U. Ecke

A Passive-Marker-Based Optical System for Computer-Aided Surgery in Otorhinolaryngology: Development and First Clinical Experiences

Objectives: To develop a new type of optical computer‐aided surgery (CAS) device that overcomes some of the restrictions of common systems and to examine its accuracy and usability under laboratory and intraoperative conditions.

Der Einsatz eines optischen Navigationssystem in der Nasennebenhöhlenchirurgie

ZusammenfassungHintergrund. Für die moderne Nasennebenhöhlenchirurgie stehen heute verschiedene CAS-Systeme zur Verfügung.Das Vector-Vision-Compact®-System stellt erstmals ein speziell für Nasennebenhöhleneingriffe konzipiertes optisches Gerät dar.Seine Praktikabilität und Zuverlässigkeit wurde in der Nasennebenhöhlenchirurgie überprüft. Patienten und Methode. Das System wurde bei 60 Patienten mit polypöser Pansinusitis verwendet.Die Bestimmung der Systemgenauigkeit erfolgte visuell und wurde mit etablierten Systemen verglichen.Fehlerquellen sowie systembedingte Komplikationen wurden überprüft. Ergebnisse. Die Systemgenauigkeit betrug 1,9 mm und war anderen Navigationssystemen gleichwertig. In 83,3% aller Fälle konnte problemlos navigiert werden.Schwierigkeiten traten durch Sichtverlust der Referenzkugeln und bei Verwendung weiterer Operationsinstrumente auf. Schlussfolgerung. Das VectorVision Compact® erwies sich für die endonasale Nasennebenhöhlenchirurgie als geeignet. Künftige Verbesserungen der freien Instrumentenanbindung können die Applikation erweitern.AbstractBackground. There are several CAS-systems in use in modern endonasal sinus surgery. The VectorVision Compact is the first optoelectrical system especially designed for such surgery.This paper investigates its reliability and practicability. Patients and methods. The system was used for intraoperative navigation in 60 patients suffering from chronic rhinosinusitis.The accuracy was measured by visual estimation and compared with other navigated systems. Results. The accuracy was 1.9 mm which is comparable to other systems on the market. Navigation was successful and reliable in 83.3% of the patients.Problems occurred mainly due to loss of sight of the referencing balls and when using other surgical instruments. Conclusion. The VectorVision Compact was adequate for endonasal sinus surgery. Further improvements incorporating various surgical instruments should broaden its clinical usefulness.

Intraoperative Navigation in der Chirurgie der Nasennebenhöhlen und der vorderen Schädelbasis

ZusammenfassungHintergrund und Fragestellung. Beim Einsatz der computerassistierten Chirurgie im Bereich der Nasennebenhöhlen und vorderen Schädelbasis sind einige Fehlerquellen zu beachten, die durch physikalische Gesetze, den technischen Entwicklungs- und individuellen Kenntnisstand des Anwenders bedingt sind. Patienten/Methodik. Anhand unserer Erfahrungen von 436 navigationsunterstützten Eingriffen werden Hard- und Softwarefehler, Fehler der Bildgebung und des -transfers, Fehler der Patientenregistrierung, Anwenderfehler und strategische Fehler analysiert. Ergebnisse. Bei optischen CAS-Systemen führt die Blockade des Sichtfeldes der Kamera zu Funktionseinschränkungen, während elektromagnetische Systeme durch ferromagnetisch aktive Materialien beeinflusst werden. In Abhängigkeit vom verwendeten Navigationsgerät ist die Schichtbildgewinnung entsprechend zu gestalten. Besonderes Augenmerk ist dabei auf den Rekonstruktionsalgorithmus zu legen. Die kopfmaskenbasierte Patientenregistrierung hat sich für endonasale Eingriffe bewährt. Schlussfolgerungen. Ein kritischer Umgang mit Navigationssystemen bei Kenntnis der physikalischen Gesetzmäßigkeiten befähigt den Anwender, Anzeichen einer Fehlfunktion zu erkennen, richtig zu interpretieren und damit den Erfolg einer navigationsunterstützten Operation zu sichern.AbstractBackground and objective. Based on physical laws, stage of technical development and the users individual skills a number of possible errors have to be considered for the application of CAS in paranasal sinus and anterior skull base surgery. Patients/methods. Based on our experiences of 436 navigated cases hard- and software errors, errors of image acquisition and transfer, errors of patient registration, user related errors as well as strategic errors are analyzed. Results. Any hindrance of the camera field leads to a limitation of functionality of optical systems in the same extent as electromagnetic systems can be affected by ferromagnetic materials. The mode of image acquisition is dependent from the CAS-system involved. The reconstruction algorithm requires particular attention. The patient registration based on the headset proved to be reliable for endonasal sinus surgery. Conclusions. In dealing with navigation devices in paranasal and anterior skull base surgery the user must pay critical attention to possible malfunction in order to guarantee a successful image guided surgical procedure.

Possible roles of nitric oxide in the physiology and pathophysiology of the guinea pig cochlea.

Abstract Two nitric oxide synthase isoforms (NOS-I and NOS-III) are present in the mammalian cochlea, and many regulatory functions of the inner ear could be mediated by NO. In this study, cochlear potentials and immunohistochemical measures were analyzed by changing the concentration of NO in the guinea pig during intracochlear and intravenous application of an NOS inhibitor and an NO donor. In anesthetized guinea pigs the NOS inhibitor NG-nitro-L-arginine-methylester (L-NAME) was applied by intracochlear perfusion or intravenously. The cochlear potentials and blood pressure were measured during and after the application. Cochleae were removed and prepared for morphological and immunohistochemical examinations by light and electron microscopy. The same series of experiments was performed with the NO donor S-nitroso-N-acetyl-penicillamine (SNAP). Cochlear potentials were not altered during intracochlear perfusion or intravenous application of L-NAME or SNAP. With intravenous application of the substances, significant alterations in the systemic blood pressure were seen. No morphological alterations were noted but in the immunohistochemical investigations significant changes were detected by electron microscopy. Several possible functions of NO in the inner and outer hair cells, stria vascularis and ganglion cells are discussed. Our results suggest that NO has a major effect on the physiology of the inner and outer hair cells.

Vaskuläre Ursachen des „Kleinhirnbrückenwinkel-Syndroms”?

ZusammenfassungFragestellung: Im Kleinhirnbrückenwinkel (KHBW) vereinigen sich der N. vestibulocochlearis und facialis, bevor sie gemeinsam in den inneren Gehörgang eintreten. Pathologische Prozesse in dieser Region sind in der Regel mit Funktionseinbußen des VII. und/oder VIII. Hirnnerven verbunden. Das Akustikusneurinom gilt aus häufigste Ursache eines KHBW-Syndroms, das aber auch durch entzündliche oder vaskuläre Prozesse verursacht werden kann. Vaskuläre Malformationen stellen dabei eine Ausnahme dar. Patienten/Methoden: Es werden 5 klinische Fälle beschrieben, bei denen eine Schleifenbildung der A. basilaris, A. vertebralis oder A. cerebelli inferior anterior im KHBW-Bereich als Ursache von vestibulokochleären Störungen in Form von Drehschwindel, Hörminderung oder pulssynchronen Ohrgeräuschen in Frage kam. Bei 2 Patienten konnte diese Annahme durch eine operative Intervention bestätigt werden. Im Rahmen der Differentialdiagnostik wurden die Befunde der MRT des Cerebrums, der Angiographie, der BERA, der Tonaudiometrie und des ENG erhoben. Ergebnisse/Schlußfolgerungen: Trotz der häufigen tumorösen Ursachen können abnorme Gefäßschlingen kausal für ein KHBW-Syndrom sein und müssen differentialdiagnostisch in Erwägung gezogen werden.SummaryIntroduction: The seventh and eighth cranial nerves course toward the internal auditory canal within the cerebellopontine angle. Lesions in this region are usually related to malfunctions of these cranial nerves. Although an acoustic schwannoma is one of the main etiologies of cerebellopontine angle pathology, various inflammatory processes and vascular anomalies even though rare must be considered. Patients/Methods: We describe 5 cases with vascular loops of the basilar or vertebral arteries as a possible cause for hearing loss, vertigo and pulsatile tinnitus. In two cases the vascular lesion was confirmed at surgery, in which a decompression procedure was performed. The work-up for each patient included an auditory test battery and electronystagmography. Imaging studies included MRI and angiography in two cases. Results/Conclusions: Our experiences show that while the cerebellopontine angle syndrome is mostly caused by benign tumors an abnormal vascular loop has to be considered in any differential diagnosis.

Yamik sinus catheter in the topical treatment of patients with acute rhinosinusitis after previous sinus surgery.

Background The Yamik sinus catheter was designed as a new device for the topical treatment of rhinosinusitis. It creates intermittent positive and negative intranasal pressure after sealing the ipsilateral nostril and choana with two inflatable cuffs. Affecting the nasal cavity and all paranasal sinuses of one side at a time, it is used to evacuate mucous and secretions as well as and to introduce antiseptic, antibacterial, or antifungal solutions. Methods This study was designed to evaluate the effectiveness of the Yamik catheter in cases of acute purulent rhinosinusitis in patients who previously underwent endonasal sinus surgery for chronic rhinosinusitis. Twenty patients were treated at repeated visits to the outpatient clinic of our institution. At each visit, their clinical symptoms as well as findings on anterior rhinoscopy, nasal endoscopy, and A-mode ultrasound were evaluated. Results Acute disease resolved completely within 10 days of treatment in 17 of the 20 patients. Two patients discontinued treatment after repeated visits, showing only mild improvement. One patient felt uncomfortable during the application of the Yamik catheter and did not continue after the initial treatment. Conclusion Our results suggest that the Yamik catheter may be a helpful device in the topical treatment of acute rhinosinusitis and it appears possibly helpful in patients who suffer from episodes of acute purulent infection after previous sinus surgery.

Selective chemical vestibulectomy. Preliminary results.

In an attempt to destroy the peripheral vestibular labyrinth selectively in patients suffering from intractable vertigo as a result of end-stage Ménières disease, 25 patients underwent selective chemical vestibulectomy between 1989 and 1994. As part of the procedure a certain quantity of streptomycin was placed between the bony and the membranous part of the lateral semicircular canal. The dosage of streptomycin used for successful ablation of vertigo varied between 250 and 100 micrograms. Within 12 months following the procedure all patients experienced a tremendous improvement in their overall condition. In spite of the fact that some patients noted an overall hearing improvement, increased cochlear thresholds were observed in a number of patients, which could not be ignored. The aim of this report is to detail the reliability of control of vertigo, conservation of hearing, and change in disability 12 months after surgery in the 23 patients (of 25) available for follow-up.