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Vol 10 No 1 Archive

Presentation Abstracts: Presenting Authors M-N

DURAL ARTERIOVENOUS MALFORMATIONS OF THE SKULL BASE

Asim Mahmood, MD (presenter), Ghaus M. Malik, MD (Detroit, USA)

Dural arteriovenous malformations (AVMs) are interesting lesions which can present as diagnostic and therapeutic challenge. Such AVMs were initially described as located solely in the dural venous sinuses, but during the last decade researchers have discovered them in other locations such as tentorium and foramen magnum.

From 1975 to 1999, we have treated 400 AVMs at our institution out of which 46 were dural. Of these 46 dural AVMs, 18 could be classified as skull base AVMs. We have restricted the designation of skull base dural AVMs to those AVMs located in the tentorium or adjacent to bones of skull base. The common dural sinus AVMs are excluded from this category. Skull base dural AVMs can be further subdivided into dural AVMs of the anterior cranial fossa, dural AVMs of the caverous sinus and middle cranial fossa and dural AVMS of the tentorium and posterior cranial fossa. Two of these dural AVMs were unusual in that actual vascular nidus was located in the bone though the venous drainage was via intracranial venous sinuses. Such dural AVMs with intraosseous vascular nidus have not been reported elsewhere.

We shall discuss skull base dural AVMs concentrating on their presentation, diagnosis, and management. They have been treated by a combination of endovascular and microsurgical treatment.

ENDOSCOPIC OPTIC NERVE DECOMPRESSION IN A PATIENT WITH FIBROUS DYSPLASIA

Alberto A.J. Maillard, MD (presenter), Richard G. Urso, MD, Stilianos E. Kountakis, MD, Sherif M. El-Harazi, MD (Houston, USA)

Purpose: To report recovering vision in a patient with fibrous dysplasia involving the sphenoid bone bilaterally after endoscopic optic nerve decompression. We will present our technique of endoscopic optic nerve decompression, together with visual fields, radiological, and histopathologic presentation of the case.

Method: Endoscopic optic nerve decompression was performed through a combined approach. A biopsy of the lesion was performed for histopathologic evaluation.

Results: Visual acuity improved from counting fingers to 20/20 with complete recovery of the visual field defect.

Conclusion: Non-traumatic blindness caused by fibroid dysplasia can be reversed by endoscopic optic nerve decompression.

PREAURICULAR INFRATEMPORAL FOSSA SURGICAL APPROACH: MODIFICATIONS IN THE TECHNIQUE AND SURGICAL INDICATIONS

Ossama I. Mansour, MD (presenter), Ricardo L. Carrau, MD, Carl H. Snyderman, MD, Amin Kassam, MD, Michael Horowitz, MD (Pittsburgh, USA)

Introduction: Neoplasms may arise from any of the structures contained within the infratemporal fossa (ITF) or from adjacent tissues. The preauricular infratemporal fossa approach is indicated for those neoplasms that are contained within the infratemporal fossa and for those who exhibit superior, cephalo-caudal, and/or anterior extension. Nonetheless, infratemporal fossa approach and dissection are modified according to the structures involved and to the need for the protection of neurovascular structures.

Description: We present our experience with over 40 tumors involving the ITF. Several modifications of the technique and their surgical indications will be presented. The morbidity as well as the surgical outcome will also be discussed.

Results: Our experience suggests that the surgical approach can be modified and guided according to established anatomical landmarks.

Conclusion: The selection of the surgical approach is influenced by many factors, such as nature, origin, extension, biologic behavior of the tumor, patient's demands and needs, and the training and experience of the surgeon. We have developed some surgical modifications that can be applied to the surgery of the ITF in spite of these influences.

INTRADURAL CHORDOMAS: CASE REPORT

Jorge Alvaro-Gonzalez Martinez, MD (presenter), Murali Guthikonda, MD, Eduardo Vellutini, MD, Felix H. Pahl, MD, Marcos Telles, MD, W. Kupisky, MD, Lucia Zamorano, MD, Fernando G. Diaz, MD, PhD (Detroit, USA)

Chordomas are rare tumors of the Central Nervous System which mainly are located in the extradural space. We report two cases of intradural chordomas located in the pre-pontine cisterns. The patients, with fifty-five and sixty-two years old, had histories of cranial neuropathies and headache respectively. A pre-sigmoid and transpetrosal approaches were performed with complete resection of the tumors. The anatomo-pathology studies confirmed the diagnosis of chordoma. The follow up was uneventful, with complete recovery of the symptoms in both patients.

Intradural chordomas are difficult to differentiate from Ecchordoses Physaliphorae, a non-neoplastic entity which has similar radiological features than chordomas. Concerning this issue, MBI-1 studies were performed, confirming the diagnosis of chordoma.

A review of the literature and a discussion about the differential diagnosis between these two entities and the different surgical approaches for chordomas will be presented.

SPONTANEOUS HIGH VOLUME EPISTAXIS FROM ABERRANT PETROUS CAROTID ARTERY

Sam J. Marzo, MD (presenter) (Maywood, USA)

Epistaxis is usually results from trauma to intranasal vessels, and in most cases can be managed by nasal packing and/or cautery. We recently managed a patient who presented with spontaneous high volume epistaxis which arose from an aberrant petrous carotid artery. He failed packing and nasal cautery and ultimately required a transtemporal approach for management with preservation of his petrous carotid artery. We review the differential diagnosis of epistaxis, related skull base anatomy and vascular territories, and discuss an algorithm for management.

COMBINED TRANSCRANIAL/TRANSORAL APPROACH TO MIDLINE SKULL BASE TERATOMA IN INFANTS

McKay McKinnon, MD (presenter), David M. Frim, MD, PhD (Chicago, USA)

Introduction: Midline skull base teratomas in infants may be viewed as congenital malformations that threaten to become deformational lesions to orbital and skull base growth. The primary treatment for this lesion is surgical extirpation; however, approaches solely through the mouth or solely by craniotomy often prove inadequate to achieve total resection. We report our experience with a combined transcranial/transoral approach that can reliably provide adequate exposure to achieve total surgical extirpation.

Procedures Employed: Two children were born with obvious oral lesions that

protruded from the mouth. Biopsy revealed the pathological diagnosis of mature teratoma. In one case two failed transoral procedures brought him to our attention; in the second, an initial first stage transoral procedure was performed to provide airway decompression before a second procedure. Extirpative surgery was performed when the children neared one year of age. Both tumors were approached by bifrontal craniotomy with extradural dissection into the nasal sinuses through the anterior skull base combined with a transoral approach through the tumor bed in the palate. Total tumor removal was achieved in both cases and reconstruction of the skull base and palate was begun in anticipation of further planned reconstruction.

Summary and Conclusions: Midline skull base teratoma in infants is a lesion that can be extirpated reliably with a combined transcranial/transoral approach. Such an approach allows orbital and facial anatomy to be prepared for further reconstruction as needed.

FACIAL-CRANIAL FLAPS (FCF) TO APPROACH EXTENSIVE EXTRA/INTRACRANIAL NASOANGIOFIBROMA (NAF)

Pedro Luiz Medeiros, MD (presenter), Denise Durão, MD (Rio de Janeiro, BRAZIL)

Patients presenting extensively endocranial invading NAF have been often considered unsuitable to surgical treatment due to the possibility of life threatening complications occur.

The objective of this paper is to demonstrate that such big lesions can be safely resected through an adequated FCF as approach. The flaps have a full skin mucosa thickness. The flap extension depends on the volume and areas involved by the tumor. Thus, they can be tailored as one formed by the " maxillary and nasal part" until a very extended version formed by the "whole nasal pyramid, maxillary, zygomatic and sphenoidal part" . The last approach can be prepared as one or two complementary flaps.

Nine patients were operated on by FCF approaches. The extra and endocranial tumor were completely resected in all the cases. There were neither transoperative accidents nor postoperative flap related complications. There were only a subcutaneous abscess and a light downfall of the inferior eyelid as complications.

In conclusion, the work field provided by the FCF has been adequated to a safe and complete extra/intracranial resections of giants NAF, in only one time. Despite the facial incisions, for the clear majority of patients the cosmetic results have been excellent.

SURGICAL TREATMENT OF CRANIOCERVICAL JUNCTION TUMORS

Tatsuya Nagashima, MD (presenter), Norihiko Tamaki, MD, Kazumasa Ehara,MD, Mitugu Nakamura,MD, Masashi Morikawa, MD (Kobe, JAPAN)

Treatment for tumors locating at the craniocervical junction is challenging because of their variety and difficulty in selecting the optimal surgical approach. We studied long-term follow-up results of surgical treatment.

Materials and methods: We treated 20 tumors locating at the craniocervical junction; 7 meningiomas, 5 neurinomas, 3 chordomas, 2 neurofibromas, and 3 others. Surgical approaches were transcondylar in 6, transoral in 4, transcervical in 1, transbasal in 1 and posterior approach in 8. Cranio-cervical fixation was done in 4 cases.

Results: All meningiomas and neurinomas were totally remove. There was no recurrence after 7.3 years follow-up. While, we experienced postoperative cranio-cervical instability and recurrence after removal of 1 neurofibroma and 2 chordomas. Cranio-cervical fixation was successful in all cases. Simultaneous cranio-cervical fixation after transcondylar approach were successfully done in 2 cases.

Conclusion: Total removal of meningiomas and neurinomas at the cranio-cervical junction should be attempted. Postoperative craniocervical stability is an important factor to treat metastatic tumors, chordomas and neurofibromas invading bony structures.

THE EFFECTS OF INTERNAL AUDITORY CANAL PRESSURE ON AUDITORY EVOKED POTENTIALS IN VESTIBULAR SCHWANNOMA PATIENTS

Sarvi Nalwa, MD (presenter), G. Mark Pyle, MD, Behnam Badie, MD (Madison, USA)

Hearing loss is the most common presenting symptom in patients with vestibular schwannomas. Proposed mechanisms include mechanical injury to the cochlear nerve and vascular compromise of the auditory apparatus; however, the exact mechanism of tumor-induced hearing loss has not been identified. In this study, we examined the role of pressure within the internal auditory canal as a determinant of auditory function in vestibular schwannoma patients. We measured the internal auditory canal pressure (ICaP) after a standard retrosigmoid approach. This measurement was then correlated with auditory evoked potentials in 23 patients. A significant correlation was found between ICaP and baseline ABR I-V interval. This finding suggests that internal auditory canal pressure may be a determinant of auditory function in patients with vestibular schwannomas.

CLIVUS CHORDOMA SHOWING SARCOMATOUS TRANSFORMATION

Emilio M. Nardone, MD (presenter), Aisha Al-Hajjaj, MD, Coleslaw Lach, MD (Bloomington, USA)

A rare variant of malignant chordoma of the clivus showing a very aggressive clinical behavior is presented. Radiographic appearance, pathological features, clinical evolution will be commented along with review of the literature.

A 60 year-old lady presented with headache, painful left ophthalmoparesis and hypoesthesia of the face with left side predominance. CT/MRI of the head showed a lesion involving the sphenoid sinus, the clivus, and the left cavernous sinus. In surgery a large, highly vascular tumor was resected via a sublabial transphenoidal approach sparing the component in left cavernous sinus. The tumor progressed through radiation therapy to involve the left orbit requiring exenteration. Subsequently metastases in the brain, brachial plexus and lungs were discovered. Patient expired 7 months after initial diagnosis.

Histological evaluation showed a sarcomatoid variant of chordoma. To our best knowledge this is only the third case reported of sarcomatous transformation of chordoma in the clivus. Our case is unusual in demonstrating mostly epithelioid pleomorphic pattern without loss of antigenicity for epithelial tumor markers. Like in other electron microscopic studies this case showed accumulation of intermediate filaments and poorly developed intercellular junctions. In addition, this case shows exceptionally high proportion of cells displaying P53 over expression and exceptionally high number of dividing cells. These two parameters are often associated with very malignant tumors and to a large extent also reflected in the aggressive clinical course seen in our patient.

RECOVERY OF VISUAL LOSS FROM RESECTION OF PLANUM SPHENOIDALE MENINGIOMA IN PREGNANCY

Emilio M. Nardone, MD (presenter) (Bloomington, USA)

A case of a pregnant woman with placenta previa and planum sphenoidale meningioma causing blindness is presented with support of intra-operative video. Particular emphasis is placed on recovery of vision after resection of the lesion, on the pathophysiology of meningiomas during pregnancy and on the relationship between intra-operative findings and post-operative neurological recovery.

A 39 year-old woman from Saudi Arabia was admitted with vaginal bleeding from placenta previa and a 3-month-history of worsening vision. Her visual acuity was 20/200 on OD and no light perception was present on OS. According to patient's report she had been blind on OS for at least 3 weeks. She had an emergency cesarian section and delivered a healthy boy. A MRI of brain showed a large planum sphenoidale lesion compatible with a meningioma compressing both optic nerves and the chiasm. A craniotomy was performed 3 days after delivery with complete removal of the lesion and decompression of the optic apparatus. Patient's vision started to improve on both eyes immediately post-op. At the 3-month follow-up vision was 20/20 on OD with full perimetry and 20/400 on OS with inferior suppression. The meningioma tissue was found to be positive for progesterone receptors but not for estrogen receptors.

To the best of my knowledge, this is the first case report of visual recovery from no light perception after resection of intracranial meningioma in a complicated pregnancy.

MAILING LISTS AND SKULL BASE SURGERY

Ganesalingam Narenthiran, MB, ChB (presenter) (Mitcham, UNITED KINGDOM)

Introduction: Skull Base Surgery involves high degree of contact and dissemination of information among professionals often from different specialties. Internet mailing lists could facilitate communication among medical professionals. In this study we surveyed the leading English-medium neurosurgery mailing lists to ascertain the amount of discussion on topics related to Skull Base Surgery.

Method: The study was based on the three leading international English medium neurosurgery mailing lists: 'Neurosurgery mailing list', 'Neurosurgery Research Mailing List (NSR-ML)' and 'PEDS (pediatric neurosurgery) mailing list'. The mails posted on these mailing lists for July 2000 were allocated to sections of neurosurgery.

Results: For the month of July 2000 the combined total postings on all three mailing lists was 34: Neurosurgery mailing list (10); NSR-ML (16); PEDS (8). The postings were related to the following sub-specialties: Spine(18), Head injury (4), functional (2), Hydrocephalus (2), vascular (1) and announcements (5).

Conclusion: For the month of July 2000 there was no mail related to Skull Base Surgery posted on any of the leading Neurosurgery mailing lists. Following this small study we have started a mailing list specifically for those in neurosurgery, ENT Surgery, Head and neck Surgery, Cranio-facial Surgery, Neuro-oncology, Neuropathology and Neuroradiology with interest in Skull Base Surgery. It is hoped that a specific Skull Base Surgery Mailing List would provide an electronic avenue and facilitate and encourage discussion and exchange of information among specialists in Skull Base Surgery.

FACIAL RE-ANIMATION AFTER ACOUSTIC NEUROMA SURGERY: RESULTS AND IMPLICATIONS

Glenn Neil-Dwyer, MD (presenter), Lorraine Clapham, Dorothy A. Lang, Anne Davis (Southhampton, UNITED KINGDOM)

Objective: To assess outcome after facial re-animation using two techniques.

Design & Subjects: Retrospective review of case records of consecutive patients having acoustic neuroma surgery (using a number of standard approaches) from 1988 to 2000.

Outcome Measures: House-Brackmann (HB) Grade at 6 months (minimum) and video analysis (selected cases).

Results: Of 387 patients 40 had facial re-animation. Contemporaneous sural nerve graft was done in 6 patients (age 44-52, all female, all translabyrinthine, tumour size 2.5-3.5cms, median 3cms). At follow-up 4 were HB 2 and 2 were HB 3. 34 patients (age 23-68, 21 females) had a facio-hypoglossal anastomosis (F-H) 12 days - 17 months after tumour removal, (mean 3.5 months). In this group 5 had tumours <1.5cms, 6 were 1.6-2.5cms, 18 were 2.6cms-4cms, 5 were >4cms. One patient was HB 2, 24 were HB 3/4, 4 were HB 4 and 5 were HB 5/6.

Conclusions: Sural nerve reconstruction provides superior results. F-H anastomosis produces symmetry at rest but animation relies on mass movement. Patients report problems with facial movements during eating and a number have fine involuntary movements.