Biomedical subjects

T Klenzner

Publications and source records attributed to T Klenzner.

At least 19 recordsLinked to original sources

PubMed2006

[Cochlear protection and surgical precision in stapedotomy with Er:YAG laser].

BACKGROUND: Using laser in stapedotomy has attracted a lot of attention since the nineties. It aims at minimizing complications due to hand-operated equipment, especially inner ear lesions, and achieving higher precision. We analyzed the clinical effect of Er:YAG laser with the question whether the postulated cochlea protection and foot plate perforation, optimized for better sound conduction, are achieved, compared to conventional stapedotomy. PATIENTS AND METHODS: We evaluated retrospectively audiometrical data including pre- and postoperative bone and air conduction thresholds of 114 consecutive patients, on whom we had performed stapedotomy and had inserted platinum-teflon prostheses. The intervention was done conventionally in 72 cases and in 42 cases with Er:YAG laser. RESULTS: In the lower and middle frequencies, laser technique resulted in a more pronounced improvement of bone conduction thresholds compared to conventional stapedotomy. The improvement of air conduction was more distinct in ears after laser surgery; also, the difference between air and bone conduction was reduced at a higher degree. CONCLUSION: Er:YAG laser in stapedotomy is coupled with cochlea protection, as demonstrated under clinical conditions, and allows higher hearing benefit of air conduction compared to conventional stapedotomy. Our results emphasize the impact of innovative laser technique on stapedotomy.

Adult↗

PubMed2006

[The transverse rectus abdominis muscle (TRAM) flap. A "second defensive line" in microvascular reconstructions of defects in the head and neck area].

BACKGROUND: The microvascular anastomosed transverse rectus abdominis muscle (TRAM) island flap has been successfully used in plastic surgery for more than 10 years. In reconstructive head and neck surgery, however, it is not yet established. METHOD: We analysed the preparation and anatomical variation in TRAM flaps in an examination of eight cadavers. In a clinical case with complete reconstruction of the nose after nasal ablation and complete loss of a radial lower forearm flap that had been transplanted previously due to a recurrent tumor, the possibility of forming and modeling a TRAM flap is demonstrated. RESULTS: The flap vessels of the TRAM are comparable to the radial forearm flap, and the donor site may be primarily closed. The TRAM proved to be a suitable alternative to close lesions of the head and neck area in selected cases. The myocutaneous TRAM is bulkier than the fascio-cutaneous radial forearm flap. The subcutaneous abdominal fat of the TRAM can be reduced in relation to the vascular distribution of the perforator vessels. If the subcutaneous fat of the flap is reduced, the flap can be shaped and formed well. In the described case, it was used to close the lesion after ablation of the nose and middle face. CONCLUSION: The risk of an iatrogenic lesion of the peritoneal fascia or postsurgical herniation of the abdominal wall is low if several surgical prerequisites are taken into consideration. The myocutaneous TRAM will not replace the fascio-cutaneous radial forearm flap in microvascular head and neck surgery, but the large diameter of the donor vessels and the highly vascularized flap tissue makes it an alternative as a second line procedure in cases of unfavorable wound conditions.

Cadaver↗

PubMed2006

[A multicentre comparative study of the ESPrit and the Nucleus 22].

BACKGROUND: Cochlear implant recipients often report additional difficulty in comprehension of speech in noisy conditions and of softly spoken speech. The aim of this clinical study was to evaluate and compare the performance advantages offered by the ear level ESPrit 3G for experienced Nucleus Mini 22 cochlear implantees. PATIENTS AND METHODS: Twenty-eight German-speaking implanted subjects, who had had experience with either the Spectra 22 or the ESPrit 22 for at least 6 months, were evaluated with their current processor and the ESPrit 3G (on microphone, M, and whisper, W, settings) following a 4-week trial. Freiburger monosyllabic words (FMW) were used at soft and conversational levels in quiet conditions and Oldenburger sentences (OLSA) were used in noisy conditions to compare performance. Subjective impressions of sound quality and user aspects were evaluated and combined with data from 31 English-speaking subjects from a parallel study. RESULTS: In comparison to the previously worn processor, statistically significantly superior performance (p<0.001) was observed at soft and conversational levels in quiet conditions for FMW in 15 subjects when using the W setting and in noisy conditions for the OLSA in 21 subjects when using the M setting (p<0.001). The ESPrit 3G was preferred by 86% of subjects (51/59). CONCLUSION: The ESPrit 3G for Nucleus 22 users has the potential to further improve speech understanding in quiet conditions at soft intensity levels and also in noisy conditions at conversational levels relative to the currently worn speech processor, the Spectra 22 or the ESPrit 22, for the majority of subjects. Subjectively, together with the improvement in sound quality, the majority of subjects also reported improved ease of use and wearer comfort.

Adolescent↗

PubMed2006

[Objectivity of therapeutic results following skull base surgery using virtual model analysis].

BACKGROUND: Virtual model analysis of patient head tracking allows for objectivity and the monitoring of therapeutic results of pathologies in the skull base region. The introduction of these models in clinical routine has been impaired by the extended time needed for the preparation of radiological data. METHODS: Quality control analysis was carried out for seven cases with different pathological findings in the skull base region in patients who had undergone virtual model analysis. RESULTS: Preparation time of radiological data for the process of segmentation required, under optimal conditions, a minimum of 30 min. Virtual model analysis enables spatial visualization of regions of interest and adjacent anatomical structures. This improves case-specific pathoanatomical understanding as well as preoperative planning of surgical strategies. CONCLUSIONS: Virtual model analysis improves the physician's spatial comprehension of localized pathological findings at the dysmorphic interface of bone and soft tissue across the skull base. Therefore, it seems to be an adequate tool for quality control analysis of therapeutic results after extended skull base surgery.

Adolescent↗

PubMed2006

[Single and temporally displaced second nerve lesions in an animal model and their clinical significance].

BACKGROUND: Surgical optic decompression after trauma has been discussed controversially. The surgical trauma is supposed to produce an additional nerve lesion with the danger of complete loss of vision. Alternatively, conservative high dose cortisone therapy has been recommended. METHODS: The functional and morphological consequences of a lesion after calibrated optic compression in one or two sessions were examined in an animal model using 29 Wistar rats. RESULTS: Depending on the duration and intensity of the lesion, we observed a linear decline in the number of neurons in the RGC (retinal ganglion cell) layer as well as an increasing reactivity to GFAP (glial fibrillary acidic protein) as an indication of central gliosis of astrocytes; however, this was independent on whether optic compression was performed in one or two sessions. CONCLUSIONS: To reduce secondary damage to the visual nerve and the central visual system that might increase with a persisting lesion, the indication for surgical relief of an eye affected by afference should be considered liberally, especially in view of the low morbidity of rhinosurgical intervention.

Animals↗

PubMed2006

[Ethisorb/Ethisorb durapatch for the transnasal duraplasty procedure?].

BACKGROUND: Defects of the dura in the rhinobasal area can be closed transnasally. Various procedures with autologous or alloplastic material can be chosen. METHOD: From 2001 to 2004, we closed a rhinobasal dura defect with Ethisorb or Ethisorb durapatch in sandwich technique in 8 patients. After smoothing the bone edges, Ethisorb is applied under microscopic or endoscopic view endocranially, extradurally as "underlay" to seal and absorb the liquor pressure pillar. Additionally, another Ethisorb implant as "underlay" is applied extracranially from endonasally as "underlay", and sealed with a further layer of nasal concha mucosa with fibrin glue. RESULTS: All patients were successfully treated with this technique. There were no evidences for persisting rhinoliquorrhoe after the period of wound healing. For hemostasia, a nasal package was applied for compression at the donor site of the inferior nasal concha. The former dura defect was at all times freely accessible in order to be able to recognize a possible new rhinoliquorrhoea early and to prevent a possible congestive secretion with superinfection. DISCUSSION: The material of Ethisorb and Ethisorb durapatch is stiff and can be easily modelled, so it is an alternative as an alloplastic material for endonasal closure of defined substantial defects of the dura with rhinoliquorrhoe.

Adult↗

PubMed2005

[Methods for evaluation of perimodiolar ci electrode arrays in human temporal bones].

BACKGROUND: Cochlear implants (CI) are the established treatment for cochlear deafness. Recently, indications for cochlear implantation have been expanded to include severely hearing-impaired patients. The use of bilateral implants seems to provide additional benefit. Moreover, new electrode designs, i. e. perimodiolar electrode arrays, aim at improving benefit for patients. However, in addition to providing functional improvements, modern electrode array development must also address safety aspects, because damage to the cochlear morphology (especially the osseous spiral lamina) may lead to degeneration of residual neuronal structures and bony obliteration or scarring within the cochlear ducts. METHODS: Therefore, insertion trauma of the newly developed electrode arrays in human temporal bones must be evaluated before applied to patients. Several methods for testing electrode location and intracochlear trauma are described. RESULTS: Combining cross-sectional imaging, histological analysis and elements of risk-assessment valid information about trauma and possible consequences for use in patients can be determined, based on our experience in 57 temporal bones. CONCLUSIONS: Following our results, safety studies with prototype electrode arrays should, in addition to radiological examination, always include careful histomorphological evaluation.

Adult↗

PubMed2005

[The influence of insertion depth on the preservation of residual hearing after cochlear implantation].

BACKGROUND: Cochlear implantation may be indicated in patients with bilateral severe sensory hearing loss. Patients with minimal residual hearing have more benefit from cochlear implantation than from optimal fitted hearing aids. However, it has to be considered that inner ear structures might be damaged during electrode insertion. METHODS: We analysed the influence of insertion depth on the preservation of residual hearing in 47 cochlear implant patients (type of implant: Nucleus 22 M or 24 M) by using the pure tone audiometry. Frequency-specific analyses of pre- and postoperative audiograms on the implanted side were performed, evaluating only frequencies above 500 Hz. The insertion depth was documented by stiffening rings outside the cochlea. RESULTS: Residual hearing was more obtained in cases with complete insertion of the electrode array than in those cases with incomplete insertion. In the frequencies 1000 and 4000 Hz these results are significant. CONCLUSION: In our opinion, the perceived resistance producing intracochlear damages and preventing the complete electrode-insertion at the same time is an explanation for the significantly poorer results of the patients with incomplete insertion.

Audiometry, Pure-Tone↗

PubMed2005

[The freiburg incision for cochlear implantation -- initial results].

BACKGROUND: Cochlear implant surgery is a well standardized therapy for rehabilitation of congenital or acquired deafness at all ages. Mastoidectomy, posterior tympanotomy, cochleostomy and electrode insertion are performed consistently worldwide. Recently newly developed types of incision are taken into account. In our experience over more than 15 years the extended endaural incision has proven to be reliable with a low complication rate. OBJECTIVE: To evaluate a modified retroauricular incision for clinical use and complication rate in cochlear implant surgery with devices of different manufacturers. MATERIAL AND METHODS: We performed a prospective analysis of cochlear implant surgeries between 03/2003 and 03/2004. In all cases a modified retroauricular incision was used. Necessary adaptations of incision, depending on the device used, and postoperative complications were evaluated. RESULTS: In 76 ears a retroauricular incision was performed. Depending on the shape and size of receiver/stimulator an extension of the incision was necessary. The mean observation time was 6.3 months. Intra- or postoperative complications were not observed. In one case a skin dehiscence following trauma 28 days after surgery was reported without dehiscence of fascia or implant failure with uneventful healing after secondary suture. CONCLUSIONS: With regard to the results with the extended endaural incision the modified retroauricular incision allows a safe access for cochlear implant surgery. Observation of long term results and outcomes in revision surgery is mandatory.

Adolescent↗

PubMed2005

[Guided surgery in a subtemporal approach in CPA tumors?].

BACKGROUND: Computer assisted surgery (CAS) permits the visualization of hidden bony covered structures invisible for the human eye with radiological 3d data sets. The surgeon might be able to orientate anatomically during surgery without having to prepare the according landmarks. This would mean less surgical traumatization and a shorter and smaller operation corridor. METHOD: We determined the use of CAS in a quality assurance analysis with the subtemporal approach in 8 patients with supra-meatal tumors type A of the cerebellopontine angle. Various navigation systems and methods for referencing for the registration of the patients' heads were used. The question was whether it is possible intraoperatively without preparation of known anatomical landmarks to define the borders of an optimal positioned temporary bone cap and to identify the bony covered inner auditory canal and its neuronal structures without orienting neurostimulation. RESULT: It was possible with CAS to assess intraoperatively the borders of a temporary bone cap above the cranially positioned mastoid cell. However, the objective inaccuracy of 2 to 28 mm observed during surgery did not allow a secure identification of the inner auditory canal. CONCLUSIONS: CAS with the subtemporal approach cannot replace the conventional preparation of known anatomical landmarks nor neurostimulation to identify neural structures, due to the expected high inaccuracy with the non-invasive referencing systems that are available today.

Adult↗

PubMed2005

Influence of ionizing radiation on nucleus 24 cochlear implants.

HYPOTHESIS: To evaluate the influence of conventional or hyperfractionated radiotherapy on Nucleus CI24M or CI24R(CS) implant systems. BACKGROUND: As a consequence of more than 70,000 cochlear implant recipients worldwide, the potential need for radiotherapy is an issue requiring consideration by both implantees and implantation centers. Conditions requiring radiotherapy of the head may include head, neck, or brain tumors. METHODS: The study examines the effect of ionizing radiation on cochlear implant function. The implanted devices examined were the Nucleus CI24M and Nucleus CI24R(CS). In a modeled study, two implants of each type were treated with fraction schemes most frequently used in clinical routine (e.g., conventional fractionation [total dose, 120 Gy] and hyperfractionation [total dose, 116 Gy]). Parameters quantified were the implant output amplitude changes at high and low current level (current levels 255 and 100, respectively), the charge balance of the biphasic pulse, and the accuracy of the impedance telemetry function. RESULTS: Within the clinically relevant dose range (< 80 Gy), implant function in all four devices was normal. Failure occurred in one Nucleus CI24R(CS) device treated with hyperfractionation. A dramatic drop in the output amplitude at 106 Gy was observed, and the impedance measurement failed at a total dose of 111 Gy. CONCLUSION: The results suggest that conventional or hyperfractionated radiotherapy can be applied safely at Nucleus CI24M or CI24R(CS) implant systems in a patient-like setting. Therefore, the authors propose that the results of the study can be applicable in clinical practice.

Cochlear Implants↗

PubMed2004

[Current developments in cochlear implantation].

Over the last 20 years, cochlear implantation has become a well accepted treatment in patients suffering from hearing loss or congenital deafness. Results have been impressive,and indications for a cochlear implant have been extended continuously. Thanks to a sophisticated diagnostic procedure, optimization of the surgical technique, and the progression of interdisciplinary cooperation in the field of rehabilitation, the acceptance of cochlear implantation is growing significantly. The manufacturers of the devices are making great efforts to miniaturize the external components of the system, and new developments in electrode arrays, combined with new speech coding strategies, result in better speech understanding. The new developments in electrode design, however, are not necessarily improvements over recent years. Nevertheless, a very well functioning network of physicians, scientists, and manufacturers has acted and reacted in an outstanding manner to identify possible causes of post-implantation meningitis, have taken immediate counter measures and presented possibilities of prevention.

Cochlear Implantation↗

PubMed2004

[Navigation-controlled cochleostomy. Is an improvement in the quality of results for cochlear implant surgery possible?].

BACKGROUND: The correct positioning of the electrode, which is the limiting factor for the functional integrity of cochlear implants, is decisively influenced by the cochleostomy. Localisation and form of the drilling canal have been solely defined by the surgeon during the operation and an enlargement of the drilling canal is often necessary. Thanks to the improved resolution of new slice imaging techniques, computed tomography allows an exactly defined optimal point for cochleostomy. MATERIAL AND METHODS: In a cadaver study, we examined whether the target defined with computed tomography can be reached in a reproducible way with the help of navigated computer assisted surgery. We chose titanium screw markers as the gold standard for referencing. RESULTS: There was a real deviation of 1.6 mm in the target field. Thus, in a cochleostomy with a diameter of 0.5 mm the goal was not reached in a reproducible way. With this deviation a target of 2.56 mm(2) is defined. CONCLUSIONS: A target assessed by navigation is better than one reached without navigation in view of reproducibility and accuracy. With further technical progress navigated cochleostomy will be possible.

Cadaver↗

PubMed2004

[Does computer-aided navigation of endonasal sinus surgery improve process quality and outcome quality?].

BACKGROUND: Ever since navigation technology was introduced into endonasal surgery, its impact on process and result of surgery has been debated. In this respect, factors of investment costs and additional costs for time exposure will be discussed as well. PATIENTS AND METHODS: In a retrospective analysis of quality assurance, the results of endonasal surgery by surgeons of different experience in 56 patients were evaluated. Preparation time, preoperative setup time as well as time of actual surgery were analysed and compared with possible indications for navigation. RESULTS: From our analysis a classification resulted dividing the indications for navigation into the following four different categories: redundant, reasonable, helpful, necessary. Navigation was redundant when it was dispensable and did not result in a clear improvement of process or outcome quality. Navigation has been proved reasonable when it helped to obtain additional information for improving process quality. It was considered helpful when the information obtained by navigation had an influence at least on the course and/or result of surgery. Navigation was necessary from the surgeon's point of view when the intervention in regard to the benefit-risk-ratio could not be justified without navigation, or only intraoperative slice imaging would allow surgery. CONCLUSION: Not only redundant, but also facultative and obligatory indications for navigation in endonasal surgery result from careful consideration of the risk-benefit-cost ratio. In standardized endonasal sinus surgery, like infundibulotomy or ethmoidectomy, however, navigation can be a hindrance to process quality and does not result in any advantage for outcome quality.

Adult↗

PubMed2004

[Results with the Contour cochlear implant in patients with cochlear otosclerosis].

BACKGROUND: Results after cochlear implant surgery may be complicated by postoperative facial nerve stimulation. Aim of the study presented was to evaluate postoperative results in implanting the straight Nucleus electrode array and the preformed Contour array in patients with deafness due to cochlear otosclerosis. METHODS: A retrospective analysis of intra- and postoperative reports of all patients with cochlear otosclerosis was carried out. Results with the Nucleus straight electrode array and the Contour array were compared with regard to postoperative facial nerve stimulation. RESULTS AND CONCLUSION: None of the Contour patients (n = 7) presented with postoperative facial nerve stimulation. This is in contrast to the majority (4 of 6) of patients being implanted with the straight electrode array. Our results indicate that the use of the Contour array is advantageous in patients being at risk for facial nerve stimulation. In addition intraoperative reports suggest a more reliable insertion of the Contour electrode array in cochlear otosclerosis with partial obliteration.

Cochlear Implants↗

PubMed2004

[Caloric stimulation of the vestibular organ after cochlear implant surgery].

BACKGROUND: Alterations of the vestibular organ after intracochlear insertion of the electrode array in cochlear implant (CI) surgery are estimated in the literature to be more than 30 % . By performing a most atraumatic electrode insertion following the "soft surgery technique" as described by Lehnhardt , the risk of postoperative vestibular dysfunction should be minimised. METHODS: In the present study we compared pre- and postoperative results of the caloric stimulation test in cochlear implant patients and analysed the influence of untimely opening of the perilymphatic space under cochleostomy. In addition we used a non-validated questionnaire, asking for continuous postoperative vertigo after cochlear implant surgery. RESULTS: From patients with preoperative normal or hyperfunction on the implanted ear (n = 32) approximately 16 % showed a hypofunction or nonfunction on the implanted side postoperatively, independent of the technique of the cochleostomy. Only 12 % (n = 98) of the patients who were without vestibular problems preoperatively described postoperative vertigo longer than two days in the questionnaires. CONCLUSIONS: Although we found no significant difference regarding the influence of the technique of the cochleostomy on the preservation of vestibular function, we conclude that the concept of an atraumatic electrode insertion reduces the risk of vestibular dysfunction after CI-surgery.

Adolescent↗

PubMed2004

[Etiology and therapy of the internal jugular vein thrombosis].

BACKGROUND: Thromboses of the upper limp and neck are rare in comparison with those of the lower extremities. Internal jugular vein thrombosis (IJVT) is a serious event with a potentially fatal outcome. Complications include pulmonary embolism, sepsis with septic emboli to different organs and tissues as well as intracranial propagation of the thrombus with cerebral edema. As any thrombosis, IJVT is precipitated by Virchow's triad: endothelial damage, alteration of blood flow and hypercoagulability. The history and examination in patients with an IJVT may be vague and misleading. Patients may present with a painful swelling of the neck but they may also be absolutely asymptomatic. Imaging procedures frequently used to diagnose an IJVT include sonography with color-coded duplex sonography, computed tomography, magnetic resonance imaging as well as magnetic resonance venography. Up to date, there is no standardized treatment regimen for patients with an IJVT. PATIENTS AND METHODS: This retrospective study includes all ten patients with an IJVT who were seen at our department between January 2000 and January 2004. There were six female and four male patients. The average age was 49.7 years, ranging from 28 to 79 years. RESULTS: In five cases, the thrombosis was associated with a malignant tumor. In four patients, it was caused by a deep neck space infection and in one case the IJVT was due to cervical, intravenous drug abuse. Two patients were found to be pregnant (one tumor patient and one patient with a deep neck space infection). In all cases, a ten day treatment regimen with intravenous antibiotics and anticoagulant therapy was initiated. Oral or subcutaneous anticoagulation was continued for six weeks to six months. No complications were seen in any patient. In three patients a revascularization of the affected vessel could be demonstrated with color-coded duplex sonography six months after the initial presentation. CONCLUSIONS: Thrombosis of the IJV is probably underdiagnosed. Since the clinical presentation may be vague or misleading, a high degree of suspicion is required to make the diagnosis. The potential complications such as pulmonary embolism or intracranial propagation of the thrombus may be fatal. Whenever the thrombosis is not caused by an inflammatory process, a malignant tumor should be excluded. We recommend a therapy with intravenous antibiotics as well as a systemic anticoagulation. Ligation or resection of the internal jugular vein is reserved for patients who develop complications despite adequate medical therapy.

Administration, Oral↗

PubMed2004

[Identification of two heterozygous mutations in the SLC26A4/PDS gene in a family with Pendred-syndrome].

BACKGROUND: Pendred-syndrome is an autosomal recessive disease that is classically characterised by sensorineural hearing loss and enlargement of the thyroid gland. The gene SLC26A4/PDS for the pendred-syndrome has been localised by linkage analysis on chromosome 7q31. This protein is expressed in the inner ear, thyroid gland, kidney and placenta. Functional analysis in Xenopus laevis oocytes revealed that it acts as an iodide/chloride and chloride/formate exchanger. METHOD: Each of the exons and flanking splice regions of the SLC26A4/PDS gene was analysed by direct sequencing. RESULTS: In the involved family two heterozygous mutations could be detected which results by combination in hearing loss and deafness. CONCLUSION: By evidences of familial background in hearing loss and thyroid disorder it is reasonable to analyse the PDS gene for mutation to have early the possibility for medical care of linguistic development through hearing aid or CI-implantation.

Child↗