scholarly journals Precise quantification of the time course of voluntary activation capacity following Botulinum toxin injections in the biceps brachii muscles of chronic stroke survivors

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
S. Chandra ◽  
B. Afsharipour ◽  
W. Z. Rymer ◽  
N. L. Suresh
Keyword(s):  
Botulinum Toxin ◽  
Time Course ◽  
Biceps Brachii ◽  
Chronic Stroke ◽  
Voluntary Activation ◽  
Stroke Survivors ◽  
Precise Quantification ◽  
Botulinum Toxin Injections ◽  
Activation Capacity

scholarly journals The Effects of Botulinum Toxin Injections on Spasticity and Motor Performance in Chronic Stroke with Spastic Hemiplegia

Toxins ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 492
Author(s):  
Yen-Ting Chen ◽  
Chuan Zhang ◽  
Yang Liu ◽  
Elaine Magat ◽  
Monica Verduzco-Gutierrez ◽  
...  
Keyword(s):  
Muscle Strength ◽  
Motor Performance ◽  
Biceps Brachii ◽  
Elbow Flexion ◽  
Force Variability ◽  
Stroke Survivors ◽  
Modified Ashworth Scale ◽  
Before And After ◽  
Spastic Hemiplegia ◽  
Botulinum Toxin Injections

Spastic muscles are weak muscles. It is known that muscle weakness is linked to poor motor performance. Botulinum neurotoxin (BoNT) injections are considered as the first-line treatment for focal spasticity. The purpose of this study was to quantitatively investigate the effects of BoNT injections on force control of spastic biceps brachii muscles in stroke survivors. Ten stroke survivors with spastic hemiplegia (51.7 ± 11.5 yrs; 5 men) who received 100 units of incobotulinumtoxinA or onabotulinumtoxinA to the biceps brachii muscles participated in this study. Spasticity assessment (Modified Ashworth Scale (MAS) and reflex torque) and muscle strength of elbow flexors, as well as motor performance assessment (force variability of submaximal elbow flexion) were performed within one week before (pre-injection) and 3~4 weeks (3-wk) after BoNT injections. As expected, BoNT injections reduced the MAS score and reflex torque, and elbow flexor strength on the spastic paretic side. However, motor performance remained within similar level before and after injections. There was no change in muscle strength or motor performance on the contralateral arm after BoNT injections. The results of this study provide evidence that BoNT injections can reduce spasticity and muscle strength, while motor performance of the weakened spastic muscle remains unchanged.

scholarly journals Prolonged time course of population excitatory postsynaptic potentials in motoneurons of chronic stroke survivors

2019 ◽  
Vol 122 (1) ◽  
pp. 176-183
Author(s):  
Jongsang Son ◽  
Xiaogang Hu ◽  
Nina L. Suresh ◽  
William Z. Rymer
Keyword(s):  
Time Course ◽  
Chronic Stroke ◽  
H Reflex ◽  
Reflex Response ◽  
Excitatory Postsynaptic Potential ◽  
Stroke Survivors ◽  
Potential Mechanism ◽  
Spinal Motoneurons ◽  
Hemispheric Stroke ◽  
Ia Epsp

Hyperexcitability of spinal motoneurons may contribute to muscular hypertonia after hemispheric stroke. The origins of this hyperexcitability are not clear, but we hypothesized that prolongation of the Ia excitatory postsynaptic potential (EPSP) in spastic motoneurons may be one potential mechanism, by enabling more effective temporal summation of Ia EPSPs, making action potential initiation easier. Thus, the purpose of this study is to quantify the time course of putative EPSPs in spinal motoneurons of chronic stroke survivors. To estimate the EPSP time course, a pair of low-intensity electrical stimuli was delivered sequentially to the median nerve in seven hemispheric stroke survivors and in six intact individuals, to induce an H-reflex response from the flexor carpi radialis muscle. H-reflex response probability was then used to quantify the time course of the underlying EPSPs in the motoneuron pool. A population EPSP estimate was then derived, based on the probability of evoking an H-reflex from the second test stimulus in the absence of a reflex response to the first conditioning stimulus. Our experimental results showed that in six of seven hemispheric stroke survivors, the apparent rate of decay of the population EPSP was markedly slower in spastic compared with contralateral (stroke) and intact motoneuron pools. There was no significant difference in EPSP time course between the contralateral side of stroke survivors and control subject muscles. We propose that one potential mechanism for hyperexcitability of spastic motoneurons in chronic stroke survivors may be associated with this prolongation of the Ia EPSP time course. Our subthreshold double-stimulation approach could provide a noninvasive tool for quantifying the time course of EPSPs in both healthy and pathological conditions. NEW & NOTEWORTHY Spastic motoneurons in stroke survivors showed a prolonged Ia excitatory postsynaptic potential (EPSP) time course compared with contralateral and intact motoneurons, suggesting that one potential mechanism for hyperexcitability of spastic motoneurons in chronic stroke survivors may be associated with this prolongation of the Ia EPSP time course.

scholarly journals Can the positions of the spastic upper limb in stroke survivors help muscle choice for botulinum toxin injections?

2019 ◽  
Vol 77 (8) ◽  
pp. 568-573 ◽  
Author(s):  
André Luiz Salcedo Gomes ◽  
Francisco Falleiros de Mello ◽  
Jorge Cocicov Neto ◽  
Marcelo Causin Benedeti ◽  
Luis Felipe Miras Modolo ◽  
...  
Keyword(s):  
Botulinum Toxin ◽  
Upper Limb ◽  
Botulinum Toxin A ◽  
Neuromuscular Block ◽  
Stroke Survivors ◽  
Motor Impairments ◽  
Brazilian Sample ◽  
Pronator Teres ◽  
Elbow Flexors And Extensors ◽  
Botulinum Toxin Injections

ABSTRACT Motor impairments in stroke survivors are prevalent and contribute to dependence in daily activities, pain and overall disability, which can further upper-limb disability. Treatment with botulinum toxin A (BoNT-A) is indicated for focal spasticity and requires knowledge of biomechanics and anatomy to best select muscles to be injected in the limb. Objective: We aimed to describe the frequency of posture patterns in a Brazilian sample of stroke survivors and correlate them with recommendations of muscle selection for treatment with BoNT-A. Methods: Fifty stroke patients with spastic upper limbs scheduled for neuromuscular block were photographed and physically examined, to be classified by three independent evaluators according to Hefter's classification. Muscles that were injected with BoNT-A by their routine doctors were retrieved from medical charts. Results: Pattern III and IV were the most common (64.7%, 21.6%). We further subclassified pattern III according to the rotation of the shoulder, which effectively interfered in muscle choice. The muscles most frequently treated were shoulder adductors and internal rotators, elbow flexors and extensors, in forearm, the pronator teres and finger and wrist flexors, and, in the hand the adductor pollicis. Conclusion: Frequencies of upper-limb postures differed from previous reports. Other clinical features, besides spasticity, interfered with muscle choice for BoNT-A injection, which only partially followed the recommendations in the literature.

Voluntary activation failure contributes more to plantar flexor weakness than antagonist coactivation and muscle atrophy in chronic stroke survivors

2010 ◽  
Vol 109 (5) ◽  
pp. 1337-1346 ◽  
Author(s):  
Cliff S. Klein ◽  
Dina Brooks ◽  
Denyse Richardson ◽  
William E. McIlroy ◽  
Mark T. Bayley
Keyword(s):  
Muscle Atrophy ◽  
Muscle Activation ◽  
Voluntary Contraction ◽  
Chronic Stroke ◽  
Voluntary Activation ◽  
Stroke Survivors ◽  
Plantar Flexor ◽  
Plantar Flexors ◽  
Emg Amplitude ◽  
Magnetic Resonance Imaging Mri

The contributions of nervous system muscle activation and muscle atrophy to poststroke weakness have not been evaluated together in the same subject. Maximal voluntary contraction (MVC) torque, voluntary activation (twitch interpolation), and electromyographic (EMG) amplitude were determined bilaterally in the plantar flexors of seven chronic stroke survivors (40–63 yr, 24–51 mo poststroke). Volumes of the plantar flexor muscles were determined bilaterally with magnetic resonance imaging (MRI). The mean (±SD) contralesional (paretic) MVC torque was less than one-half of the ipsilesional leg: 56.7 ± 57.4 vs. 147 ± 35.7 Nm ( P = 0.006). Contralesional voluntary activation was only 48 ± 36.9%, but was near complete in the ipsilesional leg, 97 ± 1.9% ( P = 0.01). The contralesional MVC EMG amplitude (normalized to the maximum M-wave peak-to-peak amplitude) of the gastrocnemii and soleus were 36.0 ± 28.5 and 36.0 ± 31.0% of the ipsilesional leg. Tibialis anterior (TA) EMG coactivation was not different between the contralesional (23.2 ± 24.0% of TA MVC EMG) and ipsilesional side (12.3 ± 5.7%) ( P = 0.24). However, TA EMG coactivation was excessive (71%) in one subject and accounted for ∼8% of her weakness based on the estimated antagonist torque. Relative (%ipsilesional leg) plantar flexor and gastrocnemii volumes were 88 ± 6% ( P = 0.004) and 76 ± 15% ( P = 0.01), respectively. Interlimb volume differences of the soleus, deep plantar flexors, and peronei were not significant. Preferred walking speed (0.83 ± 0.33 m/s) was related to the contralesional MVC torque ( r2 = 0.57, P = 0.05, N = 7), but the two subjects with the greatest weakness walked faster than three others. Our findings suggest that plantar flexor weakness in mobile chronic stroke survivors reflects mostly voluntary activation failure, with smaller contributions from antagonist activity and atrophy.

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