[Diagnosis of sleep disordered breathing using portable methods]. / Diagnostik schlafbezogener Atmungsstörungen mittels portabler Verfahren.

Portable monitoring of sleep disordered breathing is the first diagnostic method not only in Germany but today in other countries as well. The conditions under which portable monitoring can be done with reliable results are now well defined. The limitations for the use of portable monitoring are specified as well. The devices used for portable monitoring are classified in four categories according to the number and the kind of signals recorded. New technical developments in the field of portable monitoring (polygraphy) use an indirect assessment of sleep disordered breathing based on signals not directly recording respiration. The recording of ECG and deriving respiration, the analysis of the plethysmographically recorded pulse wave, the recording of jaw movements using magnets, and advanced analysis of respiratory sounds are recent approaches. These new methods are presented with few studies until now. More and larger clinical studies are needed in order to show which of these systems is useful in the diagnosis of sleep disordered breathing and which are the specific strengths and weaknesses.

[Portable sleep monitoring in patients with disorders in falling asleep or maintaining sleep]. / Erweiterte ambulante Polygraphie bei Patienten mit Ein- und/oder Durchschlafstörungen.

BACKGROUND: The most common diagnoses in sleep medicine are insomnia, sleep disordered breathing (SDB) and periodic leg movements (PLM). These disorders may coincide. This study examined the role of portable sleep monitoring in the diagnostic process and which sleep medicine diagnoses are additionally found in patients with disorders of initiating and maintaining sleep. METHODS: A total of 217 patients, including 103 men (47.5%) and 114 (52.5%) women aged 52.2 ± 13.6 years with disorders of initiating or maintaining sleep were included in the study. Patients with known SDB were excluded. Patients were investigated using a stepwise diagnostic procedure with clinical interviews, questionnaires, clinical examination and portable sleep recording with electromyography (EMG) of the tibialis anterior muscle to diagnose SDB and PLM. RESULTS: Of the patients 125 (57.6%) were diagnosed with insomnia according to the International Classification of Sleep Disorders (ICSD) and 70 (56%) had no other sleep disorder. Out of the 217 patients SDB was found in 107 (49.3%) patients, PLM in 90 patients (41.5%) and in 78 patients (35.9%) restless legs syndrome (RLS) was diagnosed. Among the 125 patients with insomnia 44 patients had RLS/PLMD and 35 had SDB in addition whereas SDB and RLS/PLMD were found in 33 subjects. All 3 disorders insomnia, RLS/PLMD and SDB were found in 24 subjects. CONCLUSIONS: Out of 217 patients with a complaint of non-restorative sleep only 125 were finally diagnosed with insomnia. As 25.3% of patients showed combinations of sleep disorders, 49.3% with SDB and 41.5% with RLS/PLMD portable monitoring with electromyography of the legs is recommended. The investigation with a portable sleep monitoring system including an EMG of the tibialis muscle is very useful in patients with insomnia in addition to a clinical interview and questionnaires.

Spontaneous gallbladder pathology in baboons.

BACKGROUND: Gallbladder pathology (GBP) is a relatively uncommon, naturally occurring morbidity in both baboons and humans. METHODS: A retrospective analysis was performed on 7776 necropsy reports over a 20 year period to determine the prevalence of baboon GBP. RESULTS: Ninety-seven cases of GBP were identified, yielding a 20 year population prevalence of 1.25%. GBP is more common in adult female baboons, occurring with a female to male ratio of nearly 2:1. Among gallbladder pathologies, cholecystitis (35.1%) and cholelithiasis (29.9%) were the most prevalent abnormalities, followed by hyperplasia (16.5%), edema (15.5%), amyloidosis (5.2%), fibrosis (4.1%), necrosis (4.1%), and hemorrhage (1.0%). CONCLUSION: Many epidemiologic similarities exist between GBP in baboons and humans suggesting that the baboon may serve as a reliable animal model system for investigating GBP in humans.

Mutations in the familial Mediterranean fever gene of patients with IgA nephropathy and other forms of glomerulonephritis.

Glomerulonephritis, particularly IgA nephropathy (IgAN), seems to be more common in familial Mediterranean fever (FMF), an inherited disease caused by mutations in the MEditerranean FeVer gene (MEFV). The present study is aimed to determine, in populations not suffering from FMF, whether carriage of MEFV mutations may modify or precipitate IgAN and other forms of primary glomerulonephritis (PGN). Forty patients with biopsy proven IgAN and 40 with PGN were surveyed for the presence of the three most common MEFV mutations (M694V, V726A and E148Q), using polymerase chain reaction amplification and restriction enzyme analysis. The rate of MEFV mutations in the patients was related to the expected carrier rate in the general population of the same ethnic extraction. The effect of mutation carriage on the disease course was determined in the IgAN patient group. The frequency of MEFV mutations in IgAN or PGN was comparable to that found in ethnically adjusted general population (p = 0.1 and 0.5, respectively). Carriage of mutated MEFV was not associated with the course and severity of the disease or findings in kidney biopsy and urine analysis. In a population, mostly of Jewish extraction, MEFV mutations do not seem to predispose to the development of IgAN and other forms of PGN or affect the phenotype.

A CMOS-based microelectrode array for interaction with neuronal cultures.

We report on the system integration of a CMOS chip that is capable of bidirectionally communicating (stimulation and recording) with electrogenic cells such as neurons or cardiomyocytes and that is targeted at investigating electrical signal propagation within cellular networks in vitro. The overall system consists of three major subunits: first, the core component is a 6.5 mm x 6.5 mm CMOS chip, on top of which the cells are cultured. It features 128 bidirectional electrodes, each equipped with dedicated analog filters and amplification stages and a stimulation buffer. The electrodes are sampled at 20 kHz with 8-bit resolution. The measured input-referred circuitry noise is 5.9 microV root mean square (10 Hz to 100 kHz), which allows to reliably detect the cell signals ranging from 1 mVpp down to 40 microVpp. Additionally, temperature sensors, a digital-to-analog converter for stimulation, and a digital interface for data transmission are integrated. Second, there is a reconfigurable logic device, which provides chip control, event detection, data buffering and an USB interface, capable of processing the 2.56 million samples per second. The third element includes software that is running on a standard PC performing data capturing, processing, and visualization. Experiments involving the stimulation of neurons with two different spatio-temporal patterns and the recording of the triggered spiking activity have been carried out. The response patterns have been successfully classified (83% correct) with respect to the different stimulation patterns. The advantages over current microelectrode arrays, as has been demonstrated in the experiments, include the capability to stimulate (voltage stimulation, 8 bit, 60 kHz) spatio-temporal patterns on arbitrary sets of electrodes and the fast stimulation reset mechanism that allows to record neuronal signals on a stimulating electrode 5 ms after stimulation (instantaneously on all other electrodes). Other advantages of the overall system include the small number of needed electrical connections due to the digital interface and the short latency time that allows to initiate a stimulation less than 2 ms after the detection of an action potential in closed-loop configurations.

Single-chip microelectronic system to interface with living cells.

A high degree of connectivity and the coordinated electrical activity of neural cells or networks are believed to be the reason that the brain is capable of highly sophisticated information processing. Likewise, the effectiveness of an animal heart largely depends on such coordinated cell activity. To advance our understanding of these complex biological systems, high spatiotemporal-resolution techniques to monitor the cell electrical activity and an ideally seamless interaction between cells and recording devices are desired. Here we present a monolithic microsystem in complementary metal oxide semiconductor (CMOS) technology that provides bidirectional communication (stimulation and recording) between standard electronics technology and cultured electrogenic cells. The microchip can be directly used as a substrate for cell culturing, it features circuitry units per electrode for stimulation and immediate cell signal treatment, and it provides on-chip signal transformation as well as a digital interface so that a very fast, almost real-time interaction (2 ms loop time from event recognition to, e.g., a defined stimulation) is possible at remarkable signal quality. The corresponding spontaneous and stimulated electrical activity recordings with neuronal and cardiac cell cultures will be presented. The system can be used to, e.g., study the development of neural networks, reveal the effects of neuronal plasticity and study cellular or network activity in response to pharmacological treatments.

[Are there alternative therapeutical options other than CPAP in the treatment of the obstructive sleep apnea syndrome]. / Gibt es Alternativen zum nCPAP-Verfahren in der Behandlung des obstruktiven Schlafapnoesyndroms?

Many patients with the obstructive sleep apnea syndrome (OSAS) look for alternative conservative or surgical therapies to avoid to be treated with continuous positive airway pressure. In view of the high prevalence and the relevant impairment of the patients lots of methods are offered which promise definitive cure or relevant improvement of OSAS. The working group "Apnea" in the German Society of Sleep Medicine and Research established a task force to evaluate the scientific literature on non-CPAP therapies in the treatment of OSAS according to the standards of evidence-based medicine. This paper summarizes the results of the task force. The data were unsatisfactorily for most of the methods. Sufficient data were available for intraoral appliances (IOA) and the maxillomandibular osteotomy (MMO). IOA's can reduce mild to moderate respiratory disturbances, MMO are efficient in the short and long term but are performed only in special situations such as craniofacial dysmorphias. Weight reduction and body positioning cannot be recommended as a single treatment of OSAS. Most surgical procedures still lack sufficient data according to the criteria of evidence based medicine. Resections of muscular tissue within the soft palate have to be strictly avoided. But even success following gentle soft palate procedures is difficult to predict and often decreases after years. Results in other anatomical regions seem to be more stable over time. Today combined surgeries in the sense of multi-level surgery concepts are of increasing interest in the secondary treatment after failure of nasal ventilation therapy although more data from prospective controlled studies are needed. There is no evidence for any other treatment options.

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia diagnosed by transbronchial lung cryobiopsy: a case report.

BACKGROUND: Micronodular lesions are common findings in lung imaging. As an important differential diagnosis, we describe a case of diffuse idiopathic pulmonary neuroendocrine cell hyperplasia; it is notable that the diagnosis of diffuse idiopathic pulmonary neuroendocrine cell hyperplasia is often delayed. This case provides supporting evidence to establish lung biopsy by cryotechnique as the option of first choice when considering a diagnostic strategy for micronodular lung lesions. CASE PRESENTATION: We report a case of a 65-year-old white woman who presented with obstructive symptoms of chronic coughing and dyspnea confirmed by conventional lung function tests. A computed tomography scan presented disseminated micronodules in all the lobes of her lungs. With the help of bronchoscopic cryobiopsy it was possible to obtain a high yield sample of lung parenchyma. On histologic examination, the micronodules correlated with a diffuse neuroendocrine cell hyperplasia. In the context of clinical symptoms, radiological aspects, and histomorphological aspects we made the diagnosis of a diffuse idiopathic pulmonary neuroendocrine cell hyperplasia. Obstructive symptoms were treated with inhaled steroids and beta-2-mimetics continuously. A comparison between current computed tomography scans of our patient and scans of 2014 revealed no significant changes. Last ambulatory checks occurred in January and May of 2016. The course of disease and the extent of limitation of lung function have remained stable. CONCLUSIONS: The diagnosis of diffuse idiopathic pulmonary neuroendocrine cell hyperplasia is best made in a multidisciplinary review including clinical presentation, lung imaging, and histomorphological aspects. This report and current literature indicate that transbronchial lung cryobiopsy can be used as a safe and practicable tool to obtain high quality biopsies of lung parenchyma in order to diagnose micronodular lesions of the lung.

Dementia. Age-dependent incidence, prevalence, and mortality in the old old.

Age has been reported as a strong risk factor for dementia. Supporting data have been derived mainly from prevalence studies, which had varied criteria and sample compositions that precluded direct comparisons, especially among those aged 85 years and older. Data regarding rates of dementia are presented based on 85 incident cases in the Bronx (NY) Aging Study, a prospective study of 488 initially nondemented, old old persons (mean age on entry, 79 years). Overall, the incidence rate over 8 years of follow-up for all-cause dementia was 3.4 per 100 per year (43% Alzheimer's disease, 30% mixed Alzheimer's and vascular, and 27% other). Incidence rose significantly, irrespective of gender, as subjects were followed up through three age intervals--ages 75 to 79 years (1.3/100 per year), 80 to 84 years (3.5), and 85 years and older (6.0). The comparable age-associated prevalence rates of dementia were 3.7%, 12.2%, and 23.9%, respectively, with an overall period prevalence of 22.8%. Additionally, there was a threefold greater mortality associated with dementia. In conclusion, despite the shortened life expectancy of demented persons, dementia is a highly prevalent condition among those aged 85 years and older. Public policy attention is warranted, since this group is the fastest growing population subgroup.

Identification of normal and pathological aging in prospectively studied nondemented elderly humans.

Results of a standardized histochemical and immunocytochemical analysis of the brains of 14 nondemented elderly humans for whom prospective neurological and neuropsychological data had been collected for 3 to 8 years before death suggested that nondemented elderly humans fall into two pathological subgroups that are not clinically distinguishable. One was associated with moderate to marked cerebral amyloid deposition ("pathological aging"), while the other had either minimal or no amyloid deposition ("normal aging"). Neocortical and hippocampal neurofibrillary degeneration was either completely absent or of very limited degree in both subgroups. Both subgroups had ubiquitin-immunoreactive dystrophic neurites in the cerebral cortex and granular degeneration of myelin in white matter. These ubiquitin-immunoreactive structures seem to be a universal and invariant manifestation of brain aging, but the same cannot be said for amyloid deposition and neurofibrillary degeneration. Pathological aging might be preclinical Alzheimer's disease, but it currently cannot be distinguished from normal aging by even sensitive neuropsychological measures. These findings provide strong support for the hypothesis that cerebral amyloid deposition is not necessarily associated with clinically apparent cognitive dysfunction and that additional factors, such as neuronal or synaptic loss or widespread cytoskeletal aberrations, are necessary for dementia in AD.

Effect of low-calorie diets on the sympathetic nervous system, body weight, and plasma insulin in overweight hypertension.

When weight reduction was found to decrease blood pressure in the overweight hypertensive patient, it was hailed as the causative factor. A growing number of recent studies indicate that this association may be secondary to a correlation between diet-associated metabolic change and the sympathetic nervous system. A select group such as overweight hypertensive patients may have a genetic predisposition for such a correlation. In overweight hypertensive patients, low-calorie diet and especially very-low-calorie diet, correlate with improved glucose metabolism, a decrease in plasma insulin concentration, and altered norepinephrine concentrations and thus sympathetic nervous system activity. Several of these studies also show a lack of effect of salt intake on blood pressure. Thus, it seems that metabolic changes caused by the decrease in caloric intake are responsible for the decrease in blood pressure. These must be investigated to understand the effect of the different diets on blood pressure. Very low-calorie diets were found very useful in breaking the vicious circle of severe nonresponsive hypertension to medication.

Associations of status and change measures of neuropsychological function with pathologic changes in elderly, originally nondemented subjects.

OBJECTIVE: To describe the association between status and change of neuropsychological function and postmortem neuropathologic findings in subjects with Alzheimer's disease, vascular dementia, normal aging, and pathologic aging. DESIGN: Volunteer cohort study. SETTING: Volunteers were interviewed and tested in outpatient-clinical research offices. PARTICIPANTS: Nondemented, healthy, community-residing subjects, initially between 75 and 85 years of age, who participated in the Bronx Aging Study and had at least 2 years of neuropsychological data and quantitative neuropathologic examinations. MAIN OUTCOME MEASURES: Initial summary neuropsychological score, rate of change score. RESULTS: Summary neuropsychological scores at baseline in subjects who subsequently developed pathologically confirmed Alzheimer's disease or vascular dementia were 0.8 z units lower than those of subjects classified in the normal or pathologic aging subgroups (P < .05). Subjects with Alzheimer's disease showed more neuropsychological change over time than subjects in the normal or pathologic aging groups (P < .001). Normal subjects and subjects with pathologic aging did not differ in baseline scores or rate of change. Level of education was strongly associated with initial neuropsychological scores (P < .004), but not with change scores. CONCLUSIONS: Among elderly, initially nondemented subjects who were followed up until death, subjects with pathologically confirmed Alzheimer's disease or vascular dementia had lower neuropsychological scores at initial evaluation than normal subjects or subjects with pathologic aging. Subjects with Alzheimer's disease had a more rapid rate of decline than normal subjects or subjects with pathologic aging.

Patients with stroke confined to basal ganglia have diminished response to rehabilitation efforts.

Prediction of the functional outcome for patients with stroke has depended on the severity of impairment, location of brain injury, age, and general medical condition. This study compared admission and discharge functional outcome (Functional Independence Measure, FIM) and deficit severity (Fugl-Meyer, F-M) scores in a retrospective study of patients with similar neurologic impairments: homonymous hemianopia, hemisensory loss, and hemiparesis. CT-verified stroke location was the independent variable: cortical (n = 11), basal ganglia and internal capsule (normal cortex and thalamus, n = 13), or combined (cortical, basal ganglia, and internal capsule, n = 22). By 3 months on average after stroke, all groups demonstrated significantly improved motor function as measured by F-M scores. Patients with cortical lesions had the least CT-imaged damage and the best outcome. Patients with combined lesions and more extensive brain injury had significantly higher FIM scores (P < 0.05) than patients with injury restricted to the basal ganglia/ internal capsule. Patients with basal ganglia/internal capsule injury were more likely to have hypotonia, flaccid paralysis, and persistently impaired balance and ambulation performance. While all patients had a comparable rehabilitation experience, these results suggest that patients with stroke confined to the basal ganglia and internal capsule benefited less from therapy. Isolated basal ganglia stroke may cause persistent corticothalamic-basal ganglia interactions that are dysfunctional and impede recovery.

Neuropsychological prediction of dementia and the absence of dementia in healthy elderly persons.

Identification of elderly individuals with low and high risk for future dementia has emerged as an important clinical and public health issue. To address this issue, we assessed neuropsychological performance in 317 initially nondemented elderly persons between 75 and 85 years of age and followed them for at least 4 years as part of the Bronx Aging Study. Four measures of cognitive function from the baseline assessment (delayed recall from the Buschke Selective Reminding Test, recall from the Fuld Object Memory Evaluation, the Digit Symbol subtest from the Wechsler Adult Intelligence Scale, and a verbal fluency score) can identify one subgroup with an 85% probability of developing dementia over 4 years and another with a 95% probability of remaining free of dementia. The model achieved an overall positive predictive value of 68%, or three times the base rate, for prediction of the development of dementia in our sample. The overall negative predictive value for prediction of absence of dementia was 88%. Baseline measures of cognitive function, often performed many years before the actual diagnosis of dementia, can provide important information about dementia risk. The group likely to develop dementia becomes a target for preventive or early therapeutic interventions, and the group unlikely to develop dementia can be reassured.

Chronic oral physostigmine without lecithin improves memory in Alzheimer's disease.

Sixteen patients with early Alzheimer's disease (AD) completed a 3-month outpatient double-blind parallel trial of oral physostigmine versus placebo. Ten subjects received drug; six received placebo. After a dose-titration phase, each patient was placed on his or her best dose of drug or placebo. Subjects were evaluated with both memory and nonmemory tasks. Seven of the ten drug-treated patients, but none of the six placebo-treated patients, demonstrated improvement on a selective reminding task, a test of verbal memory. Family members reported improvement in six of ten drug-treated patients and none of six placebo-treated individuals. There was a trend toward greater improvement with increasing drug dose. There was no improvement on the nonmemory tests administered. The data indicate that oral physostigmine improves memory but not other areas of cognition.

Berg balance scale and outcome measures in acquired brain injury.

OBJECTIVE: To examine the relationship of the Berg Balance Scale (BBS) to outcome after acquired brain injury. METHODS: Forty consecutive patients with acquired brain injury were admitted for multidisciplinary rehabilitation. Patients were assessed with the BBS. The BBS was originally designed as a quantitative measure of balance and risk for falls in community-dwelling elderly patients. The BBS comprises 14 different tasks graded on a 56-point scale. Community-dwelling elders with a BBS score of < or = 42 have > 90% risk for falls. RESULTS: In our study, there were 27 patients with a low BBS score (< or = 42) and 13 patients with a high BBS score (> or = 43). The discharge total Functional Independence Measure (FIM) scores were lower in the low BBS patients (96.4 +/- 21.2) compared with the high BBS patients (111.5 +/- 12.5) (p < 0.007). The length of stay (LOS) was significantly longer in the low BBS patients (38.9 +/- 18.5 days) compared with the high BBS patients (14.2 +/- 6.1 days; p < 0.000). Among the three patients that experienced falls during their hospitalization, all exhibited low BBS scores. The admission BBS score strongly correlated with admission total FIM scores (r = 0.86; p < 0.000) and moderately correlated with discharge total FIM scores (r = 0.56; p < 0.000) and LOS (r = -0.55; p < 0.000). Using a multiple regression analysis, the admission FIM score was found to be the better predictor of discharge FIM scores, and time admitted after injury was the better predictor of LOS. CONCLUSIONS: Prediction of rehabilitative outcome might be enhanced by the use of the BBS scores in combination with other clinical measures on admission to inpatient acute rehabilitation.

Promotion of neural cell adhesion by electrochemically generated and functionalized polymer films.

New strategies for spatially controllable cell adhesion have been developed for brain cells from embryonic chicken. They are based on electrochemically active phenol and pyrrole derivatives, and can be used for the selective coverage of electroconductive substrates. Besides mimicking standard laminin-related adhesion promoting mechanisms by means of an electroactive monomer-linked 18-peptide segment from laminin (SRARKQAASIKVAVSADR), electrochemically generated thin (6-30 nm) polymer films of 3-hydroxybenzyl-hydrazine (3HBH) and 2-(3-hydroxyphenyl)-ethanol (2(3HP)E) with and without mechanically entrapped or covalently linked D-lysine have proved to promote cell adhesion in serum-free medium on indium-doped tin oxide (ITO) substrates during the first 6 culturing days in vitro. The effectiveness of the peptide was strongly density-dependent. Unexpectedly, laminin itself or a combination of laminin and poly-D-lysine (PDL) did not promote cell adhesion and neuron differentiation in serum-free cultures on ITO. However, they worked perfectly well on regular polystyrene substrates in serum-free medium or on ITO when medium with serum was used. This finding might suggest that the adhesion efficiency of laminin does not depend only on the kind of medium supplement but also on the type of substrate. In contrast, the adhesion-promoting properties of "artificial" polymeric films seemed to be based on a more direct cell-film interaction, with the film masking the substrate properties.

CMOS microelectrode array for the monitoring of electrogenic cells.

Signal degradation and an array size dictated by the number of available interconnects are the two main limitations inherent to standalone microelectrode arrays (MEAs). A new biochip consisting of an array of microelectrodes with fully-integrated analog and digital circuitry realized in an industrial CMOS process addresses these issues. The device is capable of on-chip signal filtering for improved signal-to-noise ratio (SNR), on-chip analog and digital conversion, and multiplexing, thereby facilitating simultaneous stimulation and recording of electrogenic cell activity. The designed electrode pitch of 250 microm significantly limits the space available for circuitry: a repeated unit of circuitry associated with each electrode comprises a stimulation buffer and a bandpass filter for readout. The bandpass filter has corner frequencies of 100 Hz and 50 kHz, and a gain of 1000. Stimulation voltages are generated from an 8-bit digital signal and converted to an analog signal at a frequency of 120 kHz. Functionality of the read-out circuitry is demonstrated by the measurement of cardiomyocyte activity. The microelectrode is realized in a shifted design for flexibility and biocompatibility. Several microelectrode materials (platinum, platinum black and titanium nitride) have been electrically characterized. An equivalent circuit model, where each parameter represents a macroscopic physical quantity contributing to the interface impedance, has been successfully fitted to experimental results.

Characterization and optimization of microelectrode arrays for in vivo nerve signal recording and stimulation.

Revealing the complex signal-processing mechanisms and interconnection patterns of the nervous system has long been an intriguing puzzle. As a contribution to its understanding the optimization of the impedance behavior of implantable electrode arrays with via holes is discussed here. Peripheral axons will regenerate through these holes allowing for simultaneous nerve stimulation and signal recording. This approach is part of the ESPRIT project INTER and may eventually lead to devices driving sensory motor prosthesis with closed loop control. In the first set of experiments, micromachined platinum electrode arrays were prepared, characterized and optimized for nerve signal recording. The results of these studies are based on impedance spectroscopy and microscopic techniques. Equivalent circuits were modeled describing formally the electrical response behavior with ohmic resistances between 500 omega and 10 k omega. To attain low impedances for all electrodes on the INTER device, platinum from H2PtCl6 was electrodeposited, and sputter technology as well as electrochemical deposition from H2IrCl6 solution were used to produce thin iridium films. For the former, a lift-off process was established at one of the institutes to generate electrode structures with a line width of 5 microns. As a result in all three cases the electrodes showed almost constant impedances over the entire frequency range (10 Hz-1 kHz), which is relevant for nerve signal recording. In the second set of experiments, electrodes were optimized to allow for nerve stimulation. For this purpose, the charge delivery capacity (CDC) had to be increased and the impedance had to be decreased. Iridium oxide is the material of choice, because its CDC is much higher than the CDC of platinum at 75 microC/cm2 (Ziaie et al., 1991, IEEE Sensors & Actuators Transducers, 6, 124-127). A significant increase of the electrochemically active surface of the electrode structures could be observed by measuring the surface roughness. In first experiments, an activated iridium oxide film was formed with cyclic voltammetry and was evaluated using scanning force microscopy and impedance spectroscopy. The evaluation of the cyclic voltammograms showed a CDC up to 400 mC/cm2 for sputter deposited and oxidatively treated iridium films. Further investigations are directed towards increasing the stability of the iridium oxide electrodes with regard to long-term implants. Parallel experiments aim at the controlled axon adhesion without changing the impedance behavior of the described electrodes.