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R Heermann

Publications and source records attributed to R Heermann.

At least 19 recordsLinked to original sources
PubMed2006

[Paediatric cochlear implantation in the first year of life: preliminary results].

BACKGROUND: The success of cochlear implants in children was followed by a stepwise reduction in age at time of surgery. As a result of newborn hearing-screening (NHS) and the reliable audiologic diagnostic procedure, the question is raised as to whether an implantation before the age of 1 year is effective and safe in terms of surgery and rehabilitation. METHOD AND PATIENTS: This retrospective study included 27 children implanted before the age of 1 year (Gr. 1) and 89 children implanted between the age of 1 and 2 years (Gr. 2). Patient related data were analysed for individual history, surgery, rehabilitation and speech understanding. RESULTS: The incidence of complications was not increased in Gr. 1. The fitting of a speech processor was effective and uneventful in all children. The development of hearing and speech understanding showed better results after 2 years in Gr. 1. This development is more obvious for absolute age and not to rehabilitation time. CONCLUSION: In order to achieve an optimal timing for the development of speech understanding, cochlear implantation should be performed before the age of 2 years. This study revealed no additional risks for children in Gr. 1, but the development of speech understanding was better. As a consequence, cochlear implantation should be considered for very young children with an identified bilateral profound hearing loss.

Cochlear Implantation↗
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

In vitro measurement conditions for optical coherence tomography (OCT).

CONCLUSION: Tissue marking with soot-covered fine needles enables the optical coherence tomography (OCT) scanning plane to be localized within the histological specimen to an accuracy of approximately 50 microm. Tissue water content is an especially important parameter for in vitro measurements. Dehydration tends to produce an increase in surface reflections and a reduction in imaging depth. OBJECTIVES: The aim of this in vitro study was to evaluate parameters relevant to the visualization and conservation process to allow optimal images to be generated for later differentiation between healthy and degenerated tissue in vivo. MATERIALS AND METHODS: Various methods of marking samples were applied in vitro to achieve accurate overlaps of the OCT scanning plane and the corresponding section of the histological specimen. The influence of temperature and tissue water content was investigated using both porcine and human tissue. Samples were marked using fine needles, ablation craters generated by laser application, and colour markers introduced into the tissue. RESULTS: It was demonstrated that the water content of tissue exerts a direct influence on OCT imaging, whereas above 15 degrees C temperature had no effect on image quality. With regard to the marking of samples, the best results were obtained using sooted fine needles.

Adipose Tissue↗
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↗
PubMed2005

The laryngeal tube for difficult airway management: a prospective investigation in patients with pharyngeal and laryngeal tumours.

BACKGROUND AND OBJECTIVE: Since the introduction of the laryngeal mask into clinical practice, various additional supraglottic ventilatory devices have been developed. Although it has been demonstrated that the laryngeal tube is an effective airway device during positive pressure ventilation no clinical study has been performed thus far regarding its use in patients with predicted ventilation and intubation difficulties. METHODS: The aim of this study was to prospectively evaluate the use of the laryngeal tube for temporary oxygenation and ventilation in adult patients with supraglottic airway tumours scheduled to undergo a pharyngeal-laryngeal oesophagoscopy and bronchoscopy under general anaesthesia. In addition to our standard airway management with face mask ventilation and rigid bronchoscopy, all patients were temporarily ventilated with an laryngeal tube. Also, in patients requiring laryngeal biopsies, endotracheal intubation was performed with a 6.0 mm microlaryngeal tracheal tube. Minute ventilation volumes, tidal volumes, ventilation pressures, end-expiratory CO2 concentration, oxygen saturation and arterial blood gas samples were measured. RESULTS: From 54 enrolled patients only patients with relevant tumour masses were evaluated (n = 23). Mask ventilation was performed without difficulty in 15 of 23 patients. Mechanical ventilation with the laryngeal tube was possible in 22 of 23 patients with an audible leak present in three. Conventional endotracheal intubation was successfully performed in 19 of 23 patients. During face mask ventilation, minute volume, tidal volume, ventilation pressure, end-tidal CO2, oxygen saturation and arterial PO2 were significantly lower and PCO2 significantly higher (P < 0.05, paired t-test). No statistically significant differences were noted between the laryngeal tube and the microlaryngeal tracheal tube. CONCLUSIONS: The possibility of difficult ventilation and intubation must always be considered, in patients with supraglottic airway tumours. In these cases, the laryngeal tube can be considered for routine airway management and may be useful in the 'cannot-intubate' situation although difficulties should be anticipated in patients with previous irradiation, specifically of the throat area.

Adult↗
PubMed2005

Effect of loteprednol etabonate nasal spray suspension on seasonal allergic rhinitis assessed by allergen challenge in an environmental exposure unit.

BACKGROUND: Loteprednol etabonate (LE) is a novel soft steroid that was designed to improve the benefit/risk ratio of topical corticosteroid therapy. This study assesses the clinical efficacy and safety of three different doses of LE nasal spray in seasonal allergic rhinitis (SAR). METHODS: In this single-center, double-blind, placebo-controlled, parallel-group trial 165 subjects with SAR to grass pollen received daily single doses of either 100, 200, 400 microg LE nasal spray, or placebo for 14 days. The patients underwent three 4-h allergen challenges with grass pollen in an environmental exposure unit at a screening visit (baseline) and on days 7 and 14 of treatment. Standardized nasal symptom scores were obtained every 20 min. Nasal flow, nasal secretions, and FEV(1) were measured every hour during allergen challenges. RESULTS: After 14 days of treatment, patients who received 400 microg LE had significantly lower total nasal symptom scores compared with those receiving placebo (P = 0.007). LE400 reduced rhinorrhea, nasal congestion, nasal itching, the amount of nasal secretions, and improved nasal flow as compared with placebo (P < 0.05). LE100 and LE200 were not significantly different from placebo. All treatments were well tolerated. CONCLUSIONS: Loteprednol 400 microg once daily is superior to placebo and the only effective dose tested in improving nasal symptoms and objective parameters in patients with SAR.

Administration, Intranasal↗
PubMed2004

Analysis of two-component signal transduction by mathematical modeling using the KdpD/KdpE system of Escherichia coli.

A mathematical model for the KdpD/KdpE two-component system is presented and its dynamical behavior is analyzed. KdpD and KdpE regulate expression of the kdpFABC operon encoding the high affinity K+ uptake system KdpFABC of Escherichia coli. The model is validated in a two step procedure: (i) the elements of the signal transduction part are reconstructed in vitro. Experiments with the purified sensor kinase and response regulator in presence or absence of DNA fragments comprising the response regulator binding-site are performed. (ii) The mRNA and molecule number of KdpFABC are determined in vivo at various extracellular K+ concentrations. Based on the identified parameters for the in vitro system it is shown, that different time hierarchies appear which are used for model reduction. Then the model is transformed in such a way that a singular perturbation problem is formulated. The analysis of the in vivo system shows that the model can be separated into two parts (submodels which are called functional units) that are connected only in a unidirectional way. Hereby one submodel represents signal transduction while the second submodel describes the gene expression.

Base Sequence↗
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↗
PubMed2003

[Navigation-supported surgery in the head and neck region].

Few of the pioneering manufacturers who attempted to develop navigation systems have been able to establish themselves within the market long-term. The same applies to the technological basis of these systems which aid intraoperative anatomical orientation. The first few systems registered the mechanical displacement of the navigational instrument's axes. Optoelectronic and electromagnetic methods are now prevalent. In contrast to electromagnetic systems, the "line of sight" between the camera system, the reference markers placed on the patient's head and the navigation instruments must remain unobstructed during the navigation process when using electrooptical navigation systems. Whereas, in the past, only preoperative CT scans were used for navigation, the integration of MRI and sonography--whose images can now be fused with each other and with those provided by other intraoperative imaging techniques such as fluoroscopy and endosonography--has become increasingly popular. Navigation systems require input of information about spatial conditions. This is carried out via procedures of registration and referencing, by means of which the relative position of reference markers at the head of the patient is correlated with the image data. The equipment is calibrated in the same way. Headsets, headbands and bone-anchored adapters are available for the fixation of the markers in the patient's head. Whereas the use of a headband or headset requires considerably less time, bone-anchored referencing increases the precision of the navigation system. The surgeon must be able to manage the different methods. In order to reduce the time required for preoperative preparation and to enhance the handling of the navigation processor for the surgeon, it is essential to have a clear menu. The surgeon is able to plan the steps involved in the surgery using the processor, define the access to the surgical site and control the surgery intraoperatively. Preoperative segmentation of functionally and clinically relevant structures enables minimally invasive surgery to be carried out, such as procedures with the aim of acquiring biopsy tissue and the search for foreign bodies. Following the technical development of the systems, the manufacturers are endeavouring to simplify their handling in close coordination with the users. The next step has to be the clinical evaluation of the navigation systems in accordance with the EBM standard, in order to establish this assistive method as routine clinical practice while applying meaningful medical criteria.

Endosonography↗
PubMed2002

[Pyoderma gangraenosum. Case report and comparison with necrotizing fasciitis].

The differential diagnosis of patients with ulcerative trachelophyma repeatedly causes difficulties. Particularly in view of the possibly fatal outcome, early differentiation between two clinical pictures is very important. Necrotizing fasciitis is often misdiagnosed or the diagnosis is delayed with a mortality rate of approximately 25-40%. It is characterized by local disintegration of the subcutaneous fascia and extensive gangrene of the skin. Sometimes it is not even possible to control the disease using combined antibiotics. Early surgical exploration is mandatory to stop progression of the disease. Pyoderma gangrenosum develops following an initial lesion with pustules and bullae in an ulceration with slight bleeding. Therapy consists of i.v. glucocorticoids (60-200 mg prednisolone/day) administered as early as possible. In complete contrast to the therapy for necrotizing fasciitis, surgical intervention should be strictly avoided in cases of pyoderma gangrenosum.

Adult↗
PubMed2002

[Application of Optical Coherence Tomography (OCT) in middle ear surgery].

BACKGROUND: Middle ear surgery has reached an advanced stage of development over the last few decades. The use of biocompatible materials offers new possibilities in ossiculoplasty. The exact calculation concerning the length of the implant to be used, however, still poses considerable difficulties and is an additional cause for a remaining air conduction difference or a further surgical intervention. METHODS: Optical coherence tomography (OCT) is a non-invasive imaging procedure for the imaging of tissue structures with a resolution accurate to micrometres. OCT can be operated touch-free and for this reason does not require any means of contact between applicator and sample. In the present study an optical coherence inferometre was coupled to an operating microscope and used in 5 stapedoplasties and 5 tympanoplasties type III in order to determine the length of the prosthesis to be used. RESULTS: The use of OCT implies an intraoperative measuring time of only a few seconds. The coupling in the optical path of an operating microscope allows trouble-free handling. The measurement of middle ear structures has an accuracy of 30 micrometer. The postoperative audiological results show a good auditory performance. CONCLUSIONS: Initial experience with OCT indicates that the technology will be extremely interesting for otosurgery. Improvements in functional pattern will enable routine intervention in connection with an operating microscope. Further OCT applications for tissue differentiation will have to follow.

Equipment Design↗
PubMed2001

[Skull base surgery with an opto-electronic navigation system].

BACKGROUND AND OBJECTIVE: The exact localization of pathological anatomy is the basis of a successful operation. Malformations, tumors, or previous operations can make intraoperative orientation considerably more difficult. Navigation systems can be useful tools in such cases. METHODS: The OTS is an optoelectrical navigation system which was used on 34 patients with disorders of the skull base region. Clinical accuracy, practicability, and intraoperative usefulness of the system were evaluated. RESULTS: In clinical use, an accuracy of approximately 1.5 mm could only be achieved with the use of head fixation and bone-anchored reference markers. When using the VBH mouthpiece for dynamic referencing with flexible head positioning, deviations of less than 2 mm were observed. The preoperative preparation time was 15-25 min, depending on the operation schedule. CONCLUSIONS: The intraoperative orientation system represents a significant aid for orientation, particularly where anatomical alterations are present. Further modifications to improve both accuracy and the integration of the system into working practice are, however, essential.

Adult↗
PubMed2001

[CAS-System MKM(R): use and results in lateral skull base surgery].

BACKGROUND: Computer assisted surgery has reached an advanced stage of development and offers new possibilities in daily surgical procedures. METHODS: The MKM(R) - is a navigation system fitted with a laser-guided, autofocus-microscope for referencing purposes. The coordinates can be set using various marker systems and a special workstation is used for preoperative planning. It is possible to add landmarks and display them in the surgeon's eyepiece. The clinical integration, the time required for the use of the navigation system and the intraoperative accuracy of the system were evaluated on the basis of 136 lateral skull base procedures. RESULTS: The degree of accuracy is determined by the type, amount and positioning of markers. The adjustment of reference points should be carried out following macrosurgery in order to avoid shifting factors. For an additional increase in accuracy, an improvement in the spatial resolution of the CT scans is required, with a section thickness of 1 mm and a pixel size of 0.5mm. The bone-anchored structures of the temporal bone do not underlie shifting or extensive intraoperative swelling. Skull base surgery is, therefore, ideally suited for the application of CAS. We found that registration was accurate to less than 1 mm (0.68 mm +/- 0.17 mm) and that the MKM(R) system made an additional contribution to surgical safety by identifying important structures. CONCLUSIONS: A practical accuracy found to be approximately one millimetre suggests that the non-invasive referencing system may be effective, accurate and useful for computer assisted identification of vital structures. We expect navigation systems to improve the quality and reduce the risks of surgical intraventions.

Adult↗