Search PubMed⌕ Search

Biomedical subjects

K Schwager

Publications and source records attributed to K Schwager.

35 records · Page 2Linked to original sources
PubMed1998

[Epithelialization of titanium prostheses in the middle ear of the rabbit. Possible model of mucosa development].

BACKGROUND: The epithelialization of middle ear implants is regarded as a sign of biocompatibility of the implant material. METHODS: The mucosal coverage of titanium was studied in the middle ear of rabbits in light microscopy. Implants were used as middle ear prostheses or as a free implants. Studies were performed after 28, 84, 168, 336, and 504 days. RESULTS: The prostheses were seen to be covered by regular mucosa after 28 days. The free implants were not seen to be totally epithelialized even after 504 days. There were no inflammation cells on the surface of the material, nor were unusual amounts of fibrous tissue observed. The middle ear mucosa was initially thickened, but soon returned to normal values. CONCLUSIONS: The results of this animal experiment show that titanium is a suitable material for ossicular replacement.

Animals↗
PubMed1998

Lymphadenopathy: differentiation of benign from malignant disease--color Doppler US assessment of intranodal angioarchitecture.

PURPOSE: To differentiate reactive from malignant lymphadenopathy by using color Doppler ultrasonographic (US) findings of intranodal blood vessels. MATERIALS AND METHODS: Color Doppler US was performed in 117 lymph nodes in 100 consecutive patients before performance of surgical biopsy (47 nodes), neck dissection (62 nodes), or high-speed core biopsy (eight nodes). The presence of malignant changes in intranodal angioarchitecture (focal perfusion defects, aberrant course of central vessels, displacement of intranodal vessels, subcapsular vessels) was evaluated in each node. Inter- and intraobserver variability were evaluated. RESULTS: Histopathologic examination demonstrated 48 reactive lymph nodes (longest diameter +/- standard deviation, 13.5 mm +/- 6.0), 56 nodal metastases (longest diameter, 19.2 mm +/- 8.8), 12 malignant lymphomas (longest diameter, 23.2 mm +/- 10.5), and one node infiltrated by Langerhans cell histiocytosis. At color Doppler US, 103 (88%) nodes were classified correctly, with a specificity of 77% and a sensitivity of 96%. Reproducibility was 90%-96% (kappa = 0.79-0.91, P < .001). CONCLUSION: Color Doppler US is a reliable and reproducible method for help in the differentiation between reactive and malignant alterations of superficial lymph nodes by using findings of intranodal angioarchitecture.

Adolescent↗
PubMed1998

Titanium as an ossicular replacement material: results after 336 days of implantation in the rabbit.

OBJECTIVE: Titanium in other parts of the body, well known for its biocompatibility, was examined in an animal model for its use as an ossicular replacement material. STUDY DESIGN: The biocompatibility of titanium was studied in the middle ear of rabbits using light and scanning electron microscopy. Titanium pins were placed as middle ear prostheses or as free implants and were examined after 28, 84, 168, and 336 days. RESULTS: After 28 days, the prostheses were covered by regular mucosa. The free implants took up to 336 days to be totally epithelialized. There were no inflammatory cells observed on the surface of the material nor were unusual amounts of fibrous tissue seen. In addition, the titanium material exhibited an affinity toward bone. CONCLUSIONS: The results of this animal experiment indicate that titanium is a useful material for ossicular replacement prostheses.

Animals↗
PubMed1997

[Gunshot injuries of the ENT area caused by blank cartridge weapons].

Different types of gunshot injuries caused by warning weapons are demonstrated. Most important are contract shots, causing major tissue damage that can differ from that caused by classical projectiles. Possible consequences, besides direct trauma to the eye and ear, are airway distress because of extensive swelling and rupture of major neck vessels. The detailed examination includes endoscopy and radiologic imaging. Any major permanent cavity in the tissue bears a high risk of wound infection. For different reasons the fact of a gunshot wound may be kept secret by the victims.

Adolescent↗
PubMed1997

[Endocranial complications of acute and chronic otitis media in children and adolescents].

BACKGROUND: After introduction of antibiotics endocranial complications in otitis media are less common, but there are still diagnostic and therapeutic problems. PATIENTS: 124 patients (5 months-16 years) underwent mastoidectomy. The number, type and therapy of otitic complications is presented. RESULTS: Nine percent of the patients showed up with endocranial complications. Besides lateral sinus thrombosis (five patients), meningitis (five patients) and epidural abscess (five patients), one cerebral and one cerebellar abscess was found. Four patients developed more than one complication. THERAPY: A complete mastoidectomy was performed with exploration of the dura and punction of the lateral sinus. In several cases these procedures gave the first diagnostic hint for endocranial complications. CONCLUSION: The occurrence of endocranial complications in the era of antibiotics should not be underestimated. Cholesteatoma is still a main risk factor for severe complications. If there is any doubt, further imaging studies (CT, MRI) are necessary. Diagnosis and therapy makes a close cooperation between neurosurgeon and ear surgeon and other specialties mandatory.

Acute Disease↗
PubMed1995

Influence of myelography on the developmental curve of auditory brainstem responses and hearing loss.

Auditory threshold and auditory brainstem response studies were conducted in 50 patients before and after myelography. Analysis of amplitudes and latencies of auditory brainstem measurements demonstrated significant disorders of function of the cochlea and auditory pathway. The Jewett I wave showed a prolongation of latency from 1.92 to 1.98 ms using an average of all repetition rates. The Jewett III wave showed prolongation from 4.01 to 4.14 ms and the Jewett V wave prolongation from 6.01 to 6.16 ms. At the same time average amplitudes for Jewett III and V decreased. In most of the patients these disorders of function were found to be subclinical. However, 12 patients had changes ranging from a subjectively slight hearing loss to an audiometrically defined acute hearing loss. The reasons for these disorders could not be clarified. An open cochlear aqueduct through which perilymph can enter the subarachnoid space, leading to secondary endolymphatic hydrops, was suggested as the cause for the losses found. Changes in brainstem audiometry were also explained by changes in osmolality of inner ear fluids, leading to the development of an endolymphatic hydrops.

Adult↗
PubMed1995

[Therapeutic concept in hemangioma--photocoagulation with the copper vapor laser].

The copper vapor laser emits light with a wavelength of 578 nm and is well suited for photocoagulation of oxyhemoglobin and for selective destruction of vascular tissue. In 46 children hemangioma of different proliferation stages was treated by yellow laser photocoagulation. In 15 cases surgical treatment of the subcutaneous component of the hemangioma was necessary in addition to the laser photocoagulation. Most of the children in early proliferation stages could be treated with a single session of photocoagulation. The risk of hypotrophic oder hypertrophic scaring using the copper vapor laser is minimum (less than 1%) because the overlying dermis remains largely unaffected. In this article we present a therapy plan for conservative treatment and laser photocoagulation using the copper vapor laser.

Child, Preschool↗
PubMed1995

[Facial nerve abnormalities in malformed temporal bone].

Between 1987 and 1993, 4500 tympanoplasties and stapedectomies were performed at the ENT Department of the University of Würzburg. In 134 cases, surgery was performed for malformation of the middle ear. The surgery reports of these patients were analyzed for anomalies of the facial nerve. Forty cases (29.9%) showed an anomaly of the facial nerve, more often congenital aural atresia or major malformation (30.4%) than minor malformation (29.1%). The most frequent finding was a dislocation of the nerve over the oval niche and resulting narrowing of the oval window (22 cases). Eleven cases showed the facial nerve without bony covers, in two cases there was an exposed nerve over the oval niche. An acute-angled course between horizontal and vertical segment in the mastoid, doubling of the nerve, lateralization of the mastoidal segment, and anterior shift of the Fallopian canal in the mastoid were observed once. To reduce the risk of facial nerve injury, high resolution CT scan studies should be performed before surgery in the presence of congenital aural atresia.

Diagnosis, Differential↗
PubMed1995

[Microsurgery of large middle ear abnormalities. Technical surgical considerations].

From 1988 to 1994, 75 patients with congenital aural atresias were operated on at the University ENT Department, Würzburg. Sixty-two patients (70 ears) could be followed up in their postoperative outcomes. The surgical approach used in all patients was a direct one through the atresia plate. To avoid infection and stenosis of the new meatus, a neo-tympanic membrane was built up in a far lateral position. This was possible by using a long ossicular prosthesis. The mean postoperative gain was 17.8 dB and the mean postoperative airbone gap was 31.0 dB. Twenty-two percent of the ears had postoperative infections or stenosis of the ear canal. Thirty-four percent of the ears had to undergo revision surgery. Jahrsdoerfer's grading system for congenital aural atresia showed good correlation in 64% of the ears when comparing preoperative status and postoperative outcome.

Adolescent↗
PubMed1995

[Fibrous dysplasia and ossifying fibroma. 2 unusual fibro-osseous lesions of the paranasal sinuses].

Fibrous dysplasia and ossifying fibroma are locally destructive and deforming benign lesions that can occur anywhere in the craniofacial skeleton, including the paranasal sinuses. Differentiation between these two diseases is essential because of their differing natural histories, and distinctions must be made by correlating clinical information with radiological and histological findings. The cases of fibrous dysplasia and ossifying fibroma described in this report illustrate the subtle differences between these two fibroosseous lesions. Emphasis is placed on the differing natural history and management of these two unusual lesions in order to expedite aggressive treatment when required.

Bone Cysts, Aneurysmal↗
PubMed1994

[A laser therapy concept in telangiectasis and naevus flammeus].

The superficial lesions of the telangiectasia and the ectatic vessels in port-wine stains are a suitable aim for photocoagulation using yellow light lasers. Yellow light of the wavelength 575-585 nm provides good absorption by oxyhaemoglobin and only minimal damage to the overlying skin. After the use of continuous wave dye lasers, therapeutic progress has been achieved with pulsed lasers such as the copper vapour and flashlamp pumped dye lasers (FLPD). Advantages of the copper vapour laser are in the treatment of telangiectatic lesions that can be traced easily with the spot size of 100 microns, as well as in severe port-wine stains in adults (cobble-stone formation). The FLPD laser is feasible in the treatment of port-wine stains in children. Examples are shown of telangiectasia and port-wine stains of different grades and the resulting consequence for yellow light laser treatment.

Adolescent↗
PubMed1993

[Effect of myelography on the curve of the auditory evoked early brain stem potentials].

In 50 patients auditory threshold and brain stem evoked potential studies were carried out before and after myelography. Due to the analysis of amplitudes and latencies of auditory brain stem measurements, significant functional disorders of the hearing organ and the auditory pathway could be demonstrated. In most of the patients these functional disorders were found to be subclinical, whereas 12 patients showed alterations extending from a subjectively slight hearing loss to an audiometrically objectified acute hearing loss depending on its intensity in each case. The reasons of these functional disorders could not be clarified. An open cochlear aqueduct through which perilymph enters the subarachnoidal space leading to a secondary endolymphatic hydrops can be considered as the cause in cases where manifest symptoms develop. The changes in brain stem audiometry can be additionally explained by changes in osmolality of the inner ear fluids which may lead to the development of an endolymphatic hydrops.

Auditory Pathways↗
PubMed1993

[Yellow light laser photocoagulation of vascular malformations in the head and neck area].

Laser surgery techniques have become well established in otolaryngology. Yellow light lasers emit light in the visible spectrum. Laser light in the spectrum of 380-700 nm shows different effects after absorption at a specific chromophore. For the treatment of vascular lesions of the skin controlled absorption of energy by blood is necessary to avoid uncontrolled damage and vaporization. Chromophores of the skin which absorb energy transmitted by laser light are hemoglobin, bilirubin, oxyhemoglobin, beta carotene, collagen and melanin. The penetration of the laser light depends on its wavelength. In vascular lesions oxyhemoglobin is the chromophore whereas melanin is the chromophore in pigmented malformations. The argon-pumped dye laser, copper vapor and flash-lamp pumped dye laser emit laser light of 577, 578 and 585 nm. These lasers are especially useful for photocoagulation of oxyhemoglobin and for selective destruction of vascular tissue. The risk of hypotrophic or hypertrophic scarring is minimal (< 1%) because there is less alteration of the overlying dermis. The aim of the present study was to test, in a clinical setting, the copper vapor laser in vascular lesions of the head and neck.

Adolescent↗
PubMedDate not supplied

Titanium and glass-ionomer cement as ossicular replacement materials: biocompatibility results after implantation in the rabbit.

The middle ear poses unique challenges when finding suitable materials for ossicular reconstruction, primarily because of its link to the external environment via the eustachian tube, which leads to a greater potential for exposure to infectious agents. In this animal study, the biocompatibilities of titanium and glass-ionomer cement were assessed in the middle ear of the rabbit after being implanted as total ossicular replacement prostheses (TORPs) or as free pins. Animals were sacrificed after 28, 84, 168, 336, or 504 days or 2 years, and a cutting saw technique was used to prepare slides for light microscopy. Slides were examined for mucosal coverage and any sign of foreign body reaction. Both materials showed good acceptance in the middle ear. After 28 days, the TORPs were covered by middle ear mucosa. As expected, it took a longer time (up to 504 days) to cover the free implants. An interesting finding was the growth of new bone on both the surface of the titanium implants and the glass-ionomer prostheses. The results of this animal study indicate that both titanium and glass-ionomer cement are favorable materials for ossicular replacement prostheses.

Animals↗