Biomedical subjects
Publications and source records attributed to A Kübler.
This paper describes the outcome of discussions held during the Third International BCI Meeting at a workshop charged with reviewing and evaluating the current state of and issues relevant to brain-computer interface (BCI) clinical applications. These include potential BCI users, applications, validation, getting BCIs to users, role of government and industry, plasticity, and ethics.
People with severe motor disabilities can maintain an acceptable quality of life if they can communicate. Brain-computer interfaces (BCIs), which do not depend on muscle control, can provide communication. Four people severely disabled by ALS learned to operate a BCI with EEG rhythms recorded over sensorimotor cortex. These results suggest that a sensorimotor rhythm-based BCI could help maintain quality of life for people with ALS.
BACKGROUND: The purpose of this manuscript is to give a cost-effectiveness analysis of the photodynamic therapy by means of Foscan (Foscan-PDT) in Germany. The basis for this paper is provided by a study performed in Great Britain which analyses the costs of Foscan-PDT compared to the costs of palliative chemotherapy and to the option of no treatment in patients with advanced head and neck cancer. METHOD: In order to calculate the cost-effectiveness, an already published model developed on the base of English data was fed with German cost-data. For consideration of the different characteristics of cost-parameters as well as to minimize the over- or underestimation of the costs, sensitivity analyses were performed. RESULTS: The Foscan-PDT revealed the highest health-related effectiveness compared to all other above-mentioned options -- 129 additional days of life in comparison to no treatment or 48 days in comparison to four cycles of palliative chemotherapy. The costs per therapy of Foscan-PDT ( 8,761 euros) were lower than those of four cycles of palliative chemotherapy (11,600 euros). CONCLUSION: Foscan-PDT is a cost-effective treatment option for patients suffering from advanced head and neck cancer. For patients who up to now had only very limited treatment possibilities at their disposition, Foscan-PDT offers a chance for reduction of the tumor, remission, and a prolonged expectancy of life.
Many studies have shown the negative effects of cocaine on neuropsychological and cognitive performance in drug-dependent individuals, but little is known about the underlying neuroanatomy of these dysfunctions. The present study addressed attention switching between items held in working memory (WM) with a task in which subjects were required to store and update two items held in verbal or visuospatial WM. Attention-switching frequency varied between trials, thereby allowing us to isolate the switching component of task performance. Behavioural data revealed that cocaine addicts performed worse than healthy controls in all tasks. On the visuospatial task addicts performed at chance levels revealing particular impairment in visuospatial WM. On the verbal task, in which controls and users could be matched for performance, we identified attenuated responses in prefrontal and cingulate cortices and in striatal regions, while other areas such as dorsolateral prefrontal cortex did not differ between healthy controls and users. The results reveal that addiction may be accompanied by specific rather than ubiquitous hypoactivation in prefrontal and subcortical areas and suggest a compromised ability in users to control their attention to their thoughts as might be particularly relevant when required to switch away from drug-related thoughts, and thus the dysfunction in attention switching may contribute to the maintenance of addiction.
AIM: Alveolar ostitis occurs with an incidence of 3-25% after tooth extraction. Antimicrobial photodynamic therapy (aPDT) with HELBO Blue and TheraLite laser enables local decontamination of the extraction socket. The aim of the study was to evaluate the possibility of aPDT with HELBO Blue and diode soft laser to reduce the prevalence of alveolar ostitis. MATERIAL AND METHODS: In an intraindividual study with 100 patients in 130 jaws, one or multiple contralateral teeth were removed at 1-week intervals. Randomly each side was treated with or without aPDT with a standardized protocol. At recall the evaluation of the extraction socket was performed by the investigator and the postoperative pain sensation was judged by the patient on an analog pain scale (0-100). RESULTS: In the group with aPDT alveolar ostitis occurred at one extraction site and in the control group without aPDT in 13 cases. The subjective pain assessment on the day after tooth removal was scored with 11.2+/-9.8 in the aPDT-group and with 19.0+/-12.2 in the control group. One week after extraction the pain sensation in the aPDT group was scored with 2.4+/-9.2 and in the control group with 13.1+/-25.2. The difference was significantly lower with p=0.000 for the 1st and 8th post-surgical days in the aPDTgroup. CONCLUSIONS: The significantly lower incidence of alveolar ostitis after antimicrobial photodynamic therapy seems to be a new and promising possibility for the prevention of alveolar ostitis.
OBJECTIVE: Direct brain-computer communication utilizes self-regulation of brain potentials to select letters, words or symbols from a computer menu. Selection of letters or words with brain potentials requires simultaneous processing of several tasks such as production of certain brain potentials at predefined time points simultaneously with processing of presented letter strings. This study addresses the question of whether the self-regulation of slow cortical potentials (SCP) automatizes with practice and can thus be considered as a skill comparable to motor or cognitive skills. METHODS: Two nearly completely paralysed patients learned over several months to produce electrocortically negative and positive SCP by means of visual feedback. Improved performance and a reduction in performance variability were regarded as behavioural indicators for automaticity, while the topographic focalization of cortical activation was considered as a neurophysiological indicator for automaticity. Different indicators of automaticity were expected to covary along with practice. RESULTS: In patient 1, performance measured as the percentage of correct SCP shifts increased simultaneously with the topographic focalization of cortical activation. His performance became more stable with practice. For this patient the criteria for automaticity were all met. In patient 2, performance also improved, but his cortical activity became topographically less focal. His performance was less stable than that of patient 1. CONCLUSIONS: The present findings, albeit on only two subjects, provide preliminary evidence that SCP self-regulation may automatize with long-term practice and can therefore be considered a skill.
Attention switching between items being stored and manipulated in working memory (WM) is proposed to be an elementary executive function. Experiment 1 reveals a similar attentional limitation within and between verbal and visuospatial WM and identifies a supramodal switching process required for switching between WM items. By using functional magnetic resonance imaging, Experiment 2 investigated brain activation correlates of parametrically varied attention switching within and between these two WM modalities. Attention switching activation was broadly distributed, was quite similar across the three conditions, and, in almost all areas, increased with increasing switching demand, indicating that attention switching recruits and modulates the entire WM network. Dorsolateral prefrontal cortex was implicated in both within- and between-modality attention switching, but no significant activation was found in ventrolateral areas, supporting dorsal-ventral process models of prefrontal organization. A functional dissociation between anterior frontal and dorsolateral prefrontal cortex was found with the former being more activated when switching attention between modalities was required. The data challenge the notion of an anatomically separate attention switching executive function, but suggest that anterior frontal areas are recruited for the additional demand of coordinating the verbal and visuospatial WM slave systems.
OBJECTIVE: This case study describes how a completely paralyzed patient, diagnosed with severe cerebral palsy, was trained over a period of several months to use an electroencephalography (EEG)-based brain-computer interface (BCI) for verbal communication. METHODS: EEG feedback training was performed in the patient's home (clinic), supervised from a distant laboratory with the help of a 'telemonitoring system'. Online feedback computation was based on single-trial analysis and classification of specific band power features of the spontaneous EEG. Task-related changes in brain oscillations over the course of training steps was investigated by quantifying time-frequency maps of event-related (de-)synchronization (ERD/ERS). RESULTS: The patient learned to 'produce' two distinct EEG patterns, beta band ERD during movement imagery vs. no ERD during relaxing, and to use this for BCI-controlled spelling. Significant learning progress was found as a function of training session, resulting in an average accuracy level of 70% (correct responses) for letter selection. 'Copy spelling' was performed with a rate of approximately one letter per min. CONCLUSIONS: The proposed BCI training procedure, based on electroencephalogram (EEG) biofeedback and concomitant adaptation of feature extraction and classification, may improve actual levels of communication ability in locked-in patients. 'Telemonitoring-assisted' BCI training facilitates clinical application in a larger number of patients.
This retrospective study aimed to demonstrate the incidence and the aetiological factors involved in osteoradionecrosis (ORN) in a group of 830 head and neck tumour patients who received radiotherapy between 1969 and 1999. The data showed an over all incidence of 8.2% and a 3-fold higher incidence for men than for women. Osteoradionecrosis was most commonly located in the body of the mandible. Concerning the risk factors, a negative influence was shown for advanced tumours, segmental resections of the mandible and pre-/post-radiation tooth extractions. Tooth extractions were found to be responsible for 50% of all cases. The osteoradionecroses were observed significantly earlier in patients who received pre-surgical radiotherapy than those who received post-surgical radiotherapy. Combined pre-surgical radio- and chemotherapy significantly hastened the appearance of osteoradionecrosis compared to pre-surgical radiotherapy alone. Only 40% of patients with osteoradionecrosis could be healed completely by means of surgery and antibiotic medication. Hyperbaric oxygenation (HBO) therapy was performed only in individual cases. The data suggest that osteoradionecrosis has a multifactorial aetiology. Therefore, a very close follow-up of tumour patients and a strict prophylactic management are required.
This paper describes a paralyzed patient diagnosed with severe infantile cerebral palsy, trained over a period of several months to use an EEG-based brain-computer interface (BCI) for verbal communication. The patient learned to "produce" two distinct EEG patterns by mental imagery and to use this skill for BCI-controlled spelling. The EEG feedback training was conducted at a clinic for Assisted Communications, supervised from a distant laboratory with the help of a telemonitoring system. As a function of training sessions significant learning progress was found, resulting in an average accuracy level of 70% correct responses for letter selection. At present, "copy spelling" can be performed with a rate of approximately one letter per minute. The proposed communication device, the "Virtual Keyboard", may improve actual levels of communication ability in completely paralyzed patients. "Telemonitoring-assisted" training facilitates clinical application in a larger number of patients.
BACKGROUND: Several craniofacial deformities and syndromes feature hypoplasia of the midface skeleton. Until now different treatment options were based primarily on a modified LeFort III osteotomy: (1) the conventional LeFort III osteotomy with bone transplantation and intraoperative osteosynthesis, (2) distraction using subcutaneous distraction devices fixed on both sides at the os zygomaticum, and (3) bone distraction using a rigid external distraction device (RED distractor), which is fixed to the skull and pulling at the maxilla or the upper teeth. METHODS AND RESULTS: A modification of the distraction technique using the RED distraction device is presented. The tensile forces are applied to the ramus infraorbitalis or the apertura piriformis, and the tensile wires penetrate through the skin laterally to the nose. By using this new approach near the center of rotation or the center of resistance, optimal control of the vector of distraction is guaranteed. With sufficient distraction of the midface, overcorrection of the os zygomaticum can be avoided. Clinical data of seven patients are presented. DISCUSSION: Due to the good clinical results, external transfacial distraction with tensile forces pulling at the apertura piriformis seems to improve the treatment of these complex facial deformities.
BACKGROUND: Complications and local extension of dentogenous and paranasal sinus infections most often involve the periorbit and frontal cranium. Because of the widespread use of antibiotics, intracranial extension of maxillofacial sinusitis is rarely seen today. Nevertheless, the clinician must be aware of the potential for these complications, because late recognition of this condition and delay in treatment can increase morbidity and mortality rates. CASE REPORT: A case report of sinogenic intracranial complications is presented, with sinogenic empyema, cerebritis, and subdural empyema. The mechanisms and potential for intracranial spread of infection from the frontal, sphenoid, and ethmoid sinuses are discussed. The management of complications is outlined, including the use of computed tomography and the role of surgical drainage.
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An EEG-based communication system has been developed to re-establish communication in severely paralyzed patients who operate the device by generating shifts of their slow cortical potentials. Training to gain control over slow cortical potentials was based on visual feedback and operant conditioning strategies. The vertical movement of a graphic signal on a computer screen informs the patients about the course of their slow cortical potential amplitude. Positive slow cortical potential shifts move the cursor up, negative shifts move it down. These shifts are then translated into binary responses. When a patient has achieved reliable control over his/her slow cortical potential shifts, these responses can be used to select or reject items presented at the bottom of the screen. As learning processes and applications differ considerably between patients, the present paper describes the data from one patient with amyotrophic lateral sclerosis. After about three months of training, this patient gained stable, near-perfect control over his slow cortical potentials. This skill enabled him to operate a specially designed program to communicate messages to his caregivers.
CONTEXT: Activation of the coagulation system and depletion of endogenous anticoagulants are frequently found in patients with severe sepsis and septic shock. Diffuse microthrombus formation may induce organ dysfunction and lead to excess mortality in septic shock. Antithrombin III may provide protection from multiorgan failure and improve survival in severely ill patients. OBJECTIVE: To determine if high-dose antithrombin III (administered within 6 hours of onset) would provide a survival advantage in patients with severe sepsis and septic shock. DESIGN AND SETTING: Double-blind, placebo-controlled, multicenter phase 3 clinical trial in patients with severe sepsis (the KyberSept Trial) was conducted from March 1997 through January 2000. PATIENTS: A total of 2314 adult patients were randomized into 2 equal groups of 1157 to receive either intravenous antithrombin III (30 000 IU in total over 4 days) or a placebo (1% human albumin). MAIN OUTCOME MEASURE: All-cause mortality 28 days after initiation of study medication. RESULTS: Overall mortality at 28 days in the antithrombin III treatment group was 38.9% vs 38.7% in the placebo group (P =.94). Secondary end points, including mortality at 56 and 90 days and survival time in the intensive care unit, did not differ between the antithrombin III and placebo groups. In the subgroup of patients who did not receive concomitant heparin during the 4-day treatment phase (n = 698), the 28-day mortality was nonsignificantly lower in the antithrombin III group (37.8%) than in the placebo group (43.6%) (P =.08). This trend became significant after 90 days (n = 686; 44.9% for antithrombin III group vs 52.5% for placebo group; P =.03). In patients receiving antithrombin III and concomitant heparin, a significantly increased bleeding incidence was observed (23.8% for antithrombin III group vs 13.5% for placebo group; P<.001). CONCLUSIONS: High-dose antithrombin III therapy had no effect on 28-day all-cause mortality in adult patients with severe sepsis and septic shock when administered within 6 hours after the onset. High-dose antithrombin III was associated with an increased risk of hemorrhage when administered with heparin. There was some evidence to suggest a treatment benefit of antithrombin III in the subgroup of patients not receiving concomitant heparin.
OBJECTIVES: Severely paralyzed patients could learn to voluntarily generate slow cortical potential (SCP) shifts in their electroencephalogram and to use these signals to operate a communication device. To enhance the patients' autonomy, the present study describes the development of a permanently available communication system that can be turned on and off by locked-in patients without external assistance. A skill necessary for turning the system on is the ability to regulate one's slow potentials in the absence of continuous feedback. METHODS: A stepwise learning approach was employed to train two paralyzed patients to regulate their SCPs without continuous feedback. Elements of the original communication system were gradually removed and elements of the new stand-by mode were introduced. RESULTS: At the end of the learning procedure, both patients achieved correct response rates of above 84% in training sessions without continuous feedback. This skill enabled them to turn the communication device on and off without assistance from others. CONCLUSIONS: These findings suggest that severely paralyzed individuals can learn to operate an EEG-based communication device autonomously.
With the increasing efficiency of life-support systems and better intensive care, more patients survive severe injuries of the brain and spinal cord. Many of these patients experience locked-in syndrome: The active mind is locked in a paralyzed body. Consequently, communication is extremely restricted or impossible. A muscle-independent communication channel overcomes this problem and is realized through a brain-computer interface, a direct connection between brain and computer. The number of technically elaborated brain-computer interfaces is in contrast with the number of systems used in the daily life of locked-in patients. It is hypothesized that a profound knowledge and consideration of psychological principles are necessary to make brain-computer interfaces feasible for locked-in patients.
OBJECTIVE: To test a training procedure designed to enable severely paralyzed patients to communicate by means of self-regulation of slow cortical potentials. DESIGN: Application of the Thought Translation Device to evaluate the procedure in patients with late-stage amyotrophic lateral sclerosis (ALS). SETTING: Training sessions in the patients' homes. PARTICIPANTS: Two male patients with late-stage ALS. INTERVENTIONS: Patients learned voluntary control of their slow cortical potentials by means of an interface between the brain and a computer. Training was based on visual feedback of slow cortical potentials shifts and operant learning principles. The learning process was divided into small steps of increasing difficulty. MAIN OUTCOME MEASURES: Accuracy of self-control of slow cortical potentials (percentage of correct responses). Learning progress calculated as a function of training session. RESULTS: Within 3 to 8 weeks, both patients learned to self-regulate their slow cortical potentials and to use this skill to select letters or words in the Language Support Program. CONCLUSIONS: This training schedule is the first to enable severely paralyzed patients to communicate without any voluntary muscle control by using self-regulation of an electroencephalogram potential only. The protocol could be a model for training patients in other brain-computer interface techniques.