Effect of Menstrual Cycle in Long Latency Reflex of Abductor Pollicis Brevis Among Healthy Female Volunteers.

Background: Long Latency Reflex (LLR) is one of the late responses occurring after H reflex from a mixed nerve by submaximal stimulation. LLR has been found to be absent in patients with multiple sclerosis, spastic patients and in Huntington’s disease. A change in body temperature affects conduction velocity. It is a known fact that there is a change in body temperature during menstrual cycle. However, no studies are available to indicate changes in latency of LLR during the menstrual cycle. Aim: To determine the effect of menstrual cycle on Long Latency Reflex of Abductor Pollicis Brevis among healthy female volunteers. Material and Methods: A cross sectional study was carried out in 30 healthy female volunteers aged 20-30 yrs. The study was conducted between 9.00 a.m.-11.00 a.m using Digital Nerve Conduction/EMG/EP machine (Recorders Medicare system, India) in a laboratory maintained at 22º±3ºC. LLR was recorded during early follicular and mid-luteal phases by stimulation of median nerve while abducting the thumb and recording the EMG response of Abductor Pollicis Brevis. Body temperature was recorded. Latency of LLR obtained during two phases of menstrual cycle was compared. Result: The mean value of latency for LLR was 45.45±2.95 ms (mean±SD) in the mid luteal phase. It was significantly (Wilcoxon test, p<0.001) shorter than the value in the early follicular phase 47.10±2.51ms (mean±SD). This is possibly due to the higher body temperature in the mid luteal phase. Conclusion: Long Latency Reflex was found to be affected during the phases of the menstrual cycle in healthy female volunteers.

Relationship between long latency activities from wrist flexor and performance during target match task of the wrist joint / 体力科学

A study was conducted to investigate the relationship between long latency activities evoked by a sudden muscle stretch of the right wrist flexor and a peformance during a target match task accompanying wrist movement. The index of performance was the target match time (TMT) from onset of a handle displacement untill the handle position output was matched with a traget line. The standard deviation of TMT (TMT-S.D.) was calculated. Sixteen healthy men, ranging in age from 20 to 27 yr., participated in the study. A DC torque motor was used to generate an angular displacement at the right wrist joint. Analysis of the surface electromyogram recorded from the wrist flexor showed that the short and long latency reflex components (Ml, M 2 and M3) were evoked by muscle stretching. In the target match task, the amplitude of the M 2 and M 3 components for all subjects were significantly smaller than the M 1 component (p<0.01) . In some subjects the M 3 component was not identifiable, since its amplitude was very small in the target match movement. There were significant correlations between the M 2 amplitude and performances (TMT : r=0.857, p<0.01 and TMT-S. D. ; r=0.651, p<0.01) during the target match task. In shoat, the smaller the M 2 amplitude was, the shorter the TMT became and the smaller the TMT-S. D, became. These results suggest that the change in the M 2 component is related to motor control for the target match task.

Relationships between long-latency reflex components in wrist flexor and premotor time with reaction movement during wrist flexion / 体力科学

A study was undertaken to investigate whether the amplitudes of reflex EMG components (M1, M2 and M3) induced by sudden muscle stretching in the wrist flexor, are modified according to the reaction movement during wrist flexion, and how the aspects of reflex EMG components are related to premotor time under conditions of stretch stimulus (SS-PMT) and light stimulus (LS-PMT) . Fifteen healthy men, ranging in age from 22 to 28yr, participated in the study. A DC torque motor was used to evoke the reflex EMG activities on the wrist flexor. Analysis of the surface electromyogram recorded from the wrist flexor showed that short and long latency reflex components appeared in response to muscle stretch. In almost subjects, the amplitude of the M2 component was higher during reaction task than during no reaction task. The subjects were classified into two groups (I, II) according to the presence or absence of reflex components and their EMG amplitudes. SS- and LS-PMTs in group I were significantly shorter than those in group II. The amplitude of M2 in group I was significantly higher than in group II. In group I the M3 component was not identified, since the M2 component was followed by a voluntary EMG burst.<BR>These results showed that the amplitudes of long latency reflex components increased during the reaction task in the flexion direction, and suggest that long latency components contribute to the initiation of voluntary movement in subjects with a shorter premotor time.

Usefulness of SEP and LLR for the evaluation and the programming of rehabilitation in patients with multiple sclerosis / 日本温泉気候物理医学会雑誌

when the relation between N20 and LLR was examined based on the results of somatosensory-evoked potentials (SEPs) and long-loop reflexes (LLRs) obtained from 50 upper limbs of 25 normal subjects by stimulating the median nerve, four regions were set up in a latency correlation diagram. N20 and LLR were assumed to represent mainly the afferent and the efferent functions, respectively. The results of N20 and LLR obtained from 70 upper limbs of patients with multiple sclerosis were discriminated according to the presence or absence of pyramidal sign and/or vibratory sense impairment and were plotted on the four regions of the diagram. As a result, asymptomatic lesion in the afferent pathway was found in 5 out of 18 cases (28%) and that in the efferent pathway, in 9 out of 17 cases (41%). Simultaneous measurement of SEPs and LLRs is useful for evaluating the afferent and efferent pathways in the central nervous system, and those results are useful for programming and evaluating rehabilitation of patients with multiple scleosis.