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Biomedical subjects

W Witzke

Publications and source records attributed to W Witzke.

10 recordsLinked to original sources
PubMed2004

How vegetative is the vegetative state? Preserved semantic processing in VS patients--evidence from N 400 event-related potentials.

Event-related potentials (ERPs) can provide valuable information about cognitive capabilities in severely brain-damaged patients. This study examined 120 patients with severe brain damage using event related potentials ERPs (N 400) to gain information about their remaining semantic processing capabilities and to contribute to differential diagnosis. Patients were classified into three diagnostic groups: patients in vegetative state (VS), patients in near vegetative state (NEVS) and patients not in vegetative state (NOVS). N400 ERPs were analyzed on an individual basis. All three groups could be differentiated by N400. While VS-patients as a group were least likely to show N400, some VS-patients (approx. 12%) showed clear semantic N400 potentials as an indication of semantic processing capabilities. Patients in NEVS showed significantly more intact semantic capabilities (76.74%) than the VS-group despite little clinical differences between the two groups. Thus, ERPs provide valuable information about patients with brain injury whose clinical conditions often do not allow a true assessment of their cognitive capabilities. Given these findings, we would espouse that both ethical and legal debate should take into account results of ERP studies of such patients.

Adult↗
PubMed2002

Using semi-automated image processing and desktop systems to incorporate actual patient volumetric data in immersive surgical planning and viewing systems for multiple patients.

This paper describes how patient specific volumetric data are managed from image acquisition through final processing for the purposes of creating a 3D VR rendering of user selected and manipulated 3D models. The system described here allows for the development of quick, inexpensive, and clinician manipulated patient-specific models. The utility of this process is demonstrated by being able to move VRML models to desktop or immersive environments for both pre-operative planning and patient-specific surgical and anatomical training.

Computer Simulation↗
PubMed2001

Losing the error related negativity in the EEG of human subjects: an indicator for willed action.

When people make errors in a discrimination task, a negative-going waveform can be observed in scalp-recorded EEG that has been coined the error-related negativity (ERN). We hypothesized that the ERN only occurs with slips, that is unwilled action errors, but not if an error is committed willingly and intentionally. We investigated the occurrence of the ERN in a choice reaction time task that has been shown to produce an ERN and in an error simulation task where subjects had to fake errors while the EEG was recorded. We observed a loss of the ERN when errors were committed in willed actions but not in unwilled actions thus supporting the idea that the production of the ERN is tied to slips in unwilled actions but not mistakes in willed actions.

Cerebral Cortex↗
PubMed2001

The development and implementation of a computerized database for clinical research in minimal access surgery. An international pilot study.

BACKGROUND: The measurement of outcomes after minimal access surgery (MAS) relies on the maintenance of an accurate, prospective clinical database. The development of a system for data management often proves to be challenging, expensive, and extremely time-consuming. METHODS: We developed a computerized relational database for MAS using Microsoft Access 97 to reside on a hospital server, taking advantage of existing network connections, security, and backup systems. The design of the database includes a point-and-click approach with dropdown boxes for diagnoses, procedures, and complications (limited free-text entry). A fundamental feature of this database allows surgeons and surgical trainees to record clinical information at the point and time of data acquisition. RESULTS: A "beta version" or fully functional draft of the database was presented to a group of surgeons from a variety of specialties (n = 8), and a structured interview based on a questionnaire was used to elicit the surgeon's evaluations of the database. Using the information from the interviews, the database was extensively revised and restructured. CONCLUSIONS: We have developed a relational database that reflects the needs of surgeons interested in clinical research. This database may serve as a template for other centers. It can be expanded to adopt new procedures or modified for other surgical specialties.

Attitude of Health Personnel↗
PubMed1999

Contingent negative variation and attention in schizophrenic and depressed patients.

Contingent negative variation (CNV) is supposed to be a psychophysiological indicator of attention and arousal. Both have been reported to be deteriorated in schizophrenic and depressed patients. Thirty-four patients with major depression, 43 patients with schizophrenia and 49 healthy subjects were investigated during acute illness with a complex three-stimulus go/no-go task which requires different states of attention: trials consisted of three complex figures that were tachistoscopically presented. Three identical figures had to be confirmed by pressing a button (target condition). CNV was measured: (1) after the first figure waiting for the second (baseline condition), (2) after two identical figures waiting for the third (response-relevant condition), (3) after two different figures waiting for the third (response-irrelevant condition). The response-relevant condition compared to baseline significantly intensified CNV in healthy controls and to a minor extent in depressed patients but not in schizophrenics. In the response-relevant conditions in healthy controls, CNV was significantly reduced compared to the response-relevant condition. This clear discrimination between response-relevant and response-irrelevant conditions was not observed in either group of patients. Thus, the applied CNV paradigm was able to discriminate schizophrenic and depressed patients from healthy controls. Furthermore, subtle differences between schizophrenic and depressed patients were detected, reflected by the different CNV development across experimental conditions.

Adult↗
PubMed1989

Psychotropic drug use in a representative community sample: the Upper Bavarian study.

A sample of 1979 community residents aged 15 years and above was assessed in a major survey of health status and consumption of psychotropic medication. Interviews were conducted in the subjects' home by a psychiatrically trained physician, who actually inspected the subjects' medical supplies. Of all subjects 6.9% (4.3% of the males and 9.0% of the females) had used a drug containing a benzodiazepine at least once in the 4 weeks preceding the interview. In the same period 3.6% had taken a medication containing a barbiturate, 2.2% a medicine containing an opioid (mainly codeine), 1.8% had taken a neuroleptic drug, 1.5% an antidepressant, 0.8% a carbamine-acid derivative and 0.1% lithium. High use of psychotropic medication was associated with higher age, female sex, higher psychiatric morbidity, higher somatic morbidity, reduced work capacity and higher neuroticism but not with social class and not with the personality factor extra- or introversion.

Adolescent↗
PubMed1989

The use of psychiatric facilities by depressives: results of the Upper Bavarian Study.

Utilization of psychiatric facilities by noninstitutionalized persons aged 20 years and older, identified as "depressive cases", was examined. Data were based on the representative community sample of the Upper Bavarian follow-up field study with an original sample size of 1668 people. In the 5-year follow-up 1384 (83%) subjects were interviewed, while 80 subjects (4.8%) had died. The 5-year prevalence of depressive disorders, according to the definition used, was 10.3%. We analyzed which people with depressive disorders sought help from mental health professionals according to type of depressive disorder, sociodemographic data, psychosocial factors and course of disorder. The psychiatric treatment rate (in- or outpatient) was 23.9% of the depressive cases. The majority of treated persons were outpatients. Patients with the diagnosis of endogenous depression were most likely to have received psychiatric treatment. Limitation in the ability to work due to depression was the most important psychosocial factor influencing help-seeking behavior. The highest consultation rate in psychiatric facilities was obtained from the depressives who had grown up without their parents.

Adult↗
PubMed1989

The role of the general practitioner in the care of mentally disturbed subjects in the general population--results of the Upper Bavarian Study.

The role of the general practitioner in the care of mentally disturbed non-institutionalised persons aged 20 years and older was examined. Data were based on the representative community sample of the Upper Bavarian Field Study with a sample size of 1495 interviewees--aged 20 years and older. The 5-year prevalence of mental illness according to the definition used was 32.8%. 38.5% of all persons, identified as cases, consulted their general practitioner because of psychiatric or emotional problems. Females and the elderly were most likely to have received treatment by their general practitioner. The majority of treated persons were neurotic and psychosomatic patients. The general practitioner provided care for more psychiatric patients than the psychiatrist and for 25% of all "cases", without additional psychiatric consultation.

Adult↗