Recovery functions of short and long latency reflexes in hand muscles evoked by paired stimulation of peripheral nerves.

Double-shock bifocal peripheral nerves stimulation with varying interstimulus intervals (ISI) from 1 ms to 5000 ms was applied to healthy human subjects. Short (SLRs) and long latency reflexes (LLRs) from the slightly active first interosseus dorsalis muscle were recorded after an electrical conditioning stimulation of the index finger and test stimulation of the median nerve. It was found that with intervals from 1 to 5 ms the size of the SLR and LLRs after the second shock was unstable and almost oscillated around that evoked by a single shock, possibly due to transmitter depletion at these short ISIs. With intervals of 10 ms and longer, the test responses progressively increased: the SLR to 100 ms ISI, the LLR1 to 500 ms ISI and the LLR2 to 2000 ms ISI, probably due to temporal summation and some release of the transmitter substance after the conditioning cutaneous stimulus. All the recovery curves fully returned to the control value at 2000 ms and 3000 ms ISI, respectively. The main result is that cutaneous conditioning stimulation is not able to reduce or even to block the test SLR and LLRs. Interference phenomena did not occur between different afferents when paired stimulation was applied bifocally as the conditioning input in respect to a test nerve volley, was very limited. On the contrary, the test responses were far larger than the control response, probably due to some temporal summation with double-shock stimulation and because of the enhanced spinal excitability during slight voluntary contraction.

Analysis of stability of human upright posture based upon the measurement of the head sway.

The paper is dealing with the description of a simple and inexpensive technique for recording and measuring of the head sway during upright stance. In particular the recording system and the evaluation of the body sway data are highlighted. The objectives of the head sway signal analysis are the determination of sway components in the side-to-side (lateral) direction and forward-backward (anteroposterior) direction. It is anticipated that it will be possible to extract from the digitized data some information about the transfer characteristic and stability margin of the neuromuscular control system concerned with the maintenance of equilibrium. Additional information of potential clinical significance could be obtained by correlating the measured sway data with electromyographically determined changes in the activity of the main postural muscles. The information obtained is comparable to that gathered by more sophisticated, and more expensive conventional devices. A special feature is the easy portability of the system which permits collection of stabilometric data even in remote locations, while the analysis on which the diagnostic assessment is based can be performed at a later date in a central facility equipped with the necessary instrumentation.

[The role of short and long latency reflexes in the small muscles of the hand in the diagnosis of movement disorders--an electrophysiology study]. / Prínos krátkolatentných a dlholatentných reflexov v drobných svaloch ruky pre diagnostiku pohybových porúch--elektrofyziologická stúdia.

EMG changes of short (SLR) and long latency reflex (LLR) responses to electric stimulation of digital nerves of the index finger were recorded from the interosseous dorsal muscle I during its slight isometric contraction. Abnormalities of SLR and LLR were found at least on one hand in 9 of 11 patients with nosologically different dysfunctions of the nervous system. SLR latency can yield information on lesions of the peripheral motoneuron. LLR latency proved to be a sensitive indicator of spinal and supraspinal lesions, and since it has also an efferent branch and, unlike SEP, it can detect also lesions of the descending corticospinal pathway. Prolonged SLR latency occurred frequently in s. m. Assessment of muscle reflexes is a valuable auxiliary method in identifying lesions of the peripheral and particularly of the central nervous system.

[Computer analysis of muscle reflex responses to electric stimulation of peripheral nerves]. / Pocítacová analýza reflexných svalových odpovedí na elektrickú stimuláciu periférnych nervov.

A computer program is described which allows analysis of reflex muscle responses to electric stimulation of peripheral nerves. Basically, the program is derived from an older methodic approach, yet the process of evaluating the obtained means of reflex muscle responses is in this computer assisted procedure simpler and of a higher quality. The proposed improvement of the original methodic approach provides an important advantage for clinical practice in significantly speeding up the investigation and evaluation of reflex muscle responses on using financially accessible computer technique of Czechoslovak make. The paper points out the possibility of using the program also for analysis of other biological signals and of adjusting it for more efficient types of personal computers.

[Methodologic problems in short and long latency muscle reflex responses in man]. / Niektoré metodické otázky krátkolatentných a dlholatentných reflexných svalových odpovedí u cloveka.

The procedure used in the study of short and long latency reflex muscle responses is described in detail. The author defines the basis of the method of summation and averaging of rectified muscle activity based on the principle of the time dependence of electrophysiological manifestations of muscles induced by a repeated electric stimulus. The effect of the parameters chosen for processing the EMG signal (filtration, amplification, rectification) on the resulting pattern of the averaged reflex muscle responses is highlighted. Potential uses of the method in studying reflex muscle responses during electric stimulation both in the healthy population and in clinical diagnosis of different disorders of mobility are presented.