NASBS News and Upcoming Events

Vol 10 No 1 Archive

Presentation Abstracts: Presenting Authors E-F

Said El-Shihabi, MD (presenter), Ossama Al-Mefty, MD (Little Rock, USA)

Purpose: Stereotactic radiosurgery has been more frequently utilized as a mode of treatment for initial, residual, and/or recurrent benign intracranial tumors Contrary to copious literature, a less commonly reported result of radiosurgery is the immediate rapid growth and clinical deterioration of certain tumors following stereotactic treatment. The purpose of this paper is to present three separate case reports that revealed radiological and clinical worsening of histologically benign intracranial tumors following stereotactic radiosurgery.

Patients: Three patients (meningioma, pituitary adenoma, and acoustic neuroma) are presented. Two of the patients had attempted surgical resection prior to Gamma Knife radiosurgery (GKRS), while the acoustic neuroma received it as the initial therapy.

Results: All three patients showed a rapid radiological, histopathological, and clinical deterioration following radiosurgery. One of the patients (pituitary adenoma) displayed a more malignant tumor following therapy. Another patient (acoustic neuroma) died within a month of treatment.

Conclusions: Although GKRS has become quite prevalent in treatment of benign intracranial neoplasms, caution must. be taken and awareness of microsurgery as the initial therapy of choice should be considered.

TUBERCULOUS ARACHNOIDITIS WITH GRANULATION TISSUE AT CRANIO VERTEBRAL JUNCTION

D. Elangovan, MCh (presenter), V. Elangovan, MBBS, R. Kathirvel, DA (Dindigul, INDIA)

Tuberculosis can present in any form and affect the central nervous system. Even though Spinal tuberculosis is very common its affection at cranio vertebral junction -foramen magnum level is rare. We had 26 cases of spinal tuberculosis. 4 had a filling defect with cord compression at foramen magnum extending more anteriorly to the base. All presented with quadriplegia. 2 Cases underwent suboccipital craniectomy with CI post arch removal for the removal of the granulation tissue. In another 2 cases a transoral approach was done and the granulation tissue and the pus were removed. Post operatively all patients received anti tuberculous treatment and 3 improved well. One patient died of respiratory embarrassment and had Gr "0" quadriplegia preoperatively. Early diagnosis and basal approach will give a good results.

NEURONAVIGATION; DOES MR IMAGE SEQUENCE ALTER THE ACCURACY?

Muftah S. Eljamel, MBBCh, MD, FRCSI, FRCS(SN) (presenter) (Dundee, UNITED KINGDOM)

Neuronavigation has become an integrated tool in most of neurosurgical operating rooms. Its accuracy depend on many factors, of which image acquisition and manipulation plays an important rule. We collected data prospectively on 60 consecutive patients undergoing neurosurgical procedures using the Surgical Microscope Navigator (SMN, Zeiss, Germany). All patients had two MRI sequences obtained with same skin markers. Registration was performed using each MRI data set separately and the system calculated the average relationship of the markers' positions. The mean age was 49.8 years (range 14-76 years). The mean volume of the lesions was 28.5 ccm (range 1-100 ccm). Sixteen were schwanomas, 9 pituitary adenomas, 9 gliomas, 8 meningiomas, 7 metastasis, 2 colloid cysts, 2 AVMs and one each of chordomas, epidermoid, choleastatoma, CPP, CSFF, PCL and neuroblastoma.

Comparing the value obtained using T1 weighted data set the mean registration accuracy was 2.04 mm (SD 1.28 mm), while for T2 weighted MRI data set the mean was 2.35 mm (SD 1.42 mm). The difference between the two data sets was statistically significant (p value < 0.05).

Conclusion: Image data set significantly affect the accuracy of Neuronavigation systems. T1 weighted MRI images introduce less distortion compared to T2 weighted data set and therefore we recommend T1 data set whenever possible for Neuronavigation.

COMPUTER ASSISTED SURGERY IN THE MANAGEMENT OF PITUITARY ADENOMAS

Muftah S. Eljamel, MBBCh, MD, FRCSI, FRCS(SN) (presenter) (Dundee, UNITED KINGDOM)

Pituitary adenomas lend themselves to intraoperative Neuronavigation by virtue of their relative immobility in the sella tursica. Therefore we investigated the use of the Surgical Microscope Navigator in 25 consecutive pituitary surgery to establish its rule as intraoperative navigation tool. Eighteen procedures were performed through the trans-nasal trans-sphenoid route and seven transcranial sub-frontal approach. Skin markers were used in all cases and T1 weighted MRI with contrast was used. The mean age was 57.5 years (SD 16, range 18-76 years). Sixteen were non-functioning adenomas and the rest were secreting adenomas (3 acromegaly, 2 cushings, 4 prolactinomas).

The mean application accuracy in this group was 1.11 mm (SD 0.68). The surgeon's comments following surgery indicated that the system was excellent navigating tool in 12%, very good in 72% and very helpful in the rest of cases. No hazards or complications occurred in this group which could be attributed to the use of the system.

Neuro-navigation therefore is quite useful tool during pituitary surgery and eventually may replace the use of fluoroscopy during these procedures.

COMPUTER ASSISTED SURGERY AND NEUROPHYSIOLOGICAL MONITORING DURING CPA SURGERY

Muftah S. Eljamel, MBBCh, MD, FRCSI, FRCS(SN) (presenter) (Dundee, UNITED KINGDOM)

The outcome of acoustic neuroma surgery and other lesions lying close to the petrous temporal bone, depends upon careful dissection of the lesion and leaving the facial and VIII complex anatomically and functionally intact. Neuronavigation has the potential in delineating the inner ear, the jugular bulb and the brain stem, all of which are often obscured from view by the tumour.

We have used the Surgical microscope navigator in 38 consecutive CPA lesions, 32 acoustics, 3 trigeminal, 1 facial , 1 epidermoid and one CPA meningioma. Nineteen were females and 19 were males. The mean age was 48.5 years (Range 23 - 75 years). The application accuracy of the system in this group of patients was 2.3 mm (SD 1.5mm) The mean size of these tumours was 3 cm (range 1 to 7 cm). Useful hearing was preserved in 10 out of 13. Continuous monitoring of auditory evoked potentials was performed in all patients with useful hearing. Facial monitoring was used in all patients. The anatomical facial nerve preservation rate was achieved in all but one. Normal facial function was achieved in 94% of patients by 6 months follow up in tumours less than 3 cm , 89% in those with tumours between 3-6 cm and 78 % in those which were more than 6 cm in diameter. The average length of stay in hospital was 7 days. There were no deaths, 3% developed CSF picture compatible with meningitis although there were no organisms seen or isolated, 6% developed CSF leakage requiring shunts. Surgical comments about the value of Neuronavigation in helping identify risk zones such as the cochlea, venous sinus or the jugular bulb were excellent in 9%, very good in 87% and fair in 2% and poor in 2%.

Neuro-navigation therefore is quite useful tool during acoustic CPA surgery and particularly helpful in identifying risk zones.

NEUROSURGICAL MANAGEMENT OF VESTIBULAR SCHWANNOMA: A PRIVATE PRACTICE PERSPECTIVE

Thomas S. Ellis, MD (presenter) (Fort Worth, USA)

Introduction: Vestibular schwannomas represent 6-8% of all intracranial tumors and is the most common tumor of the cerebellopontine angle. Surgical resection remains the preferred treatment. Many authors indicate, however, that such surgical therapy by private practice neurosurgeons is inappropriate and that such surgery should only be performed by academic neurosurgeons at academic training institutions. In order to compare surgical outcomes in private practice with those reported in the literature, a consecutive series of 20 tumors surgically treated over a 28-month period in a private practice setting is presented.

Methods: 20 consecutive vestibular schwannomas were operated upon via the retrosigmoidal approach by a single neurosurgeon. Tumor size (largest extracanalicular dimension) ranged from 0.5cm to 5.0 cm. Intra-operative somatosensory evoked potentials, facial nerve monitoring and stimulation, and brainstem auditory evoked potentials were used in each case. Gross total resection with facial nerve preservation and hearing preservation were the goals in each case.

Results: Gross total resection was achieved in all cases and documented with CT after surgery and MRI at 3-6 months post-operatively. Anatomic preservation of the facial nerve was achieved in 95%. House-Brackmann grade 1-2 facial nerve function was obtained in 93% of patients with grade 1-2 pre-operatively. One patient improved from grade 4 to grade 2. Hearing preservation (Gardner-Robertson class I-II) was achieved in 40% of patients with class I-II hearing pre-operatively. There were no deaths. One patient developed CSF rhinorrhea, which was treated with lumbar drainage. There were no major neurologic complications (hemiparesis, brainstem injury, lower cranial nerve injuries, or cerebellar hematomas).

Conclusions: With appropriate surgical techniques, experience and training, and the use of intraoperative neurophysiologic monitoring, results comparable to those presented in the neurosurgical literature are achievable in a private practice setting.

THE EFFICACY OF GORE-TEX VERSUS HYDROXYAPATITE AND BONE GRAFT IN RECONSTRUCTION OF ORBITAL FLOOR DEFECTS

Hesham Elmazar, MD (presenter), Ian T. Jackson, MD, Dan Degner, DVM, Takeshi Miyawaki, MD, Khaled Barakat, MD, M. Bradford, LVT, Lee Andrus, LVT (Southfield, USA)

Fractures of the orbital floor are very common injures which can result in severe complications such as double vision (diplopia), sinking back of the globe (enophthalmos), and even blindness. These fractures often need to be reconstructed with rigid materials to provide a new orbital floor. Besides bone grafts, many synthetic materials such as Gore-Tex and hydroxyapatite may be used to reconstruct orbital floor fractures. One of the recently introduced materials is expanded polytetrafluoroethylene (PTEE) reinforced with fluorinated ethylene propylene (FEP) known as reinforced S.A.M. Gore-Tex. This is more rigid, yet a soft and malleable material from which special implants can be fashioned and introduced into the orbit. Placing these materials into the confines of the orbit raises concern about causing pressure on the eye or resulting in ocular displacement and other visual problems.

In this study we plan to compare the efficacy and biocompatibility of S.A.M. Gore-Tex both reinforced and non-reinforced in reconstruction of orbital floor defects to that of hydroxyapatite and autogenous bone graft.

Four groups each of six felines will be utilized for this study. The left orbit will serve as the experimental side, while the normal right side will function as the control. An orbital floor defect will be created surgically in all experimental orbits while the control side will be left alone. In group A, the defect will be reconstructed with autogenous corticocancellous bone graft harvested from the iliac crest at the time of surgery. In group B the defect will be reconstructed with hydroxyapatite. In group C, the defect will be reconstructed using non-reinforced Gore-Tex. In group D, the defect will be reconstructed using reinforced Gore-Tex.

The cats will be subjected to: (1) Orbital floor defect (1.5cm-1.0cm); (2) Reconstruction for the created defect with different materials; (3) Pre and post CT scans will be done to evaluate the results; (4) Postoperative histological specimens will be taken to study the biocompatibility of the materials.

ENDOLYMPHATIC SAC TUMORS: REPORT OF TWO CASES AND REVIEW OF THE WORLDS LITERATURE.

Mauro A.T. Ferreira, MD (presenter), Fernando L. Gonzalez, MD, Joseph M. Zabramski, MD, Pushpa Deshmukh, MD, Mark C. Preul, MD, Robert F. Spetzler, MD (Phoenix, USA)

Endolymphatic sac tumors are rare, low-grade, locally invasive tumors of the temporal bone that extend into the posterior fossa. An extensive review of the literature reveals only 69 reported cases of endolymphatic sac tumors. We present two pathologically proven cases, a 45-year-old male and a 13-year-old female (the youngest patient yet reported). Clinical presentation, radiographic studies and pathological findings were reviewed and compared with the literature. Findings in these two patients are in accordance with those in the literature reporting local recurrence but long-term survival. Key diagnostic features include anatomic location and the characteristic high-signal intensity of the tumor on non-contrasted T1-weighted images. Early recognition and surgical treatment are important factors affected outcome.

THE FRONTO-ORBITO-ZYGOMATIC APPROACH: SURGICAL TECHNIQUES AND THE BNI EXPERIENCE

Mauro A.T. Ferreira, MD (presenter), Joseph Zabramski, MD, Fernando Gonzalez, MD, Pushpa Desmukh PhD, Mark C. Preul, MD, Robert F. Spetzler, MD (Phoenix, USA)

The various methods to perform the orbitozygomatic approach were examined in this study.

OZ approaches were performed in three cadaveric specimens. Dissections were carried out in a stepwise fashion and recorded in stereo pictures. Three variations of the OZ approach were studied using one, two or three bone flaps. Attention was focuses on the scalp incision, temporal muscle dissection, and the bone cuts. The medical records of 194 patients undergoing OZ approach between January 1992 and August 2000, were reviewed with attention to indications and complications of this approach.

We found no difference in the exposure provided by the three variations of the OZ approach. However, the one-bone flap technique is more complex and time consuming to perform.

We conclude that the OZ approach performed with two bone flaps provides excellent exposure and is relatively simple and safe to perform. Trauma to the frontalis branch of the facial nerve with this approach can be avoided by using deep subfascial dissection of the temporalis fascia. Avoiding use of Bovie cautery for dissection minimizes atrophy of the temporalis muscle.

THE SUBCRANIAL APPROACH FOR ANTERIOR SKULL BASE TUMORS

Dan M. Fliss, MD (presenter), Gideon Zucker MD, Aharon Amir, DMD, MD, Jacob T. Cohen, MD, Albert Gatot, MD, Sergei Spektor, MD (Tel-Aviv, ISRAEL)

The purpose of this study is to present the technique of the extended subcranial approach to the anterior skull base, and to review the results in 56 patients.

A retrospective review was conducted on the records of 56 patients who underwent this procedure for the treatment of various neoplasms originating in the nasal cavity, nasopharynx, paranasal sinuses, orbit or meninges, in an academic tertiary referral medical center. Preoperative patient evaluation, the surgical technique and complications are also reviewed. 19 patients had malignant tumors and 37 patients had benign tumors. There was one perioperative death (fulminant meningitis an postoperative day 28). Significant complications consisted of meningitis occurring in two patients and five cases of osteoradionecrosis with bone cutaneous fistula. The most common late complication was anosmia (27 patients). Based on this review, we feel that the extended subcranial approach to the anterior skull base is a safe, versatile and effective procedure for the surgical treatment of tumors involving the anterior skull base.

ANTERIOR SKULL BASE SURGERY WITHOUT PROPHYLACTIC AIRWAY DIVERSION PROCEDURES

Dan M. Fliss, MD (presenter), Ziv Gil, MD, PhD, Jacob T. Cohen, MD, Albert Gatot DMD, MD, Sergey Spektor, MD (Tel-Aviv, ISRAEL)

Although craniofacial resection has become a relatively safe and effective procedure, postoperative complications remain a serious problem. A most devastating complication of anterior skull base procedures is pneumocephalus. For the prevention of this serious complication, many authors have recommended prophylactic airway diversion procedures, including prolonged endotracheal intubation or prophylactic tracheotomy. Such procedures may mask neurological deterioration and delay maneuvers to correct it (e.g. prolonged intubation), or postpone rapid rehabilitation (e.g. tracheotomy). The purpose of this study was to determine the need for airway diversion procedures in anterior skull base surgery. The study reports our experience of 109 anterior skull base operations performed without prophylactic airway diversion. Fifty-nine patients underwent oncologic resection of tumor, 34 patients had reduction of complex fronto-naso-orbital and skull base fractures, 13 patients underwent repair of cerebrospinal fluid leak, and 3 patients were operated due to anterior skull base fungal infections. The overall complication rate of nontension pneumocephalus was 4/109 (3.6 %), including 2 oncological patients, and 2 patients suffering from skull base fractures. This complication rate is similar or even lower then previously reported for operations performed with airway diversion procedures. It is concluded that prophylactic airway diversion such as prolonged intubation or elective tracheotomy is unnecessary in routine skull base operations, and may be remained only in cases in which factors predisposing to the risk of tension pneumocephalus are identified.

THE ROLE OF HAIR REMOVAL IN SKULL BASE SURGERY

Dan M. Fliss, MD (presenter), Ziv Gil, MD, PhD, Jacob T. Cohen, MD, Albert Gatot DMD, MD, Sergey Spektor, MD (Tel-Aviv, ISRAEL)

The routine of hair shaving before surgery has been a common procedure in craniofacial and skull base surgery. Hair shaving may cause an additional psychological stress to the patient, slowing the restoration of a normal self-image. We have performed skull base operations without hair removal in 169 patients (ages from 3 to 81 years). The objective of this study was to evaluate the surgical wound infection rate of this group of unshaved patients. The surgical procedures included skull base operations due to: tumors, trauma, fungal infections, brain abscess, cerebrospinal fluid leaks, vascular disorders, and reconstruction procedures. The operative region was scrubbed before surgery with chlorhexidine and water. Perioperative antibiotics were administered using a combination of Cefuroxime and/or Metronidazole. The overall surgical wound infection rate was 1.1% (2/169). In one patient the wound infection was associated with perioperative radiation therapy. The infection rate found in this retrospective study, is similar to that found in cranial and skull base operations conducted with hair shaving. It is concluded that skull base surgery without hair removal is safe and is not associated with increased risk of infections. Unshaving of cranial hair is desired by most of the patients, and allows rapid rehabilitation and reinstatement of normal daily life.

SURGICAL MANAGEMENT OF AGGRESSIVE FUNGAL INFECTION INVOLVING THE ANTERIOR SKULL BASE

Dan M. Fliss, MD (presenter), Ilan I. Hochman, MD, Gideon Zucker, MD, Jacob T. Cohen, MD, Albert Gatot DMD, MD, Hanoch Elran, MD, Sergey Spektor, MD (Tel-Aviv, ISRAEL)

Mucormycosis and some other opportunistic fungi cause invasive life threatening infections of the nose and paranasal sinuses usually in immunocompromized hosts. This fulminant process quickly invades the orbit and anterior cranial base. We describe the successful application of the extended subcranial approach to the anterior skull base for access and extripation of this often lethal fungal infection in three patients. This surgical technique may be applied to advanced infectious processes of the anterior skull base in combination with specific antimicrobial medication without gross disfigurement of the patient and with a greater chance of recovery.

POSTERIOR FRONTAL SINUS WALL - A UNIQUE CALVARIAL BONE DONOR SITE

Dan M. Fliss, MD (presenter), Aharon Amir, MD (Tel-Aviv, ISRAEL)

Cranial bone grafts are the ideal substitute for reconstructing defects of the craniofacial skeleton given the optimal conditions for survival and incorporation. An unusual calvarial bone graft site, the posterior frontal sinus wall was used in 5 patients who underwent the extended subcranial approach for anterior cranial base tumors or trauma. The bone defects comprised the nasal and orbital bones to a varying degree. In all but one case reconstruction was successful and in one case due to inadequate soft tissue coverage part of the bone graft was removed. We recommend the use of this donor site in cases of anterior cranial base especially when using the extended subcranial approach thereby minimizing operating time and donor site morbidity.

SKULL BASE RECONSTRUCTION FOLLOWING ANTERIOR SUBCRANIAL RESECTION

Dan M. Fliss, MD (presenter), Ziv Gil, MD, PhD, Gideon Zucker, MD, Jacob T. Cohen, MD, Eyal Gur, MD, Aharon Amir, MD, Albert Gatot MD, Sergey Spektor, MD (Tel-Aviv, ISRAEL)

The technical approach for skull base surgery has progressed considerably during the last decade. However, there is no single accepted method, for reconstruction of skull base defects following anterior skull base resection. Skull base reconstruction is required to provide support to the frontal lobes, to construct a barrier to avoid CSF leak, to prevent pneumocephalus, and to eliminate intracranial spread of nasopharyngeal bacteria. The purpose of this study was to present a simplified approach to skull base reconstruction. The study reports our experience of 94 anterior skull base reconstruction procedures. The patients underwent tumor excision, reduction of complex fronto-naso-orbital and skull base fractures, repair of CSF leaks, and extirpation of anterior skull base fungal infections through the extended subcranial approach. Skull base defects were reconstructed with multi-layered fascia lata - 54 cases, temporalis fascia - 27 cases, temporalis muscle - 8 cases, and gallea frontalis - 5 cases. Bony defects were restructured with the use of external calvarial table graft, posterior frontal sinus wall (6 and 4 cases respectively) and Hydroxyapatite paste in 11 cases. It is concluded that fascia lata and temporalis fascia provides a simple and reliable reconstruction material for the base of skull. Accordingly, this procedure results in a low rate of CSF leakage, intracranial infections and sinus dysfunction.

THE EXTENDED SUBCRANIAL APPROACH TO THE ANTERIOR SKULL BASE: MODIFICATIONS AND COMBINATIONS.

Dan M. Fliss, MD (presenter), Gideon Zucker, MD, Albert Gatot, DMD, MD, Jacob T. Cohen, MD, Sergey Spektor, MD (Tel-Aviv, ISRAEL)

The subcranial approach is becoming a single stage alternative to the classical craniofacial resection for tumors involving the anterior skull base. The advantages of this approach include the avoidance of facial incisions minimal retraction of the frontal lobe and wider exposure of the skull base from below. While in the majority of cases this approach allows circumferential exposure of the tumor there are still cases in which extensions of particularly voluminous tumors are not easily reached by the subcranial approach. In cases of extensive inferior extensions into the lower nasal cavity, inferior maxillary walls and maxillary antrum we elected to use a combined subcranial and mid-facial degloving approach as a one-stage procedure. The addition of a unilateral pterional approach adds exposure to the most lateral aspects of the ipsilateral orbit the retro-orbital region as well as the sellar and chiasmatic regions. Dissection in the regions of the cavernous sinus is also made easier by this combined subcranial-pterional technique. We review the background of these two surgical combined approaches and describe the technique and limitations.

THE SURGICAL ONE STAGE MANAGEMENT OF FRONTO-BASAL FRACTURES

Dan M. Fliss, MD (presenter), Gideon Zucker, MD, Jacob T. Cohen, MD, Aharon Amir, MD, Sergey Spektor, MD, Albert Gatot, DMD, MD (Tel-Aviv, ISRAEL)

We present a retrospective review of 38 trauma cases that underwent the subcranial approach to the anterior skull base and facial skeleton during a period of 5 years. Patients were retrospectively reviewed and tabulated for age, sex and indications for procedure. Special emphasis was placed on early outcome and complications. Preoperative radiologic evaluation with a new technique the: 30-degree tilt axial CT scan will be presented. Complications included one case with postoperative CSF leakage and pneumocephalus necessitating two secondary operations. One patient had transient pneumocephalus that resolved spontaneously. Bone flap infection occurred in one patient. Enophthalmos and telecanthus occurred in four patients each. The most common postoperative complication was anosmia, which occurred in thirteen patients. It is concluded that the subcranial approach offers a favorable exposure of the critical zones of the anterior skull base thus facilitating reduction and reconstruction.

THE SUBCRANIAL APPROACH FOR THE MANAGEMENT OF CEREBROSPINAL RHINORRHEA

Dan M. Fliss, MD (presenter), Sergey Spektor, MD, Jacob T. Cohen, MD, Gideon Zucker, MD, Aharon Amir, MD, Albert Gatot, DMD, MD (Tel-Aviv, ISRAEL)

Because of the likelihood of intracranial complications, optimal treatment for cerebrospinal fluid (CSF) fistula is to have the leak closed. We elected to use the extended subcranial approach in a group of 11 patients with CSF rhinorrhea. Selection criteria included large defects of the anterior skull base (>15 mm), defects not accessible by endoscopes, fistula sites that could not be localized preoperatively, and multiple and transverse fractures of the cribriform area. Resolution of rhinorrhea was achieved in all patients. Anosmia was the only postoperative, complication. The indication for this approach, the surgical technique and various aspects concerning reconstruction are highlighted.

TREATMENT OF MELANOMA OF THE EXTERNAL AUDITORY MEATUS

Robert A. Forte, DDS, MD (presenter), Michael LaRouere, MD, Jack Kartush, MD, Dennis Bojrab, MD, Daniel Pieper, MD (Southfield, USA)

Melanoma of the external auditory meatus is a rare condition that in the past has been treated mostly piece meal Because the tumor can grow to a large extent without symptoms, diagnosis is usually delayed, We present a series of three such cases, which may be the largest in the world. All were treated and reconstructed in the same manner, with long term follow-up. The purpose of this paper is to discuss the diagnosis, staging, prognosis and treatment of melanoma of the external ear meatus.

All patients underwent a temporal bone resection, parotidectomy, modified neck dissection and reconstruction with a split thickness skin graft.

One patient died of melanoma at ten months postoperative. The other two are still alive at two and five years.

LIMITATIONS OF CRANIOFACIAL RESECTION FOR INVASIVE ANTERIOR SKULL BASS MALIGNANT NEOPLASMS

James K. Fortson, MD (presenter), Susan Douglas, MD, Hal Shaw, MB, DDS, FRCS (Atlanta, USA)

The purpose of this presentation is to examine the indications and limitations of craniofacial resection in the treatment of invasive malignant anterior skull base tumors. A case report of a 30 year-old black mate with the complaint of nasal obstruction with occipital and parietal headache when lying down is presented. Clinically, the patient has proptosis. chemosis, ophthalmoplegia, blindness and fixation of the left pupil. Intranasal examination reveals medial displacement of the inferior and middle turbinate without discharge. There are no lesions in the nasopharynx, oropharynx, oral cavity or neck. MRI reveals a mass in the left frontal, ethmoid and sphenoid sinus with erosion of the posterior medial wall of the orbit. The mass extends through the sphenopalatine fossa into the pterygopalatine fossa and infratemporal fossa. The mass extends inferiorly through the foramen ovale involving the left cavernous sinus and surrounding the left carotid artery. The mass erodes the ethmoid sinus without distinct involvement of the frontal or temporal lobe. Nasal endoscopy and biopsy revealed adenoid cystic carcinoma.

Surgical approaches of extensive skull base tumors continue to evolve. Craniofacial resection is indicated in the treatment of some malignant tumors involving the anterior skull base, Malignant neoplasms with sinonasal, orbital and intracranial extension presents a challenge to the most experienced skull base surgical team. Dural invasion, positive margins, tumor grade, invasion of the carotid artery and cavernous sinus are usually associated with poor prognosis. A variety of complications exist with extensive craniofacial resection. This presentation discusses the limitations of craniofacial resection in invasive malignant neoplasms.

UTILIZATION OF A NEW HYDROXYAPATITE BONE SUBSTITUTE MIMIX FOR CRANIAL RECONSTRUCTION AFTER THE CREATION OF BONY CRANIAL DEFECTS IN SKULL BASE SURGICAL APPROACHES

Paul C. Francel, MD, PhD (presenter), Jayesh Panchal, MD (Oklahoma City, USA)

At the University of Oklahoma Health Sciences Center we have organized a multidisciplinary skull base surgical team for the treatment of skull base tumors. These approaches are based on the fact that approaches through the bony skull base afford better exposure to the pathology with less morbidity to the patient (particularly in terms of brain retraction or injury to cranial nerves and vessels) than an approach taken more closely to these structures. Because of the bone removal, reconstruction is required at the end of the case or at a subsequent period in order to create both the protective barrier to the cranial and facial structures and a reasonable cosmetic appearance.

We have recently utilized since its new availability a hydroxyapatite polymer entitled "MIMIX" which is created from the reaction of calcium tetratriphosphate with sodium citrate. We have found this material easy to handle and to prepare in the operating room and is a very effective bone substitute particularly for the protection of underlying dura. It can maintain its shape well and shows some early incorporation into bony margins. This material can also be used in non-skull base type approaches during craniotomies to fill in burr holes, craniotomy defects, or to provide on-lay grafting in regions in which bony or soft tissue defects may be created creating cosmetic disfigurement.

In this presentation we will present numerous cases using this new bone substitute material that are illustrative examples of the utilization of this technique and we recommend its utilization at the time of reconstruction to obtain both a cosmetically acceptable result as well as necessary brain protection.

COMBINED UTILIZATION OF VARIOUS SKULL BASE APPROACHES AND THE GAMMA KNIFE FOR MULTI-MODALITY TREATMENT OF CRANIAL BASE TUMORS

Paul C. Francel, MD, PhD (presenter) (Oklahoma City, USA)

We have recently established a Skull Base Tumor Center at the University of Oklahoma beginning in 1997. A multidisciplinary skull base team has been assessed and this includes not only neurosurgeons, plastic surgeons, ear, nose, throat surgeons, oromaxillofacial surgeons and ophthalmologists, but in addition has recently incorporated extensively Gamma Knife radiosurgical treatment. This presentation evaluates the use of these two modalities in surgical treatment of patients with cranial base tumors.

Since the organization of the University of Oklahoma Skull Base Center, over 30 skull base tumors have been treated through some form of combined approach of surgical resection and Gamma Knife radiosurgery. These have involved different forms of skull base approach including anterior craniofacial approaches, lateral skull base approaches, and suboccipital, transcochlear, and cervical approaches to tumors of the skull base. In some instances, a near total tumor removal could be performed with a small amount of residual tumor in high morbidity regions of the cranial base and these tumors were subsequently treated by Gamma Knife radiosurgery to the small residual with total obliteration of tumor and/or excellent control. In other instances, total gross tumor removal was followed years later by Gamma Knife radiosurgery for small tumor recurrence. Rarely was Gamma Knife radiosurgical treatment the only treatment for such a tumor except in tumors of very small size, but the combined multi-modality treatment appears to show a high success rate with minimal morbidity. Further discussion of ways to coordinate the skull base surgical team plan with the Gamma Knife radiosurgical plan will also be delineated.

EXTRADURAL ANTERIOR CLINOIDECTOMY: TECHNICAL NOTE AND REFINEMENT

Sebastien C. Froelich, MD (presenter), Khaled M. Abdel Aziz, MD, PhD, Paul L. Cohen, MD, Walter C. Jean, MD, Joannis P. Fouyas, MD, PhD, Jeffrey T. Keller, PhD, Harry R. van Loveren, MD (Cincinnati, USA)

Objectives: To add a new surgical step for a safer extradural anterior clinoidectomy.

Methods: We studied five cadaveric heads injected with colored silicone. One block of the caverno-orbital junction was obtained for histological examination.

Results: We divided the anterior clinoid process into the base, body, and tip. The clinoid space is obtained after removal of the anterior clinoid process, and is limited medially and inferiorly by critical neurovascular structures. We defined the bridge of periosteum stretched between the periorbita along the superior orbital fissure and the temporal fossa dura as the "orbito-temporal periosteal band."

Technical development: Cutting the orbito-temporal periosteal fold allows elevation of the dura propria from the inner membranous layer of the anterior cavernous sinus, thus increasing surgical exposure of the anterior clinoid process.

Conclusions: Extradural anterior clinoidectomy is a technically challenging procedure. The added step to the extradural technique increases exposure and enables a safer removal of the anterior clinoid process.

SURGICAL RESECTABILITY OF MENINGIOMA INVADING THE CAVERNO-ORBITAL JUNCTION: ANATOMICAL AND CLINICAL STUDY

Sebastien C. Froelich, MD (presenter), Khaled M. Abdel Aziz, MD, PhD, Paul L. Cohen, MD, Jeffrey T. Keller, PhD, Harry R. van Loveren, MD (Cincinnati, USA)

Objectives: To study the microsurgical anatomy of the caverno-orbital (CO) junction and to evaluate the resectability of meningiomas invading the CO junction.

Materials and Methods: Sixteen cadaveric heads were microdissected (1 used for histological and anatomical examination). Charts of 31 patients (1990-1999) with meningiomas invading the CO junction were retrospectively analyzed.

Anatomical Results: The CO junction is the continuation of the anterior cavernous sinus into the orbital apex, incorrectly called the superior orbital fissure. Dural layers and neurovascular structures of the CO junction were studied.

Clinical Results: Meningiomas can invade the CO junction laterally through the lateral wall, or posteriorly along the CN arachnoidal covering. We achieved partial resection, not beyond the lateral wall of the cavernous sinus or the periorbita, in 18/31 patients, with resulting ocular CN (III, IV, VI, V1) morbidity in 3/18 patients. We attempted radical resection of tumor portions inside the CO junction in 13/31 patients, with resulting ocular CN morbidity in all 13 patients.

Conclusion: The CO junction is an anatomically complicated region. Resection of meningiomas invading the CO junction should not extend beyond the lateral wall. Residual tumor can be controlled by radiation therapy.

ORBITAL RECONSTRUCTION

Romauldo Rodrigues Froes, MD (presenter), Marcus Vinicius Martins Collares, MD, PhD, Rinaldo de Angeli Pinto, MD, Roberto Corrêa Chem, MD, PhD (Porto Alegre, BRAZIL)

The orbit with its unique location, structural diversity is a reconstruction challenge. It is affected and need to be rebuilt in many congenital, trauma, tumors or developmental craniofacial anomalies.

It is well established when we operate on the orbital walls we aim to decompress, to restore appropriate vision, to improve social interaction and/or to isolate or approach the skull base.

However, some topics remain open to discussion in both soft tissues and skeleton reconstruction: proper palpebral and prosthesis placement; types of hard tissue grafts; need for bone graft fixation; role of alloplastic materials; osteotomy, grafting and/or bone distraction.

The discussion will address the pitfalls in orbital/ocular prosthetization, the indications for bone, cartilage grafts or alloplastic materials and fixation methods. Based on that some statements are made.

COMBINED PET/CT EVALUATION OF RECURRENT SKULL BASE NEOPLASM: A NEW TOOL

Melanie B. Fukui, MD (presenter), C.C. Meltzer, MD, C. Snyderman, MD, A.B. Kassam, MD, D. Townsend, MD (Pittsburgh, USA)

Purpose: Distinguishing recurrent neoplasm from post treatment effect may be extremely difficult in the skull base. A new modality, the PET/CT, permits simultaneous co-registration of anatomic (CT) and metabolic (FDG-PET) data. We present preliminary experience with the prototype PET/CT in the evaluation of recurrent skull base neoplasm.

Methods: Four patients (3 females, one male; age range: 23 to 73 years old; mean: 56 years old) underwent FDG PET/CT scanning for suspected recurrent cranial base neoplasm. Images were interpreted by two radiologists. Elevated FDG uptake, localized to non-physiologic areas on CT, was considered indicative of neoplasm.

Results: 3/4 patients had foci of increased FDG uptake in the region of clinically suspected neoplasm. In one case with histologically-proved invasion of V2, PET/CT did not demonstrate perineural invasion seen on MRI, but showed unsuspected recurrence in the right masticator space.

Conclusion: FDG PET/CT is a valuable technique for the evaluation of recurrent skull base neoplasms that merits further investigation.