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Biomedical subjects

Th Lenarz

Publications and source records attributed to Th Lenarz.

10 recordsLinked to original sources
PubMed2006

Intraoperative computed tomography in otorhinolaryngology.

CONCLUSIONS: Intraoperative CT surgery provides the surgeon with additional information about the altered surgical site in difficult anatomical situations. The skull base and lamina papyracea may be revealed by means of intraoperative CT, which may be beneficial in endonasal sinus surgery involving difficult surgical sites, although individual ethmoid cells cannot be assessed owing to blood artefacts. This provides the surgeon with valuable information that may facilitate the procedure considerably. In soft-tissue surgery it is advisable to apply a contrast agent in order to achieve good soft-tissue contrast, thus allowing the tumour to be adequately distinguished from benign tissue. The intraoperative application of CT is a fairly time-consuming procedure, partly owing to the preparation time (set-up of the appliance; 10-min warming-up phase) and partly due to the length of time required to calculate each image (15 s). OBJECTIVE: CT is a well-established imaging method for the assessment of osseous and soft-tissue structures in the head and neck region. Saving information and transferring it to the intraoperative site may, however, be problematic. Computer-assisted navigation systems are now able to assist difficult surgical procedures in the field of otolaryngology. To investigate the indications for intraoperative CT, we used it in various surgical procedures in the head and neck region. MATERIAL AND METHODS: Intraoperative CT was applied using the Tomoscan M in 46 cases in order to demonstrate the surgical benefit of the following procedures: endonasal surgical procedures on the paranasal sinuses (maxillary and ethmoidal sinusitis, anterior fracture of the sphenoidal sinus); tumour removal by means of laser surgery (carcinomas of the hypopharynx and larynx); and cochlear implantation (to verify the electrode position). After positioning the patient on the CT table, the workstation was set up in the operating theatre. If necessary, the gantry could be moved over the patient's head without repositioning the patient. RESULTS: Intraoperative CT was used to assist in the exposure of the skull base and lamina papyracea in endonasal surgery of the paranasal sinuses. Individual ethmoidal sinuses could not be evaluated owing to blood artefacts. Intraoperative imaging proved particularly helpful in revision surgery for chronic sinusitis in cases with missing anatomical landmarks owing to previous surgeries, where there is an increased risk of inflicting damage to the skull base or orbita. The resection margins can be determined in craniofacial resections. In soft-tissue procedures, such as tumour removal by means of laser surgery, it proved possible to visualize the resection borders of malignant tumours. Assessment of the electrode position in cochlear implantation is particularly useful in revision cases and in cases of cochlear obliteration.

Cochlear Implantation↗
PubMed2006

Four years' experience with the minimally invasive surgical approach in cochlear implant surgery.

This is a prospective study on 808 profoundly or totally deaf patients who underwent either unilateral or bilateral cochlear implantation, involving a minimally invasive surgical approach, at the Medical University of Hannover's Department of Otolaryngology between May 2001 and May 2005. Advanced Bionics, Cochlear and MED-EL devices were used, the latter having been in use at our department since the beginning of 2003. The aim of our investigation was to determine the optimal surgical technique, evaluate safety aspects and gauge patient satisfaction with this minimally invasive surgical approach during cochlear implantation. Surgical technique is analysed. Complications such as skin flap problems did not occur. The use of this minimally invasive surgical technique did not increase the surgical risk. This procedure proved both cosmetically and psychologically beneficial for patients, especially for children and their parents.

Adult↗
PubMed2004

[Bone ablation using ultrashort laser pulses. A new technique for middle ear surgery].

OBJECTIVES: Laser applications within the tympanic cavity area are widely accepted. Commonly used systems are CO(2), argon, KTP and erbium devices. The disadvantages are heat development and/or acoustic load of the inner ear. A new laser with ultra short pulses was examined concerning its ablation characteristics and tested for possible applications in the tympanic cavity. METHODS: Investigations on human ossicles and porcine compacta were performed with a femtosecond laser in order to determine the ablation parameters. This included measurements of the dependency of the threshold energy on the pulse duration and the determination of the ablation ratio using different pulse energy levels. On the basis of histological slices the thermal damages of the bone were examined. Additionally, the processed samples were analyzed with an optical microscope and with a scanning electron microscope in order to evaluate the quality of the perforations. RESULTS: The measurements showed that the threshold energy has a lower level than the threshold energy of the conventional laser systems. At a pulse duration of 180 fs the smallest fluence, with which an erosion can be achieved, is below 1 J/cm(2). With increasing pulse duration the necessary threshold energy also rises. Due to the low energy level necessary for ablation and the extremely short pulse duration, less thermal damage is induced to the surrounding bone tissue as compared to conventional laser systems. The analysis of the scanning electron microscope demonstrates the extreme precision of this laser system. The achieved accuracy of the incisions and drillings ranges in the microm-area. CONCLUSIONS: The fs laser represents a new surgical tool for middle ear surgery. It works efficiently and in a touch-free procedure. Due to its high precision and the reduced side effects an advantage in the handling of bony structures is to be expected in relation to other laser systems. Apart from the perforation of the stapes footplate, in particular the handling and modelling of the incus, a further field of applications includes enhanced coupling, e. g. for implantable hearing aids and ossicular chain replacement prosthesis.

Animals↗
PubMed2004

[Use of the round window micro cath for inner ear therapy - results of a placebo-controlled, prospective study on chronic tinnitus].

BACKGROUND: The local therapy of inner ear diseases provides a means of directly applying pharmacological substances and delivering electrical stimulation to inner ear structures. Problems relating to dosage, systemic effects and the blood-cochlear barrier are thus avoided, which is not the case with systemic therapy. The preferred access point is the membrane of the round window. PATIENTS AND METHODS: An appropriately shaped catheter (DURECT Corporation, Cupertino, CA, USA), whose double-lumen passage system permits the variation of concentration and flow, is inserted into the round window niche. In a prospective, placebo-controlled clinical study, this application system was tested in 20 patients with chronic tinnitus. Following implantation the substances lidocaine, glutamate, glutamic acid and caroverine were applied via an attached external micropump. RESULTS: The values for tinnitus loudness, level of irritation caused by the tinnitus and subjective effectiveness of the therapy - measured by means of the visual analog scale (VAS) - showed no significant change, although the most marked improvement was indicated for caroverine. CONCLUSIONS: These results indicate that a positive effect was observable only in a proportion of the patients. Continuous therapy of tinnitus and inner ear diseases will only be possible once a totally implantable microdosage system has been developed.

Administration, Topical↗
PubMed2004

[The value of dynamic posturography (Equitest) in preparing an expert's report].

BACKGROUND: Expert appraisals of vestibular disorders and their effects on daily life are essentially based on an evaluation of the patient's subjectively described symptoms. The aim of the present study was to ascertain the extent to which dynamic posturography is able to assist in the preparation of expert's reports. MATERIAL AND METHODS: 60 patients underwent a survey of their balance impairment. Both a nystagmus analysis, with its objective criteria, and dynamic posturography were carried out. The investigation into reduction of fitness for work (MdE) made reference to the criteria specified in the table by STOLL. The data obtained were subjected to both correlation and variance analysis. RESULTS: Although the results of this analysis revealed no direct statistical dependency, they indicated a tendency for the composite values to be correlated with the nystagmus scores and/or the MdE values (when the nystagmus score and/or the MdE increases, the composite value decreases). CONCLUSIONS: The Equitest is, according to the available data, not able to replace the currently valid MdE scores. Nevertheless, it represents a means of providing objective data about the vestibulo-spinal reflex. The test also reveals any tendencies towards simulation and aggravation. In the context of a specific nystagmus analysis, the Equitest offers an additional means of providing an objective background to back up the more subjective assessment of MdE.

Adolescent↗
PubMed2004

[The interesting case -- case number 61].

A 58-year-old patient presented after having undergone radiation therapy, afterloading therapy and chemotherapy of a T4 nasopharynx carcinoma. On the basis of the MRI findings, local tumour recurrence was suspected. The samples taken from the nasopharynx and the left maxillary sinus confirmed this diagnosis. Neuroradiological imaging showed that the tumour extended into the area around the left skull base and also revealed an irregular formation located in the left temporal flap. Therefore not only tumour resection (Fisch approach type C) but also a temporal craniotomy was indicated in order to determine the degree of intracerebral tumour extension. The dura mater, which had been intact, was intraoperatively opened and revealed vital brain tissue, i. e. tumour infiltration had not reached the brain. It was concluded that the radiological findings probably indicated a postradiogenic necrosis of the temporal flap. The presented case illustrates the rare differential diagnostic procedure carried out in a patient with radiogenic necrosis while taking into account the possibility of local tumour infiltration into the brain parenchyma.

Brachytherapy↗
PubMed2003

[Pediatric cost-benefit analysis].

BACKGROUND: The aim of this study was to explore the cost-benefit-ratio of pediatric cochlear implantation for congenitally deaf and prelingually deafened children compared to children with hearing aids. The payers' perspective was chosen as this is the most relevant for cost discussions. The study should verify the hypothesis that educational and associated full costs increase with the age at implantation and that these can be below costs for children with hearing aids. METHODS: Children implanted at different ages (group 1: 0 - 1.9 yr., group 2: 2 - 3.9 yr., group 3: 4 - 6.9 yr.) were compared with deaf children using hearing aids (group 4). Payers were sick funds and public authorities, the first paying for medical and indirect costs, the latter paying for education. Educational settings were used as measure for benefit. All costs related to the hearing deficiency were included up to the age of 16 years (end of primary education) based on 1999 costs. RESULTS: Discounted medical and indirect costs for a pediatric cochlear implant user varied between DM 112,000 (53,300 US dollars) and DM 91,000 (43,300 US dollars) depending on the age at implantation. Costs for a hearing aid user added up to DM 36,000 (17,100 US dollars). These costs were paid by the sick funds. Costs for education varied between DM 159,000 (75,700 US dollars) for group 1 and DM 257,000 (122,400 US dollars) for group 3 compared to DM 277,000 (131,900 US dollars) for hearing aid users. These differences are mainly based on the use of mainstream schools. Total costs for sick funds and public authorities ad up to DM 271,000 (129,000 US dollars), DM 334,000 (159,000 US dollars) and DM 348,000 (165,700 US dollars), respectively, for the three age groups of implanted children compared to DM 313,000 (148,600 US dollars) for hearing aid users. CONCLUSION: This study supports the view that pediatric cochlear implantation provides positive cost-benefit ratios compared to hearing aid users depending on the age at implantation. From a societal/payer perspective implantation of prelingually deafened children is especially recommended for children under the age of 2 years. Implantation between ages 2 and 3,9 can be recommended from an educational perspective. Implantation at ages >7 years must be based on individual decisions considering psychosocial environment, speech and language status and type of communication.

Adolescent↗
PubMed2002

[Long term results in adenoidcystic carcinoma].

BACKGROUND: Due to the discreet initial symptoms and the locally aggressive infiltration with perineural spread the adenoidcystic carcinoma (ACC) presents a special diagnostical and therapeutical challenge. PATIENTS: : In a retrospective study the forms of 54 patients were analysed, whose average age was 55.5 (24 - 77) years. RESULTS: The sex ratio showed a slight female preponderance with 57 % to 43 %. The major salivary glands were affected in 26 cases. The exact distribution of the ACC was: parotid gland (n = 18), submandibular gland (n = 8), oral cavity (n = 10), paranasal sinuses (n = 11), nasopharynx (n = 4) and larynx (n = 3). The most common symptoms were a tumor-related swelling and pain which persisted for a duration of several months after final diagnosis could be established. Facial palsy was observed in 4 patients. Histological examination revealed a tubular subtype in 4 cases, in 28 cases a cribriforme and in 12 cases a solid subtype. No definitive differentiation was possible in 10 specimens. The skull base was infiltrated in 16 patients. Except one patient all 54 underwent surgical therapy. Postoperative radiotherapy was additionally given in 25 cases which was combined with a chemotherapy in 6 patients. Nevertheless ACC recurred in 60 % of our patients. Lymphnode metastases were observed in 13 patients after a latency of 3.3 years in average, but predominantly pulmonary metastases as distant spread developed in 18 patients after 5.8 years significantly later. The overall survival rate was 84.38 % after 2 years, 75.90 % after 5 years, 50.49 % after 10 years and 20.11 % after 20 years. Male sex, infiltration of the skull base and histological evidence of perineural and perivascular spread proved to be statistically significant factors for an unfavourable prognosis. CONCLUSIONS: Due to the uncommon biological behaviour with a slow growth on the one hand side and an aggressive local invasion on the other hand side the ACC can be regarded as a challenging malignant disease for the clinician whose adequate therapy does not allow any standardized regime. The tendency for recurrence even after a period clinically free of symptoms makes a life long follow-up mandatory.

Adult↗
PubMed2002

The results in patients implanted with the nucleus double array cochlear implant: pitch discrimination and auditory performance.

OBJECTIVE: In patients with total or surgically inaccessible cochlear obliteration, only a reduced number of active electrodes can be inserted with standard cochlear implants, resulting in below average auditory performance. Therefore, a special implant with two electrode arrays was developed on the basis of the Nucleus 22 cochlear implant, the socalled Double Array. One electrode array with 11 active electrodes is inserted into the basal turn of the cochlea, while the second array with 10 active electrodes is inserted into the second turn. The Double Array is now available on the basis of the more advanced Nucleus 24 with 11 active electrodes on each array and two reference electrodes, one at the case and the second one an additional ball electrode, which is placed under the temporalis muscle. For device description and surgical technique see Lenarz et al. (2001). This paper presents psychophysical data on pitch discrimination and auditory performance of patients implanted with a Double Array on the basis of the Nucleus 22. STUDY DESIGN: A prospective intra-individual study using a Latin square paradigm was performed in six adult patients with obliterated cochlea who received the Nucleus 22 Double Array. After appropriate fitting and loudness balancing, patients were tested either with the basal, the apical or both electrode arrays. Apart from auditory performance tests including numbers and monosyllable word tests, pitch discrimination was determined with a defined procedure. RESULTS: When activating each array alone, auditory performance was better with the basal array than with the apical array. Both arrays together showed marked improvement compared with the basal array, indicating an additional effect of the second array. Pitch discrimination was significantly better for the electrodes in the basal turn than in the second turn, indicating differences in electrical excitation of the auditory nerve fibers. Pitch discrimination was positively correlated with auditory performance data. CONCLUSION: The additional apical array leads to significant improvement in auditory performance in patients with obliterated cochleae by increasing the number of intracochlear electrodes. Despite reduced pitch discrimination, the apical array provides important information for speech recognition. For this reason the Double Array provides a profound advantage for patients with obliterated or surgically inaccessible cochleae.

Acoustic Stimulation↗