Showing papers by "Gert Pfurtscheller published in 1987"

Continuous and simultaneous monitoring of EEG spectra and brainstem auditory and somatosensory evoked potentials in the intensive care unit and the operating room.

Abstract: Individual monitoring of EEG and evoked potentials is gradually becoming standard in neurosurgery: compressed power spectra during carotid endarterectomy, brainstem auditory evoked potentials (BAEP) during posterior fossa surgery, and somatosensory evoked potentials (SEP) mainly during spinal cord surgery. In this paper, a new technique is described in which EEG, BAEP, and SEP are recorded and evaluated simultaneously and continuously. This allows a better survey of different neuronal structures and systems in the brain and brainstem. First results from intraoperative and intensive care patient monitoring are reported.

Quantification of autonomic activity in the brainstem in normal, comatose and brain dead subjects using heart rate variability.

Abstract: The heart rate variability is defined as variation in distance between sequential ventricular complexes in the electrocardiogram and can be given in percent by referring the standard deviation to the average values of heart rate The bivariate distribution of heart rate variability and of heart rate shows a discrimination of the group of comatose patients from brain dead subjects and normals

[Acoustically evoked brain stem potentials. Prerequisites for clinical use, data quality and sources of error].

Abstract: Ninety patients were subjected to brain-stem auditory evoked potential (BAEP) measurements in the intensive care unit. The data are analyzed and discussed with respect to their quality, reliability, and reproducibility. BAEPs of a quality satisfactory for diagnosis were found in 90% of the patients. About 10% of the measurements were distorted by artifacts and could not be used for diagnostic purposes. Reasons for these artifacts and problems of interpretation are discussed. Examples of single BAEPs and on-line monitoring of BAEPs in the form of "compressed BAEPs" are shown.

Muitimodal evozierte Potentiale und Herzratenvariabilität bei komatösen Patienten - Teil 1: Meßmethode und Normbereiche

Abstract: Multimodal EPs and heartratevariability-measurements in comatose patients have been performed for few years at the university hospitals of Graz and ErlangenThe following data and parameters are analysed and discussed: brainstem auditory evoked potentials, mechanical evoked long-latency SEP, VEP recorded over the central and occipital region and heartratevariability (HRV) The method of data acquisition and processing is described and normative data are introduced For the long-latency EP-components a signal-to-noise-ratio (SNR) is calculated SNR is defined as ratio of the largest EP peak-to-peak amplitude and the mean amplitude (standard deviation) of a period prior to the stimulation An unmeasureable or questionable EP is defined when SNR < 2,6 For the vertex-SEP the following mean + standard deviation was obtained: SNR = 10,6 ± 4,6; the vertex VEP was calculated with SNR = 7,0 ± 3,0 The SNR of the bipolar recorded occipitally VEP was 3,9 ± 2,0 Heartratevariability measurements in normal persons revealed the following mean ± standard deviation at a heartrate of 67,8/min ± 10,8/min: HRV = 7,8 % ± 2,5 % Seit einigen Jahren werden multimodale EP-Untersuchungen und Messungen der Herzratenvariabilitat an komatosen Patienten der Universitatskliniken in Graz und Erlangen durchgefuhrt Dabei werden im einzelnen bewertet: akustische Hirnstammpotentiale, durch mechanische Vibrationsreize ausgeloste spate SEP, zentrale und okzipitale VEP und Herzratenvariabilitat In dieser Arbeit sind die Mesmethoden beschrieben und werden die Normbereiche der einzelnen Signale bzw Parameter definiert Fur die Bewertung spater EP-Komponenten wird ein Signal-Storverhaltnis verwendet, das sich aus dem Quotienten aus maximaler Peak-to-peak Amplitude und der mittleren Streuung vor der Stimulation ergibt Bei einem Signal-Storverhaltnis < 2,6 wird das EP als fraglich bzw nicht vorhanden klassifiziert Fur das Vertex-SEP wurde ein Signal-Storverhaltnis = 10,6 ± 4,6 (Mittelwert ± Streuung) und fur das Vertex-VEP ein Signal-Storverhaltnis = 7,0 ± 3,0 errechnet Das bipolar okzipitale VEP ergab ein Signal-Storverhaltnis = 3,9 ± 2,0 Die Herzratenvariabilitat an Normalpersonen liegt im Bereich von 7,8 % ± 2,5 % bei einer Herzrate von 67,8/min ± 10,8/min