Development of a multiple thin-film semimicro DC-probe for intracerebral recordings.

A thin-film multiple-electrode probe for measuring de potentials at eight sites with interdistances of 1 mm was constructed for the investigation of slow potential changes in deep regions of the human brain during surgery. The thin-film electrodes had to be placed on curved cylinder-shaped surgical instruments with dimensions of 2 mm diameter and 33 cm length used with the Freiburg stereotactic equipment. Several novel technological steps had to be introduced for the solution of the encountered problems: 1) Structuring of the metal layers on curved substrates was accomplished by using flexible masks. 2) Special feed-through technologies had to be invented in order to obtain reliable connections between the thin-film sensors and the copper wires inside the stereotactic instrument. 3) Thin-film Ag-AgCl electrodes had to be formed in order to obtain satisfying recordings of slow potential changes below 10 Hz. Slow potential changes were recorded from different depths in interdistances of only 1 mm with these new miniaturized thin film Ag-AgCl electrodes and bipolar recordings with an electrode interdistance of only 3 mm showed clearly the appearance of Bereitschaftspotentials.

[Clinical and experimental results with acupuncture-analgesia (author's transl)]. / Klinische und experimentelle Ergebnisse mit der Akupunktur-Analgesie

Operations under acupuncture analgesia have been performed in Vienna since March 1972. A total of 102 procedures has been performed with "classical" Chinese acupuncture analgesia. Additionally given analgesics, psychodynamic factors and neurophysiological components are of joint importance. Our success rate in these cases was 64 p.c. Since October 1972 we call "two-phase-acupuncture-analgesia". Up to June 1975 72 operations were performed under some modifications of this method. In a neurophysiological study 17 volunteers and in 2 patients undergoing stereothalamotomies depression or even disappearance of evoked potentials was be observed during acupuncture with alectrical stimulation. Thus an interaction between pain stimuli and acupuncture stimuli in the thalamus could for the first time be demonstrated in man.

[Computer sensomtery as objective examination of sensation in the finger area]. / Die Komputersensometrie als eine objektive Untersuchung der Sensibilität im Fingerbereich

The authors described what they believe to be a more objective method for evaluation of sensation within the digital pulp. It requires the use of electronic equipment including EEG to record the evoked potentials. With further refinement this method should become a valid tool in the objective examination of sensory patterns.