With the aim of studying peripheral physiological mechanisms involved in transcutaneous electrical nerve stimulation (TENS) for the suppression of pain, the authors have examined 14 healthy volunteers in the perceptual part and 8 in the microneurographic part of this study. For pain suppressing stimulation they have used ring electrodes and stimulators capable of producing rectangular, sine wave, triangular and hybrid wave forms. Pain was induced with electrical stimuli on the distal phalanx of the middle finger.TENS with rectangular, sine wave and triangular pulses activates mainly A [beta], but also some A [delta] fibres. Pain suppressing capacity of different wave forms used was the same and was achieved with stimuli close to the threshold for pain. Pain was most effectively dimished when noxious and pain suppressing stimuli were applied to the same finger; this effect was smaller with the two stimuli on neighbouring fingers and very weak when pain suppressing stimulus was applied to the contralateral hand. Increases in stimulus frequency resulted in an increased and variable latency as well as intermittent blocking of those spike components which had been near threshold at low frequency stimulation. This is interpreted as being due to local changes in excitation threshold. In surface-recorded averaged electroneurograms this effect was seen as amplitude decrement and increased response duration, but was not due to impulse transmission failure in A [delta] fibres as seen microneurographically. On continuous high frequency stimulation, the intensity of sensation elicited diminished, although there was no change in the microneurogram.The authors conclude that the peripheral contribution to the analgesic effects of TENS seems to be unimportant.

Single fibre electromyography was used to analyse responses of the pelvic floor muscles to electrical stimulation such as applied for the treatment of urinary incontinence. Using latency variation of consecutive responses of single motoneurons as a criterion, responses of the following types have been identified in the pelvic floor muscles: direct responses due to stimulation of the motor axons, oligosynaptic reflex responses, polysynaptic reflex responses conducted through different numbers of interneurons, and recurrent responses of antidromically activated motoneurons. It has been shown that the largest proportion of the obtained motor effect is due to the polysynaptic reflex responses. This implies several important advantages as compared to direct stimulation of motor axons, e.g. the physiological recruitment order of the motor units, and coordination and plasticity of the response. Therefore, electrical stimulation seems promising in cases of upper motoneuron lesion in which the spinal reflex arcs remain preserved.

Background. The clinical electroretinogram is a flash-evoked potential of the retina recorded by surface electrodes. The electroretinography is a noninvasive and objective examination which has been - nonstandardised - in clinical practice for many years. International Society for Clinical Electrophysiology of Vision (ISCEV) wishes to standardise electroretinographicexamination and had therefore published parameters, which should be considered in laboratories to record more comparable results. Aim ofthis study was to record first electroretinographic responses according to ISCEV standards at the University Institute for Clinical Electrophysiology, totest the recommended procedures and mode of examination with the elaborationof normative values. This will enable the laboratory to accept the standardised examination in its routine clinical practice. We also tested a new laboratory produced non-corneal HK-loop electrode. Methods. Electroretinograms (ERGs) were performed in 40 healthy volunteers and 12 patients with retinitis pigmentosa. As active electrodes we used non-corneal HK-loop electrodes. The preparation of patients as well as parameters of the electroretinographic system were adjusted according to the ISCEV standards. Results obtained in a group of volunteers produced normative electroretinographic data. The electroretinographic responses of patients withretinitis pigmentosa were compared with those obtained in healthy volunteers. Conclusions. The method proved to be efficient in electrophysiological evaluation of retinal function. Our volunteers and patients reported the non-corneal HK-loop electrode comfortable and we find itstable and sensitive enough for reliable flash ERG recording. Variability ofthe ERG signals recorded with HK-loop electrode was approximately in the same range as reported with corneal electrodes. (Abstract truncated at 2000 characters).