To evaluate normal healthy persons without spasticity to observe normal findings of the elbow stretch reflex using a newly developed, portable, hand-driven spasticity-measuring system.
Thirty normal persons without any disease involving the central or peripheral nervous system were enrolled in this study. The portable hand-driven isokinetic system is able to measure the joint angle, angular velocity, electromyographic (EMG) signals, and torque during elbow passive extension-flexion. One set of 10 passive elbow extension and flexion movements was performed for data acquisition at each angular velocity, including 60, 90, 120, 150 and 180 degrees per second (°/sec). Electromyographic data were collected from the biceps brachii and the triceps brachii. Torque data were collected from sensors around the wrist.
We were able to detect EMG activity and torque in all subjects by using the new portable hand-driven isokinetic system. EMG activity and torque increased with incremental increase of angular velocities. The joint angle of maximal EMG activity according to different angular velocities did not show any significant difference (116°-127° in elbow extension and 37°-66° in elbow flexion). The joint angles of maximal torque according to different angular velocities were not significantly different either.
Using the portable hand-driven isokinetic system on the elbows of normal subjects, we were able to obtain expected results. By considering our normal findings of the elbow stretch reflex using this system, we propose that the various aspects of spasticity-related data can be measured successfully.
Citations
Method: Spinal cords of 25 rabbits were contused by 20 g⁓20 cm weight drop in the 11th thoracic spine. After 2 weeks, muscle stretch reflex was measured. Triceps surae was dissected and stretched for 5 mm at the rate of 2 mm/sec and the length-tension curve were obtained. The slope in the length-tension curve was defined as stiffness index (SI). After baseline measurement, group I (n=6) received 50 mg/kg GBP IM injection and group II (n=8) received 100 mg/kg GBP IM injection, but control group (n=5) did not. Muscle stretch reflex was measured again after 30 minutes and 60 minutes, and then after sciatic nerve section. Active tension was calculated by subtracting passive tension from total tension. Proportion of SI was calculated by dividing follow-up SI with baseline SI.
Results: The proportion of SI of active tension reduced significantly at 30 minutes and 60 minutes compared to baseline (p＜0.001, p＜0.001). The proportion of SI of active tension in both group I and group II reduced significantly than control group (p=0.041, p＜0.001). The proportion of SI of active tension in group II reduced than group I, but it was not statistically significant (p=0.166).
Conclusion: The GBP reduced significantly muscle stretch reflex in spinal cord injured rabbits and showed dose-response tendency.
Objective: The purpose of this study is to develop an experimental spinal cord injury spasticity model using rabbits and to evaluate a quantitative spasticity measure.
Method: After an general anesthesia, 19 rabbits out of total 24 rabbits were laminectomized posteriorly and the spinal cords contused with 15 g⁓20 cm weight drop around 11th and 12th thoracic cord. After two weeks, behavioral analysis and clinical measurements of hindlimb spasticity were assessed. After that, rabbits' triceps surae was dissected and the length-tension plot was obtained by stretching it 5 mm, 2 mm/sec. And then the stiffenss of stretch reflex was determined from the length-tension plot. The stiffness of stretch reflex of the five normal control group was measured.
Results: 1) The measure was possible among 15 out of 19 spinal cord injured rabbits. One out of 19 rabbits was died
from urinary infection. Two rabbits was died from intraop-
erative bleeding at 2 weeks. Another one was excluded from the measurement due to joint contracture. 2) All of 15 rabbits showed clinical spasticity of hindlimb in 2 weeks. The spasticity was increased after the 4th day. 3) On the length-tension plot, the stiffness of stretch reflex of 15 rabbits significantly increased more than that of 5 normal group. 4) The total stiffness is correlated with the deep tendon reflex of knee and muscle tone of ankle. The stiffness of stretch reflex is weakly correlated with the deep tendon reflex of knee, digital hyperreflexia and ankle clonus.
Conclusion: The experimental spinal cord injury model and the quantitative spasticity measure method would contribute to measure the effect of the new therapy of spasticity more accurately, and to establish a principle of the new therapy. In addition, the study is expected to contribute to establish pathophysiology of spasticity. (J Korean Acad Rehab Med 2002; 26: 37-45)
Objective: The purpose of this study was to investigate the influence of hyperactive stretch reflexes and contralateral adductor spread on the prognosis of gait in cerebral palsy with spastic diplegia and to investigate the reflex characteristics of spastic patients according to motor development.
Method: Thirty three children with spastic diplegia were examined. Compound muscle action potentials elicited by electrical hammer were used for quantification of stretch reflexes. Clinical spasticity was evaluated with the modified Ashworth scale and re-evaluation was done at least for 18 months. The patients were classified as 3 groups according to the stage of motor development: Group I consisted of children who were unable to sit; Group II children were able to pull to stand but unable to walk independently; Group III children could walk independently more than ten steps. Reflex irradiation, amplitudes of compound muscle action potentials, amplitude ratios, and Ashworth scores were analyzed and compared between the groups. Twenty four normal infants and 18 children were examined as control.
Results: Contralateral adductor responses were elicited with patellar tendon tap stimulation in all spastic diplegic children. The amplitudes of contralateral adductor were 2.41 mV in group I, 1.75 mV in group II, and 1.21 mV in group III. The amplitude ratio of contralateral adductor to rectus femoris were 0.53 in group I, 0.40 in group II, and 0.26 in group III, respectively, and correlated with the degree of spasticity.
Conclusion: The stretch reflex responses in children with cerebral palsy with spastic diplegia were highly exaggerated, and correlated with motor development. Spread of reflexes to contralateral adductor muscle would be in clinical and electrophysiological value.
Objective: This study was designed to evaluate the usefulness of stretch reflex threshold speed (SRTS) in biomechanical assesment of spasticity of hemiplegic patients.
Method: Thirty-eight hemiplegic patients and twenty-seven control subjects were studied. The spasticity of ankle plantar flexor muscles were assessed both clinically and biomechanically. Modified Ashworth scale (MAS) and Brunnstrom stage were used in clinical assessment. For biomechanical assessment, ankle plantar flexor muscles were stretched isokinetically while EMG signals were recorded simultaneously. SRTS was defined as a minimum angular velocity in which EMG signals evoked by stretch reflex were recorded.
Results: SRTSs of ankle plantar flexors were 128.1⁑47.1o/sec in control group, 163.7⁑79.7o/sec in intact legs, and 83.4⁑69.1o/sec in involved legs of hemiplegic group. STRS was significantly lower in involved legs of hemiplegic group than in intact legs of hemiplegic group and control group. Significant reverse correlation was observed between SRTS and MAS. There was significant difference in SRTS between MAS 0 group and other groups. The patients with Brunnstrom stage 3 and 4 groups showed decreased SRTS compared to the patients with other groups.
Conclusion: SRTS is thought to reflect increased excitability of stretch reflex and seems to be one of useful parameters in quantitative assessment of spasticity.
Objective: The purpose of this study was to titrate the nerve block effect of phenol with different concentrations of phenol solution by electrophysiological and mechanical measurements.
Method: Right tibial nerves of twenty three adult rabbits were blocked by phenol solution with different concentrations (3%, 5%). Nerve conduction study for compound muscle action potential (CMAP), tension by electrical stimulation, and stiffness (slope) of stretch reflex of the triceps surae were performed after nerve block (4 weeks, 8 weeks, 16 weeks). The ratios of each values of right limb to those of left limb were used to evaluate the nerve block effect.
Results: The ratios of CMAP amplitude, tension, and slope of 3% group were 0.36, 0.55, and 0.56 at 4 weeks and those of 5% group were 0.21, 0.25, and 0.58. There were statistically significant differences of the CMAP amplitude and tension ratios, however there was no statistically significant difference of the slope ratio between two groups at 4 weeks. The ratios of CMAP amplitude, tension, and slope of 5% phenol group were increased with time.
Conclusion: Nerve block effects by 5% phenol solution were greater than 3%. These data suggest that nerve block effect can be titrated with concentration of phenol solution.
Objective: The aim of this study was to develop objective evaluation method which reflect the velocity dependent increase of stretch reflex in spasticity using the pendulum test and dynamic electromyography.
Method: Kinematic analysis for knee angle and angular velocity measurement, and dynamic electromyography were performed simultaneously during pendulum movement of spastic lower extremity in supine position for nineteen spastic hemiplegia patients and ten normal control subjects. Angular relaxation index (ARI), Maximum angular velocity (MAV), Angular threshold (AT) and Angular velocity threshold (AVT) were used for the evaluation of spsticity.
Results: 1) ARI was 1.64⁑0.04 in normal, 1.28⁑0.14 in modified Ashworth scale (MAS) I, 1.18⁑0.16 in MAS II, 1.02⁑0.13 in MAS III, 2) MAV was 325.0⁑29.4 in normal, 301.7⁑37.8 in MAS I, 269.2⁑29.7 in MAS II, 232.4⁑28.2 in MAS III, 3) In normal subjects EMG activity did not occur, whereas in spastic hemiplegic patient a stretch reflex appears in thigh muscle. AT and AVT were 57.39⁑4.45, 256.24⁑14.07 in MAS I, 38.59⁑4.26, 184.45⁑12.7 in MAS II, 19.13⁑7.13, 136.06⁑12.88 in MAS III, respectively, 4) Correlation coefficients of the ARI (r=0.786), AT (r=0.960), AVT (r=0.949) showed significantly negative correlations with the MAS.
Conclusion: 1) AT and AVT are more sensitive parameters than ARI for documenting spasticity in hemiplegic patients. 2) An evaluation of spasticity using pendulum test and dynamic electromyography would provide consistent results with little error and would not be influenced by the change of examiner or environment. Thus we can get very reliable results using this method.
Objective: To find the developing features of H reflex by the gradual increase of stimulation intensity, to evaluate the variability of each H reflex latency, and to verify the consistency of the side-to-side difference of bilateral H reflex latencies in normal population.
Method: Fifty normal persons (100 limbs) were studied. H reflexes were elicited using standardized technique from Braddom and Johnson.
Result: H reflex developed in the stimulation intensity at which M response was not evoked in 46 of total 100 limbs. The latency difference between the longest and shortest in each ipsilateral evoked potential was 0∼2.1 ms (mean 0.65±0.44 ms). In the side-to-side latency difference between the variously evoked H waves, the mean value of maximal one was 1.28±0.63 ms (0.4∼2.6 ms), and the mean value of the minimal one was 0.24±0.35 ms (0∼1.5 ms). The mean side-to-side latency difference between the H waves of maximal amplitudes was 0.69±0.46 ms (0.1∼1.6 ms), and the mean side-to-side difference between the shortest latencies was 0.61±0.53 ms (0∼2.1 ms). Among these findings the latency difference of the maximal amplitude was observed in 47 cases with 0∼1.5 ms, in 3 cases with more than 1.5 ms.
Conclusion: In diagnosing the S1 radiculopathy with the side-to-side latency difference it will be reasonable to use the latency of maximal amplitude or the shortest latency as diagnostic tool, and reevaluation will be needed with the diagnostic criteria of 1.5 ms latency difference.
Objective: We designed this study to evaluate muscle tone by using a biomechanical method and to provide data for the future studies about muscle tone.
Method: We evaluated 29 subjects without known neuromuscalar diseases using the biomechanical method. Both plantar flexors of each subject were passively stretched by isokinetic dynamometer from 30oplantar flexion position to 10odorsiflexion position. Peak eccentric torque (PET) and torque threshold angle (TTA) were calculated at angular velocity of 10o/sec, 90o/sec and 300o/sec. Regression lines from torque/position curve at 10o/sec and 300o/sec were considered an intrinsic stiffness index (ISI) and total stiffness index (TSI). Stretch reflex threshold speed (SRTS) was defined as the minimum speed of plantar flexion movement in which EMG reflex activity in plantar flexor muscles is induced.
Results: The mean of TTA was higher in 10o/sec than in 300o/sec. The means of ISI and TSI were 0.11⁑0.08, and 0.18⁑0.04. The mean of SRTS was 125.2⁑48.3o. No statistical difference in each parameter was found according to the side or gender.
Conclusion: ISI, TSI, PET, TTA and SRTS using a biomechanical method are thought to be useful parameters for the quantitative assessment of muscle tone change of ankle plantar flexors.
Objectives: To determine the effect of facilitation on H reflex side-to-side amplitude ratio and to determine the effect of averaging under the assumption that an averaging could further stabilize the amplitude ratio in a facilitated condition.
Method: FCR H reflex amplitude ratios of direct and averaged potentials were measured in fifty asymptomatic subjects under three conditions, during rest, during a constant 5 pound isometric contraction under the hand-dynamometer monitoring, and during a moderate constant isometric contraction under the electromyographer's verbal guidance.
Results: The lower limits of the amplitude ratios that encompass 97.5% of subjects by the percentile method under three conditions were as follows; (1) during the rest (n=37); 0.47 (direct) and 0.50 (average), (2) during the constant 5 pound isometric contraction under the hand- dynamometer monitoring; 0.47 (direct) and 0.48 (average), and (3) during the moderate constant isometric contraction under the electromyographer's verbal guidance; 0.48 (direct) and 0.46 (average), respectively.
Conclusion: There seems to be no definite effect of facilitation and averaging on H reflex amplitude ratio. H reflex amplitude ratio measured in facilitated condition without averaging is still useful for the diagnosis of unilateral radiculopathy.
Objective: To compare the diagnostic significance of H reflex and somatosensory evoked potential(SEP) in the diagnosis of S1 radiculopathy, and to explore the possible interpretations on the discrepancies of the test results.
Method: Twenty-eight patients who were diagnosed as a S1 radiculopathy by the clinical and radiological correlations, and thirty-five controls with no evidence of S1 radiculopathy by the clinical or radiological studies were studied by the H reflex, sural SEP, and needle electromyography.
Results: The sensitivity of H reflex study was 64% for the S1 radiculopathy, and the specificity was 86%. The sensitivity and the specificity of the sural SEP study for the S1 radiculopathy were 50% and 80% respectively. Within 1 month from the onset, the sensitivity of H reflex increased to 75%. The needle electromyography showed 19% for the sensitivity and 100% for the specificity. The probability of the S1 radiculopathy was 70% in 10 cases who had the abnormal H reflex and normal SEP values and 36% in 8 cases who had the normal H reflex and abnormal SEP values.
Conclusion: H reflex study was the most sensitive test in the electrodiagnosis of the S1 radiculopathy and the electrodiagnostic significance of sural SEP was obscure.
The effect of electrical nerve stimulation are controversial because of the inconsistent variables of stimulating current and electrophysiologic study. The purposes of this study are to reconfirm the electrophysiolgic changes by electrical stimulation of the peripheral nerve that had been reported in 1993, and to monitor how long they will be maintained. In this study, the following conditioning stimulations were applied to 20 healthy volunteers; interferential current(frequency: 80∼100 Hz, intensity: 27∼34 mA) on the sacral paraspinal area. The H reflex, the F response, and the somatosensory evoked potential(SEP) of the tibial nerve were evaluated as the electrophysiologic study before, immediately after, 30 minutes, 60 minutes, and 120 minutes after the above conditioning stimulation. The following results were obtained;
1) Latencies of the H reflex, the F response and the SEP(P1), and the F wave conduction time, the F wave conduction velocity and the F ratio in the tibial nerve conduction study were increased by conditioning stimulation of the proximal peripheral nerves(P＞0.01).
2) Changes of the amplitude of the H reflex, the H/M ratio, and the amplitude(P1N1) of the tibial SEP were not significant in the same conditioning stimulation(P＞0.05).
3) Prolongations of the latencies of H reflex, F response and P1 SEP of the tibial nerve were the most significant immediately after conditioning stimulation and sustained for 45 minutes after conditioning on average (P＜0.01).
The above results suggest that certain conditional electrical stimulation of the peripheral nerves causes reversible changes in the conduction of the H reflex, the F response and the SEP and they may be inhibitory effect of the proximal conduction via the spinal cord.
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