Initial experience with intraoperative ultrasound in navigated soft tissue operations of the neck and below the base of the skull.

Aim: Ultrasound (US) is a cost effective and time saving examination method for diseases of the neck,and can be used without any known side effects or limitations. US tied into modern navigation devices may significantly improve intraoperative orientation in regions with soft tissue characteristics.

Methods: 22 patients with soft tissue tumours of the head and neck underwent surgical procedures assisted by CAS system LandmarX (Medtronic) in combination with the US system DynaVievP II (Aloka).

Comparison of Different Computer-Aided Surgery Systems in Skull Base Surgery.

Computer-aided surgery (CAS) based on high-resolution imaging techniques represents an important adjunct to precise intraoperative orientation when anatomical landmarks are distorted or missing. Several commercial systems, mostly based on optical or electromagnetic navigation principles, are on the market. This study investigated the application of EasyGuide(R), VectorVision(R), and InstaTrak(R) CAS systems in ENT surgery under practical and laboratory conditions.

[Common errors of intraoperative navigation in lateral skull base surgery].

Background And Objective: The knowledge of disturbing factors for navigated surgical procedures in lateral skull base surgery will help the user to identify, avoid, and correct these errors.

Patients/methods: Based on our experiences with 85 patients undergoing surgery of the lateral skull base, errors of hard- and software, of image acquisition and image transfer, of patient registration, user-related errors as well as strategic errors were analyzed.

Results: Any impairment of the camera field leads to functional limitation of optical systems to the same extent as electromagnetic systems can be affected by ferromagnetic materials.

[The effects of Streptolysin-O and sodium hyaluronate on the permeability of the round window membrane in guinea pigs--an electrophysiologic study].

Background: The round window membrane (RWM) acts like a barrier for topically applied substances into the middle ear preventing diffusion into the perilymphatic fluid compartment.

Material And Method: In an animal model, modulation of the permeability of the RWM was attempted using Streptolysin-O (SLO) in various concentrations and sodium hyaluronate. Thereafter, the effect of intratympanically applied Lidocain 2 % on hearing threshold measured by auditory brainstem response was tested for Lidocain 2 % and Lidocain 2 % in combination with SLO or sodium hyaluronate.

[The application of an optical navigation system in endonasal sinus surgery].

Background: 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.