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11.5 Modulation of multisegmental monosynaptic reflexesrecorded from leg muscles during walking and running in human subjects
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Chapter 11. Physiology of motor control: healthy and pathological human models'
SwayStarTM system. Each test was performed after a 3-minutes rest period, the subsequent test was performed after repeating the test activity twice, that is, "warmed up". Results: One-legged stance and gait tests (tandem gait, walking backwards, walking 3 m with head rotation, walking up and down 2 stairs) showed trunk sway amplitudes and task durations greater than normal prior to warming-up, but normal balance control once warmed up. The get-up-and-go test and two-legged stance tests were not affected. Conclusion: We conclude that balance deficits in generalized myotonia patients are present in leg muscles after rest and that "warming-up" improves balance control. Measurements of trunk sway during difficult gait tasks may be an adequate quantification technique to initially define myotonia and transient paresis in these patients, prior to more sensitive, but expensive, laboratory tests. It may also serve as an objective outcome measure to document the effects of symptomatic treatment.
closed (EC), head back eyes open (HBEO), and head back eyes closed (HBEC). Unpaired t-tests and Pearson product moment correlations were used. Results: Patients with BC had significantly worse SOT scores (p 0.005, BC 64.7±13.6, C 81.80±3.83) and CoP velocities with EC (p 0.031, BC 2.25±l.18cm/s, C 1.16±0.42cm/s), HBEO (p 0.024, BC 1.46±0.65cm/s, C 0.81±0.28cm/s), and HBEC (p 0.025, BC 2.19±l.2cm/s, C 1.03±0.44cm/s) when compared to controls. There was also a significant correlation between neuropathy severity and postural sway (r 0.769, p 0.001). Discussion and Conclusion: Women who have undergone taxane therapy for breast cancer have worse postural control compared to agematched healthy women and to patients with diabetic PN[1]. Patients with taxane-induced peripheral neuropathy may benefit from physical therapy for balance retraining to help them maintain normal postural control during and after treatment.
References
[•5]
Modulation of multisegmental monosynaptic reflexes recorded from leg muscles during walking and running in human subjects
P. Dyhre-Poulsen, C. Dy, G. Courtine, S. Harkema, Y.P. Gerasimenko.
Brain Research Institute, University of California Los Angeles', 1000 Veteran Ave Suite A3 86, Los' Angeles', CA 90095 7147, USA Introduction: The amplitude of the soleus H-reflex varies during
locomotion. Due to anatomical conditions it is difficult to elicit H reflexes in other leg muscles, especially during locomotion. Methods: With a new technique it is possible to elicit multisegmental monosynaptic (MM) reflexes in leg muscles simultaneously by stimulating the dorsal roots percutaneously with single 1 ms stimuli. An electrode placed on the skin between the spinous processes of T1 l-T12 was used as cathode and two large anodal electrodes were placed on the abdomen. The thick afferents in the dorsal roots are readily stimulated and monosynaptic reflexes can be elicited bilaterally without stimulation of the motor efferents. If the stimulating electrode is placed lower at about L4, then motor efferents may be activated. Results: We have recorded MM reflexes in 8 leg muscles: medial hamstrings, vastus lateralis, rectus femoris, gastrocnemius, soleus, tibialis anterior, extensor and flexor digitorum brevis bilaterally during walking and running. The MM reflexes were profoundly influenced by the gait pattern. In general the MM reflexes in the leg extensor muscles were depressed during swing while MM reflexes in the leg flexor muscles were depressed during stance. Discussion: The elicited responses were suppressed by vibratory stimulation to muscle tendons. The responses to a second stimulus 50 ms after the first stimulus were lowered indicating that the responses are of reflex nature. Also head/neck position influenced the responses, thus corroborating their reflex nature. Conclusion: With this method it is possible to elicit H-reflexes simultaneously and reliably in multiple muscles during locomotion.
[ 1 ~ ] Impairments in postural control resulting from taxane-induced peripheral neuropathy in women with breast cancer M. Edwards. Department of Physical Therapy and Rehabilitation Science, University of California, San Francisco and San Francisco State University, San Francisco, CA, USA Introduction: Peripheral neuropathy (PN) affects up to 60% of people who take paclitaxel and docetaz~el for cancer treatment. The purpose of this study was to examine if patients with taxane-induced PN have increased center of pressure (COP) velocity and postural sway, as found in patients with diabetic neuropathy [1]. Methods: Subjects included 9 women who underwent taxane therapy for BC (BC 49.33±6.16 years) and 5 healthy women matched by age (C 50.20±5.63 years). All subjects underwent testing of peripheral nerve function, the Sensory Organization Test (SOT), and four conditions on a static Kistler force plate: eyes open (EO), eyes
[1] Simoneau, G.G., et al. Postural instability in patients with diabetic sensory neuropathy. Diabetes Care 1994; 17(12): 1411 21.
[ 1 ~ ] Muscle activity modulation in climbing stairs with non uniform risers C. Frigo 1, M. Rabuffetti2, A.E. Patla 3. 1TBMLab, Dept. of Bioengineering, Polytechnic of Milan, Milan, Italy; eBioengineering Centre-FDG, Don Gnocchi Onlus LR.C.C.S. Foundation, Milan, Italy," SDept. of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada Introduction: Our study was aimed at understanding the compen-
satory mechanisms adopted in stair climbing when this motor task was perturbed by an unpredicted change of a step height. Method: An experimental study was carried out on nine healthy young subjects (age range 24 32 years) walking over a five steps staircase in which the height of one step was randomly changed in the range from 60 to +60 mm. Kinematic, kinetic and EMG data were collected by a TV-camera based motion analyser, force sensors embedded in the steps, and a telemetric EMG system respectively. Results: Almost all the muscles analysed exhibited a change in EMG peak amplitude and delay consistent with the increased or decreased step height. The most correlated ones were the ankle plantarflexors, particularly in the push-off phase of the trailing limb. Discussion and conclusion: The muscle analysed can have a different compensatory effect depending of whether their activity occurs before or after the time of leading foot contact on the varied step. In the first case they can contribute to the proper foot placement, in the second case they are mostly confronted with changed mechanical requirements (Centre of Mass rising and balancing control). Deeper analysis of the correlations between segment kinematics, dynamics and EMG will help clarifying the role of proprioception and vision in these compensatory mechanisms.
[ 1 ~ ] Changes in quadriceps voluntary activation and stretch reflex profile in ACL deficiency S.E Hsiao 1, RH. Chou 2, J.S. Li 1. 1School of Physical Therapy, Kaohsiung Medical University, Taiwan," eDepartment of Orthopaedic Medicine, Chung-Ho Memorial Hospital, Kaohsiung Medical University, Taiwan Introduction: ACL is a neural resource in adjusting knee stability.
Quadriceps weakness in ACL deficiency (ACL-D) may be caused by the loss of ACL reflex to prevent excessive tibia displacement. This study investigated the voluntary activation and the stretch reflex (SR) of bilateral quadriceps in ACL-D. Methods: With ethical approval, 23 patients diagnosed with ACL-D were recruited and tested for quadriceps strength. Voluntary activation failure was estimated with twitch superimposition technique at 70 o of knee flexion. Patella tendon SR was also obtained from the same
Chapter 11. Physiology of motor control: healthy and pathological human models'
SwayStarTM system. Each test was performed after a 3-minutes rest period, the subsequent test was performed after repeating the test activity twice, that is, "warmed up". Results: One-legged stance and gait tests (tandem gait, walking backwards, walking 3 m with head rotation, walking up and down 2 stairs) showed trunk sway amplitudes and task durations greater than normal prior to warming-up, but normal balance control once warmed up. The get-up-and-go test and two-legged stance tests were not affected. Conclusion: We conclude that balance deficits in generalized myotonia patients are present in leg muscles after rest and that "warming-up" improves balance control. Measurements of trunk sway during difficult gait tasks may be an adequate quantification technique to initially define myotonia and transient paresis in these patients, prior to more sensitive, but expensive, laboratory tests. It may also serve as an objective outcome measure to document the effects of symptomatic treatment.
closed (EC), head back eyes open (HBEO), and head back eyes closed (HBEC). Unpaired t-tests and Pearson product moment correlations were used. Results: Patients with BC had significantly worse SOT scores (p 0.005, BC 64.7±13.6, C 81.80±3.83) and CoP velocities with EC (p 0.031, BC 2.25±l.18cm/s, C 1.16±0.42cm/s), HBEO (p 0.024, BC 1.46±0.65cm/s, C 0.81±0.28cm/s), and HBEC (p 0.025, BC 2.19±l.2cm/s, C 1.03±0.44cm/s) when compared to controls. There was also a significant correlation between neuropathy severity and postural sway (r 0.769, p 0.001). Discussion and Conclusion: Women who have undergone taxane therapy for breast cancer have worse postural control compared to agematched healthy women and to patients with diabetic PN[1]. Patients with taxane-induced peripheral neuropathy may benefit from physical therapy for balance retraining to help them maintain normal postural control during and after treatment.
References
[•5]
Modulation of multisegmental monosynaptic reflexes recorded from leg muscles during walking and running in human subjects
P. Dyhre-Poulsen, C. Dy, G. Courtine, S. Harkema, Y.P. Gerasimenko.
Brain Research Institute, University of California Los Angeles', 1000 Veteran Ave Suite A3 86, Los' Angeles', CA 90095 7147, USA Introduction: The amplitude of the soleus H-reflex varies during
locomotion. Due to anatomical conditions it is difficult to elicit H reflexes in other leg muscles, especially during locomotion. Methods: With a new technique it is possible to elicit multisegmental monosynaptic (MM) reflexes in leg muscles simultaneously by stimulating the dorsal roots percutaneously with single 1 ms stimuli. An electrode placed on the skin between the spinous processes of T1 l-T12 was used as cathode and two large anodal electrodes were placed on the abdomen. The thick afferents in the dorsal roots are readily stimulated and monosynaptic reflexes can be elicited bilaterally without stimulation of the motor efferents. If the stimulating electrode is placed lower at about L4, then motor efferents may be activated. Results: We have recorded MM reflexes in 8 leg muscles: medial hamstrings, vastus lateralis, rectus femoris, gastrocnemius, soleus, tibialis anterior, extensor and flexor digitorum brevis bilaterally during walking and running. The MM reflexes were profoundly influenced by the gait pattern. In general the MM reflexes in the leg extensor muscles were depressed during swing while MM reflexes in the leg flexor muscles were depressed during stance. Discussion: The elicited responses were suppressed by vibratory stimulation to muscle tendons. The responses to a second stimulus 50 ms after the first stimulus were lowered indicating that the responses are of reflex nature. Also head/neck position influenced the responses, thus corroborating their reflex nature. Conclusion: With this method it is possible to elicit H-reflexes simultaneously and reliably in multiple muscles during locomotion.
[ 1 ~ ] Impairments in postural control resulting from taxane-induced peripheral neuropathy in women with breast cancer M. Edwards. Department of Physical Therapy and Rehabilitation Science, University of California, San Francisco and San Francisco State University, San Francisco, CA, USA Introduction: Peripheral neuropathy (PN) affects up to 60% of people who take paclitaxel and docetaz~el for cancer treatment. The purpose of this study was to examine if patients with taxane-induced PN have increased center of pressure (COP) velocity and postural sway, as found in patients with diabetic neuropathy [1]. Methods: Subjects included 9 women who underwent taxane therapy for BC (BC 49.33±6.16 years) and 5 healthy women matched by age (C 50.20±5.63 years). All subjects underwent testing of peripheral nerve function, the Sensory Organization Test (SOT), and four conditions on a static Kistler force plate: eyes open (EO), eyes
[1] Simoneau, G.G., et al. Postural instability in patients with diabetic sensory neuropathy. Diabetes Care 1994; 17(12): 1411 21.
[ 1 ~ ] Muscle activity modulation in climbing stairs with non uniform risers C. Frigo 1, M. Rabuffetti2, A.E. Patla 3. 1TBMLab, Dept. of Bioengineering, Polytechnic of Milan, Milan, Italy; eBioengineering Centre-FDG, Don Gnocchi Onlus LR.C.C.S. Foundation, Milan, Italy," SDept. of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada Introduction: Our study was aimed at understanding the compen-
satory mechanisms adopted in stair climbing when this motor task was perturbed by an unpredicted change of a step height. Method: An experimental study was carried out on nine healthy young subjects (age range 24 32 years) walking over a five steps staircase in which the height of one step was randomly changed in the range from 60 to +60 mm. Kinematic, kinetic and EMG data were collected by a TV-camera based motion analyser, force sensors embedded in the steps, and a telemetric EMG system respectively. Results: Almost all the muscles analysed exhibited a change in EMG peak amplitude and delay consistent with the increased or decreased step height. The most correlated ones were the ankle plantarflexors, particularly in the push-off phase of the trailing limb. Discussion and conclusion: The muscle analysed can have a different compensatory effect depending of whether their activity occurs before or after the time of leading foot contact on the varied step. In the first case they can contribute to the proper foot placement, in the second case they are mostly confronted with changed mechanical requirements (Centre of Mass rising and balancing control). Deeper analysis of the correlations between segment kinematics, dynamics and EMG will help clarifying the role of proprioception and vision in these compensatory mechanisms.
[ 1 ~ ] Changes in quadriceps voluntary activation and stretch reflex profile in ACL deficiency S.E Hsiao 1, RH. Chou 2, J.S. Li 1. 1School of Physical Therapy, Kaohsiung Medical University, Taiwan," eDepartment of Orthopaedic Medicine, Chung-Ho Memorial Hospital, Kaohsiung Medical University, Taiwan Introduction: ACL is a neural resource in adjusting knee stability.
Quadriceps weakness in ACL deficiency (ACL-D) may be caused by the loss of ACL reflex to prevent excessive tibia displacement. This study investigated the voluntary activation and the stretch reflex (SR) of bilateral quadriceps in ACL-D. Methods: With ethical approval, 23 patients diagnosed with ACL-D were recruited and tested for quadriceps strength. Voluntary activation failure was estimated with twitch superimposition technique at 70 o of knee flexion. Patella tendon SR was also obtained from the same