Steurer M

Advantages of Recurrent Laryngeal Nerve Identification in Thyroidectomy and Parathyroidectomy and the Importance of Preoperative and Postoperative Laryngoscopic Examination in More Than 1000 Nerves at Risk

Objectives/Hypothesis Recurrent laryngeal nerve palsy (RLNP) is a major obstacle in thyroid and parathyroid surgery. Therefore, methods that reduce the number of temporary and, especially, permanent recurrent laryngeal nerve palsies are of great interest. One promising way to ensure the integrity of the recurrent laryngeal nerve (RLN) is to identify the nerve always. The first question raised in the present study was whether RLN preparation reduces the number of recurrent laryngeal nerve palsies or whether it introduces additional risks. Second, from former cases we know that the absence of postoperative hoarseness does not exclude RLNP, nor does postoperative hoarseness exclusively imply RLNP. Besides, misdiagnosis is not uncommon. Therefore, preoperative and postoperative laryngoscopic examination was given attention.

Does choir singing cause noise-induced hearing loss?

Although health problems in musicians have been previously reported; not much is known about noise-induced hearing loss due to choir singing. However, there are data to show that peak levels of more than 110 dB SPL are produced in choir singing, and major parts of sound energy can be found below 1 kHz and even 500 Hz but not below 100 Hz. To find out about possible hearing loss due to professional choir singing, we measured the hearing threshold level of 62 choir singers in a large opera choir. Most publications about noise-induced hearing loss report that the high-frequency region is impaired most. However, in our study the low frequency region was affected most, when compared with normative data (especially ISO 7029). Control groups of women and men with normal auditory function did not show pure-tone hearing thresholds different from ISO 7029. The permanent threshold shifts at 250 Hz and above are most likely noise induced with choir singing as noise source. However, hearing losses at 125 Hz and possibly partial at 250 Hz are caused by some other effect. An (unproven) hypothesis is that singing might lead to increased endolymph pressure, and thus might cause hearing loss especially in the low-frequency region. Whether more choirs show similar hearing impairment and whether singing raises cerebrospinal fluid pressure will be the subject of further investigations.

Ultrastructural Morphology of a Middle Ear Ceruminoma

The ultrastructural morphology of a ceruminous gland adenoma in the middle ear was examined electron microscopically. The epithelial tumor cells displayed apocrine caps, microvilli, cell junctions, secretory granules, vacuoles, lipid droplets and siderosomes, which are the characteristic ultrastructural features of apocrine glands. Concentric membranous bodies of the endoplasmic reticulum, phagocytic activity of the tumor cells, intracytoplasmic lumina, ciliated cells and also spiny collagen in the tumor stroma could be seen. The myoepithelial cells are an important tumor marker in the differential diagnosis between ceruminomas and adenomas of the middle ear. The ectopic origin in the modified apocrine ceruminous glands, the specific localization, the clinical features and the extremely rare occurrence of the ceruminoma makes this tumor a unique neoplastic entity.

Soft-tissue effects of the holmium:YAG laser: An ultrastructural study on oral mucosa

The specifics of the ablation mechanism of the holmium:YAG laser remain largely unexplored. Following laser exposure to the oral mucosa of rats, the ultrastructural damage profile obtaining to varying degrees in blood vessels, erythrocytes, nerves, and muscle cells was examined. An attempt was made to relate the cytoplasmatic alterations to the tissue ablation modes of midinfrared lasers described in the literature.

Holmium:YAG-Laserchirurgie eines Nasopharynxkarzinoms

Der Holmium:YAG-Infrarotlaser, ein neuartiger, gepulster Hochenergiefestkorperkristallaser mit einer Wellenlange von 2120 nm, kombiniert die Vorteile des CO2- und des Nd:YAG-Lasers. Bei dieser Wellenlange liegt ein im Vergleich zu herkommlichen endoskopisch anwendbaren Lasersystemen wie KTP, Nd:YAG oder Argon ein hoher Absorptionskoeffizient von 18 cm−1 in Wasser vor, der eine Eindringtiefe von 450 μm in das Gewebe impliziert. Diese geringe Eindringtiefe in Kombination mit Hochenergiepulsbetrieb erlaubt ein nahezu kaltes, photoablatives Abtragen von Hart- und Weichgeweben mit geringen Randbereichstraumen, wodurch ein gefahrloser Einsatz an der Schadelbasis und in Gefasnahe moglich wird.

Experimentelle Laserchirurgie bei ossifizierter Kochlea

Die Ergebnisse nach Versorgung tauber Patienten mit intracochlearen Implantaten sind denen nach extracochlearer Implantation uberlegen. Patienten mit ossifizierter Cochlea werden bislang extra-cochlear oder im Falle der Moglichkeit der Eroffnung der basalen Schneckenwindung mit konventionellem Instrumentarium partiell intracochlear plazierte Elektroden implantiert. Die Verwendung von Lasern mit Abtragen von Hartgewebsstrukturen im Mittel- und Innenohr ist bei Verwendung herkommlicher fasergangiger ARGON, KTP oder Nd-YAG-Laser-Systeme aufgrund ausgedehnter Schadigungszonen nicht moglich.

Experimental laser surgery of the ossified cochlea

A pulsed holmium: YAG-laser (lambda = 2120 nm) was used to reopen the basal turn of artificially obliterated human cochleas in freshly dissected cadavers for intracochlear insertion of the stimulation electrode of a cochlear implant under simulated surgical conditions. Laser energy was transmitted through a 400 microns nylon fibre via the opened facial recess directly to the round window niche. At an energy level of 500 mJ/2.5 microseconds pulse, a repetition rate of 2 Hz, and an exposure time of 20-30 s, the photo-ablative mechanism of laser-bone interaction, which has only a limited thermal component, led to recanalisation of the basal turn of the cochlea in a length of 8-10 mm without damaging the surrounding structures. Light microscopic changes in the cochlea were evaluated following laser recanalisation. The artificial bony occlusion and the recanalised basal turn of the cochlea were visualised by means of computed tomography and histological thin section technique.