NASBS News and Upcoming Events

Vol 10 No 1 Archive

Presentation Abstracts: Presenting Authors T-Z

SELECTIVE CEREBRAL REVASCULARIZATION

Gordon Tang, MD (presenter), C. Michael Cawley, MD, Daniel L. Barrow, MD (Atlanta, USA)

Introduction: Treatment of skull base lesions often requires interruption of native vasculature followed by revascularization. We aimed to examine outcome and risk factors in order to work toward an algorithm for patient selection for revascularization.

Methods: Review of 32 patients who underwent revascularization as an adjuvant treatment during a 5 year period with a mean 3 year follow-up.

Results: Revascularization procedures consisted of STA-MCA (22), ECA-MCA (4), A2-A3 (1), M2-M2 (2) and ECA-P2 (2). Intraoperative angiography allowed correction of graft occlusion in two of 26 cases. Of 22 patients who had balloon test occlusions (BTO), three failed. In the remaining 19 patients, 13 patients had hypoperfusion on SPECT scans. Other patients underwent bypass due to young age. Good outcome was achieved in 81%. Three patients had severe neurologic deficits (9%) with three deaths (9%). Five of six cases with long-term angiographic follow-up maintained patency. On multivariate analysis, failure to tolerate BTO was related to poor outcome (p=0.063). In follow-up, no ischemic events were recorded.

Conclusion: Cerebral revascularization protects against ischemic events in comparison to historical controls. A significant complication rate favors selective revascularization. Guidelines for revascularization include failed BTO, decreased perfusion on SPECT scan and young age.

COMPREHENSIVE MICROSURGICAL ANATOMY OF THE JUGULAR FORAMEN AND REVIEW OF TERMINOLOGY

Ibrahim Tekdemir, MD (presenter), Eray Turcar, MD, Asim Aslan, MD, Alaittin Elhan, MD, Mehmet Ersoy, MD, Haluk Deda, MD (Ankara, TURKEY)

Introduction: We aimed to review the three-dimensional anatomy of the JF and the relationships of its internal structures. Relevant terminology is also discussed in light of the literature review.

Materials and methods: The microsurgical anatomy of the jugular foramen was studied in 12 formalin preserved cadavers (24 foramina) and 40 dry-skulls (80 foramina).

Results: The jugular foramen was exposed by microsurgical dissection with drilling from superior to inferior direction. Observations regarding dural architecture of the jugular foramen and relationships between neurovascular structures passing through the foramen were noted in cadavers. Normal bony construction of the foramen and its variational anatomy were examined in dry-skull specimens. Using photographs and drawings, the anatomy of the jugular foramen is presented and related terminology is discussed in the light of literature review.

Conclusion: Knowledge of the complex and three-dimensional anatomy of the jugular foramen is essential for any surgeon dealing with the jugular foramen lesions.The jugular foramen is a canal. It is better to term it as the jugular canal. Compartmentalization of jugular canal should be termed as the petrosal part, intrajugular part and sigmoid part according to the structures, which passed through the JF.

PIGMENTED VILLONODULAR SYNOVITIS OF THE TEMPOROMANDIBULAR JOINT

Fuat Tosun, MD (presenter), Ricardo L. Carrau, MD, Jane L. Weissman, MD (Pittsburgh, USA)

Introduction: Pigmented villonodular synovitis is a benign lesion of obscure etiology involving the synovial membranes of joints, bursae and the sheaths of tendons. Its occurrence in the temporomandibular joint is distinctly rare. Despite its benign nature, pigmented villonodular synovitis is locally destructive and can infiltrate the surrounding tissues.

Description: We present a case of pigmented villonodular synovitis of the left temporomandibular joint involving the left infratemporal fossa and left mid-cranial base in a 60-year-old man.

Results: Preoperative computerized tomography, magnetic resonance imaging, and fine needle aspiration biopsy were used to determine the extent of the lesion and to establish the diagnosis preoperatively. A complete excision of the lesion was performed using a preauricular infratemporal fossa approach with a subtemporal craniectomy. The patient is free of disease at 5 years follow-up.

Conclusion: Complete surgical resection is the treatment of choice for this rare lesion.

NEUROSURGICAL IMPACT IN THE MANAGEMENT OF MALIGNANT TUMORS INVOLVING THE LATERAL SKULL BASE: REVIEW OF 49 CASES

Aymara I. Triana, MD (presenter), Chandranath Sen, MD, David Hiltzik, Peter Costantino, MD (New York, USA)

Despite the advances (improved understanding of the anatomy, high resolution imaging modalities, innovative surgical approaches and multidisciplinary collaboration) in managing lateral skull base malignancies it still remains a difficult and yet evolving problem for the surgeon, if compared with the well established treatment modalities for sinonasal CA's involving the anterior skull base.

We analyzed retrospectively the hospital and office records of 49 patients who underwent surgery for the treatment of head and neck subcranial cancers at our institution. The aim was to asses the impact of the neurosurgical participation in the multidisciplinary effort in terms of morbidity and outcome. Chordomas and low grades chondrosarcomas, also considered malignant, were excluded of the study since they pose a different management problem.

The series includes 24 primary tumors and 25 recurrent tumors. The variables used to asses the neurosurgical aspect of the management of these pathologies were: type of tumor, time to recurrence, anatomical areas involved, type of neurosurgical procedure performed, number of those procedures, complications, length of hospital stay (as well as the one related to the involved areas), functional status and survival. The statistical analysis applied was of the simple descriptive type.

Squamous Cell CA appears to be more aggressive and more frequent than other types. Adenocystic CA recurred most often and had the shortest time to recurrence. 61% of patients had 3 or 4 anatomical areas involved. 45% of patients required two or more operations. The most frequent complication, among others, was the cranial nerves impairment. 73,4% of patients regressed after surgery in the Karnofsky Performance Score.

Head and Neck CA's that invade the lateral Skull Base has a poor prognosis. Involvement of the Cavernous Sinus, the Internal Carotid Artery or the Temporal bone are unfavorable factors. CS excision has formidable risks and has to be decided in a patient by patient basis. An aggressive tumor resection allows prolongation of life but complications are higher for this group of patients. The extent of the disease was directly proportional to the length of hospital stay. The quality of life was influenced by the morbidity of the operation, the time of hospitalization as well as the functional capacity afterwards.

RHINORRHEA; A COMPLICATION OF TRANSSPHENOIDAL SURGERY

Hakan Tuna, MD (presenter), Agahan Ünlü, MD, Kaan Tun, MD, Gökalp Silav, MD, Ertekin Arasil, MD (Ankara, TURKEY)

Pituitary adenomas constitute 10 % of all intracranial tumors and 50% of sellar-parasellar region tumors. Tumors larger than 10 mm are classified as macroadenomas which sometimes needs extensive approaches, tumors smaller than 10 mm are classified as microadenomas which transsphenoidal route are used in all cases.

Transsphenoidal approach is one of the major techniques used in management of pituitary adenomas and intrasellar tumors. It was also used for some clival tumors such as chordomas and chondromas.

Although it is safe, many complications reported in most of the series. Rhinorrhea, anterior pituitary gland functional deficiencies and diabetes insipidus are frequent complications. 163 patients, who had been operated by transnasal transsphenoidal route at Ankara University Medical School Neurosurgery Department between January 1990 and October 1998, were reviewed retrospectively. Patients are classified with the Hardy system according to their tumor size and incidence of postoperative rhinorrhea is evaluated.

There were postoperative rhinorrhea in 12 (7.36 %) patients. 4 of patients with rhinorrhea were in grade A (10.25%), 2 patients were in grade B (4.00%), 2 patients were in grade C (7.40%), one patient was in grade D (6.66%) and 3 patients were in grade E (9.37%).

In 9 patients spinal taps were performed for 4 days 3 times in a day and rhinorrhea subsided in 7 of those patients. In 3 patients spinal external drainage were performed with a successful result. 2 (1.22%) patients were re-operated at postoperative 4^th and 5^th days in whom spinal drainage and spinal taps were of no use.

In this presentation incidence of rhinorrhea that follows the transnasal surgery and repair techniques are presented and discussed.

PARACLINOIDAL ANEURYSMS

Hakan Tuna, MD (presenter), Ayhan Attar, MD, Agahan Ünlü, MD, Nihat Egemen, MD (Ankara, TURKEY)

Paraclinoidal aneurysms pose unique surgical challenges due to their inmate relationship to the skull base and optic nerve. The key success in the complete exposure of the lateral aspect of the optic canal.

In this presentation we report our experience on eleven patients with paraclinoidal aneurysms over four years. Between October 1996- September 2000, eleven patients underwent craniotomy for treatment of paraclinoidal carotid artery aneurysms, all of which were proven to be intradural, at the University of Ankara. Three of the eleven patients came to clinical attention due to SAH. Hunt-Hess Grades of the patients as follows; 7 patients were in Grade 0, 3 patients were in Grade 1 and one patient was in Grade 2. Ten of the patients were women. Total 15 aneurysms were angiographically identified in this series; 4 patients were found to harbor multiple aneurysms. All but one aneurysms were clipped surgically. One aneurysm was coiled via interventionally.

Post-operative control angiograms were obtained for all patients and were revealed that complete clipping for all 14 aneurysms.

There were no perioperative mortality and no permanent neurological deficit. Excellent and good results were achieved in 10 and 1 patients respectively. One patient reoperated for osteomyelitis of cranial bone flap, who was operated initially 4 years ago, and infected bone was replaced with cranioplasty material.

By strictly adhering the some principles such as obtaining safe proximal control of internal carotid artery and with good exposure of lateral optic canal and mobilization of optic nerve, which were done by exposing cervical carotid artery and anterior clinoid removal by intra- or extradurally depending on previous SAH and incising the falciform ligament respectively in our series, paraclinoidal aneurysms can be clipped safely.

TRANSPETROSAL APPROACHES: IMPORTANCE OF VENOUS STRUCTURE AND COMPLICATION AVOIDANCE

Hakan Tuna, MD (presenter), Haluk Deda, MD, Ali Savas MD (Ankara, TURKEY)

Transpetrosal approaches offer distinct advantages over traditional approaches to the petroclival area.

The goal of this study is to avoidance the venous complications of the transpetrosal surgery. We report on 16 consecutive cases operated via transpetrosal approach at the University of Ankara, Ankara, Turkey. Total surgical resection was achieved in 75% of cases, partial resection in 25%. The most common tumor was meningioma, which were consisted 7 patients of this series (44%). There were four deaths (25%); two patients died because of venous infarct documented by cerebral CT scan, another patient died as a result of brain stem edema, and the other patient died because of a pulmonary embolism. Complications occurred in 40% of patients. Two of the patient suffered some degree of venous infarction in the temporal lobe postoperatively, but in their last follow-up, they have no permanent neurological deficit. We and some other authors have observed postoperative venous complications after transpetrosal approaches even when care was taken to preserve the vein of Labbé.

With experience of previous venous complications, we did not sacrifice the superior petrosal sinus and it's tributes in last 6 cases and had no complication related to venous structures. Tentorium incised without sacrificing superior petrosal sinus, which has no difficulty related to it, to connect middle and posterior fossa.

Transpetrosal surgery, in particular when venous structures were preserved, is a safe approach. We do not sacrifice the superior petrosal sinus unless sacrificing the sinus unavoidable for sake of venous complications. We recommend looking for and preserving all venous structures during the transtemporal approaches. For preserving the venous structures, sharp dissection and less retraction are essential. Preservation is still the best way to reduce the venous complications in lateral cranial base approaches.

We would like to highlight to importance of venous complications related to transpetrosal approach and avoidance of complications.

DUMBBELL-SHAPED JUGULAR FORAMEN SCHWANNOMAS: REPORT OF FIVE CASES

Ugur Ture, MD (presenter), Haluk Deda, MD, Necmettin M. Pamir, MD (Istanbul, TURKEY)

Object: Jugular foramen schwannomas are relatively uncommon tumors comprise only 1.4 - 2.9% of all intracranial schwannomas. No large series exists in the literature and less than 120 such cases have been reported in the literature. Jugular foramen region presents considerable surgical challenge when involved by tumors because of its complex anatomy.

Methods: Five cases with dumbbell-shaped jugular foramen schwannoma, which were treated surgically, are presented. Their age were ranging between 20 to 52 (average, 38.4). There were three men and two women.

Results: Total surgical resection was accomplished with combining extreme lateral transjugular approach with an infralabyrinthine procedure in four cases. However, a lateral suboccipital approach was performed in one case, which subtotal tumor removal was accomplished. There was no surgical mortality.

Conclusions: Recent advances in surgical approaches to the skull base have improved surgical results of this uncommon tumor. In our experience, extreme lateral-transjugular approach is safe and effective approach for removal of the dumbbell-shaped jugular foramen schwannomas. Lateral suboccipital approach found to be ineffective which we used this approach for one case and we were not able to total removal of tumor.

RECONSTRUCTION OF SKULL DEFECTS IN IRRADIATED PATIENTS WITH TITANIUM MESH

Frank D. Vrionis, MD, PhD (presenter), Donna Saatman, MD, Steven Brem, MD, Thomas V. McCaffrey, MD, PhD (Tampa, USA)

Patients that have undergone previous irradiation for brain or skull base neoplasms are at high risk for bone flap infection, as the flap represents devitalized bone surrounded by marginally vascularized tissues. In this study, we prospectively studied 16 patients who had previously undergone radiation therapy for intrinsic or skull base brain tumors or had skull base neoplasms that extended into the paranasal sinuses. In those cases, we replaced the bone flap with Leibinger titanium mesh (single or double layer). A vascularized tissue, such as pericranium or temporalis muscle was used to cover the mesh. None of the patients developed an infection or abscess postoperatively. The cosmetic result was good. We conclude that skull reconstruction with titanium mesh possibly reduces the risk of infection in high risk patients with brain or cranial base tumors.

SKULL BASE NEUROSURGERY IN PRIVATE PRACTICE

Darryl M. Warner, DO (presenter), Javed Siddiqi, MD, DPhil (Colton, USA)

Skull base neurosurgery is one of the most technically challenging subspecialties in neurosurgery today. The consensus opinion is that the majority of these approaches should only be undertaken at large, academic centers. Skull base surgery is technically and labor intensive and carries a significant peri-operative morbidity and mortality. Additionally, for optimum outcome, a dedicated neurosurgical ICU is a necessity, and neurophysiologic or other types of monitoring, including image guidance, may be required. Here we offer a summary of our experience with skull base surgery in our institution over the past three years with illustrated examples.

Conclusions: Skull base neurosurgery can be performed safely and effectively with good outcomes in non academic centers as long as the surgeons are appropriately trained, the necessary support systems are available, and the volume and variety of cases keeps the surgeon current with the individual approaches.

EXTRAMEDULLARY PLASMACYTOMA OF THE SKULL BASE

Richard O. Wein, MD (presenter), Saurin R. Popat, MD, Paul O. Dutcher, MD, Timothy D. Doerr, MD (Rochester, USA)

Educational Objective: At the conclusion of this presentation, the participant should be able to identify the typical presentation and treatment considerations for skull base plasmacytoma.

Patients and Methods: 3 patients with extramedullary plasmacytoma of the skull base are reviewed. This case series identified common characteristics of presentation and examines treatment response.

Results: The average age at the time of diagnosis was 39 (range 28 - 48 years). Presentation included nasal obstruction, intermittent epistaxis, periorbital headache and facial paresthesias. All patients received external beam radiation with variable response. Extensive disease at presentation was noted in two of the patients. One patient's course progressed to multiple myeloma.

Conclusions: Skull base plasmacytoma is an uncommon tumor with a limited number of previously reported cases. The response to primary radiotherapy is variable and surgery for recurrent disease or selected primaries may be considered. The potential progression to multiple myeloma dictates continued surveillance in this patient population.

IMAGE GUIDANCE FOR OCCIPITAL-CERVICAL SPINAL RECONSTRUCTION FOLLOWING SKULL BASE SURGERY: A CRITICAL APPRAISAL

William C. Welch, MD (presenter), Amin B. Kassam, MD, Michael B. Horowitz, MD (Pittsburgh, USA)

Object: Occipital-cervical spinal reconstruction is oftentimes a necessary component following extensive skull base procedures. We have used three different image-guidance systems to facilitate spinal reconstruction in these patients. The purpose of this abstract is to provide a critical appraisal of image-guidance in this setting.

Methods: This was a retrospective, case controlled study of 21 patients who underwent destabilizing skull base procedures including transoral odontoid decompression and occipital condyle resection. Three image-guidance systems were assessed including the ISG Technologies multi-articulated arm device, and the In-Site and Stealth freehand systems. Most patients underwent preoperative placement of a halo-vest followed by image guidance protocol using fine cut CT slices. Once in the operating room, the fiducials were registered by standardized protocol. Clinical accuracy of the image guidance device was assessed before beginning surgery by touching the pointer tip to a fixed, easily-definable landmark such as a halo pin or interdental space. During the course of surgery, accuracy was re-assessed by touching prominent bony landmarks such as the ring of C1 or the clivus. The computer-generated video pictures were correlated with fluoroscopic and plain radiographic images whenever possible. The errors were recorded when they exceeded 2 mm.

Results: Image guidance was felt to be helpful and accurate in 47 of 50 procedures. Registration was easier with the freehand systems than with the mechanical articulated arm system (ISG). In no case was surgery started unless the directly observed accuracy was within 2mm. During the course of one procedure, the ISG attachment arm was partially dislodged and accuracy became unacceptably poor. Re-registration could not be performed because of the lack of readily definable points within the surgical field. In another procedure, the In Site system crashed during registration and the system was not used. There was a general trend to reduced accuracy in the ISG system, perhaps related to repeated use and wear on the position sensors. Software was comparable between systems and each were relatively user-friendly.

Conclusions: Image guidance systems may provide an increased measure of safety and accuracy over standard surgical techniques provided that the registration is accurate and there exists a means by which intraoperative accuracy can be assessed.

OCCIPITAL-CERVICAL STABILIZATION TECHNIQUES FOLLOWING CRANIOCERVICAL SURGERY

William C. Welch, MD (presenter), Amin Kassam, MD, Peter C. Gerszten, MD, James P. Burke, MD, Ricardo Carrau, MD, Carl Snyderman, MD (Pittsburgh, USA)

Cervical myelopathy due to degenerative, neoplastic, infectious and traumatic changes at the skull base may require extensive surgical resection for adequate brainstem and spinal cord decompression. These surgical techniques create craniocervical instability and require reconstructive procedures. The purpose of this prospective study was to review the craniocervical reconstruction techniques applied to patients undergoing skull base surgery.

Methods: This was a prospective, institutional review board approved, case controlled study. Each of the 21 patients in this study underwent skull base procedures involving surgical resection of the odontoid process or occipital condyle. All patients included in this study underwent posterior or anterior stabilization procedures (41 operations in total) following the skull base procedures. Patients were prospectively evaluated for neurologic and functional status evaluation. Peri-operative and post-operative radiographs were compared to assess status of fusion and craniocervical stability.

Results: All patients underwent successful biopsy or resection of the lesions causing neurologic deficits. 21 patients underwent surgical procedures involving the odontoid, 4 patients were treated for occipital tumors involving the condyles. Surgical stabilization procedures consisted of Brooks-type fusions (17), placement of anterior (4) or posterior (13) C1-2 transarticular screws, occiput-subaxial spinal instrumented fusions using a contoured Luque-type construct with Songer cables (3), occiput-subaxial spinal non-instrumented fusion (1), and C1 laminoplasty (3). Image guidance was used in most patients and intraoperative neurophysiologic monitoring was used in all patients. There was no 30 day postoperative mortality. Most patients required transfer to an inpatient rehabilitation service. 15 patients had improved neurologically at discharge, the remainder were unchanged. There were no occurrences of SSEP response deterioration during surgery. Morbidity included pneumonia, sepsis, emergent tracheostomy, palate incision breakdown, transient worsening of neurologic deficit during pre-operative imaging, urinary tract infection, decubitus ulcer formation and affectual depression. The posterior fusions included the stereotactic placement of C1-2 transarticular screws or instrumented occiput-subaxial spine fusion. Most patients were maintained in a peri-operative halo vest. Neurologic and general medical status was evaluated at varying post-operative intervals.

Conclusions: There are a number of potentially successful methods to obtain craniocervical fixation and subsequent fusion in patients undergoing destabilizing skull base procedures. The most appropriate method(s) of stabilization depends on application of functional biomechanical principles, patient factors, and surgical experience. The stabilization techniques are technically involved procedures but can yield excellent long-term results. Image guidance and other surgical adjuncts allow the stabilization procedures to be performed with extremely low neurologic morbidity. Augmentative treatments such as halo placement, bone growth stimulators, and correction of nutritional deficits may be necessary in certain patients.

THE TRANSMAXILLER APPROACH IN EXTENSIVE BASILLAR INVAGINATION AND PLATYBASIA: REPORT OF TWO CASES

Faruk Yldan, MD (presenter), Metin Tuna, Alp Yskender Gocer, Tahsin Erman, Erdal Cetinalp (Balcaly-Adana, TURKEY)

The exposure of complex lesions of the anterior skull base and craniovertebral junction is still considered a surgical challenge in neurosurgery . Severe basilar invagination leads to an upward translocation of the upper cervical spine and clivus into the foramen magnum and may be a primary condition or secondary to bone softening disorders. Rheumatoid arthritis and other bone-softening diseases such as Paget's disease, osteogenesis imperfecta, rickets, osteomalacia, and hyperparathyroidism have the potential to destabilize the upper cervical spine.

Symptoms relating to direct neuraxial compression, obstruction to cerebral spinal fluid outflow, and vascular compromise all have been reported in this disease. Although the standard transoral, transpharyngeal approach provides excellent exposure of the body of C-2 and the arch of C-1, transmaxiller approach provides greater access to the upper and middle third of the clivus in profound basilar invagination It provides superior exposure without significant morbidity. We used this approach in two cases with extensive basilar invagination combined with posterior decompression and fusion with cervifix. This article discusses the use of this approach to gain access to the cranial base in severe basilar invagination and the authors' experiences with this technique.

STENTING OF CAROTID ARTERY STENOSIS USING SHAPE-MEMORY-ALLOY-RECOVERABLE-TECHNOLOGY STENTS

Kevin Yoo, MD (presenter), Harish Shownkeen, MD, A.G. Chenelle, MD, T.C. Origitano, MD, PhD (Maywood, USA)

The new self-expanding, Nitinol, Shape-Memory-Alloy-Recoverable-Technology (SMART) stents has only been recently available for treatment of carotid artery disease and is proposed to be superior to the previous balloon expandable stents due to its self-expandability once placed. We are reporting our experience with 15 patients with carotid artery stenosis who were treated using these stents. The patient population consisted of 7 males and 8 females with ages ranging from 50 to 76 years and average age of 68. Technical success was achieved in all 15 cases. More importantly, such success was obtained without the use of any post-stent angioplasty, which reduces the risk of distal emboli. No complications from the SMART stents occurred in all patients. All patients were symptom-free after the procedure. They were placed on anticoagulation therapy, and were discharged one or two days later. They also remained with no evidence of transient ischemic attacks or new strokes during an average follow-up period of 8 months ranging from 1 to 19 months. Follow up carotid doppler studies have shown no post-stenting occlusions or restenosis. In conclusion, the initial results for SMART stents is good and can be used safely and effectively without the need for post-stent placement angioplasty, therefore, theoretically reducing the risks of distal emboli.

PEDIATRIC CONGENITAL VERTEBRAL ARTERY ARTERIOVENOUS FISTULA TREATED SUCCESSFULLY WITH ENDOVASCULAR TECHNIQUES

Kevin Yoo, MD (presenter), Harish Shownkeen, MD, A.G. Chenelle, MD, T.C. Origitano, MD, PhD (Maywood, USA)

Arteriovenous fistulas (AVFs) involving the vertebral artery are rare. They are most commonly associated with trauma and are most often found in adults. Congenital vertebral artery AV fistulas found in children are exceedingly rare. Prior to the advancement in endovascular therapy of vascular lesions, surgical obliteration at the time of diagnosis of these lesions was the treatment of choice frequently with significant morbidity. We report a case of a vertebral AVF in a 2-year-old treated successfully with Guglielmi detachable coils only. The AVF was located at about C1-2 with high flow communication with the posterior cervical venous plexus and internal jugular vein such that the distal vertebral artery filled only faintly. The child presented with progressively worsening symptoms including sleepiness, irritability, wobbling, falling over, and periods of near aspiration with feeding. After two embolizations with multiple GDC coils, patient's symptoms completely resolved, and patient suffered no ill consequences of this treatment. The distal vertebral artery was patent and filled much better than prior to treatment on follow up angiograms. In conclusion, we would like to report a successful endovascular treatment of a congenital pediatric vertebral artery AVF and propose that such lesions can be treated with endovascular means only with virtually no morbidity.