Sergije Jovanovic

Ventilation time of the middle ear in otitis media with effusion (OME) after CO2 laser myringotomy

Objective The aim of this study was to investigate the transtympanic ventilation time, the healing course of the tympanic membrane, the early and late complications, and the recurrence rate of otitis media with effusion (OME) within 6 months after CO2 laser myringotomy with the CO2 laser otoscope Otoscan.

Experimental studies on the suitability of the erbium laser for stapedotomy in an animal model

Animal experiments in mature guinea pigs were devised to determine whether and to what extent inner ear damage can be caused by in vivo use of the erbium laser for stapedotomy. The present study examined the laser effect in connection with perforation of the basal convolution of the cochlea and subsequent application in the opened cochlea. Acoustic evoked potentials as compound action potentials (CAP) were recorded for changes in inner ear function. Findings demonstrated that five applications of the erbium:YSGG (yttrium-scandium-gallium-garnet) laser (energy, 85 mJ/pulse; energy density, 36 J/cm2) were needed to create a footplate perforation of 500–600 μm and did not lead to CAP alteration in any animal (n = 20). An increase of the repetition rate from 1 to 5 Hz likewise caused no CAP alteration (n = 17). Application of high total energies in the open cochlea (n = 5) to determine the safety of the laser system for stapedotomy revealed that a 10-fold increase in the total energy required for adequate perforation led to irreversible CAP alterations and no CAP could be recorded at a 15-fold increase in total energy. In contrast, a 5-fold maximum increase in total energy caused no CAP alterations. These results demonstrate the safety of the Er:YSGG laser comparable to that of the CO2 laser for stapedotomy, supporting its utility as an alternative method for surgery.

Bilateral synchronous tonsillar carcinoma in cervical cancer of unknown primary site (CUPS)

In addition to panendoscopy and imaging for staging, ipsilateral tonsillectomy is a standard procedure in the search for the primary tumor in cervical cancer of unknown primary site (CUPS). It is not clear from the literature, whether bilateral tonsillectomy has been established as the standard procedure in cancer of unknown primary origin. A bilateral synchronous tonsillar carcinoma has thus far only been described three times in the literature. We report on a case of CUPS in which a bilateral tonsillar carcinoma was detected after bilateral tonsillectomy. We also discuss the inclusion of bilateral tonsillectomy as a standard procedure in the search for primary malignancies. To diagnose and adequately treat a bilateral synchronous tonsillar carcinoma without losing time, we recommend bilateral tonsillectomy as a standard procedure in cervical CUPS.

Das NEN®-HNO-Navigationssystem Erste klinische Anwendung

ZusammenfassungHintergrund. Die intraoperative Navigation wird in naher Zukunft eine wichtige Rolle in der Chirurgie der vorderen und seitlichen Schädelbasis spielen. Elektromagnetische Navigationssysteme bieten gegenüber den optischen Systemen Vorteile, wie z. B. eine bedienungsfreundliche Größe der Hardware oder die uneingeschränkte Bewegungsfreiheit des Chirurgen. Patienten und Methode. Das NEN-Navigationssystem (Nicolet Electromagnetic Navigation System) wurde bei 22 Patienten mit einer polypösen Pansinusitis während der mikroskopisch/endoskopischen Nasennebenöhlenoperation eingesetzt. Es handelt sich um den Prototypen eines neuen Systems, bei dem die Positionsbestimmung über die Messung gepulster elektromagnetischer Gleichfelder realisiert wird. Dieses System wurde für die spezielle Anforderung der HNO-Heilkunde/Kopf-Halschirurgie modifiziert. Die präoperative Bildgebung bestand aus einer axialen Computertomographie (CT) mit einer Schichtdicke von 1 mm bei unwesentlich höherer Strahlenbelastung wie bei einem konventionellen koronaren CT der Nasennebenhöhlen. Die Erfahrungen, die während der klinischen Anwendung gesammelt wurden, wurden genutzt, um die Navigationsgenauigkeit zu optimieren. Ergebnisse. Die Anzahl und die Positionen der Marker wurden schrittweise modifiziert und verbessert. Sechs Marker, die das Volumen der Nasennebenhöhlen umschließen (drei frontal, zwei mastoidal und ein medianer Marker im Bereich der Sutura parietooccipitalis), ergaben die höchste Genauigkeit. Der Einfluss ferromagnetischer Instrumente wie v. a. Nasenspekula, die die Navigationsgenauigkeit beeinflussen, wurden durch Titaninstrumente ersetzt. Des Weiteren wurde eine Registrierungsmöglichkeit der intraoperativen Kopfbewegung mit Hilfe einer sensortragenden Zahnschiene entwickelt, die am Oberkiefer fixiert werden kann. Mit diesen Modifikationen war es möglich eine Navigationsgenauigkeit von 1,5 mm im Bereich des Keilbeins bei freier Kopfbewegung des Patienten zu erreichen. Schlussfolgerung. Die präzise computergestützte Navigation wird mittelfristig ein unverzichtbares Hilfsmittel in der Schädelbasischirurgie werden. Das beschriebene elektromagnetische System bietet eine akzeptable Genauigkeit im Bereich der vorderen Schädelbasis. Für den Routineeinsatz wie z.B. in der endonasalen Nasennebenhöhlenchirurgie müssen die Navigationssysteme preisgünstiger werden und einfach zu bedienen sein.AbstractBackground. Intraoperative computer navigation will soon play an important role in procedures performed on the anterior and lateral skull base. Electromagnetic systems compared to optical systems offer some advantages such as small hardware dimension and free unimpaired mobility of the surgeon. Patients and methods. The NEN navigational system (Nicolet Electromagnetic Navigation System) was used in 22 patients who underwent microscopic/endoscopic surgery for polypoid rhinosinusitis. It is the prototype of a new system, which localizes the surgical probe via the measurement of pulsed electromagnetic DC fields. This system was modified for the needs of head and neck surgery. Preoperative imaging data consisted of an axially oriented spiral computed tomography (CT) resulting in a slice thickness of 1 mm with a radiation dose slightly higher than a routine coronary CT scan of the paranasal sinuses. Results. The data acquired during clinical application was used to optimize navigation accuracy. The number and positions of the markers were gradually modified and improved. Six markers including the volume of the paranasal sinus system (three non-coplanar frontal markers, one on each of the mastoid processes and one median marker on parietooccipital junction) offered the best navigation precision. Additionally, all surgical instruments measured as ferromagnetic, i.e., nasal specula, were replaced by titanium instruments. An adapter affixed to the maxilla designed to hold a second sensor used to track the patients head was developed. With these modifications, it was possible to improve navigation accuracy to 1.5 mm in the plane of the sphenoid bone while retaining free head movement of the patient. Conclusion. For routine procedures such as microscopic/endoscopic endonasal sinus surgery, the systems have to be cost effective and easy to operate.

CO2 laser in stapes surgery

Stapedotomy is not only one of the most successful interventions in otology but also one of the most dangerous for the inner ear. To reduce the risk of damaging middle and inner ear structures through manipulations with conventional instruments, the CO2 laser beam is used for perforating the footplate and removing the suprastructures. This non-contact technique aims at precise and controlled management of middle ear structures. Consideration is given to the impact of experimental data on the clinical application of the CO2 laser in stapes surgery. The discussion covers the advantages and disadvantages with regard to optical and tissue-related properties and points out possible dangers to the inner ear. Our experimental and clinical experience is taken as a basis for examining the surgical technique and the varying demands made on the laser beam in treating the stapedial tendon, crura and footplate. Attention is called to the need for additional instruments. Effective energy parameters for CO2 laser stapedeotomy are evaluated for different lasers. Application of the CO2 laser contributes towards optimization of this high-precision intervention and promises to reduce the incidence of inner ear damages in large numbers of cases. This technique appears useful particularly in difficult anatomic situations and, above all, for revisional operations.

Thermic effects in the "vestibule" during laser stapedotomy with pulsed laser systems.

Apart from the ablation properties at the stapes footplate, the degree of thermic loading in the inner ear is important in determining the suitability of pulsed lasers for stapedotomy. The aim of the study is to compare the thermic effects in the vestibule with different pulsed laser systems.

Influence of pulsed laser irradiation on the morphology and function of the guinea pig cochlea

Recent experimental and clinical studies have demonstrated that several pulsed laser systems are also suitable for stapedotomy. The aim of the study was to investigate morphological and functional inner ear changes after irradiating the basal turn of the guinea pig cochlea with two pulsed laser systems of different wavelengths. The Er:YSGG (lambda=2.78 mcm) and Ho:YAG (lambda=2.1 mcm) lasers were used applying the laser energies necessary for perforating a human stapes footplate. The cochleas were removed 90 min, 1 day, 2 weeks, or 4 weeks after laser application. Acoustic evoked potentials (compound action potentials) were measured before and after laser application and at the above times immediately before removal of the cochleas. The organ of Corti was examined by scanning electron microscopy. Application of Er:YSGG laser parameters effective for stapedotomy had no adverse effects on Cortis organ in the guinea pig cochlea. On the other hand, effective Ho:YAG laser parameters cause damage to the outer hair cells with fusion of stereocilia and formation of giant cilia leading to partial or total cell loss. The inner hair cells and supporting cells were usually normal. These morphological data show a good correlation with the electrophysiological measurements. Our results clearly demonstrate that, besides achieving efficient bone management, the Er:YSGG laser has high application safety. On the other hand, the Ho:YAG laser is not well tolerated in our animal study. Its use in stapedotomy would be unreliable and dangerous for the inner ear.

Combined intratumor cisplatinum injection and Nd:YAG laser therapy

Objectives/Hypothesis: Interstitial laser therapy (ILT) has become useful for tumor palliation in patients with advanced head and neck cancer. Cisplatinum chemotherapy also is a frequent adjuvant treatment for recurrent tumors, but systemic toxicity limits application. Intratumor cisplatinum injection combined with ILT may improve therapy of these recurrent tumors with reduced toxicity. Study Design: Prospective. Tumor transplants were injected with cisplatinum in a gel implant before ILT to evaluate treatment response and toxicity in a preclinical study. Methods: UCLA‐P3 human squamous cell carcinoma tumors were grown as subcutaneous transplants in nude mice and treated by intratumor injection of 2 mg/mL cisplatinum in a slow‐release, collagen‐based gel carrier 4 hours before interstitial implantation of Nd:YAG laser fiberoptics to induce local tumor hyperthermia. Treatment efficacy and toxicity were followed for 12 weeks after combined drug and laser therapy compared with ILT alone. Results: Combined cisplatinum gel and ILT was a significant improvement (P < .01 by chi‐square test) and induced 57% complete responses without regrowth in 21 transplanted tumors compared with only 24% in 21 tumors after ILT alone during 12‐week follow‐up. Recurrences in both cases appeared to result from nonuniform laser energy delivery within tumors via the implanted fiberoptic tip. Conclusions: The results of this experimental combined cisplatinum and ILT study suggest it may be possible to improve treatment of advanced head and neck cancer by intratumor injection of gel implants containing the drug followed by interstitial Nd:YAG laser hyperthermia.

New Developments in CO2 Laser Stapedotomy

Summary The idea of applying the CO2 laser as a precise and contact-free instrument in middle-ear surgery and especially in stapes surgery is based on the desire to reduce the complication rate of these interventions by further optimizing the surgical techniques. Today, using high-precision micromanipulators, the laser beam can be focused to a spot diameter of 180 μm. New application modes combined with scanner systems enable an exact adjustment to the demands of stapes surgery, thus permitting the finest microsurgical work. “One shot” stapedotomy can be achieved by microprocessor-controlled movement of the focused laser beam over a defined area (diameter: 0.5 to 0.7 mm) by rotating mirrors. On the basis of experimental data, effective and safe parameters were determined with the CO2 laser and applied in the clinical routine. Compared to conventional techniques the CO2 laser irradiation enables precise and contact-free procedures on middle ear structures. The risk of chain luxation, particularly footplate mobilization (floating footplate) or damage to the adjacent middle and inner ear structures is practically impossible with the limitation of the energy parameters used here.

Development of a tympanic membrane model for laser myringotomy

This study investigates guinea-pig and horse tympanic membranes, sheep dura and chicken eggshell membranes in terms of thickness, histology and tissue interaction with the carbon-dioxide and the erbium:YAG laser. Comparison with formalin-fixed human tympanic membranes as reference structure has provided a suitable model for further research in laser myringotomy. The horse tympanic membrane seems to meet our demands regarding the three parameters mentioned above.