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Upper-extremity spinal reflex inhibition is reproducible and strongly related to grip force poststroke.
PurposeImpaired reflex regulation is assumed to contribute to upper-extremity motor impairment poststroke; however, the relationship between reflex inhibition and motor function remains unclear. To address this question, it is first necessary to determine the reproducibility of reflex responses. The objective of this study was to establish the test-retest reliability of flexor carpi radialis H-reflex inhibition in healthy control and stroke participants and investigate the correlation between H-reflex inhibition and grip strength.Materials and methodsEighteen persons poststroke (mean ± SD: age 63 ± 13 years; 6 ± 5 years poststroke; 13 males) and 16 healthy controls (age: 62 ± 12 years) participated. Reflex inhibition was tested on 2 separate days by conditioning the H-reflex with radial nerve stimulation at two different interstimulus intervals: 13 ms (presynaptic Ia inhibition-PSI) and 0 ms (disynaptic inhibition). Pearson's and intraclass correlation coefficients [two-way mixed model-ICC (1, 2)], and standard error of measurement (SEM) were calculated.ResultsRelative reliability (ICCs) ranged from good to excellent (0.61-0.78). SEM was low (range 10-19%, stroke; 15-20%, healthy controls). Paretic grip strength and paretic limb PSI revealed a positive correlation (r = 0.70; p < 0.0125). Disynaptic inhibition and paretic grip strength were not correlated.ConclusionsTo our knowledge, this is the first study to demonstrate reproducibility of reflex inhibition in individuals poststroke. Furthermore, we quantify smallest real differences, which provide an estimate of the magnitude of effect required to determine a meaningful change, exceeding measurement error. The correlation between PSI and grip strength suggests the potential contribution of PSI to grip force production and upper-extremity motor function
Revisiting physiologic and psychologic triggers that increase spasticity
Objective: The aims of this study were to systematically identify and summarize the literature examining the impact of physiologic and psychologic triggers on spasticity and discuss the evidence supporting various types of triggers. Design: PubMed, EMBASE, CINAHL, and PEDro databases were searched using specific keyword combinations. Only studies using clinical tests or self-reports of spasticity were included. Results: A total of 1152 articles were scanned for relevance, and of 44 relevant articles, 24 were reviewed. Pregnancy, posture, cold, circadian rhythm, and skin conditions increased spasticity and were measured using objective clinical tests. Self-reports of spasticity suggest that triggers such as bowel- and bladder-related issues, menstrual cycle, mental stress, and tight clothing can all increase spasticity. No literature evidence of increase in spasticity in response to heterotopic ossification, hemorrhoids, deep vein thrombosis, fever, and sleep patterns was found. Conclusions: Although self-reports indicate a strong possibility of increasing spasticity, without objective examination, the true effects of these triggers on spasticity remain inconclusive. Most studies reviewed here were performed in the spinal cord injury population; therefore, it is not known whether these triggers induce similar effects in persons with other neurologic etiologies. Copyright © 2013 by Lippincott Williams & Wilkins
Adverse Clinical Effects of Botulinum Toxin Intramuscular Injections for Spasticity
Objective: The adverse events (AEs) with botulinum toxin type-A (BoNTA), used for indications other than spasticity, are widely reported in the literature. However, the site, dose, and frequency of injections are different for spasticity when compared to the treatment for other conditions and hence the AEs may be different as well. The objective of this study was to summarize the AEs reported in Canada and systematically review the AEs with intramuscular botulinum toxin injections to treat focal spasticity. Methods : Data were gathered from Health Canada (2009-2013) and major electronic databases. Results : In a 4 year period, 285 AEs were reported. OnabotulinumtoxinA (n=272 events): 68% females, 53% serious, 18% hospitalization, and 8% fatalities. The type of AEs reported were - muscle weakness (19%), oropharyngeal (14%), respiratory (14%), eye related (8%), bowel/bladder related (8%), and infection (5%). IncobotulinumtoxinA (n=13): 38% females, 62% serious, and 54% hospitalization. The type of AEs reported were - muscle weakness (15%), oropharyngeal (15%), respiratory (38%), eye related (23%), bowel/bladder related (15%), and infection (15%). Commonly reported AEs in the literature were muscle weakness, pain, oropharyngeal, bowel/bladder, blood circulation, neurological, gait, and respiratory problems. Conclusion: While BoNTA is useful in managing spasticity, future studies need to investigate the factors that can minimize AEs. A better understanding of the underlying mechanisms of the AEs can also improve guidelines for BoNTA administration and enhance outcomes
Impact of Spasticity on Balance Control during Quiet Standing in Persons after Stroke
Background. Balance impairments, falls, and spasticity are common after stroke, but the effect of spasticity on balance control after stroke is not well understood. Methods. In this cross-sectional study, twenty-seven participants with stroke were divided into two groups, based on ankle plantar flexor spasticity level. Fifteen individuals with high spasticity (Modified Ashworth Scale (MAS) score of ≥2) and 12 individuals with low spasticity (MAS score ud_less_than2) completed quiet standing trials with eyes open and closed conditions. Balance control measures included centre of pressure (COP) root mean square (RMS), COP velocity, and COP mean power frequency (MPF) in anterior-posterior and mediolateral (ML) directions. Trunk sway was estimated using a wearable inertial measurement unit to measure trunk angle, trunk velocity, and trunk velocity frequency amplitude in pitch and roll directions. Results. The high spasticity group demonstrated greater ML COP velocity, trunk roll velocity, trunk roll velocity frequency amplitude at 3.7 Hz, and trunk roll velocity frequency amplitude at 4.9 Hz, particularly in the eyes closed condition (spasticity by vision interaction). ML COP MPF was greater in the high spasticity group. Conclusion. Individuals with high spasticity after stroke demonstrated greater impairment of balance control in the frontal plane, which was exacerbated when vision was removed.Peer Reviewe