteotomy [1].

A review of the neurosurgery and orthopedic literature revealed that halo complications relate primarily to the skull pins [2-6]. In most cases these complications can be prevented if the device is carefully applied and monitored [3,4]. Early recognition and prompt treatment of complications are important.

After experience with this system for advancement at the LeFort III level, six patients with various syndromes involving the craniofacial skeleton have undergone LeFort III level distraction osteogenesis with the RED device in combination with a planned and stabilized frontosupraorbital advancement. In one of these cases, a 7-year-old child fell on the device after discharge from hospital and sustained a compound depressed skull fracture which required debridement and repair.

The implications of this accident and suggestions on modifications of the positioning of the apparatus will be presented.

SKULL BASE APPROACHES IN THE TREATMENT OF GIANT INTRACRANIAL ANEURYSMS

Howard A. Riina, MD (presenter), G. Michael Lemole, Jr, MD, Robert F. Spetzler, MD (Phoenix, USA)

Giant intracranial aneurysms, defined as lesions greater than 25 mm, are rare intracranial lesions. They usually present as a result of hemorrhage, mass effect, or thromboembolism. Because of their complexity, these lesions often are associated with a poor prognosis. Central to preoperative planning and intraoperative success is the use of skull base approaches to these lesions. We often use the orbitozygomatic approach to approach giant aneurysms of the anterior circulation. This technique emphasizes the removal of bone to improve exposure and minimize brain retraction. We use one of four approaches to treat giant aneurysms of the posterior circulation: (1) the extended orbitozygomatic approach, (2) transpetrosal approach, (3) extended far-lateral approach, and (4) combination approach. For treating giant intracranial aneurysms, skull base approaches to both the anterior and posterior circulations are a vital part of preoperative planning and intraoperative success.

TIMING OF RADIATION THERAPY AND ADJUVANT HYDROXYUREA IN THE MANAGEMENT OF AGGRESSIVE INTRACRANIAL MENINGIOMAS

Raul A. Rodas, DO (presenter), Micahel Prados, MD, Robert Fenstermaker, MD (Bloomington, USA)

Aggressive intracranial meningioma provide a formidable challenge for control. Our experience draws from 6 atypical and 10 malignant meningioma tumors A gross total resection was obtained in 7 patients (Simpson grade 1) and a panel resection was obtained in 9 patients. The 5 partially resected patients who underwent SRS (mean dose 14 Gy to 80% demonstrated a quicker and more complete tumor response than did the 4 partially resected patients who were offered standard radiation therapy (mean dose 54.5 Gy). The use of hydroxyurea demonstrated a positive response in 6 of the 9 partially resected tumors followed over a 30 month period (range 8 - 40 months). Our observations demonstrated both an earlier response and a better control of tumor growth from the use SRS over conventional radiation therapy in the management of aggressive meningioma at first resection. Co-administration of hydroxyurea did seem to improve the overall response to radiation.

INTRA-OPERATIVE MAGNETIC RESONANCE IMAGING (IMR)-GUIDED MENINGIOMA RESECTION

Gregory J. Rubino, MD (presenter), Julie Byrd, RN, J. Pablo Villablanca, MD, Keyvan Farahani, PhD, Barbara Van de Weile, MD (Los Angeles, USA)

Introduction: Does IMR-guidance increase the safety and efficacy of meningioma resection?

Methods: Over the last 12 months, 10 meningiomas were resected using IMR-guidance. Intra-operative imaging was acquired during 3.3 [3-4] imaging sessions/case, producing 9.4 [6-13] studies/case and 126 [80-204] images/case. Contrast was administered after the bone flap had been removed and the dural blood supply had been interrupted.

Results: An imaging-complete tumor removal was accomplished in 9/10 cases. There were no intra-operative complications. Post-contrast images in 4 cases demonstrated partial tumor enhancement after removing the dural blood supply.

Conclusions: IMR-guidance provides useful neuronavigation and allows the surgeon to minimize the surgical exposure. Surgical progress may be assessed for large tumors, complete tumor removal may be confirmed, and complications may be diagnosed early. Partial tumor enhancement suggests pial vascularization and adhesion between tumor and cortical arachnoid. IMR-guidance provides important benefits and appears to improve upon the current standard.

INTRA-OPERATIVE MAGNETIC RESONANCE IMAGING (IMR)-GUIDED PITUITARY TUMOR RESECTION

Gregory J. Rubino, MD (presenter), Daniel Kelly, MD, Barbara Van de Weile, MD, J. Pablo Villablanca, MD, Keyvan Farahani, PhD (Los Angeles, USA)

Introduction: Image guidance has not been traditionally used for pituitary tumor resections. Does IMR-guidance make pituitary tumor resection more safe or effective?

Methods: Over the past 12 months, we performed transsphenoidal pituitary tumor removal using IMR-guidance in 8 patients. Intra-operative imaging was performed 2.4 [2-4] times/case producing 8.4 [4-15] studies/case and 83 [58-140] images/case.

Results: An imaging-complete tumor removal was accomplished in 6 of 8 cases. Two patients with extensive cavernous sinus disease had residual tumor. There were no intra-operative complications.

Conclusions: IMR-guidance may replace fluoroscopy when navigating the transnasal, transsphenoidal approach. Surgical progress may be assessed and complete tumor removal may be confirmed intra-operatively. For macroadenomas, IMR reveals when the optic chiasm has been decompressed. For tumors invading the cavernous sinus, IMR assists the surgeon in achieving maximal tumor removal. IMR-guidance provides important benefits during pituitary tumor resection and appears to improve upon the current standard of care.

FRAMELESS CRANIAL NEURONAVIGATION; EXPERIENCE WITH THREE HUNDRED THIRTY TWO CONSECUTIVE CASES

George Samandouras, MD (presenter), Muftah S. Eljamel, MD, FRCSI, FABI (Dundee, UNITED KINGDOM)

Introduction: Many neuronavigation systems are now widely used. Our experience with the technique, use and limitations of articulated arms and LED systems in routine neurosurgical practice is presented.

Patients-methods: Three hundred thirty two consecutive cases were operated in our institution using frameless neuronavigation systems. The arm-based system was used in 169 patients. Mean age was 49. Forty-nine percent had benign tumors, 32 % malignant tumors,

5.4 % vascular and 15.6 % other lesions. The armless system was used in 163 patients. Mean age was 49.6 years. Forty-six percent had benign tumors, 36 % malignant tumors, 4.6% vascular and 14.4% other lesions.

Results: Both systems were integrated efficiently into the operative routine. The arm-based system was more cumbersome; the armless system required a clear line of optical contact between transmitters and detectors of infrared light. Registration accuracy in arm-based system was 2.4 mm (range 0.4-4.5 mm); application accuracy was <3 mm in 85%. The procedure was abandoned in 4.6% of cases. Registration accuracy in armless system was 1.4 mm. Application accuracy was <1 mm (in 27%), 1-2 mm (in 45%), >2 mm (in 28%). The procedure abandoned in 3% of cases.

Conclusions: Frameless neuronavigation technology is here to stay. However, the many steps of navigation are fraught with potential sources of error. Forthcoming technologies have potential advantages for the elimination of registration errors.

THE USE OF TITANIUM MESH CRANIOPLASTY IN SKULL BASE SURGERY

George Samandouras, MD, FRCS (presenter), Benjamin Lopez, FRCS, Ian Sabin, FRCS (London, UNITED KINGDOM)

Introduction: For large acoustic neuromas where attempts at hearing preservation are impractical, translabyrinthine surgery is commonly used. This leaves a large bony defect and there is significant risk of CSF leak. The impact of titanium mesh cranioplasty in effective restoration of the skull base surface and the impact on CSF leak rate were evaluated.

Methods: Patients undergoing skull base procedures were prospectively evaluated for restoration of bony contour and CSF leak. From August 1996 to January 2000 twenty eight patients underwent skull base surgery in which titanium mesh was used. Patients' age ranged from 27 to 78 years (median 56). The median follow up period was 10 months (range 1 - 38 months). Nineteen underwent translabyrinthine resection of a vestibular schwannoma, one retromastoid; three had microvascular decompression of the trigeminal nerve; other skull base tumours excised in five.

Results: The bony contour was restored in all cases without significant prolongation of the operative time. All patients were satisfied with the cosmetic results. Persistent CSF leak requiring repacking of the mastoid cavity occurred once. CT and MRI imaging was not obscured by artefact.

Discussion/Conclusions: Titanium mesh cranioplasty was found to reconstruct effectively the bony contour, and to reduce the rate of CSF leak without interfering with imaging.

PATHOLOGICAL AND FUNCTIONAL STATUS ANALYSIS OF TRANSBASAL MENINGIOMAS

Stephen Santoreneos, MB, FRACS (presenter), Fred Gentili, MD, FRCSC, Kirollos W Ramez, MD, FRCS (Toronto, CANADA)

We present a review of 15 "transbasal" meningiomas with complex extension into both the intra- and extra-cranial compartments, treated surgically during a 16-year period.

The aims of this study were two-fold: A comprehensive pathological review to identify characteristics that could explain their aggressive clinical behavior and an in depth Quality of Life (QoL) assessment (SF-36) to determine if there is a quality survival benefit and progression free survival that justifies radical non- curative surgery in these patients.

There were 23 surgical procedures, most involving a multidisciplinary ENT and neurosurgical intra- and extra-cranial approach. The recurrence rate was 40%. All patients are alive at an average follow-up of 6 years.

All meningiomas were of transitional or meningiothelial type. Areas of nuclear pleomorphism were not infrequent but mitosis and necrosis were rarely seen. A consistent observation was the aggressive infiltration of dura, muscle, connective tissue planes, mucosa and bone. Details of immuno-histopathological features including markers of proliferation will be presented.

Analysis of SF-36 quality of life survey demonstrated postoperative functional status consistent with independent living comparable to controls. Physical functioning, bodily pain, general health, social functioning, vitality and mental health were all within the normal range for the general population. Role emotional (RE) scores were slightly lower than population norms suggesting difficulties with work or other daily activities as a result of ongoing emotional problems.

Radical surgical resection is recommended for transbasal meningiomas. Although surgery is often non-curative, modern skull base techniques can provide prolonged periods of quality progression-free survival in the majority of patients.

MICROSURGICAL EXCISION OF LARGE VESTIBULAR SCHWANNOMAS USING THE RETRO SIGMOID APPROACH: LONG TERM RESULTS

Satish Sathyanarayana, MD, MCh (presenter), Ajay Jawahar MD, Brian Willis, MD, Anil Nanda MD (Shreveport, USA)

Objective: To retrospectively analyze the outcomes of microsurgical excision using only the retrosigmoid approach in patients with vestibular schwannomas that are more than 3 centimeters in size.

Material and Methods: Over a 9-year period, 16 patients with vestibular schwannomas (3 cm or larger) were operated on using exclusively the retrosigmoid approach. Patient demographics, operative findings, postoperative cranial nerve functional status, imaging results, and complications were reviewed. Factors including the tumor size, extent of excision, facial nerve monitoring, VII and VIII nerve functions and recurrence during follow-up were analyzed.

Results: The median follow-up was 48 months (range 5 to 102 months). All patients were alive at the last follow-up. Tumor size varied between 3 and 5.5 cm (mean 4.2 cm). Gross total excision of the tumor was achieved in 14 (87.5%) patients and 2 (12.5%) had a subtotal excision. Facial nerve was anatomically preserved in 12 (75%) patients. Post- operative complications included CSF leak (n=2) and permanent facial nerve dysfunction (n=6). Two patients required CSF shunt procedures postoperatively. Symptomatic recurrence warranting repeat surgery occurred in only 2 patients (12%).

Conclusion: Simple retrosigmoid approach is a safe and effective option for excision of large vestibular schwannomas. This approach, in addition to being familiar to neurosurgeons, yields results similar to those with the more complex translabyrinthine or combined approaches.

MR-VISUALIZATION OF THE SKULL BASE: COMPARISON OF UNFIXED, SHORT-TIME-FIXED AND THIN-SLICE-PLASTINATED CADAVERS

Wolfgang Schmidt, MD, PhD (presenter), H. Steinke, Th. Schulz, MD, G. Strauss, MD, Chr. Trantakis, MD (Leipzig, GERMANY)

Objectives: Surgery of the skull base is characterized by the narrow topography. Cadaver studies used for educational training of young surgeons. This study compares the differences in various cadaver-conditions to improve the quality of preoperative planing, simulation and training.

Methods: We defined 3 different cadaver-conditions: unfixed, fixed (ethanol), thin-slice-plastinated. Imaging is performed using an open 0.5T MR scanner. We compared significant structures defined by skull-base-surgeons.

Results: It is demonstrated that the visualization of the skull base is significantly improved in fixed cadavers. In fresh, unfixed cadavers demarcation of soft tissue and cerebellopontine angle is less then in other materials

Conclusions: The fixation of cadaver led to improved quality in skull base surgery-education. Computer-assisted-image-guided technologies should attend this quality difference.

EVOLUTION IN CAROTID ARTERY MANAGEMENT IN SKULL BASE SURGERY

Victor L. Schramm, Jr., MD (presenter), Stephen Johnson, MD, Mario J. Imola, MD, DDS, FRCSC (Denver, USA)

Management of the petrous carotid artery is the most challenging aspect of skull base surgery. Tumor extent, prior therapy and the outcomes in 94 consecutive patients who have undergone surgical dissection of the petrous carotid artery is evaluated to determine the optimal method of surgical approach. Seventy-seven percent (72) of the patients were treated for malignant disease and nearly one-half (45) had undergone prior radiation therapy. Follow-up ranged from 3 to 13 years. Preoperative angiography and test balloon occlusion with or without cerebral blood studies were obtained in nearly two-thirds (60) of patients and were predictive of acute vascular outcome in 90 percent of the patients. However, long term follow-up revealed that 21% of those who passed pre-operative testing suffered an ischemic event if the carotid was injured or resected. The most vulnerable parts of the carotid are at the proximal and distal portions of the petrous canal. Patients with prior radiation and advanced age (over 60 years) experienced the highest stroke rate. Carotid preservation has become more feasible in recent years with advances in radiation therapy to effectively treat residual disease. Carotid artery preservation has had no apparent influence on local tumor persistence when postoperative external beam or gamma knife radiation is included in the treatment. Petrous carotid artery preservation during skull base tumor surgery is recommended to significantly lower stroke rates and optimize patient outcome.

SKULL BASE SURGERY WITH A COMPACT INTRAOPERATIVE MRI SYSTEM

Michael Schulder, MD (presenter), Thomas A. Sernas, PA, Peter W. Carmel, MD, DMSc (Newark, USA)

Introduction: A compact system for intraoperative magnetic resonance imaging (IMRI) and surgical navigation (SN) has been developed. The device, the PoleStar N-10, employs two magnet poles with a 25 cm vertical gap. This narrow opening poses a potential problem for use in patients with lesions of the skull base.

Patients and procedures: 16 patients have undergone removal of skull base lesions using the PoleStar N-10. Craniotomy was used in 8 patients and transsphenoidal resection in the other 8. All patients were positioned supine except one who underwent surgery in the lateral position.

Results: In 15/16 patients surgery was completed using the PoleStar N-10. Image quality was excellent in 44% of scans, adequate in 42%, and poor in 14%. Infrared-based surgical navigation was accurate in all surgeries. In one obese patient, who had an orbital meningioma, the system was used only for imaging before and after craniotomy.

Conclusions: The PoleStar N-10 is a useful IMRI tool for patients with lesions at the skull base. In the occasional obese patient the 25 cm vertical gap may limit use of the system.

DIRECTED SKULL BASE BONE REMOVAL FOR VARIOUS ANTERIOR CIRCULATION ANEURYSMS

Marc S. Schwartz, MD (presenter), Allan H. Fergus, MD, Daniel L. Friedlich, AB (Albany, USA)

Bone removal at the anterior skull base facilitates operative exposure for many anterior circulation aneurysms. However, the amount and location of bone removed is not uniform for aneurysms in different locations. Rather, depending upon the surgical access required, extent of dissection must be tailored to each specific aneurysm site.

Approaches to aneurysms of the anterior circulation can be divided into those directed more toward the skull base in the region of the proximal supraclinoid carotid artery and to those directed more distally along the cerebral vasculature. For aneurysms of the proximal intracranial carotid artery, deep bone removal, e.g., anterior clinoidectomy, may be crucial. For aneurysms of the carotid bifurcation or more distal circulation, deep bone removal is not necessary; however, removal of superficial structures, e.g., orbital rim, improves exposure and reduces brain retraction. Orbital osteotomy is of limited value for aneurysms situated more proximally.

Twenty-five anterior circulation aneurysms have been surgically treated using the principles of directed skull base bone removal. For ophthalmic aneurysms (n=3), anterior clinoidectomy was carried out in all cases; for posterior communicating aneurysms (n=8), anterior clinoidectomy was utilized selectively; for middle cerebral aneurysms (n=4), orbital osteotomy was used for only larger aneurysms; and for anterior communicating aneurysms (n= 10), orbital osteotomy was always performed. Using these principles, excellent exposure was provided in all cases with the minimization of unnecessary operative time and risk of morbidity.

NON-GROWING ACOUSTIC NEUROMAS: STANDARDIZATION OF CRITERIA FOR TREATMENT

Marc S. Schwartz, MD (presenter), Simon A. Salerno, MD (Albany, USA)

The question of optimal acoustic neuroma (AN) management is extremely controversial. Especially with smaller tumors, two major options exist, microsurgery and radiosurgery. Because the diagnosis of AN can reliably be made from MR imaging and without pathological examination, radiosurgery is a viable treatment option. Also, ANs are known to be benign, generally very slow growing tumors. These attributes taken together support a third option for the management of many ANs: In patients in whom an AN is unlikely to cause significant additional symptomatology during their expected actuarial lifespans, no treatment may be necessary.

Over a two-year period, 24 patients have been surgically treated for AN. During this time at least 12 additional patients, generally older and with already poor hearing, have been seen and simply followed with serial MR imaging. Several of these patients had been followed for over 5 years without tumor growth.

With microsurgery, the effects of treatment are generally immediate in terms of both complications and effectiveness. With radiosurgery, however, the effects are more hidden. Certainly, complications, in the form of cranial neuropathy, may become manifest; however, efficacy of tumor control is only verified by serial imaging over many years. The fact that some ANs do not grow even without treatment confounds this determination of efficacy. Certainly, the best way to determine optimal treatment of ANs would be with a randomized study. Failing this, it is proposed that in a subset of patients (older, smaller tumors, poor hearing) tumor growth should be proven via serial MR imaging before either treatment is undertaken.

COMPARATIVE ANALYSIS OF QUALITY OF LIFE OUTCOME SCALES IN CRANIAL BASE TUMOR POPULATION AND THE DEVELOPMENT OF A NEW DISEASE SPECIFIC INSTRUMENT

Greta Seever, RN (presenter), Amin Kassam, MD, Michael Horowitz, MD, Ricardo Carrau, MD, Carl Snyderman, MD, William Welch, MD, Michael Pless, MD (Pittsburgh, USA)

Cranial base tumors affect thousands of Americans annually resulting in death or lasting disability. Survivors are often left with emotional, physical and cognitive deficits which are difficult to quantify or inadequately evaluated. Neurosurgeons need to move beyond the general outcomes scales to deliver quality patient care and determine what the true results are of their procedures. Using established Quality of Life (QOL) scales, practitioners may leave many unanswered questions for the cranial base tumor patient and others involved in their care. Current scales are not specific for pathology of the cranial base. We sought to establish the reliability and validity of four currently existing measuring instruments and compare them against a cranial base specific instrument designed at the University of Pittsburgh Medical Center.

The University of Pittsburgh Cranial Base Outcome Scale (UPCBOS) was developed using standard psychometric techniques (ie., focussed group construct, pairing techniques, reliability assessments, and thresholding). The scale assesses QOL following skull base resection. The first part consists of a series of general questions that use global ratings to allow the patient to give an overall rating of his/her QOL. The second half of the scale is composed of twelve disease specific items such as appearance, speech, vision, hearing, etc. The subjects are asked to rate on a scale of 1-5 to what degree the item has changed or affected their QOL. The patients also rate the importance of the item to their own personal QOL. The scale ends with a supplemental section for patient input into these areas that may have not been addressed.

A prospective study of 40 cranial base surgery patients was carried out using the UPCBOS. The UPCBOS scores were compared to those scores from other established non-disease specific scales.

SIMPLE AND EFFECTIVE RECONSTRUCTION TECHNIQUES USING VASCULARIZED TEMPORAL MUSCLE AND FASCIA FLAP FOR THE ANTEROLATERAL SKULL BASE (ALSB) MENINGIOMA - CLINICAL CASES & CADAVER STUDY

Mauro A. Segura Lozano, MD (presenter), K. Uchida, MD, M. Katayama, MD, T. Hayashi, MD, H. Nakajima, MD, T. Kawase, MD (Tokyo, JAPAN)

Using a cadaver, we show the reconstructive techniques performed at our Institute after ALSB meningioma removal and surgical experience.

The advances in skull base (SB) surgery techniques have increased the life expectancy on treated patients. Meningiomas require wide removal including dura and involved bone; thus, the importance of reconstructive techniques have gained wide recognition. Several techniques for the reconstruction of SB have been used mainly based on frontobasal approaches. However, our technique is focuses on vascularized temporal muscle and fascia (VTMF) flap and bone reconstruction as part of the ALSB procedure.

First, the requiring planning for the surgery is conducted including VTMF and pericranial flap cut by considering location, extension and nature of the tumor, as well as remaining bone and dural defects. Upon the removal of the tumor, this VTMF and pericranial flap is placed extradural to avoid brain herniation, cerebrospinal fluid leakage, and undesired linking of the cranial cavity and upper respiratory tract.

Since 1984, we performed reconstructive techniques for over 68 patients including recurrent cases of sphenoid wing (41 cases), parasellar (21 cases) and others middle or infratemporal fossa (6 cases) meningiomas removal with successful functional and cosmetic results verified in the follow up.

The VTMF and pericranial flap is a simple and effective technique, it has proved superior to other methods for SB reconstruction. For its success, particular attention is due to the temporal muscle blood supply.

ENDOSCOPE ASSISTED NEUROSURGERY: A REVIEW OF 120 PROCEDURES

Laligam N. Sekhar, MD (presenter), Pranatartiharan Ramachandran, MBBS, MCh, Peter Hechl, MD (Annandale, USA)

Introduction: The endoscope is a valuable addition to the armamentarium of the modern neurosurgeon However its usefulness and problems associated with its optimal use alongside microneurosurgery are not fully established. The aim of the study was to review its usage in a series of 120 procedures.

Methods: 120 endoscope assisted procedures were done during a period of 2.5 years. They were classified into four grades based on the usefulness of the endoscope. The type of scopes, the diameters and viewing angles used in the procedures were also recorded. All procedures were recorded on video so that a qualitative study could be made of the factors interfering with the optimal use of the endoscope.

Results: Endoscope assisted microsurgery was used to treat 60 tumors,40 aneurysms, 14 neurovascular compression syndromes,5 arachnoid cysts and 1 post traumatic CSF leak. In 91 procedures(76%) the endoscope assisted in visualization only, in 17(14%) it was used for part of the procedure, in 5 (4%) it was of primary use and in 7 (5.8%) it had no definite role. There was one endoscope use related complication. The problems encountered were repeated fogging of the lens, limited use in a bloody field,and difficulty in immobilizing and positioning the scope in an already narrow field.

Conclusions: Endoscope assisted microsurgery has a definite role in modern microneurosurgery. However problems remain to be sorted out before optimal use is achieved.

POSTERIOR PETROUS FACE MENINGIOMAS

Samuel H. Selesnick, MD (presenter), Teri D. Nguyen BS, Philip H. Gutin, MD, Michael H. Lavyne, MD (New York, USA)

Objective: To define the clinical presentation, treatment options and outcomes for a subset of meningiomas of the posterior fossa skull base that arise from the posterior petrous face between the region of the porus acousticus and the sigmoid sinus.

Study Design and Setting: A retrospective chart review from a large skull base surgery practice at a tertiary care institution

Results: This cohort of patients presented with minimal symptoms, yet large tumors, averaging 3.8 cm and causing significant cerebellar compression. Retrosigmoid craniotomies afforded excellent exposure.

Conclusion and Significance: Patients with large tumors emanating from the posterior fossa aspect of the temporal bone should be evaluated on the basis of their site of origin. Patients with tumors emanating from the anterior or ventral portion of the temporal bone have greater symptoms and greater operative complications, than those emanating from the posterior petrous face, between the porus acousticus and sigmoid sinus.

MANAGEMENT OF ORBITOFACIAL FIBROUS DYSPLASIA

Ramesh Kumar Sharma, MCh (presenter), BS Sharma, MCh, MK Tiwari, MCh (Chandigarh, INDIA)

The authors share their experience in management of eight cases of orbital fibrous dysplasia over the last 4 years. All the cases were associated with varying degrees of cranial and facial involvement.The presenting features were headache and cranio-orbital deformity. All patients had an element of exophthalmos.The sites most commonly involved were lateral wall and roof (all cases). The medial wall was involved in six cases leading to obliteration of ethmoid and sphenoid sinuses. The involvement appeared to be unilateral in all the cases clinically, however radiology revealed it to be bilateral in three cases. The patients had no gross deterioration of vision although perimetry demonstrated constriction of peripheral field of vision in 50% of the cases. However, the fundus examination was normal in all the cases. All the patients were underwent surgical management irrespective of the presence or absence of ocular signs. The approach was through coronal incision and orbito- facial disassembly technique. In six patients the roof or orbit and lateral wall were grossly diseased necessitating reconstruction with cranial bone graft. In two patients the involved segments could be recontoured to proper size and shape. In all the patients the optic nerve was deroofed from pole of the globe to optic foramen. There was improvement in peripheral vision of all the patients. In none of the patients there has been regrowth of the fibrous dysplasia so far (follow up one to three years).

FACIAL NERVE NEUROMAS: A REPORT OF TEN CASES AND REVIEW OF THE LITERATURE

Jonathan D. Sherman, MD (presenter), Elias Dagnew, MD, Myles L. Pensak, MD, Harry R. van Loveren, MD, John M. Tew, MD (Cincinnati, USA)

Objective: To compare our patients with facial nerve neuromas with the natural history in the literature.

Methods: Retrospective data were collected on 10 patients who underwent resection of their facial neuromas. In addition, a review of the literature was performed to comprehensively compile data of patients with facial neuromas.

Results: Patients (means: age, 47 years; follow-up, 33.1 months) presented most commonly with hearing loss (60%) and facial paresis (50%). No patient had worsening of hearing as a result of surgery. Five patients required cable graft repair of the facial nerve, 80% improving to House grade 3 facial function. Five patients had anatomic continuity of the facial nerve preserved, 80% regaining normal facial function. No tumors have recurred during observation. These results are compared with complete review and compilation of cases reported in the literature and CPA/IAC-limited tumors (5 patients) are discussed.

Conclusions:This series documents that facial neuromas can be safely resected with preservation of facial nerve and hearing function.

STENTING OF PARENT VESSELS AND IN FAILED BALLOON ASSISTED (REMODELING) TECHNIQUE IN PATIENTS WITH ANEURYSM REGROWTH

Harish N. Shownkeen, MD (presenter), Kevin Yoo, MD, L. Hopkins, MD, Douglas Anderson, MD, T.C. Origitano, MD, PhD (Maywood, USA)

Regrowth of previously coiled wide neck aneurysms can be problematic, as repeat coiling often does not occlude the residual necks permanently due to coiling compaction. Stenting of the parent vessel and coiling through the stent is a technique that is now being tried for these hard to treat aneurysms. We are reporting our experience with 3 patients with aneurysms that grew back after initial coiling with the remodeling technique and then had stents placed prior to repeat coiling. The patients included 1 male and 2 female patients with ages 37, 48 and 59, respectively. Their aneurysms were giant vertebral-basilar junction (21 mm), superior hypophyseal (13 mm), and posterior communicating artery aneurysms (7 mm), respectively. Cordis Velocity stent placement and angioplasties were performed followed by placement of Guglielmi detachable coils through the struts of the stent. The aneurysms were seen to be completely occluded and the parent vessels fully patent in all 3 patients. Follow up angiograms 3-6 months later in each patient showed good occlusion of the aneurysms with patent parent vessels. In conclusion, stenting of parent vessel prior to repeat coiling of regrown aneurysms is a reasonable alternative technique for permanent treatment of these aneurysms rather than surgery which is more difficult in previously coiled wide neck aneurysms.

SURGICAL MANAGEMENT AND LONG-TERM OUTCOME IN GIANT SKULL BASE PROLACTINOMAS

Raj K. Shrivastava, MD (presenter), Marc Arginteanu, MD, Wesley A. King, MD, Kalmon D. Post, MD (New York, USA)

Introduction: Giant prolactinomas are a rare category of skull base tumors. We report the first series of long-term follow-up and outcome of Giant Prolactinomas.

Methods: Retrospective chart and clinical review of over 2,000 cases of pituitary tumors presenting to our institution, out of which 10 prolactinomas met the criteria for inclusion in our study (Prolactin level greater than 500, radiologic diameter greater than 4 cm and clinical signs of hyperprolactinemia). Patients were followed for a minimum of 10 years after initial treatment.

Results: Over 90% of our series were cured by medical treatment with bromocriptine alone. Tumor volume was decreased by 60%, at a faster rate and in greater quantity when treated with bromocriptine.

Conclusions: In Giant Prolactinomas prolactin level does not correlate with size. Our main indication for early surgery is intra-tumoral hematoma. Indications for late surgery are: CSF leak, medical failure/resistance or an increasing prolactin level despite medical therapy. Sending prolactin levels in suspicious sellar/suprasellar lesions maybe diagnostic and prevent unnecessary surgery. Giant Prolactinomas maybe a separate category of prolactin-secreting skull base tumors altogether that arise from cells that may become invasive.

FACIAL BONE SWING OSTEOTOMIES IN SKULL BASE TUMOR SURGERY

Richard Simman, MD (presenter), Ian T. Jackson, MD, Blaise Audet, MD (Southfield, USA)

In the facial area bony segments can be osteotomized and swung on their blood supply to obtain very good exposure. A further advantage is that their vascularity is preserved, and in addition reconstruction can be perfect.

Lateral Orbital Swing: The lateral wall of the orbit can be swung on the temporalis muscle as can the temporal bone. This provides good exposure to the area of the orbital apex and the anterior temporal fossa.

Maxillary Swing: This can be unilateral at the LeFort I or LeFort III level to provide excellent exposure of the clival area.

Mandibular Swing: This provides relatively wide exposure to the infratemporal fossa for many tumor types, both benign and malignant. It makes dissection of the carotid system simple and safe. The technique of performing these osteotomies, their indications, the possible danger areas, and their advantages will be described with representative cases being presented.

ENDOSCOPE-ASSISTED SKULL BASE SURGERY - OUR EXPERIENCE OF 24 CASES

Pawel Sloniewski, MD, PhD (presenter), Piotr Zielinski, MD, PhD (Gdansk, POLAND)

During the last year we operated on 24 endoscope-assisted skull base surgery cases. There were basilar tip and C2-C3 aneurysms. We used also this kind of procedure during the PCA, sellar and parasellar region surgery. Integration of two simultaneous visual information was achieved using the head-mounted LCD screen. Using this kind of tools we had sufficient control of the operating field without unnecessary retraction of the brain and neurovascular structures. Particularly, usefulness of endoscope-assisted surgery has been seen during the clipping of the basilar artery aneurysms. We perceived it especially in the so-called high or low positioned neck of the basilar aneurysm. On the strength of our still small experience, we can recommended the endoscope-assisted skull base surgery which in our opinion can improve the results of treatment.

ASSESSMENT OF ENDOSCOPIC TECHNIQUES FOR MANAGEMENT OF SINONASAL TUMORS

Carl H. Snyderman, MD (presenter), Hassan M. Hegazy, MD, Ricardo L. Carrau, MD, Mohamed A. Khalifa, MD, Amin B. Kassam, MD (Pittsburgh, USA)

Endoscopic techniques are now used for the surgical treatment of many benign and malignant sinonasal tumors. We reviewed our experience with 105 patients at the University of Pittsburgh Medical Center from 1990-2000 with benign (44) and malignant (61) sinonasal tumors in order to determine if endoscopic techniques resulted in an improved outcome compared to traditional external approaches. Procedures were classified as endoscopic, endoscopic-assisted, and external approaches. Outcome measures included operative time, operative blood loss, duration of hospitalization, complications (major and minor), and tumor recurrence. Separate analyses were performed for histologic groups and anatomic sites. Endoscopic and endoscopic-assisted approaches were used in 29% and 29% of patients, respectively. Endoscopic approaches were associated with less cost (operative time, duration of hospitalization) and less morbidity (blood loss, complications). There was no difference in tumor control between endoscopic and external approaches. Data was insufficient for comparison of different approaches for specific pathologies and sites.

A META-ANALYSIS OF PROGNOSTIC FACTORS FOR LOCAL RECURRENCE OF ESTHESIONEUROBLASTOMA

Carl H. Snyderman, MD (presenter), Barlas Aydogan, MD, Frank D'Amico, Ph.D, Ricardo L. Carrau, MD, Amin B. Kassam, MD (Pittsburgh, USA)

Although craniofacial resection is now considered standard therapy, controversy persists regarding the optimal management of patients with esthesioneuroblastoma. In order to identify important prognostic factors and compare the efficacy of different treatments, a meta-analysis of published cases of esthesioneuroblastoma from 1980-2000 was performed. Including 24 patients from our institution, 477 were identified of which 338 were evaluable. The 5-year disease-free survival rate was 38%. Clinical stage, orbital involvement, and intracranial extension without dural or brain involvement were significant predictors of survival. Patients who had a craniofacial resection +/- radiation therapy as part of their treatment had a decreased risk of local recurrence compared to all other treatments (p=0.008). A survival advantage for postoperative radiation therapy or chemotherapy could not be demonstrated.

INTER-DURAL SPHENOPARIETAL SINUS STRIPPING TECHNIQUE IN INTRADURAL TEMPOROPOLAR APPROACH

Shigeo Sora, MD (presenter), Tuneyoshi Eguchi, MD (Chiba, JAPAN)

Objective: To identify the benefit and pitfalls of the sphenoparietal sinus stripping technique in intradural temporopolar approach.

Material and Methods: Since October 1997 we have used a technique for stripping sphenoparietal sinus from the meningeal dura matter. Before retracting temporal lobe, the dura matter around the sinus is dissected free interdurally for a length of 5 to 10 mm distally from the entry of the dura. Fourteen aneurysmal surgeries were performed using this method. Indication and usefulness of this technique was examined.

Results: Stripping the sinus from the dura matter makes visualization of a lesion possible. The length of stripped depends upon the width of brain retraction necessary for the subsequent procedure. Around the entry of the sinus, the dura matter could be easily dissected. While the distal portion usually remains tightly adherent.

Conclusions: This stripping technique could be useful in developing new access to the lesion in intradural temporopolar approach.

APPLICATION OF THE FRONTO-ORBITAL APPROACH IN PEDIATRIC NEUROSURGERY

Sergey Spektor, MD (presenter), Vit Siomin, MD, Shlomi Constantini, MD, Dan Fliss, MD (Tel Aviv, ISRAEL)

Objective: The aim of this study was to evaluate the benefits and indications for fronto-orbital approach (FOA) in pediatric patients.

Methods and results: The authors report their recent experience with the use of the FOA in 6 patients, 5 male and 1 female. The ages ranged from 3.6 to 15 years (mean 9.7 years). Follow-up period extended from 6 to 15 months (mean 10.2 months). Two patients were operated on for large suprasellar craniopharyngiomas, two for giant hypothalamic-chiasmatic astrocytomas, one for a recurrent hypothalamic gangliocytoma, and one for a hypothalamic hamartoma. In 4 cases a neuronavigation system (BrainLab) was utilized. The lesions were removed totally in 4 patients and subtotally in 2 patients. There was no mortality in this series. There were no complications related to the surgical approach.

Conclusions: The experience with this series of patients suggests that FOA is safe and beneficial in pediatric patients and provides an obvious improvement of exposure of the suprasellar area, which facilitates tumor removal.

COMPLICATIONS INVOLVING EMBOLIZATION OF THE EXTERNAL CAROTID ARTERY PRIOR TO MENINGIOMA RESECTION: A TEN YEAR EXPERIENCE AND REVIEW OF THE LITERATURE.

Richard M. Spiro, MD (presenter), Atul Patel, MD, Michael Horowitz, MD, Amin Kassam, MD, Misha Pless, MD, Charles Jungreis, MD (Pittsburgh, USA)

Background: Meningiomas are surgically curable tumors. A complete resection affords a patient with the best outcome and lowest chances for recurrence. Since meningiomas are highly vascular tumors, endovascular embolization has been employed as a safe and effective means to reduce intraoperative blood loss and improve outcome. The complications associated with over 100 embolizations of the external carotid artery for meningiomas are presented and compared to the available literature. Complication avoidance during this common procedure is discussed.

Methods: From January 1990 to September 2000, 103 embolizations of the external carotid artery were performed prior to resection of large or complex meningiomas at two tertiary care referral centers. The charts of all of these patient retrospectively reviewed and all complications related to the embolizations were examined.

Results: Seven of the 103 patients had a major complication (6.7%) associated with the embolization. Two patients were left blind secondary to the embolization. One patient experienced intratumoral hemorrhage necessitating emergency craniotomy. Two patients were left with cranial nerve deficits and there were two direct injuries to the middle meningeal artery.

Conclusion: Endovascular embolization is effective in reducing intraoperative blood loss for many large or complex meningiomas and facilitating the operative resection. A variety of complications can be associated with these procedures. This review describes several major complications. The technical considerations are stressed in hopes of preventing future complications and making endovascular embolization a safe and valuable adjuvant therapy to surgical resection.

EXTRA-AXIAL CAVERNOUS HEMANGIOMA - A DISTINCT CLINICOPATHOLOGIC ENTITY?

Robert D. Strang, MD (presenter), Ossama Al-Mefty, MD, A. Al-Ferayan, MD (Little Rock, USA)

Introduction: Approximately 80% of cavernous malformations are intra-axial supratentorial lesions, but they are also found in the brain stem, cerebellum, pineal region, and spinal cord. Extra-axial variants are uncommon and are often associated with dural sinuses and high operative morbidity. These extra-axial lesions are clinically and radiographically dissimilar and may represent a distinct clinicopathologic entity.

Patients and Methods: The medical records and operative data of 12 patients with histologically proven extra-axial cavernous hemangioma were reviewed retrospectively.

Results: In all patients, histological examination revealed typical features of a cavernous hemangioma. All of the cavernous malformations were associated with a dural sinus. The cavernous sinus was the most common location (9 of 12 patients, 75%). Several salient features that distinguish extra-axial cavernous hemangiomas clinically and radiographically from their intraparenchymal counterparts were identified and are discussed.

Conclusions: Extra-axial cavernous hemangiomas are distinct in their clinical behavior and radiographic appearance when compared to intra-axial cavernomas. This is particularly important in preoperative planning since these lesions have been known to have high operative morbidity and mortality rates secondary to overwhelming hemorrhage.

INTEGRATION OF PRE- AND INTRAOPERATIVE MULTI-MODALITY DATA SETS IN THE SURGERY OF THE SKULL BASE: ENHANCED COMPUTER-ASSISTED-SURGERY (ECAS)-NEW QUALITY IN CAS?

Gero Strauss, MD (presenter), Bootz Friedrich, MD PhD, Trantakis Christos, MD, Kahn Thomas, MD PhD, Bublat Martin (Leipzig, GERMANY)

Objectives: Surgery of the skull base is characterized by the narrow topography. Both conventional computer-assisted surgery (CAS) based on preoperative data sets and intraoperative image-guided systems are used for surgical guidance. Currently, only few imaging methods are available to supply intraoperative data, e.g., intraoperative MRI, iCT and ultrasound.

Methods: Interventional imaging and navigation is performed using an open 0.5T MR scanner (GE Signa SP). We developed an integrated MR/CT image-based navigation system (LOCALITE Navigator). Depending on the position and orientation of a 3D location device a corresponding slice is extracted in near real time (about 4 images/second) from a previously acquired volume data set.

Results: The first evaluation of the prototype system was performed on 21 lab-data-sets and 6 patients with tumours of the skull base. It is demonstrated that the CAS is significantly improved by adding complementary real-time high-resolution data.

Conclusions: The integration of information from preoperative CT data with that of intraoperative MR data led to significant improvement navigation in skull base surgery. The current system can be adjusted to integrate other relevant imaging modalities as well, e.g., functional MRI or PET. The eCAS system combines the advantages of conventional CAS systems and intraoperative imaging and creates an interface for other applications in the open MR environment.

MENINGIOMAS OF THE ANTERIOR CRANIAL FOSSA REVIEW OF 62 CASES

Gil E. Sviri, MD (presenter), Menashe Zaarror, MD, DsC (Haifa, ISRAEL)

The authors report 62 cases of meningiomas of the anterior cranial fossa treated surgically in Rambam medical center over the last ten years, the most frequent origins of tumors were olfactory groove (26) and planum sphenoidale (13). 12 tumors were from the tuberculum selle or both from tuberculum selle and planum sphenoidale. Other tumors were from anterior clinoid and mixed origins. 81%were over 4 cm in diameter. IN 20% the surgeon reported an encasement of main blood vessel. The average pre-operative symptom duration was 22 months. Presenting symptoms were visual disturbances (61%), headache (53%), behavioral problems (42%), and anosmia (29%) as well as convulsion, endocrinological disturbances. Two patients presented with acute brain herniation. Operation was done through bifrontal craniotomy (68%), and subfrontal approach. Complete removal was preformed in 70% and in 21%a residual of less then 1 cm² was left. Partial removal was done in 11%, all of them because of vessel encasement. Mortality was 6.5%. 78% of the patients were discharge from hospital to their home in a good functional state. 15.5% needed rehabilitation. Postoperative complications were pneumonia (23%), intracerebral hematomas (6%), deep vein thrombosis (4.8%), CSF leak (1.6%) and meningitis (1.6%). In 2 patients radiosurgery was given for small residual tumor. The management of those difficult tumors and the surgical technique are discussed. Early diagnosis of these tumors and abounding the use of autonomic retractors during the resection are stress.