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Biomedical subjects

H Weerda

Publications and source records attributed to H Weerda.

At least 37 records · Page 2Linked to original sources
PubMed1996

[Ultrasound measurement of skin and cartilage thickness in healthy and reconstructed ears with a 20-MHz ultrasound device].

BACKGROUND: The surgical reconstruction of the external ear according to Weerda is a proven method to correct malformed or amputated auricles. Our goal was to test the usefulness of high-frequency ultrasound in measurement of layer-thickness of auricles. METHOD: Using a 20-MHz B-Mode ultrasonographic method (Dermascan C, adn-Medizintechnik, Hamm, Germany) we measured the thickness of skin and cartilage layers in patients with normal auricles (n = 47) and reconstructed auricles (n = 15) in vivo. RESULTS: The average thickness of the cutis of normal auricles was 0.8 mm, the subcutis and the cartilage layer 0.6 mm thick on average. In reconstructed auricles, the thickness of the cutis averaged 1.0 mm, the subcutis 1.1 mm, and the cartilage layer (to the extent that it could be visualized) 3.0 mm. DISCUSSION: The results demonstrate a good approximation of the thicknesses of the different layers (cutis and subcutaneous tissue) in reconstructed and natural external ears, but the cartilage of the reconstructed auricles is clearly thicker. CONCLUSIONS: The 20-MHz B-Mode ultrasound is suitable for examining the methods of plastic surgery in malformed auricles. Based on the demonstrated results, surgical modifications should be assessed in future.

Adolescent↗
PubMed1996

[High resolution computerized tomography of middle ear abnormalities].

BACKGROUND: The aim of this study was to analyze malformed petrous bones with computed tomography and to develop a radiologic score which can help to judge the indication for operative reconstructions. METHODS: One hundred forty-two petrous bones in 71 patients with unilateral or bilateral microtia, atresia of the external auditory canal, and malformations of the middle ear were evaluated with high-resolution CT. RESULTS: In 97% of patients with severe auricular dysplasia, there was dysplasia of the middle ear ossicles; in 70% the stapes was malformed. In 32% the oval window was occluded, and in 7% the round window. In 75%, the canal of the facial nerve was displaced, and 16% also showed abnormalities of the labyrinth. A close correlation between the malformation of the auricle and of the middle ear was not found. CONCLUSIONS: High-resolution CT is necessary for the evaluation of malformed middle ears. Based on the abnormalities described, we propose a radiologic score for the assessment of malformed petrous bones. This consists of the following criteria: external auditory meatus, pneumatization of the mastoid and of the tympanic space, size of the tympanic space, facial nerve, vessels, malleus and incus, stapes, oval and round window. The graded points of each structure are added up to the score, which might range between 0 and 28. This score can help to judge the indication for reconstruction of the middle ear. In bilateral malformation we suggest a middle ear reconstruction of the better hearing ear if the score is greater than or equal to 15, and in unilateral malformation if it is at least 20. In patients with lower scores, we only suggest hearing aids.

Adolescent↗
PubMed1996

[Diaphanoscopic localization of tear ducts in endonasal dacryocystorhinostomy].

BACKGROUND: Endonasal dacryocystorhinostomy is a well established technique in the surgical treatment of stenosis of the lacrimal system. Due to individual anatomic variations it can be difficult and time consuming to localize the stenosis of the lacrimal system intraoperatively. METHODS AND PATIENTS: To simplify the localization of the lacrimal system, a diaphanoscopic technique that has been used in oral surgery was modified for endonasal dacryocystorhinostomy. A sterile optical fiber is passed through the lacrimal canal from the eye into the lacrimal sac or down to the stenosis. Its light can be detected in the nose and marks the sac or the stenosis. To date we have performed twelve operations with this technique. RESULTS: In our experience, endonasal dacryocystorhinostomy is simplified and accelerated by localizing the lacrimal system with diaphanoscopy. CONCLUSIONS: The diaphanoscopic localization of the lacrimal system during endonasal dacryocystorhinostomy is a slight technical modification that is simple and helpful and could therefore be incorporated into the surgical routine.

Dacryocystorhinostomy↗
PubMed1996

[Osteosynthesis in the mid-face and forehead area].

BACKGROUND: In the beginning of the development of facial osteosynthetic techniques only relatively thick plates were available. Since then various mini- and micro-plating systems were developed for the midfacial and forehead regions. As so many different systems with different sizes are available, it is important to know which systems are appropriate for which indications. Therefore, the aim of this study was to add knowledge to some aspects of the differential indications of different systems for the middle and upper facial regions. METHODS AND PATIENTS: 1. The pull-out forces of seven different mini- and microscrews were measured. 2. The thicknesses of the facial bone were measured at 11 different points in 10 skulls. 3. The clinical experiences of midfacial and upper facial osteosynthesis in 45 patients were summarised. RESULTS: The pull-out forces increase with increasing bone- and screw-thickness and also substantially depend on the design of the screws. Although the bone thicknesses in the mid and upper facial region vary considerably, all investigated regions are suitable for osteosynthesis. In none of our patients any complication occurred that was related to the osteosynthesis. CONCLUSIONS: Microsystems with screw diameters of 0.8 mm (Howmedica) are suited for fractures of the nasoethmoidal complex. Providing the same thickness as the microplates the Panfixsystem (Howmedica) offers a better holding strength especially when using the 1.3 mm screws, and is easier to handle. For stabilising fractures of the zygoma, which might dislocate postoperatively due to the pulling force of the masseteric muscle, we still feel that the miniplating technique with compression is the method of choice.

Adult↗
PubMed1996

[Ultrasound imaging of nasal bone fractures with a 20-MHz ultrasound scanner].

High frequency B-scan ultrasonography is a proven method for the assessment of skin tumors and evaluation of the thickness of skin and cartilage layers. Only limited studies have used sonography to examine bony structures. Our goal was to evaluate the importance of ultrasonography in the diagnosis of nasal fractures. Patients with clinical and/or radiological evidence for such fractures were also examined with 20 MHz B-scan ultrasonography. Results of sonography demonstrated a significant correlation with the nasal fractures present, indicating that additional radiographic examinations are unnecessary in certain cases.

Adult↗
PubMed1996

[Familial occurrence of oculoauricolovertebral dysplasia and Franceschetti syndrome].

Oculoauriculovertebral dysplasia (OAV) and the Franceschetti syndrome (FS) are well-known complexes of anomalies that have dysplasias of the external ear as a common occurrence. In this study the specific patterns of symptoms and familial occurrences of 100 patients with external ear dysplasias were examined (88 patients with OAV dysplasia and 12 patients with FS). Analyzing the pedigree data of the probands, we ascertained the relatives with striking symptoms and associated anomalies of OAV dysplasia. The aim of this study was to determine the influence of genetic transmission on OAV dysplasia in comparison to FS. A striking family history was found in 66.6% of the patients with FS. In 26.1%, family members of patients with OAV dysplasia had external ear dysplasias or other striking symptoms of OAV dysplasia. In this complex of anomalies we also found a higher frequency of skeletal deformities and congenital heart defects than in the normal population. On the basis of our results we suggest that there is a genetic transmission in patients with FS as well as in some cases with OAV dysplasia. Our findings show that it is absolutely necessary to analyze family history very carefully when discussing the recurrence risk or risk of genetic transmission.

Adolescent↗
PubMed1995

Experimental tissue expansion induces changes in expression of procollagen I and III messenger RNA.

Experimental tissue expansion was performed in nine dogs following placement of subcutaneous silicone balloons. The balloon expander was then filled with 300 ml saline immediately after implantation. Duration of expansion varied from 3 days to 124 days. Unaffected skin and skin over an empty expander served as control tissue. Dermal procollagen I and procollagen III gene expression in response to tissue expansion was investigated by dot-blot analysis using digoxigenin-labeled RNA probes complementary to either human procollagen-alpha 1(I) mRNA or procollagen-alpha 1(III) mRNA. Cross-hybridization of human probes with canine procollagen mRNA was demonstrated by Northern blot analysis. In response to the trauma of surgery, procollagen I and III mRNA transcriptions were found to be decreased significantly within the first few days after implantation. After 9 days of expansion, increased levels of procollagen I mRNA were found, while after 16 days increased levels of procollagen III mRNA were evident. The present study is the first to demonstrate changes in dermal collagen gene expression as a reaction to tissue expansion.

Animals↗
PubMed1995

[Experimental studies of chondrosynthesis for the larynx].

UNLABELLED: The aim of this study was to develop and investigate techniques for stabilising and reconstruction of defects in the larynx similar to osteosynthesis. MATERIAL AND METHODS: (1) 400 extrusion forces of sutures and various screws (Howmedica) in thyroid cartilage of fresh cadavers were measured. (2) A new screw specially designed for cartilage was developed. (3) A new technique for stabilising cartilage with a screw nut made out of bone was developed. RESULTS: The extrusion forces correlate with the calcification of the laryngeal skeleton depending on the investigated area of the thyroid cartilage and the type of suture and screws that are used, respectively. Besides the increased extrusion forces the advantages of chondrosynthesis are the possibility of axial stabilisation and of exact bridging of defects with or without implants.

Biomechanical Phenomena↗
PubMed1995

[A modified nasal tamponade with foam rubber protection in epistaxis].

We present a modification of a nosebleed catheter or nasal/nasopharyngeal tamponade in case of bleeding from the posterior nasal cavity. A piece of foam rubber from a "moist nose" is cut to size and drawn over the tamponade. The advantage of the method is that it protects the sides of the patient's nose against pressure ulcers and prevents the tamponade from sliding into the naso/oropharynx. Treatment would be meaningfully complemented by continuous intravenous sedation of the patient by combining a peripheral with a central analgesic.

Catheters, Indwelling↗
PubMed1995

[The technical safety of tissue expander domes].

UNLABELLED: Since leakage of an expander dome is a well-known complication that may lead to interruption of a tissue expansion procedure, the aim of this project was to study different expansion domes in relation to a medication port after perforation with various needles. MATERIAL AND METHODS: The combinations of five different expansion domes and one medication port were tested with three different needle types having two different diameters. The force-distance curves during puncturing, the puncture forces required and the leakage opening pressures were measured after single on repeated punctures with small and large forces. A total of more than 2000 experiments were performed. RESULTS: Only one of the expander domes and the medication port had sufficient pressure stability. The technical characteristics of these devices are presented. However, the different needle types and puncture techniques had only a minor influence on the pressure stability of the expander domes.

Catheters, Indwelling↗
PubMed1994

[Voice rehabilitation with the jejunum speech siphon: the biventer rein, a modification for prevention of aspiration].

The principle of operative voice rehabilitation after laryngectomy consists in forming a shunt between trachea and hypopharynx. The results of voice rehabilitation are generally good. Aspiration is the main disadvantage of this method, which negatively affects the quality of life. We modified the jejunum siphon of Ehrenberger and used this shunt operation mostly in total pharyngolaryngectomies. To avoid aspirations we formed a rein from both sides of the neck using the m. biventer. This rein hold the knee of the siphon and acts as a sphincter when the patient swallows, because the contractility of this muscle is preserved. We present this new method and compare the results of the first seven patients with those of the patients who were operated on without a rein from the m. biventer.

Adult↗
PubMed1994

[A new method of tongue reconstruction with neurovascular infrahyoid muscle-fascia flaps].

Surgical treatment of tongue cancer can lead to extended defunctionalization, depending upon the size and localisation of the defect. Great problems of swallowing arise after total glossectomy or extensive resections of the base of the tongue even after reconstruction with myocutaneous island flaps or free flaps. We developed a neuromuscular island flap derived from the infrahyoidal musculature to reconstruct a total tongue or large defects of the tongue base. This fasciomuscular flap is formed by the M. sternothyroideus, M. sternohyoideus and the upper part of the M. omohyoideus. The axial blood supply arises from the A. thyroidea sup. The innervation is derived from the Ansa cervicalis N. hypoglossi. In case of total glossectomy we took this flap from both sides of the neck. With this new method we reconstructed total tongues after glossectomy in two patients and large defects of the tongue base in six patients. In the present paper the new surgical method and the functional results are described.

Electromyography↗
PubMed1994

[Epidermal proliferation rate after skin expansion in the dog model].

The aim of this study was to evaluate the time course of the epidermal proliferation under the influence of skin expansion. Therefore 99 expanders were implanted in 18 beagles. The expansion times were between 2 hours and 4 months. Cells in the S-phase were marked by in vivo application of bromodesoxyuridine (BrdU). The tissue specimens were immunohistochemically stained and positive nuclei counted. The proliferation index increased markedly about 32 hours after the onset of the expansion and decreased afterwards slowly during the first week. Because the dog is the most appropriate species for experimental expansion studies (4,5) it can be assumed that skin expansion leads to a stimulation of the epidermal proliferation during the first few days also under clinical conditions. Nevertheless, the amount of skin that can be surgically used depends not only on the characteristics of the epidermal layer, but also on the dermis with its strong fibre system. Own studies published elsewhere (8) have shown that the dermal fibres react much slower to the expansion stimulus, so that even though there is an early epidermal proliferation increase new surgically applicable skin can only be produced by long-term expansion.

Animals↗
PubMed1994

[Complications of otoplasty and their treatment].

The multitude of otoplastic techniques, described in literature, which are based, as the case may be, on one of the three standard techniques for the correction of prominent ears, shows there is no single technique for satisfactory results. Hence, early and late complications can occur after otoplasty, both immediately and up to 2 weeks and later. These complications include granulomas, allergic reactions, keloids, reprotrusion as well as severe deformities with different defects, besides disturbances of sensitivity, often requiring repeat surgery. The management and treatment of the various complications are described and some reconstruction procedures are demonstrated, employing fascia, skin and cartilage to keep the damage at a minimum.

Adolescent↗