Iakovos Arapakis

Navigation as a quality management tool in cochlear implant surgery.

This cadaver study assessed the value of navigation in cochlear implant surgery. Cochlear implantation was simulated on a cadaver using a Stryker-Leibinger navigation system and a Nucleus 24 Contour implant. A conventional surgical strategy consisting of mastoidectomy, posterior tympanotomy, and cochleostomy was performed. The navigated surgical procedure was evaluated for accuracy, reliability, reproducibility, and practicability. The technology of computer-assisted surgery is applicable in cochlear implantation and beneficial in as much as the navigation-controlled implantation constitutes a non-invasive instrument of quality management. Nevertheless, in order to keep the point accuracy below one millimeter, a referencing method using concealed bordering anatomical structures may be further needed to perform the cochleostomy reliably under the guidance of a navigation system. More reproducible reference systems are needed if navigated lateral skull base surgery is to be fully relied upon.

Neuromonitoring—Funktionssicherung und -erhalt bei schädelbasischirurgischen Eingriffen?

ZusammenfassungHintergrundDurch die Einführung der Computerchiptechnologie hat das intraoperative Neuromonitoring eine Renaissance erfahren. Heute lassen sich mit relativ kleinen, mobilen Geräten motorische und sensorische Hirnnervenfunktionen einschließlich des II. und VIII. Hirnnerven intraoperativ sicher kontrollieren.Patienten und MethodeZur Beurteilung des Stellenwerts des intraoperativen Neuromonitoring mit dieser neuen Gerätegeneration haben wir 379 Patientenakten ausgewertet, bei denen in der Zeit von 1996 an schädelbasischirurgische Eingriffe unter einem intraoperativen Neuromonitoring erfolgten. Kontrolliert wurden insbesondere die Hirnnerven II, VII und VIII, seltener die Hirnnerven IX, X, XI und XII.ErgebnisseBei 72% der Patienten war im Verlauf der Operation ein verändertes Neuromonitoring dokumentiert. Nach Abschluss der postoperativen Wundheilungsphase war nur noch bei 29% aller Patienten ein klinisch oder elektroneuronographisch veränderte Nervenfunktion nachweisbar.SchlussfolgerungDas intraoperative Neuromonitoring stellt für den Operateur die einzige Gelegenheit dar, sich während des Eingriffs über den Funktionszustand des betreffenden Hirnnervens zu orientieren.AbstractBackgroundNeurophysiologic intraoperative monitoring (NIM) has gone through a renaissance since the advent of computer technology. Currently, both motor and sensory cranial nerves, including the IInd and VIIIth cranial nerves, can be intraoperatively controlled by means of small and mobile systems.Patients and methodsIn order to estimate the value of NIM using the new generation of computer systems, we analyzed the records of 379 patients who underwent skull base surgery since 1996. These comprised NIM of the IInd, VIIth, VIIIth cranial nerves in most cases and of the IXth, Xth, XIth, and XIIth cranial nerves in selected cases.ResultsWhereas 72% of these cases demonstrated changes in the recorded intraoperative NIM signals, only 29% of them gave evidence of either clinical or electrophysiological neural function alterations during the postoperative follow-up.ConclusionsNIM is the only available system capable of providing the surgeon with instant intraoperative neural status-related feedback.

Malignant peripheral nerve sheath tumour of the paranasal sinuses and the anterior skull base

BACKGROUND Malignant peripheral nerve sheath tumours (MPNSTs) are highly aggressive neoplasms with a marked propensity for local recurrence and metastatic spread. The management of MPNSTs continues to challenge pathologists and surgeons. As MPNSTs of the paranasal sinuses and the skull base are rare, prognostic factors and treatment modalities have not been consistently identified. PATIENTS AND METHODS We present a case of MPNST of the anterior skull base and provide an overview of all MPNSTs reported since 1970, in which the tumour location was the anterior skull base or the paranasal sinuses. RESULTS Literature review revealed 33 well-documented cases of MPNSTs in this anatomic location. These cases were analysed with emphasis on age, gender, affected site, therapy, outcome, presence of neurofibromatosis, local recurrence and metastases. CONCLUSIONS Despite multimodal therapy and advances in surgical techniques, the prognosis of MPNST located in the paranasal sinuses and the anterior skull base remains dismal. Outcome is mainly a function of local control by surgical resection. Adjuvant radiochemotherapy has shown no benefit. It may therefore be advisable to abstain from radiochemotherapy in order to improve chances for surgical intervention in case of recurrent disease. Close follow-up investigations are indispensable.

Eccrine porocarcinoma of the ear mimicking basaloid squamous cell carcinoma.

Abstract Objectives: Eccrine porocarcinoma (EP) is a rare malignant tumor arising from the eccrine sweat gland. EP of the ear is exceedingly rare; to our knowledge, only 5 cases have been reported in the American and European literature. We describe the unusual case of an EP arising in the left ear mimicking basaloid squamous cell carcinoma (SCC). Methods: A 60-year-old female patient presented with a verrucous, cauliflower-like tumor of her left ear. The patient claimed that the lesion had been present for almost 40 years. Computed tomography did not reveal any sign of bony destruction of the mastoid. Magnetic resonance imaging showed enlarged lymph nodes in the left parotid gland and the left neck. A biopsy was performed and a basaloid squamous cell carcinoma was diagnosed. Results: The patient underwent an ablation of the left ear, a subtotal left parotidectomy and a selective, ipsilateral neck dissection (levels II-IV). The final histology revealed an EP. The margins of resection were free of tumor and there were no signs of parotideal tumor infiltration or lymph node metastases. Conclusion: Extensive surgical resection represents the therapy of choice for patients with eccrine porocarcinomas. Regional lymph node metastases are found in about 20% and distant metastases in about 10% of patients. On a small biopsy the accurate distinction between EP, SCC, and basal cell carcinoma may be impossible. The case presented highlights this diagnostic histopathologic challenge. Although extremely rare, EP should be included in the differential diagnosis of skin tumors in the head and neck.

Recurrent Syncope as Presenting Symptom of Burkitt's Lymphoma at the Carotid Bifurcation

Burkitts lymphoma is rare outside of Africa, and head and neck manifestations of this disease are even more uncommon. We report a case of Burkitts lymphoma localized at the bifurcation of the right common carotid artery in a 64-year-old man. The presenting symptoms were recurrent syncopes that necessitated a pacemaker, followed by a rapid onset of cranial nerve palsies. The tumor had infiltrated cranial nerves IX, X, XI, and XII and was resected by selective neck dissection. The patient was subsequently treated with a chemotherapeutic regimen consisting of a combination of cytosine arabinoside, vincristine, ifosfamide, prednisone, and an intrathecal application of methotrexate. He also underwent external-beam irradiation of the neck. The patient has been followed up for a period of 42 months and has no evidence of recurrent disease. Repeated diagnostic testing and a coordination of multiple disciplines can speed diagnosis and therapeutic management. The current literature is reviewed and discussed.

Indikation zur navigierten endonasalen Chirurgie der Frontobasis

Eingriffe an den Nasennebenhohlen wurden bis vor ca. 15 Jahren meist extranasal durchgefuhrt. Obwohl die endonasale Nebenhohlenchirurgie bereits entwickelt worden war, hatte man sie aufgrund von schwerwiegenden Komplikationen wieder verlassen. Erst nach Entwicklung moderner bildgebender Verfahren kam es zu einer Renaissance, wobei Draf [2] als Pionier bereits fruhzeitig fur eine sorgfaltige Operationsplanung ein praoperatives Nasennebenhohlen-CT forderte. Obwohl die Nebenhohlenchirurgie heute vermehrt funktionell, d.h. gezielt beschrankt auf die tatsachlich nachweisbare Pathophysiologie, durchgefuhrt wird [8, 10], haben anatomische Varianten wie ein „gefahrliches Siebbein“ oder ein frei durch die Keilbeinhohle verlaufender Nervus opticus [7] nichts von ihrer Brisanz verloren, so dass kritische Stimmen hinsichtlich einer stetigen Erweiterung der Grenzen der endonasalen Rhino- und Schadelbasischirurgie mit Hinweis auf mogliche Komplikationen laut wurden [9].