Biomedical subjects

R Siegert

Publications and source records attributed to R Siegert.

At least 37 records · Page 2Linked to original sources

PubMed1998

Implicit learning in Parkinson's disease: evidence from a verbal version of the serial reaction time task.

Evidence suggests that patients suffering from Parkinson's Disease (PD) demonstrate less sequence learning in the serial reaction time (SRT) task devised by Nissen and Bullemer (1987). One of the problems with this task is that it is motor intensive and, given the motor difficulties which characterize Parkinson's disease (e.g., tremor, impaired facility of movement, rigidity, and loss of postural reflexes), allows the possibility that patients with PD are capable of sequence learning but are simply unable to demonstrate this through a decrease in reaction time over trials. The present study examined the performance of patients with PD and healthy controls, matched for verbal fluency, on a verbal version of the SRT task where the standard button-pressing response was replaced by a spoken response. Thirteen nondementing patients with PD and 11 healthy controls were administered the SRT task. The PD group demonstrated less sequence learning than the controls and this was independent of age and severity of illness. The results add support to those studies which have found impaired sequence learning using the standard form of the SRT task.

Adult↗

PubMed1997

Histopathology of laryngeal changes after long-term chondrosynthesis.

Two patients treated for laryngeal tumors at the University of Lübeck are presented. Both underwent laryngeal reconstructions with plate and screw fixation systems immediately following partial laryngectomies. Recurrent disease was found at 14 and 55 months, respectively, and was subsequently managed by total laryngectomy. The laryngectomy specimens with the plate and screws in situ were evaluated histopathologically, paying special attention to the reaction of local tissue to the implants. Findings showed that the metallic plates were fixed with screws in the bony trabeculae of the laryngeal skeleton. The histological response showed primary wound healing without evidence of sequestration or implant loosening, as often associated with excess mechanical stress. Furthermore, there were no signs of tissue necrosis or widespread chronic inflammation. In both patients, a small discrete area of chronic inflammation and soft tissue fibrosis was noted adjacent to the screw heads. This study supports our previously documented clinical experience that the use of chondrosynthetic techniques is almost complication-free and is an ideal system for performing precise anatomical reconstruction of the laryngeal skeleton.

Aged↗

PubMed1997

[Microcirculation of the nasal mucosa during use of balloon tamponade].

BACKGROUND: Nasal packings are commonly accepted in the treatment of severe epistaxis. Cuffed catheters are known to cause damage to the nasal mucosa most likely by interfering with tissue perfusion. In this study the effect of different pressure levels on local perfusion of septal mucosa is investigated. METHOD: In 15 healthy subjects the blood flow in septal mucosa was measured by laser doppler flowmetry by positioning a cuffed epistaxis catheter into the nasal cavity with a laser probe attached to it. Increasing pressure was administered by injecting saline solution while continuously recording intraluminal pressure, perfusion, and filling volume. The local pressure affecting the septal mucosa at the moment of stalling perfusion was determined by subtracting the extranasal cuff pressure from the current intranasal cuff pressure at same inflation volumes. RESULTS: Microcirculation of the septal mucosa stopped when the local pressure exceeded a value of Pmean = 42 mmHg. Individual variations (n = 15) were small (s = 9 mmHg). The intraluminal cuff pressure was measured to be about ten times higher due to the retraction force of the cuff. Spontaneous oscillations of the blood flow were reduced with increasing pressure to the blood vessels. Filling volumes up to 3.2 ml were sufficient to stop perfusion. CONCLUSIONS: Cuffed nasal packings stop the blood flow in nasal mucosa even at low local pressures. Depending on the material characteristics of different cuffs the pressure to dilate the cuff may, however, be several times higher than the actual local pressure. This effect may cause problems in the proper use of cuffed catheters. Laser doppler flowmetry proved to be helpful in determining reproducible perfusion values.

Adolescent↗

PubMed1997

[Psychosocial aspects in total external ear reconstruction in patients with severe microtia].

BACKGROUND: The aim of this study was to identify the psychosocial problems and expectation of patients with severe microtia and to investigate possible changes in psychosocial profile of patients after surgical reconstruction of the pinna. METHODS: Interviews were performed with 65 patients before and 39 patients after auricular reconstruction. They consisted of a questionnaire involving open and closed questions relating to the reconstruction and a personality test. RESULTS: The most frequently mentioned reasons for surgery were: personal dissatisfaction with patients own appearance, lack of self-confidence, and for younger age groups, parental anxiety about the future psychosocial development of their children. More than 90% of the patients with surgically reconstructed auricles were satisfied with the postoperative results and showed a more open and fearless personality profile. CONCLUSIONS: Auricular reconstruction enhances the development of a stable personality.

Adolescent↗

PubMed1997

[Postoperative pain therapy using on-demand analgesia after external ear reconstruction with rib cartilage harvesting].

BACKGROUND: The individual experience of postoperative pain values considerably. It is the patient who can best evaluate the intensity of pain and the effect of a given analgesic substance. Patient-controlled analgesia (PCA) enables the patient to self-administer an i.v. analgesic bolus by pressing a button of an electronic pump device within a previously set range. If needed. The resection of rib cartilage to be used for ear reconstructions is associated with intense postoperative pain. This could result in unfavorable stress responses such as impaired cough and clearance of lung secretions carrying a greater risk of bronchitis or pneumonia, prolonged mobilization, and complications of wound healing. Therefore, individually adapted pain therapy is of great importance and technically feasible with modern PCA devices. METHOD: Informed and cooperative children aged five years and older and adults without severe health risks are suitable for PCA. Management, handling, monitoring and documentation of the PCA device are discussed. A 24-hour counselling service is maintained for occurring problems. RESULTS: Almost all patients expressed their great satisfaction with the means of pain therapy. Few patients were apprehensive. The initial scepticism of the involved personnel concerning opioid abuse, over-dosage, or technical problems gave way for a support of the PCA once the great satisfaction of the patients in absence of side effects was witnessed. No patient had to be antagonized for respiratory depression. Nausea and vomiting were rare events. CONCLUSION: Patient-controlled analgesia proved to be an excellent answer to postoperative pain after resections of rib cartilage.

Adult↗

PubMed1997

[Therapy with nasal CPAP (continuous positive airway pressure) in patients with obstructive sleep apnea syndrome (OSAS). I: Long-term acceptance of nasal CPAP].

BACKGROUND: Nocturnal ventilation with nCPAP has been established as the safest and most efficient nonsurgical treatment for OSAS. Long-term results, however, are determined by the patients' compliance with therapy. The aim of this study was the objective measurement of long-term acceptability of nCPAP therapy in all patients receiving this treatment in our sleep laboratory between January 1990 and March 1995. METHODS: We prospectively investigated 41 patients (36 male, 5 female) with moderate to severe OSAS who received nCPAP therapy. Mean time of follow-up was 20.6 months, ranging from 1.2 to 53.5 months. Therapy was indicated when OSAS was confirmed by cardiorespiratory polygraphy and either (1) the patient complained of daytime sleepiness or (2) the patient possessed an apnea-hypopnea index greater than 30/h or when the mean oxygen desaturation was below 80% regardless of the presenting symptoms. The compliance with treatment was defined as a mean rate of use of over 5 hours per night calculated from the time counter on the nCPAP machine. RESULTS: 33 patients (88.5%) have continued using nCPAP until the present time but only 24 patients (59%) met our criteria for long-term acceptance and this group was identified as responders. We found no significant differences in age, body mass index, apnea-hypopnea index, and nCPAP-pressure between responders and non-responders. CONCLUSION: Although nCPAP is the safest treatment for OSAS, there is still a large group of patients with moderate to severe OSAS who are not efficiently treated with nCPAP because of the low long-term acceptability of this therapy. With respect to this group of patients, surgical approaches have to be considered as an alternative therapy.

Adult↗

PubMed1997

[Therapy with nasal CPAP (continuous positive airway pressure) in patients with obstructive sleep apnea syndrome (OSAS). II: Side-effects of nCPAP therapy. Effect on long-term acceptance].

BACKGROUND: nCPAP is a well established method for the management of OSAS. The aim of this study was to evaluate long-term side effects and complications of nCPAP therapy and their influence on the patients compliance with treatment. PATIENTS AND METHODS: Forty-one patients with OSAS were interviewed by questionnaire to elucidate the problems and adverse effects of their nCPAP therapy. The patients were divided into responders and non-responders. Non-responding OSAS patients were using their nCPAP devices less then 5 hours each night by definition. RESULTS: The number of side effects and type of complication during nCPAP therapy were the same in both the responding and non-responding groups. The most frequently reported problems were a tender region on the bridge of the nose and discomfort associated with a dry nasal mucosa. Although nCPAP treatment was initially accepted by most patients, adverse effects and other difficulties decreased patient compliance, with time, in many cases. CONCLUSIONS: Despite there being no difference between responders and non-responders with respect to the number and severity of complications, it should not be presumed that these side effects do not influence long-term patient compliance with nCPAP therapy. Patients who suffer from symptoms of OSAS tend to accept these adverse effects, while those who do not feel limited by their disease are less persistent in their use of this treatment modality. Identification and elimination of the problems associated with the use of nCPAP equipment may increase longterm patient compliance. Close monitoring in the outpatient department combined with intermittent inpatient assessment in the sleep laboratory will also help to improve acceptance of nCPAP therapy.

Adult↗

PubMed1997

[Techniques of local anesthesia in the area of the head].

In the head and neck region, many procedures can be performed under local anesthesia. The anesthetic agent can be applied onto the surface of the skin or mucosa (surface anesthesia), it can be infiltrated into the tissue to be treated, or it can be used to block the regional sensory nerve (conduction anesthesia). In this paper, the most important techniques for local anesthesia of the face are presented as a short clinical guide.

Anesthesia, Conduction↗

PubMed1997

High-resolution CT of the temporal bone in dysplasia of the auricle and external auditory canal.

PURPOSE: To determine CT findings in the external, middle, and inner ear of patients with microtia and external auditory canal dysplasia. METHODS: We used high-resolution CT, with multiplanar or axial 1-mm continuous sections, coronal or sagittal reformations, or low-dose spiral acquisitions, to examine 184 temporal bones of children with microtia. RESULTS: In cases of minor microtia, auditory canal stenosis was the most common associated abnormality; in those with major microtia, atresia was predominant. Middle ear malformations depended on the severity of the auricular anomalies. Inner ear changes could also be noted. Ossicle dysplasias occurred in 98% of patients (stapes, 72%), absence of the oval window in 36%, labyrinthine malformations in 13%, closed round window in 6%, facial canal displacement in up to 75%, and aberrations of the vascular canal in 38% of patients with third-grade auricular deformity. CONCLUSION: A variety of external, middle, and, less frequently, inner ear changes were detected in connection with microtia.

Abnormalities, Multiple↗

PubMed1997

[Bone conduction hearing aids with fluid medium].

In patients with chronic otorrhoea or middle ear pathology, traditional hearing aids which depend on air conduction are of little use. In these situations a bone conduction hearing aid is preferable. Such devices by-pass the middle ear cleft and ossicular chain by conducting sound waves through bone to the cochlea. To date, bone conduction hearing aids have transmitted sound via a vibrating transducer applied either to skin (transcutaneous) or to bone (percutaneous). Unfortunately, these hearing aids possess a number of disadvantages, which include: cost, aesthetic appeal, a general anaesthetic for percutaneous aids, and most notably pressure discomfort to the side of the head. To overcome some of these problems a new bone conducting hearing aid is being developed which differs from conventional aids in that sound transmission is through a liquid medium. This has been tentatively named the "Hydro-Hearing Aid" and a prototype is now being tested.

Adult↗

PubMed1996

Experimental and clinical evaluation of laryngeal chondrosynthesis.

The aim of this study was to investigate and develop techniques for stabilization and reconstruction of laryngeal defects with a method similar to osteosynthesis. In an anatomical study, 400 extrusion forces of sutures and various screws (Howmedica) were measured in the thyroid cartilage of fresh cadavers. A new screw was then especially designed for cartilage and a new technique was developed for stabilizing cartilage, using a screw-nut made out of bone. To date, 30 patients have undergone chondrosynthetic reconstruction of the larynx. Measurements of extrusion forces were found to depend on the degree of calcification present in the area of the laryngeal skeleton examined and the type of fixation device used. Good clinical results were achieved in all 30 patients studied and depended on stabilization of the two sides of the thyroid cartilage after thyrotomies, bridging of laryngeal defects and splinting of laryngeal fractures. Besides the increased extrusion forces the advantages of chondrosynthesis lay within the possibilities of axial stabilization and exact bridging of defects with or without implants.

Adolescent↗

PubMed1996

[Laser Doppler flow signal frequency analysis in physiological and drug modified nasal flow motion].

The term "flow motion" stands for the phenomenon of spontaneous and autonomous rhythmic variations of the contractile state of the smooth muscles of small dermal vessels. There also have been a few observations of variations in the microcirculation of the mucosa, but they have not been evaluated in detail to date. The aims of this study were to develop a method for investigation flow motion, especially in the nasal mucosa; to compare nasal flow motion to that of other skin and mucosal areas; to evaluate the influence of normal saline solution, as well as a sympathomimetic agent and histamine on flow motion. The microcirculation of the nasal mucosa of 40 healthy volunteers was measured under standardized conditions. In a first series of investigations, the microcirculations of the forehead, lobule of the ear, nose and oral mucosa were compared. In the second series, the microcirculation of the nasal mucosa was measured with laser-Doppler flowmetry before and after provocation with 0.9% saline solution, 0.25 mg oxymetazoline hydrochloride as sympathicomimetic preparation and 0.085 mg histamine in 0.5 ml of 0.9% saline solution. Evaluation of the data included signal analysis of the microcirculatory variations using fast-Fourier transformation and its changes before and after the pharmacological stimulations. Distribution of the power spectra showed that the nasal mucosa was significantly different from that of the skin of the forehead and the ear. Oxymetazoline hydrochloride led to a clear increase and histamine to a significant reduction in the frequencies of the flow motion. The results of this study demonstrated that nasal flow motion could be detected and evaluated with laser-Doppler flowmetry and a special analysis of the data recorded. Specific patterns of the flow motion frequencies could be detected in the nasal mucosa that were distinctive from those of the skin. The pattern of the flow motion frequencies reacted very sensitively to the pharmacological provocations used.

Adult↗

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

[Ultrasound diagnosis of orbital floor fractures: an alternative to computerized tomography?].

BACKGROUND: Plain radiography of the paranasal sinuses (Water's view) may fail to demonstrate typical signs of orbital floor fractures. To resolve questionable cases, computed tomography (CT) is performed. B-mode ultra-sonography (US) is investigated concerning its reliability and as a possible alternative to CT. The replacement of standard radiological techniques in primary evaluation will be discussed. METHODS: A skull was used to assess the visualization of the bony floor in the ultrasound-technique. Fifteen patients with suspected fractures of the orbital floor were investigated with plain radiographs, ultrasound of both orbits in closed-eyelid technique, and CT scans. The findings were compared. RESULTS: Thirteen patients were found to have apparent fractures in CT scans. These fractures were also diagnosed on ultrasound. In three patients, ultrasonographic localization was imprecise. These fractures were located behind the lower orbital rim or far posteriorly. Plain radiographs showed positive fracture signs only in five patients. Localization was not possible. The application of the ultrasound probe was well tolerated. CONCLUSIONS: B-mode ultrasonography is a valuable and inexpensive technique to visualize orbital floor fractures. It should be employed in primary evaluation patients with suspected isolated orbital floor fractures prior to taking plain radiographs of the paranasal sinuses. Computed tomography should be used in suspected complex fractures and questionable orbital fractures.

Adult↗

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

[Suction-irrigation attachment for the flexible endoscope without integrated operating channel].

BACKGROUND: Endoscopic inspection of the larynx in patients with long-term intubation or patients pharyngolaryngeal injuries is frequently obscured by blood and other secretions. We developed a simple procedure to improve visibility. METHODS: A flexible 4-mm endoscope without an operating channel is inserted into an 18-French suction tube through one branch of a Y-shaped connecting tube (Fig.1). Fluid can be aspirated between the endoscope and the surrounding tube. The site can be flushed in a similar manner. RESULTS: In all examined patients (n = 11) we successfully aspirated fluid (blood/saliva/etc.). CONCLUSIONS: Our proposed suction and irrigation attachment for flexible 4-mm endoscopes without an operating channel permits reliable aspiration under endoscopic inspection, simplifying endoscopic visualization of laryngeal or pharyngeal findings.

Equipment Design↗

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↗