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Biomedical subjects

D Beutner

Publications and source records attributed to D Beutner.

15 recordsLinked to original sources
PubMed2007

[Multiple primary pleomorphic adenomas of the unilateral parotid gland].

BACKGROUND: Classical lateral parotidectomy is the standard surgical procedure for the management of lateral lobe parotid pleomorphic adenomas in most clinical centres. Extracapsular dissection and subtotal lateral parotidectomy are alternatively discussed in current literature and preferred by many authors. CASE: We report on a 20-year-old patient with multiple primary pleomorphic adenomas in the unilateral parotid gland, which preoperatively presented as a solitary tumour node. CONCLUSION: Considering this case we focus on the distinctive surgical procedures for the management of parotid pleomorphic adenomas. We work out, why lateral or even total parotidectomy are justified in the treatment of solitary palpable tumours and why we account lateral parotidectomy as the standard surgical procedure for the management of lateral lobe parotid pleomorphic adenomas.

Adenoma, Pleomorphic↗
PubMed2006

[Impact of TORP diameter on fracture of the footplate].

BACKGROUND: A columella-prosthesis is the typical reconstruction procedure of the ossicular chain in cases with a destroyed stapedial arch. Lightweight titanium prostheses are commonly used for this type of surgery. The smaller the prosthesis foot the lower the risk of dislocation and friction of the prosthesis with the bony rim of the oval niche. However, using a smaller prosthesis foot, fracture of the footplate and penetration of the prosthesis into the inner ear are conceivable. METHODS: Using fresh temporal bone preparations, lacking the stapedial arch, in conjunction with a load cell, the force needed to fracture the footplate was measured. Different prostheses with different foot diameters (0.2 - 0.8 mm) were used in these experiments. Furthermore, a human stapes was evaluated morphologically by scanning electron microscopy. RESULTS: The forces leading to fracture of the footplate were measured to be between 250 mN and 980 mN. Statistical analysis showed no significant difference between 0.2 mm and 0.8 mm prosthesis foots. Moreover, different forces were attributed to varying thickness of the stapes footplate. In scanning electron microscopy the rough and uneven bony surface of the footplate could be demonstrated. CONCLUSION: Due to the uneven footplate, only punctual contact of the prosthesis foot can be achieved. Hence, the risk of footplate fracture is not considerably higher by using smaller diameters. However, the use of smaller feet in upcoming generations of TORPs seems to be appropriate.

Biomechanical Phenomena↗
PubMed2006

Structure and function of the hair cell ribbon synapse.

Faithful information transfer at the hair cell afferent synapse requires synaptic transmission to be both reliable and temporally precise. The release of neurotransmitter must exhibit both rapid on and off kinetics to accurately follow acoustic stimuli with a periodicity of 1 ms or less. To ensure such remarkable temporal fidelity, the cochlear hair cell afferent synapse undoubtedly relies on unique cellular and molecular specializations. While the electron microscopy hallmark of the hair cell afferent synapse--the electron-dense synaptic ribbon or synaptic body--has been recognized for decades, dissection of the synapse's molecular make-up has only just begun. Recent cell physiology studies have added important insights into the synaptic mechanisms underlying fidelity and reliability of sound coding. The presence of the synaptic ribbon links afferent synapses of cochlear and vestibular hair cells to photoreceptors and bipolar neurons of the retina. This review focuses on major advances in understanding the hair cell afferent synapse molecular anatomy and function that have been achieved during the past years.

Afferent Pathways↗
PubMed2006

[An accessory retropharyngeal bone as a rare cause of dysphagia].

A 77-year-old woman had a history of several-years of dysphagia. On presentation, a submucosal mass impinging on the left oropharynx was present. CT-scans showed a bony structure isolated from the cervical column. The patient underwent complete surgical resection using a transoral approach. Histological examination confirmed the radiological finding; a new formation of bone surrounded by cartilage with hematopoieses in the bone marrow. Recovery was complete within 2 weeks. Dysphagia due to cervical spine osteophytes, Forestier's disease or progressive ossifying fibrodysplasia is well known. This case adds an isolated retropharyngeal bone formation as a rare cause of dysphagia to the literature.

Aged↗
PubMed2006

[Diagnosis and therapy of auditory synaptopathy/neuropathy].

Pathological auditory brainstem responses (lack of responses, elevated thresholds and perturbed waveforms) in combination with present otoacoustic emissions are typical audiometric findings in patients with a hearing impairment that particularly affects speech comprehension or complete deafness. This heterogenous group of disorders first described as "auditory neuropathy" includes dysfunction of peripheral synaptic coding of sound by inner hair cells (synaptopathy) and/or of the generation and propagation of action potentials in the auditory nerve (neuropathy). This joint statement provides prevailing background information as well as recommendations on diagnosis and treatment. The statement focuses on the handling in the german language area but also refers to current international statements.

Brain Stem↗
PubMed2006

[Vallecular cyst as a rare cause of progressive inspiratory stridor].

BACKGROUND: Vallecular cysts are frequently observed, benign masses of the upper aerodigestiv tract. Usually they appear as harmless and asymptomatic and go unnoticed by the patient. In rare cases, obstructions of the upper airway due to monstrous vallecular cysts may become life threatening. CASE: We report on a 69-year-old otherwise healthy woman with a rapidly progressive history of dyspnea caused by a pedicled vallecular cyst. Increasing stridor prompted emergency surgical resection. CONCLUSION: Vallecular cysts that increase in size can cause dyspnea due to obstruction of the aditus of the larynx. This case demonstrates the need for surgical treatment at an early stage of pedicled vallecular cysts.

Aged↗
PubMed2005

Gustatory function in chronic inflammatory middle ear diseases.

HYPOTHESIS: Changes of gustatory function after ear surgery have been studied extensively. However, little is known on the influence of repeated/chronic inflammation within the middle ear on taste. STUDY DESIGN: Prospective study. MATERIALS AND METHODS: Forty-six patients suffering from either cholesteatoma (n = 25) or chronic otitis media mesotympanalis (n = 21) received quantitative gustatory tests. None of these patients had been operated on before these investigations. RESULTS: Side by side comparison showed a significantly lower taste function on the anterior two thirds of the tongue ipsilateral to the site of inflammation, regardless of the diagnosis. Further analyses exhibited a trend toward greater impairment in relation to the severity of the inflammatory process. CONCLUSION: These data are proof that taste function changes in relation to chronic middle ear diseases. It further shows that many of these alterations go unnoticed by the patients.

Cholesteatoma, Middle Ear↗
PubMed2004

[The cartilage guide: a solution for anchoring a columella-prosthesis on footplate].

BACKGROUND: A torp (columella-prosthesis) is the typical ossicular reconstruction in cases of a destroyed stapedial arch. Yet, many unsatisfactory hearing results are due to the lack of a stable, reliable anchoring of the base of the prosthesis on the footplate. Some solutions have been postulated, amongst them the perforation of the footplate with a tiny spike at the lower end of the prosthesis, which, however, many otosurgeons regard as too dangerous for the inner ear. Specially designed silicone sheets cannot guarantee a permanent guide of the columella. METHODS: From our good experience with cartilage in different reconstruction procedures, we therefore developed a cartilage guide for the oval window niche. An oval 2,5 x 3,5 mm cartilage with a central hole is cut out of a thin (0,2 - 0,3 mm) cartilage plate with a help of a cartilage punch, which we had designed in collaboration with Heinz Kurz manufacture. The cartilage is placed into the oval niche and its hole guides the prosthesis onto the centre of the footplate. RESULTS: Temporal bone experiments demonstrated a reliable sound transport through this guide. Revision surgery revealed a stable ingrowth of the cartilage plate into the oval niche, its perforation securely guiding the prosthesis similar to a piston on to the footplate. The first short time hearing results (max. 1 year) in 22 patients confirmed the acoustic quality of this stabilisation of a columella on the footplate as compared to a matched control group. CONCLUSIONS: The stabilization of the columella with a cartilage-guide might solve one of the many problems with unsatisfactory hearing results after the reconstruction of a completely destroyed ossicular chain.

Adolescent↗
PubMed2001

The presynaptic function of mouse cochlear inner hair cells during development of hearing.

Before mice start to hear at approximately postnatal day 10, their cochlear inner hair cells (IHCs) spontaneously generate Ca(2+) action potentials. Therefore, immature IHCs could stimulate the auditory pathway, provided that they were already competent for transmitter release. Here, we combined patch-clamp capacitance measurements and fluorimetric [Ca(2+)](i) recordings to study the presynaptic function of IHCs during cochlear maturation. Ca(2+)-dependent exocytosis and subsequent endocytic membrane retrieval were already observed near the date of birth. Ca(2+) action potentials triggered exocytosis in immature IHCs, which probably activates the auditory pathway before it becomes responsive to sound. IHCs underwent profound changes in Ca(2+)-channel expression and secretion during their postnatal development. Ca(2+)-channel expression increased toward the end of the first week, providing for large secretory responses during this period and thereafter declined to reach mature levels. The efficacy whereby Ca(2+) influx triggers exocytosis increased toward maturation, such that vesicle fusion caused by a given Ca(2+) current occurred faster in mature IHCs. The observed changes in Ca(2+)-channel expression and synaptic efficacy probably reflected the ongoing synaptogenesis in IHCs that had been described previously in morphological studies.

Action Potentials↗
PubMed2001

Calcium dependence of exocytosis and endocytosis at the cochlear inner hair cell afferent synapse.

Release of neurotransmitter at the inner hair cell (IHC) afferent synapse is a fundamental step in translating sound into auditory nerve excitation. To study the Ca2+ dependence of the underlying vesicle fusion and subsequent endocytosis, we combined Ca2+ uncaging with membrane capacitance measurements in mouse IHCs. Rapid elevations in [Ca2+]i above 8 microM caused a biphasic capacitance increase corresponding to the fusion of approximately 40,000 vesicles. The kinetics of exocytosis displayed a fifth-order Ca2+ dependence reaching maximal rates of >3 x 10(7) vesicle/s. Exocytosis was always followed by slow, compensatory endocytosis (tau congruent with 15 s). Higher [Ca2+]i increased the contribution of a faster mode of endocytosis with a Ca2+ independent time constant of approximately 300 ms. These properties provide for rapid and sustained transmitter release from this large presynaptic terminal.

Animals↗
PubMed2000

Kinetics of exocytosis and endocytosis at the cochlear inner hair cell afferent synapse of the mouse.

Hearing in mammals relies on the highly synchronous synaptic transfer between cochlear inner hair cells (IHCs) and the auditory nerve. We studied the presynaptic function of single mouse IHCs by monitoring membrane capacitance changes and voltage-gated Ca(2+) currents. Exocytosis initially occurred at a high rate but then slowed down within a few milliseconds, despite nearly constant Ca(2+) influx. We interpret the observed secretory depression as depletion of a readily releasable pool (RRP) of about 280 vesicles. These vesicles are probably docked close to Ca(2+) channels at the ribbon-type active zones of the IHCs. Continued depolarization evoked slower exocytosis occurring at a nearly constant rate for at least 1 s and depending on "long-distance" Ca(2+) signaling. Refilling of the RRP after depletion followed a biphasic time course and was faster than endocytosis. RRP depletion is discussed as a mechanism for fast auditory adaptation.

Animals↗