Silent period and H reflex from soleus muscle as an index in a neuro-muscular function after reconstruction of anterior cruciate ligament.

To clarify that the mixed nerve silent period (SP) and H reflex from soleus muscle may become an index expressed neuro-muscular function after reconstruction of anterior cruciate ligament (ACL), we studied the alteration of SP and H reflex from the soleus muscle in the patient with ACL reconstruction. Subjects were three patients with after ACL reconstruction, who were two male athletes (case A and B) and a female aerobics instructor (case C). Recording of SP and H reflex was performed longitudinally from one month post operation to six months post operation. As a result of this study, in case A, following findings were appeared; shortening of duration of SEP increasing the coefficient of variation of SP and increasing the amplitude ratio of H/M in non-operative side at the same time when his overusing activity of non-operative side. With case B, an appearance of long latency reflex (LLR) and an increase of coefficient of variation of SP in the operative side were verified in the period when many assists were required in order to correct motion image in rehabilitation. Concretely, from after the reconstruction over 5 months, LLR was appeared in SP of operative side, and increases of coefficient of variation was most remarkably in 4 months after the reconstruction, amplitude H/M ratio of operative side showed high value in 4 months after the reconstruction. With case C, remarkable problematical point was not found at the time of activity of daily life (ADL) acquisition and occupation return. So, with case C, feature findings of both SP and H reflex were not appeared. The results suggested that SP and H reflex from soleus muscle have become an index expressed neuro-muscular function of lower extremity and supra-spinal function in the patient after reconstruction of ACL.

Neuromuscular function after reconstruction of anterior cruciate ligament--a case study using evoked electromyography.

To clarify the neuro-muscular function of a lower extremity after reconstruction of anterior cruciate ligament (ACL), we studied the alteration of H reflex and Silent period (SP) from the soleus muscle in a patient with ACL reconstruction. Subject was an eighteen year-old male and high school basketball player after a reconstruction of right ACL. Recording of H reflex and SP was started at one month after operation, and ended at six months post operation with a test at every month. As a result of this study, the amplitude ratio of H/M(max) was increased at post four months after ACL reconstruction on operative side. Little variation of SP was acquired in non-operative side. However, that in operative side was increased compared with non-operative side and gradually decreased until post six months. Post six months, the variation of SP in operative side was recovered as that of non-operative side. And, on the operation side, long-latency reflex (LLR) was appeared during SP from one month to five months after, especially its appearance pattern was most markedly post four months. However, post six months, LLR disappeared during SP. The result of H reflex, SP and LLR appearance suggested a following hypothesis; until post six months after ACL reconstruction, even the small and simple task (i.e. an ankle planter flexion with a slight effort) needs to an intervention of a various supra-spinal function. In this case, autonomy of central nervous system related to an out-put mechanism in lower-extremity was acquired post six months.

Introduction of the vastus medialis oblique H-reflex during traction of the leg.

To clarify the excitability of the alpha-motoneuron pool corresponding to the vastus medialis oblique (VMO), this study investigated the H-reflex from the VMO by traction of the leg. One healthy male subject participated in this study, and retesting was performed after 3 days. The surface stimulating electrodes were applied over the course of the femoral nerve on the skin immediately distal to the inguinal ligament. An active electrode for recording the H-reflex was placed on the VMO, and a reference electrode was placed immediately proximal to the patella. The H-reflex was recorded before, during and after traction of the leg. Two patterns of H-reflex modulations were found as follows: 1) the H-reflex amplitudes tended to be lower during traction than before traction, 2) the H-reflex amplitudes tended to be higher after traction. With regard to the decrease in H-reflex amplitude during traction of the leg, the Ib inhibition for the VMO was believed to have occurred by prolonged stretching of the quadriceps tendon and patellar tendon. Also, with regard to the tendency of the VMO H-reflex to increase after traction, disinhibition of the alpha-motoneuron might have occurred in this study.

H-reflex and reciprocal Ia inhibition after fatiguing isometric voluntary contraction in soleus muscle.

This study investigated the H-reflex and reciprocal Ia inhibition during fatigue in the human soleus muscle. Ten healthy subjects participated in this study, and performed intermittent isometric voluntary contraction of the ankle plantarflexion at 50% MVC as the fatiguing task. Reciprocal Ia inhibition was evaluated by the degree of H-reflex amplitude depression in the soleus muscle by the test stimulus following conditioning stimulus to the common peroneal nerve. The difference in H-reflex amplitude between before and after fatiguing task was also checked. There was no significant difference in the degree of H-reflex amplitude depression, although the H-reflex amplitude significantly decreased after the fatiguing task (p < 0.01). From the results of this study, it was considered that the decrease in H-reflex amplitude was caused by descending inhibitory input from the supraspinal to alpha-motoneuron, and the excitability of the Ia inhibitory interneuron was not involved. It was suggested that the function of reciprocal Ia inhibition was difficult to modulate during fatigue caused by isometric voluntary contraction in this study.

M wave and H-reflex of soleus muscle before and after electrical muscle stimulation in healthy subjects.

PURPOSE: This study was the preliminary research for applying the evaluation of muscle fatigue using the evoked electromyography in the field of physical therapy. In this study, we speculated that muscle fatigue was induced by electrical muscle stimulation (EMS). And we studied the M wave and amplitude ratio of H/M before and after EMS because the M wave and amplitude ratio of H/M have been often used as the parameter in the study of muscle fatigue. METHODS: Subjects were five healthy males. In this study, the intermittent EMS (30 Hz) was administered to the soleus muscle of dominant leg for 10 minutes and we analyzed the amplitude of maximal M wave and the amplitude ratio of H/M in this study. RESULTS: The amplitude of maximal M wave after EMS significantly decreased compared with that before the EMS (p < 0.05). And the results of amplitude ratio of H/M varied as follows; decrease in two subjects, increase in one subject and unchanged results in two subjects. DISCUSSION: M wave reflects the excitability of muscle membrane related to the change in force during muscle fatigue and the amplitude ratio of H/M has been considered as the index of a relative excitability of alpha motoneuron pool. From the results of this study, we considered that muscle fatigue was induced by EMS as predictability because the amplitude of maximal M wave significantly decreased after EMS. And it was considered that the excitability of spinal neural function corresponding to fatigued soleus muscle by EMS was not consist change in this study. Therefore we thought that results of amplitude ratio of H/M might be influenced by excitability of spinal neural function in subject's ordinary state. CONCLUSION: It was suggested that the muscle fatigue was induced because the amplitude of maximal M wave significantly decreased after EMS in this study. And also it was suggested the excitability of spinal neural function corresponding with fatigued soleus muscle by EMS was not consist change in this study.

Test-retest reliability for recording the Erb's point potential with a change of recording posture.

This study was the preliminary research for testing the median nerve somatosensory evoked potentials (SEPs) with a postural alteration in the field of rehabilitation medicine. The purpose of this study was to investigate test-retest reliability for recording the median nerve SEPs with a change of recording posture. Subject was one healthy male, with an age of 28 years and a height of 176 cm. Median nerve SEPs was recorded in supine position on the bed with changing the tilting angle, which was set at each of 0, 15, 30, 45, 60, 75, and 90 degrees. We compared a coefficient of variation of the latency and amplitude of the Erb's point potential at each tilting angle. A coefficient of variation of the latency and amplitude at each tilting angle was calculated ranged from 10.0% to 20.0%. From a result in a coefficient of variation, all Erb's point potentials of median nerve SEPs with a change of recording posture were recorded reproducibly in this study.

The silent period from soleus and gastrocnemius muscles in relation to conditions of standing.

To clarify the relationship between postural instability and silent period (SP), we studied the variation of SP from soleus (SOL) and gastrocnemius (GAS) muscles on various standings. Subjects were eight healthy males, with a mean age of 23.5 +/- 2.2 (21-27) years. Standings in this study was regulated with ten kinds of situations provided by visual information, supporting or not by a finger and a width of base of support. SP evoked by single stimulation to tibial nerve at the popliteal fossa was recorded from SOL and GAS of dominant side during ten kinds of standings in random. The raw data were averaged 30 times. SP was calculated the duration from the artifact due to electrical stimulation to re-starting the electromyographical bursting of tonic muscle contraction under 100 or 200 microV|div on a screen. As a result of this study, there were not any statistical significant changes in SP from both SOL and GAS (one-way ANOVA: F = 1.797, F = 1.786) among ten kinds of standing. It is thought that a variation of SP may reflect the magnitude of facilitation or disinhibition of the central nervous system including spinal, brainstem or motor cortex. As the result of this study in healthy persons, it was suggested that the degree of facilitation or disinhibition of central nervous system related to SP from SOL and GAS was not different on ten kinds of standings regulated by visual information and a width of base of support.

Characteristics of F-wave in different stretched positions of the affected arm in patients with cerebrovascular diseases.

To investigate the effect of continued stretching of affected arms in patients with cerebrovascular disease (CVD), F-wave was tested from the abductor pollicis brevis (APB) during relaxation (trial 1) and 3 different continued stretches: stretched position with shoulder abduction (trial 2), stretched position with shoulder abduction and elbow extension (trial 3), and stretched position with shoulder abduction, elbow extension and wrist extension (trial 4) of the affected arm for 1 min. in 20 hemiparesis patients with moderate hypertonus (modified Ashworth scale of 2 or 3) caused by CVD (mean age of 49.5 years). Persistence and amplitude ratio of F/M in trial 2 were the same as those in trial 1. Persistence and amplitude ratio of F/M in trials 3 and 4 were significantly lower than those in trial 1. It was suggested that excitability of spinal neural function of the distal part, the APB, of the affected arm was reduced during continued stretching of the proximal part, shoulder and elbow joints, or all of the shoulder, elbow and wrist joints in hemiparesis patients with moderate hypertonus caused by CVD.

Effect of continued stretching of the affected arm in patients with cerebrovascular diseases by examining H-reflex characteristics.

To investigate excitability of spinal neural function during stretching excises in patients with cerebrovascular disease (CVD), H-reflex was analyzed before, during and after 1 min. continued stretching of the affected arm. 10 hemiparesis patients with hypertonus and hyperreflex, mean age of 53.2 years were tested. H-reflex was recorded from the abductor pollicis brevis on the affected side after stimulation of median nerve in supine position. The persistence, amplitude and amplitude ratio of H/M during stretching were lower than those before and after in the patients with moderately increased muscle tonus. In patients with slightly and markedly increased, H-reflex was same before, during and after continued stretching. It is suggested that excitability of spinal neural function during 1 min. continued stretching was inhibited in the patients with moderately increased muscle tonus caused by CVD.

Characteristic appearances of the H-reflex and F-wave with increased stimulus intensity in patients with cerebrovascular disease.

We experienced H-reflex may be evoked with supramaximal stimulation in patients with cerebrovascular disease (CVD). In this study, we investigated the relationship between the characteristic appearances of H-reflex and F-wave with increased stimulus intensity and neurological signs. We examined the H-reflex and F-wave of the affected arm with increased stimulus intensity during muscle relaxation in 31 patients (17 males and 14 females) with hemiparesis caused by CVD. Mean patient age was 56.0 (range 30-82) years. 30 healthy subjects, mean age of 56.2 (range 28-80) were investigated using the same method as controlled group. H-reflex and F-wave with increased stimulus intensity after the median nerve stimulation at the wrist were recorded from the opponence pollicis muscle on the affected side in patients with CVD or right arm in the healthy subjects. Appearance patterns of the H-reflex and F-wave with increased stimulus intensity was separated into four types. Type 1: F-wave appeared with increased stimulus intensity, but there was no H-reflex. Type 2: H-reflex and F-wave both appeared with increased stimulus intensity, but the F-wave followed disappearance of the H-reflex with increased stimulus intensity. Type 3: H-reflex and F-wave both appeared with increased stimulus intensity, but the F-wave appeared during the H-reflex with increased stimulus intensity. Type 4: Only the H-reflex appeared with increased stimulus intensity, but there was no F-wave. Neurological findings including muscle tone and tendon reflex were also evaluated. Findings on muscle tone and tendon reflex were classified into increased (markedly, moderately and slightly), normal and decreased. Results were analyzed as follows; 1) The characteristic appearances of H-reflex and F-wave in the healthy subjects and 2) The relationship between characteristic appearances of waves with increased stimulus intensity and neurological signs in patients with CVD. 1) Pattern of the H-reflex and F-wave with increased stimulus intensity in all healthy subjects were type 1. 2) Patterns of the H-reflex and F-wave with increased stimulus intensity in patients with markedly increased muscle tone and tendon reflex were almost always type 4. Those with moderately increased signs in this parameter demonstrated type 2 or 3. Those with slightly increased signs in this parameter demonstrated type 1 or 2. Those with normal or decreased signs were type 1. These findings suggest that the characteristic appearances of the H-reflex and F-wave was influenced by grade of neurological signs.