NASBS News and Upcoming Events

Vol 10 No 1 Archive

Presentation Abstracts: Presenting Authors I-J

REVASCULARIZED FREE TISSUE RECONSTRUCTION OF LATERAL SKULL BASE DEFECTS FOLLOWING THE INFRATEMPORAL MIDDLE FOSSA APPROACH

Mario J. Imola, MD, DDS (presenter), Victor L. Schramm, MD, Thomas Arganese, MD (Denver, USA)

The purpose of this presentation is to review our experience with free flaps to reconstruct defects following the infratemporal middle fossa (ITMF) approach to the skull base. All patients from our skull base center that underwent ITMF surgery and a free flap technique for reconstruction were included in the study. This yielded a series of 94 patients over a 12 year period. (1987-1999). Early and late complications were reviewed and functional outcomes were assessed semi-quantitatively based on data in our tumor registry. Esthetic results were based on objective analysis of post-operative photos. The follow-up time ranged from 6 months to 137 months with a mean of 46 months. Reconstructive modalities included the following free flaps: radial forearm (4), latissimus dorsi (6), rectus abdominus (41) and gastro-omental (43). Flap failure occurred in 5 patients (1 latissimus dorsi, 2 rectus abdominus, and 2 gastro-omental. Results showed an evolution towards the gastro-omental flap as the preferred reconstructive technique due to several advantages including a very long reliable pedicle, the ability to transfer a mucosal surface to reline the nasopharynx when necessary, an abundant supply of well-vascularized omentum to restore bulk and little to no long-term atrophy and fibrosis.

ANTERIOR SKULL BASE SURGERY USING A LIMITED APPROACH

Ian T. Jackson, MD (presenter), T.A.H. Hide, FRCS, W. Richard Marsh, MD, Blaise Audet, MD (Southfield, USA)

In the late 1970's, the skull base cases presented to us were postsurgical and post-irradiation. From congenital craniofacial deformity corrections, the complications of anterior cranial fossa dead space were understood. Because of this the limited anterior cranial fossa approach was developed and published in a series of articles from 1982 onwards. The technique consisted of a limited trephine in the frontal bone with total removal of the frontonasal complex and nasal septum as necessary. Excellent exposure to the anterior cranial fossa was obtained. Just as important was an understanding of using vascularized tissue in the reconstruction of the anterior cranial base to seal off the cribriform area when indicated. Bony reconstruction was not necessary. This was also adapted for trauma and deformity corrections when indicated. In over 300 cases of anterior skull base tumors, malignant and non-malignant, there have been three dead space problems requiring free tissue transfer and one cerebrospinal fluid leak requiring repair. The advantages of this approach, etc., will be further discussed.

ANTERIOR SKULL BASE SURGERY-KEEPING IT SIMPLE

Hemen J. Jaju, MCh, DNB (presenter), Dipak D. Patel, MS, MCh (Ahmedabad, INDIA)

Surgery for skull base tumors poses a surgical challenge. Post excision reconstruction of this area is usually complex. As most of these lesions are advanced, reconstruction should be aimed at keeping effective but simple.

40 skull base lesions, in patients aged 4 to 70 years, were operated over a period of 16 months from March 1999 to June 2000. The excision and reconstruction was done by a single surgeon and the average operating time was 5.5 hours. The reconstruction was kept simple using local flaps (galeofrontalis, temporalis muscle, scalping) where possible. Patients were treated with adjuvant chemotherapy/radiotherapy as indicated.

There was no perioperative mortality and no infection, meningitis, CSF leak in these patients. Nasocutaneous fistulae occurred in two patients, dystopia in 2, epiphora in 1 and dysphagia in 1. Two patients developed recurrence of the tumor.

The structural complexities of this area make the resection of these lesions difficult. The results for these lesions are encouraging even with simpler surgical options.

MICROSURGERY FOR POTENTIAL RADIOSURGICAL SKULL BASE LESIONS: A RETROSPECTIVE ANALYSIS AND COMPARISON OF RESULTS

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

Objective: To retrospectively analyze the outcomes of microsurgery in patients with skull base tumors that would have been ideal targets for radiosurgery and to compare the results with those of radiosurgery existing in literature.

Material and Methods: Over a 9-year period, 25 symptomatic patients had microsurgical excision of various skull base tumors that were 3 cm in their maximum diameter. A retrospective analysis of the follow-up for these patients was done and comparison was made with the results of radiosurgery for similar tumors published in the literature. The factors analyzed were, overall survival, tumor control, freedom from disease progression and new neurological deficits.

Results: Fourteen patients (56%) had a complete excision while 11 (44%) had subtotal excision. Two patients (8%) had a transient CSF rhinorrhoea, one patient (4%) had permanent ipsilateral abducens palsy while one had transient facial weakness. All patients were alive at median follow-up of 36 months (range 3-84). Three patients subsequently underwent repeat surgery for recurrence. The actuarial tumor control rates at 5 years and 10 years were 84.7± 6.5% and 76.2± 8.4%. The diagnosis of chondrosarcoma (p = .002) and atypical histology (p <.0001) had statistically significant influence on the outcome while the extent of excision did not affect the tumor control rates (p = .652).

Conclusion: The results and complication rate of surgery for small, well defined, benign skull base tumors does not significantly differ from that of radiosurgery.

THE SUB-TONSILLAR APPROACH TO THE FORAMEN OF LUSCHKA: AN ANATOMICAL AND CLINICAL STUDY

Walter C. Jean, MD (presenter), Khaled M. Abdel Aziz MD, PhD, Sebastien C. Froelich MD, and Harry R. van Loveren MD (Cincinnati, USA)

Conventional approaches to tumors that traverse the foramen of Luschka, the opening of the lateral recess of the fourth ventricle into the cerebellomedullary and cerebellopontine cisterns, are self-limited by needing to view the foramen from the fourth ventricle laterally (transvermian approach) or from the cerebellopontine angle medially (suboccipital approach). Upon recognition that the foramen of Luschka is actually the end of the natural cleavage plane between the cerebellar tonsil and the medulla, separated from that plane merely by a thin film of glial tissue and the tela choroidea, the optimal approach to this region is sub-tonsillar. This approach is performed through a low bilateral suboccipital craniotomy, with the patient in park-bench position and the "tumor-side-down." After complete mobilization of the cerebellar tonsil, dissection around the tumor in the cerebellomedullary fissure reveals a panoramic view to the foramen of Luschka laterally and up to the middle cerebellar peduncle superiorly. We describe the microsurgical anatomy of the foramen of Luschka and the sub-tonsillar approach, based on microdissections in five silicone-injected, specially preserved cadaveric specimens and on clinical studies in three adult patients with foraminal tumors.

GIANT CELL TUMOR OF THE PETROUS TEMPORAL BONE: A CASE PRESENTATION AND LITERATURE REVIEW

Walter C. Jean, MD (presenter), Walter C. Jean, MD, Mary Haverbusch, RN, BSN, CNRN, Myles L. Pensak, MD, Harry R. van Loveren, MD (Cincinnati, USA)

Giant cell tumors of bone are benign, skeletal neoplasms, mainly involving long bones, with a few reports of giant cell tumors of the skull, mostly in the sphenoid bone. We describe the case of a man who experienced subacute onset of disequilibrium and sudden right-sided facial palsy. MRI revealed a mass involving the mastoid and petrous temporal bone (T1 iso-intense, T2 hyperintense, bright enhancement). Near-total resection (microscopic residual, no radiographic residual) of a giant cell tumor was achieved via a temporal craniotomy and posterior petrosectomy, with complete facial nerve decompression. Because of the unpredictable, often aggressive biological behavior of these tumors, the patient received postoperative radiotherapy. Although giant cell tumor of the temporal bone is rare, skull base surgeons should include this in the differential diagnosis for osteolytic, expansive bony masses of the temporal bone. Because MRI is the diagnostic modality of choice, we present one of the first reports of the MRI characteristics of this tumor. Although reported, sarcomatous transformation after radiotherapy is exceedingly rare. Thus, aggressive resection with postoperative radiotherapy is the definitive treatment of these tumors.

EXPERIENCE OF FAR LATERAL INFERIOR SUBOCCIPITAL APPROACH

Sin-Soo Jeun, MD (presenter), Kwan Sung Lee, MD, Sang Won Lee, Joon Ki Kang (Seoul, KOREA)

Introduction: Heros introduced far lateral inferior suboccipital approach, as a modification of the unilateral suboccipital approach, for aneurysms of the vertebral artery, the vertebrobasilar junction, and the proximal basilar trunk, and for arteriovenous malformations of the inferolateral cerebellum in 1986.

Method: We performed this approach for the 2 cases of PICA (posterior inferior cerebellar artery) aneurysm, the 1 case of vertebral artery aneurysm and the 1 case of jugular foramen schwannoma that was primarily at CP (cerebellopontine) angle with moderate enlargement of jugular foramen and extension into upper cervical area in the our department during the last 2 years.

Result: In the 2 cases of PICA aneurysm, the aneurysms were satisfactorily clipped.

The vertebral artery aneurysm was fusiform aneurysm, could not be clipped.

So, the ipsilateral vertebral artery was ligated and all patient were well.

The jugular foramen schwannoma was radical subtotal removed and the patient did well.

Conclusion: Even most PICA or vertebral artery aneurysms have been handled by standard lateral suboccipital approach, far lateral inferior suboccipital approach allows to take easily a proximal control for the aneurysmal clip, and to reach the aneurysm with minimal retraction. Also we think that this approach can be useful for the tumor with extension into craniocervical junction (lower clivus, anterior foramen magnum and anterior upper cervical area).

COMPARISON OF MANDIBULAR SURGICAL TECHNIQUES FOR ACCESSING VASCULAR LESIONS OF THE CRANIAL BASE

Walter D. Johnson, MD (presenter), Michael A. Devlin, MD, DDS (Loma Linda, USA)

Purpose: The bony interference of the mandibular ramus and mastoid process limits surgical access in treatment of Zone III vascular lesions. Mandibular distraction and vertical ramus osteotomy (VRO) are two techniques that enhance access yet maintain low morbidity. This study quantified and compared the exposure gained with each of these two methods.

Methods: In ten cadaveric exposures, anterior distraction of the mandible without violation of the temporo-mandibular joint capsule, and VRO with distraction of the proximal and distal segment were evaluated. The neutrally positioned mandible served as the control. The area of surgical access defined by bony and cartilaginous landmarks was determined for each technique.

Results: VRO provided the greatest increase in surgical access with a 99.64% increase in mean area of exposure over control while mandibular distraction provided only a 28.32% increase over control. Conclusion: VRO significantly increases access to the cranial base as compared with mandibular distraction and provides sufficient area for surgical manipulation.

PROTON THERAPY FOR SKULL BASE CHORDOMAS AND CHONDROSARCOMAS: EFFECT OF RESIDUAL DISEASE ON OUTCOME

Walter D. Johnson, MD (presenter), Jerry D. Slater, MD, Lilia N. Loredo, MD, Roger I. Grove, MPH, Dana L. Winsted, BSN, Sandra L. Teichman, BSN, James M. Slater, MD (Loma Linda, USA)

Object: Local tumor control, patient survival, and treatment failure outcomes were analyzed to assess treatment efficacy in 83 patients with skull base chordomas and chondrosarcomas undergoing fractionated proton radiation therapy (RT).

Methods: Between March 1992 and January 1999, 83 patients were treated for skull base tumors, 31 for chondrosarcoma and 52 for chordoma. Target dosages ranged from 63 and 72.20 (mean 70.77) Co Gy equivalents. The range of follow-up was 6 to 95 months (mean 39.9 months).

Results: The local control rates were 83.9% for chondrosarcomas and 63.5% for chordomas. Ninety-one percent with residual tumor volumes of 25 ml or less remained locally controlled, compared with 58% of tumors larger than 25 ml (p = .001). Actuarial 5-year survival rates were 91.7% for patients with chondrosarcoma and 77.4% for patients with chordoma.

Conclusions: The extent of tumor resection greatly enhanced the delivery of full tumoricidal proton RT doses, which directly correlated with lasting local tumor control and overall survival.