Peripheral Mechanisms Contributing to Spasticity and Implications for Treatment

Muscle physiology in spasticity and muscle stiffness

This paper examines the physiological changes in spastic muscles contributing to spasticity and muscle stiffness, focusing on the underlying mechanisms and their clinical implications. Spasticity, which is prevalent in neurological conditions such as multiple sclerosis, cerebral palsy, spinal cord injury, stroke, and traumatic brain injury, is characterized by disordered sensorimotor control and often results in increased muscle stiffness and resistance to movement. Recent developments in the understanding of spasticity suggest the importance of architectural changes in muscles that may contribute to increased passive resistance, potentiate reflex mechanisms, and progression to fibrosis, with hyaluronan (HA), a glycosaminoglycan, playing a pivotal in modulating the properties of the muscle extracellular matrix (ECM). The hyaluronan hypothesis of muscle stiffness postulates that the accumulation and biophysical alteration of HA in the ECM of muscle increases its viscosity, resulting in increased passive mechanical resistance. This is turn mayincrease muscle sensitivity to stretch, potentiating spasticity, and lead to cellular differentiation of myofibroblasts to fibroblasts ultimately leading to fibrosis and contracture. A deeper understanding of HA's role in ECM dynamics offers promising avenues for novel treatments aimed at mitigating stiffness and preventing long-term disability in patients with spasticity.

Immediate effects of TECAR therapy on lower limb to decrease hypertonia in chronic stroke survivors: a randomized controlled trial

PURPOSE

To analyze immediate effects of TECAR therapy (TT) to reduce lower limb hypertonia and improve functionality in chronic post-stroke.

MATERIALS AND METHODS

It is a single-blind randomized controlled clinical trial. A total of 36 chronic stroke survivors were divided into two groups. The experimental group received a single 30-minute session of TT with functional massage (FM) on lower limb. The control group received a single 30-minute session sham treatment of TT plus FM. The primary outcome measure was hypertonia (Modified Ashworth Scale, MAS). Secondary outcomes were gait speed (4-Meter Walk-Test), standing knee-flexion (Fugl-Meyer Assessment Scale IV-item), change in weight bearing ankle dorsiflexion (Ankle Lunge Test, ALT), and functional lower limb strength (5-Times Sit-to-Stand Test). All measurements were performed at baseline, immediately and 30-minutes after treatment.

RESULTS

There was a group-time interaction in MAS-knee (p = 0.044), MAS-ankle (p = 0.018) and ALT (p = 0.016) between T1 and T0 (p<.0001) and T2 and T0 (p<.0001) for the experimental group. There was a significant increase in ALT between T1 and T0 (p = 0.003) in the control group.

CONCLUSIONS

A single session of TT performed at the same time as FM immediately reduces plantar-flexors and knee-extensor muscle hypertonia and increases change in weight bearing ankle dorsiflexion in chronic stroke survivors.

Novel Conservative Therapies in Migraine Management: The Impact of Fascia Exercises in a Randomized Controlled Trial

Background/Objectives: Migraine is a complex neurological disorder often associated with autonomic nervous system (ANS) dysfunction. This study aimed to evaluate the effects of fascia exercises on migraine symptoms and explore their potential as a novel conservative treatment approach. Methods: A prospective, randomized controlled trial was conducted with 30 migraine patients who were randomly assigned to a treatment group (fascia exercises) or a control group (conventional physiotherapy). Both groups underwent a six-week intervention consisting of two sessions per week. Pain intensity, migraine-related disability, sleep quality, anxiety, depression, heart rate variability (HRV), and patient satisfaction were assessed before and after the intervention using validated scales. Results: Significant improvements in pain intensity, attack frequency and duration, migraine-related disability, sleep quality, and anxiety levels were observed in both groups (p < 0.05). However, the treatment group demonstrated a more pronounced reduction in depression scores compared to the control group (p < 0.05). While no significant changes in HRV parameters were detected in either group, patient satisfaction was significantly higher in the treatment group (p < 0.05). Conclusions: Fascia exercises represent a promising complementary therapy for migraine management, offering significant improvements in both physical and psychological symptoms. While immediate effects on HRV were not evident, the potential to modulate autonomic balance and address migraine pathophysiology warrants further exploration. These findings highlight the value of fascia exercises as a low-cost, non-invasive approach, emphasizing the need for further research to confirm their long-term clinical benefits and integration into migraine treatment protocols.

[Sequential use of botulinum toxin A and bovhyaluronidase azoximer in the correction of post-stroke spasticity]

A clinical case of consistent use of botulinum toxin type A (BTA) and azoximer bovhialuronidase (BA) in a 69-year-old patient who suffered an ischemic stroke (II) with right-sided hemiparesis is presented. BTA (incobotulotoxin) was injected under ultrasound control (ultrasound) into the muscles of the target pathological patterns at a dose of 500 units. After 3 weeks, under the control of ultrasound navigation, BA was injected into the 2 most fibrotic shoulder muscles at a dose of 3.000 IU (1.500 IU each). The effectiveness of therapy was monitored using a modified Ashworth scale (MAS), goniometry, and electromyography. A decrease in the severity of the leading pattern of spasticity of the muscles of the upper extremity (on the MAS scale) after injection of BTA was found. After consistent application of BA, a distinct change in the structure of muscle tissue and a decrease in tone in spastic muscles were recorded. The results obtained confirm the safety of botulinum therapy and the good tolerability and efficacy of Xeomin in a patient with spasticity with contracture formation after AI. The introduction of ASTHMA after botulinum therapy makes it possible to increase the elasticity of spastic muscles by reducing the severity of fibrous changes and improving motor function.

Ultrasound Imaging Comparison of Crural Fascia Thickness and Muscle Stiffness in Stroke Patients with Spasticity

BACKGROUND/OBJECTIVE

Spasticity following stroke causes structural changes in the muscles and fascia, affecting the mobility and functional recovery of patients. Understanding these structural changes is critical to optimizing the rehabilitation strategies for patients. Therefore, in this study, we aimed to investigate the differences in crural and epimysial fascia thickness and muscle stiffness in the affected and unaffected lower limbs of chronic stroke patients with spasticity.

METHODS

A total of 88 patients with chronic stroke (mean age: 62.7 ± 10.2 years) were included in this study. Ankle range of motion, crural fascial thickness, and muscle stiffness in affected and unaffected lower limbs were assessed using ultrasound.

RESULTS

For the affected lower limbs, 59 patients (67.1%) exhibited a modified Ashworth scale score of 2, whereas 29 patients (32.9%) exhibited a score of 3. Ankle range of motion, fascia thickness, and muscle stiffness were also measured. The range of motion in ankle dorsiflexion and plantar flexion was significantly reduced on the affected side (p < 0.05). Crural fascia thickness was significantly greater in all regions of the affected side (anterior: 0.96 ± 0.14 vs. 0.72 ± 0.08 mm [p < 0.001]; lateral: 1.01 ± 0.14 vs. 0.75 ± 0.14 mm [p < 0.001]), and the epimysial fascia of the tibialis anterior muscle was similarly greater in the affected side (0.46 ± 0.07 vs. 0.34 ± 0.03 mm [p < 0.001]). However, no significant differences in muscle stiffness were observed between the affected and unaffected sides (p > 0.05).

CONCLUSIONS

Overall, these findings revealed significant fascial thickening with only minimal changes in muscle stiffness on the affected side, highlighting the importance of controlling fascial changes for post-stroke spasticity management.

The effect of fascial manipulation therapy on lower limb spasticity and ankle clonus in stroke patients

Lower limb spasticity and clonus are common sequelae after cerebral stroke. An important part of their etiopathogenesis has been related to the peripheral component of spasticity. Rheological properties of the tissues seem to be involved. Several studies highlighted anatomical and functional changes in the connective structures. The fasciae might be implicated in the pathological process. Thus, this study intends to investigate the effect of the Fascial Manipulation (FM) technique on triceps surae in stroke patients through a clinical randomized controlled trial, to provide a reference for clinical treatment of lower limb spasticity and ankle clonus. A total of 40 patients with post-stroke ankle clonus were selected and divided into a control group and an observation group by random number table method, with 20 cases in each group. Both groups received conventional rehabilitation therapy, while the FM group received Fascial Manipulation based on conventional rehabilitation therapy. Before the first treatment and after 3 weeks of treatment, the Comprehensive Spasticity Scale (CSS), the Passive Range Of Motion (PROM), the simplified Fugl-Meyer motor function score (FMA), and the Modified Ashworth Scale (MAS) were used to assess the degree of ankle clonus, ankle passive range of motion, and lower limb motor function of the two groups of patients. Before treatment, there was no statistically significant difference between the control group and the FM group in terms of CSS, PROM, FMA, and MAS of the affected lower limbs (P>0.05). After 3 weeks of treatment, the CSS and MAS of the affected lower limbs in the control group and FM group decreased, while PROM and FMA increased compared to pre-treatment evaluation, with statistically significant differences (P<0.05). Moreover, the FM group showed a statistically significant decrease in CSS and MAS, as well as an increase in PROM and FMA, compared to the control group (P<0.05). Conclusions: Fascial manipulation in addition to conventional therapy can effectively reduce spasticity and ankle clonus in stroke patients in a short time, and improve the passive range of motion of the ankle joint and the function of lower limbs.

Assessing muscle architecture with ultrasound: implications for spasticity

Botulinum Neurotoxin Type A (BoNT-A) injections using Ultrasound (US) guidance have led to research evaluating changes in muscle architecture. Controversy remains as to what constitutes increased Echo-Intensity (EI) in spastic muscles and whether this may affect outcomes. We aim to provide a narrative review of US muscle architecture changes following Central Nervous System (CNS) lesions and explore their relationship to spasticity. Medline, CINAHL, and Embase databases were searched with keywords: ultrasonography, hypertonia, spasticity, fibrosis, and Heckmatt. Three physicians reviewed the results of the search to select relevant papers. Reviews identified in the search were used as a resource to identify additional studies. A total of 68 papers were included. Four themes were identified, including histopathological changes in spastic muscle, effects of BoNT-A on the muscle structure, available US modalities to assess the muscle, and utility of US assessment in clinical spasticity. Histopathological studies revealed atrophic and fibro-fatty changes after CNS lesions. Several papers described BoNT-A injections contributing to those modifications. These changes translated to increased EI. The exact significance of increased muscle EI remains unclear. The Modified Heckmatt Scale (MHS) is a validated tool for grading muscle EI in spasticity. The use of the US may be an important tool to assess muscle architecture changes in spasticity and improve spasticity management. Treatment algorithms may be developed based on the degree of EI. Further research is needed to determine the incidence and impact of these EI changes in spastic muscles.

Top-Down and Bottom-Up Mechanisms of Motor Recovery Poststroke

Stroke remains a leading cause of disability. Motor recovery requires the interaction of top-down and bottom-up mechanisms, which reinforce each other. Injury to the brain initiates a biphasic neuroimmune process, which opens a window for spontaneous recovery during which the brain is particularly sensitive to activity. Physical activity during this sensitive period can lead to rapid recovery by potentiating anti-inflammatory and neuroplastic processes. On the other hand, lack of physical activity can lead to early closure of the sensitive period and downstream changes in muscles, such as sarcopenia, muscle stiffness, and reduced cardiovascular capacity, and blood flow that impede recovery.

Therapeutic effects of extracorporeal shock wave therapy on patients with spastic cerebral palsy and Rett syndrome: clinical and ultrasonographic findings

BACKGROUND

Extracorporeal shock wave therapy (ESWT) is reportedly effective for improving spasticity and motor function in children with cerebral palsy (CP). Because late-stage Rett syndrome has a similar presentation, this study aimed to investigate the effects of ESWT on these two diseases.

MATERIAL AND METHODS

Patients diagnosed with spastic CP and Rett syndrome received 1500 impulses of ESWT at 4 Hz and 0.1 mJ/mm2, on their spastic legsonce weekly for a total of 12 weeks. Outcomes were assessed before and 4 and 12 weeks after ESWT. Clinical assessments included the Modified Ashworth Scale (MAS), passive range of motion (PROM), and Gross Motor Function Measure 88 (GMFM-88). Ultrasonographic assessments included muscle thickness, acoustic radiation force impulse (ARFI), and strain elastography.

RESULTS

Fifteen patients with CP and six with Rett syndrome were enrolled in this study. After ESWT, patients with CP showed significant clinical improvement in the MAS (P = 0.011), ankle PROM (P = 0.002), walking/running/jumping function (P = 0.003), and total function (P < 0.001) of the GMFM-88. The patients with Rett syndrome showed improved MAS scores (P = 0.061) and significantly improved total gross motor function (P = 0.030). Under ARFI, patients with CP demonstrated decreased shear wave speed in the gastrocnemius medial head (P = 0.038). Conversely, patients with Rett syndrome show increased shear-wave speeds after ESWT.

CONCLUSION

Our study provides evidence that a weekly course of low-dose ESWT for 12 weeks is beneficial for children with both CP and Rett syndrome, with the clinical effects of reducing spasticity and improving the gross motor function of the lower limbs. The ARFI sonoelastography reveals improvement of muscle stiffness in patients with CP after ESWT, but deteriorated in patients with Rett syndrome. The diverse therapeutic response to ESWT may be caused by the MECP2 mutation in Rett syndrome, having a continuous impact and driving the pathophysiology differently as compared to CP, which is secondary to a static insult. Trial registration IRB 201700462A3. Registered 22March 2017, https://cghhrpms.cgmh.org.tw/HRPMS/Default.aspx .

Immediate Effects of TECAR Therapy on Gastrocnemius and Quadriceps Muscles with Spastic Hypertonia in Chronic Stroke Survivors: A Randomized Controlled Trial

BACKGROUND

The aim of this study was to assess changes in muscle properties after a single session of capacitive and resistive energetic transfer (TECAR) therapy on spastic gastrocnemius and quadriceps muscles in chronic post-stroke.

METHODS

A total of 36 chronic stroke survivors with lower limb hypertonia were enrolled in a double-blind randomized controlled trial. The experimental group (n = 18) received a single 30 min session of TECAR therapy in combination with functional massage (FM) on the gastrocnemius and quadriceps muscles. The control group (n = 18) received a sham treatment of TECAR therapy (without electrical stimulation) in combination with real FM. The primary outcome was muscle tone of the lower limb muscles assessed with the Modified Ashworth Scale (MAS). The secondary outcomes were goniometric degrees of the MAS (goniometer), neuromuscular properties of the gastrocnemius/quadriceps (myotonometer), and passive range of motion (inclinometer). All measurements were performed at baseline (T0), immediately after treatment (T1), and at 30 min post-treatment (T2) by a blinded assessor.

RESULTS

The MAS score ankle dorsiflexion significantly decreased at T0-T1 (p = 0.046), and the change was maintained at T0-T2 (p = 0.019) in the experimental group. Significant improvements were noted in the passive range of motion for knee flexion (p = 0.012) and ankle dorsiflexion (p = 0.034) at T2. In addition, knee flexion improved at T1 (p = 0.019).

CONCLUSION

A single session of Tecar therapy at the same time with FM on the gastrocnemius and rectus femoris immediately reduces muscle tone and increases the passive range of motion of both ankle and knee in chronic stroke survivors. There were no significant changes in the neuromuscular properties measured with myotonometer.

Exploring the relationship of static and dynamic balance with muscle mechanical properties of the lower limbs in healthy young adults

There is emerging evidence that mechanical properties of in vivo muscle tissues are associated with postural sway during quiet standing. However, it is unknown if the observed relationship between mechanical properties with static balance parameters generalise to dynamic balance. Thus, we determined the relationship between static and dynamic balance parameters with muscle mechanical properties of the ankle plantar flexors [lateral gastrocnemius (GL)] and knee extensors [vastus lateralis (VL)] in vivo. Twenty-six participants (men = 16, women = 10; age = 23.3 ± 4.4 years) were assessed for static balance [centre of pressure (COP) movements during quiet standing], dynamic balance (reach distances for the Y-balance test) and mechanical properties (stiffness and tone) of the GL and VL measured in the standing and lying position. Significant (p < .05) small to moderate inverse correlations were observed between the mean COP velocity during quiet standing with stiffness (r = -.40 to -.58, p = .002 to .042) and tone (r = -0.42 to -0.56, p = 0.003 to 0.036) of the GL and VL (lying and standing). Tone and stiffness explained 16%-33% of the variance in the mean COP velocity. Stiffness and tone of the VL measured in the lying (supine) condition were also inversely significantly correlated with Y balance test performance (r = -0.39 to -0.46, p = 0.018 to 0.049). These findings highlight that individuals with low muscle stiffness and tone exhibit faster COP movements during quiet standing, indicative of reduced postural control but also reveal that low VL stiffness and tone are associated with greater reach distances in a lower extremity reaching task, indicative of greater neuromuscular performance.

Assessing shoulder muscle stretch reflexes following breast cancer treatment and postmastectomy breast reconstruction

Muscle stiffness is altered following postmastectomy breast reconstruction and breast cancer treatment. The exact mechanisms underlying these alterations are unknown; however, muscle stretch reflexes may play a role. This work examined short- (SLR) and long-latency (LLR) shoulder muscle stretch reflexes in breast cancer survivors. Forty-nine patients who had undergone postmastectomy breast reconstruction, 17 who had undergone chemoradiation, and 18 healthy, age-matched controls were enrolled. Muscle activity was recorded from the clavicular and sternocostal regions of the pectoralis major and anterior, middle, and posterior deltoids during vertical ab/adduction or horizontal flex/extension perturbations while participants maintained minimal torques. SLR and LLR were quantified for each muscle. Our major finding was that following postmastectomy breast reconstruction, SLR and LLR are impaired in the clavicular region of the pectoralis major. Individuals who had chemoradiation had impaired stretch reflexes in the clavicular and sternocostal region of the pectoralis major, anterior, middle, and posterior deltoid. These findings indicate that breast cancer treatments alter the regulation of shoulder muscle stretch reflexes and may be associated with surgical or nonsurgical damage to the pectoral fascia, muscle spindles, and/or sensory Ia afferents.NEW & NOTEWORTHY Shoulder muscle stretch reflexes may be impacted following postmastectomy breast reconstruction and chemoradiation. Here, we examined short- and long-latency shoulder muscle stretch reflexes in two experiments following common breast reconstruction procedures and chemoradiation. We show impairments in pectoralis major stretch reflexes following postmastectomy breast reconstruction and pectoralis major and deltoid muscle stretch reflexes following chemoradiation. These findings indicate that breast cancer treatments alter the regulation of shoulder muscle stretch reflexes.

From Muscle to the Myofascial Unit: Current Evidence and Future Perspectives

The "motor unit" or the "muscle" has long been considered the quantal element in the control of movement. However, in recent years new research has proved the strong interaction between muscle fibers and intramuscular connective tissue, and between muscles and fasciae, suggesting that the muscles can no longer be considered the only elements that organize movement. In addition, innervation and vascularization of muscle is strongly connected with intramuscular connective tissue. This awareness induced Luigi Stecco, in 2002, to create a new term, the "myofascial unit", to describe the bilateral dependent relationship, both anatomical and functional, that occurs between fascia, muscle and accessory elements. The aim of this narrative review is to understand the scientific support for this new term, and whether it is actually correct to consider the myofascial unit the physiological basic element for peripheral motor control.

Effectiveness of Extracorporeal Shockwave Therapy on Controlling Spasticity in Cerebral Palsy Patients: A Meta-Analysis of Timing of Outcome Measurement

Extracorporeal shockwave therapy (ESWT) has been suggested as an alternative treatment for reducing spasticity in patients with cerebral palsy (CP). However, the duration of its effect was rarely known. A meta-analysis was performed to investigate the effectiveness of ESWT at controlling spasticity in patients with CP according to the follow-up period. We included studies in which ESWT was used to manage spasticity in patients with CP, and the effect was compared with that in a control group. Finally, three studies were included. In the meta-analysis, spasticity, measured using the modified Ashworth scale (MAS), was significantly reduced after ESWT compared with that in the control group; however, it was sustained for only 1 month. After ESWT, significant increases in passive ankle range of motion (ROM) and plantar surface area in the standing position were observed compared with those in the control group and sustained for up to 3 months. Although spasticity measured using MAS was significantly reduced for only 1 month, improvement in spasticity-associated symptoms, such as ankle ROM and plantar surface area contacting the ground, persisted for over 3 months. ESWT appears to be a useful and effective therapeutic option for managing spasticity in patients with CP.

Associations between muscle morphology and spasticity in children with spastic cerebral palsy

INTRODUCTION

Due to the heterogeneous clinical presentation of spastic cerebral palsy (SCP), which makes spasticity treatment challenging, more insight into the complex interaction between spasticity and altered muscle morphology is warranted.

AIMS

We studied associations between spasticity and muscle morphology and compared muscle morphology between commonly observed spasticity patterns (i.e. different muscle activation patterns during passive stretches).

METHODS

Spasticity and muscle morphology of the medial gastrocnemius (MG) and semitendinosus (ST) were defined in 74 children with SCP (median age 8 years 2 months, GMFCS I/II/III: 31/25/18, bilateral/unilateral: 46/27). Using an instrumented assessment, spasticity was quantified as the difference in muscle activation recorded during passive stretches at low and high velocities and was classified in mixed length-/velocity-dependent or pure velocity-dependent activation patterns. Three-dimensional freehand ultrasound was used to assess muscle morphology (volume and length) and echogenicity intensity (as a proxy for muscle quality). Spearman correlations and Mann-Whitney-U tests defined associations and group differences, respectively.

RESULTS

A moderate negative association (r = -0.624, p < 0.001) was found between spasticity and MG muscle volume, while other significant associations between spasticity and muscle morphology parameters were weak. Smaller normalized muscle volume (MG p = 0.004, ST p=<0.001) and reduced muscle belly length (ST p = 0.015) were found in muscles with mixed length-/velocity-dependent patterns compared to muscles with pure velocity-dependent patterns.

DISCUSSION

Higher spasticity levels were associated with smaller MG and ST volumes and shorter MG muscles. These muscle morphology alterations were more pronounced in muscles that activated during low-velocity stretches compared to muscles that only activated during high-velocity stretches.

[Modern view on upper limb physical rehabilitation after stroke. Literature review]

Stroke is the world's second leading cause of death and the first cause of disability among all diseases. The most common complication of a stroke is a violation of the motor function of the limbs, which significantly worsens the quality of life and the level of self-care and independence of patients. Restoring the function of the upper limb is one of the priority tasks of rehabilitation after a stroke. A large number of factors, such as the location and size of the primary brain lesion, the presence of complications in the form of spasticity, impaired skin and proprioceptive sensitivity, and comorbidities, determine the patient's rehabilitation potential and the prognosis of ongoing rehabilitation measures. Of particular note are the timing of the start of rehabilitation measures, the duration and regularity of the treatment methods. A number of authors propose scales for assessing the rehabilitation prognosis, as well as algorithms for compiling rehabilitation programs for restoring the function of the upper limb. A fairly large number of rehabilitation methods and their combinations have been proposed, including special methods of kinesitherapy, robotic mechanotherapy with biofeedback, the use of physiotherapeutic factors, manual and reflex effects, as well as ready-made programs that include sequential and combined use of various methods. Dozens of studies have been devoted to comparative analysis and evaluation of the effectiveness of these methods. The purpose of this work is to review current research on a given topic and draw up our own conclusion on the appropriateness of using and combining these methods at various stages of rehabilitation in stroke patients.

Atypical knee jerk responses in high-risk children: A longitudinal EMG-study

INTRODUCTION

We previously found that atypical responses to the knee jerk reflex, i.e., tonic responses (TRs), clonus and contralateral responses in very high-risk (VHR) infants were associated with cerebral palsy (CP) at 21 months. The current study aimed for a better understanding of pathophysiology of atypical knee jerk responses by evaluating whether infant atypical knee jerk responses are associated with CP and atypical knee jerk responses at school-age.

METHODS

31 VHR-children, who had also been assessed longitudinally during infancy, and 24 typically developing children, were assessed at 7-10 years (school-age). We continuously recorded surface EMG of thigh muscles during knee jerk responses longitudinally during infancy and once at school-age. Neurological condition was assessed with age-appropriate neurological examinations. It included the diagnosis of CP at 21 months corrected age and school-age. CP's type and severity (Gross Motor Function Classification System (GMFCS)) were reported.

RESULTS

Persistent TRs in infancy were associated with CP at school-age. TR prevalence decreased from infancy to childhood. At school-age it was no longer associated with CP. Clonus prevalence in VHR-children did not change with increasing age; it was significantly higher in children without than those with CP. Reflex irradiation was common in all school-age children, and its prevalence in contralateral muscles in VHR-children decreased between infancy and childhood.

CONCLUSIONS

In infancy, TRs indicated an increased risk of CP, but at school-age TRs were not associated with CP. In general, spinal hyperexcitability, expressed as reflex irradiation and TRs, decreased between infancy and school-age.

Effect of Stretching of Spastic Elbow Under Intelligent Control in Chronic Stroke Survivors-A Pilot Study

Objective: To assess the short-term effects of strenuous dynamic stretching of the elbow joint using an intelligent stretching device in chronic spastic stroke survivors.

Methods: The intelligent stretching device was utilized to provide a single session of intensive stretching to the spastic elbow joint in the sagittal plane (i.e., elbow flexion and extension). The stretching was provided to the extreme range, safely, with control of the stretching velocity and torque to increase the joint range of motion (ROM) and reduce spasticity and joint stiffness. Eight chronic stroke survivors (age: 52.6 ± 8.2 years, post-stroke duration: 9.5 ± 3.6 years) completed a single 40-min stretching intervention session. Elbow passive and active ROM, strength, passive stiffness (quantifying the non-reflex component of spasticity), and instrumented tendon reflex test of the biceps tendon (quantifying the reflex component of the spasticity) were measured before and after stretching.

Results: After stretching, there was a significant increase in passive ROM of elbow flexion (p = 0.021, r = 0.59) and extension (p = 0.026, r = 0.59). Also, elbow active ROM and the spastic elbow flexors showed a trend of increase in their strength.

Conclusion: The intelligent stretching had a short-term positive influence on the passive movement ROM. Hence, intelligent stretching can potentially be used to repeatedly and regularly stretch spastic elbow joints, which subsequently helps to reduce upper limb impairments post-stroke.

Comparative Effectiveness of Botulinum Toxin Injections and Extracorporeal Shockwave Therapy for Post-Stroke Spasticity: A Systematic Review and Network Meta-Analysis

BACKGROUND

The anti-spasticity efficacy of botulinum toxin (BoNT) injection has been well established for patients with chronic stroke; however, extracorporeal shock wave therapy (ESWT), i.e. focused shockwave (FSW) and radial shockwave (RSW), has recently been applied. We aimed to investigate the comparative effectiveness of BoNT vs. ESWT in the reduction of spasticity among stroke survivors.

METHODS

PubMed, EMBASE, MEDLINE and Cochrane CENTRAL were searched from the earliest record to September 2021 for randomized controlled trials. Weighted mean differences (WMDs) on the reduction of the Modified Ashworth Scale before or at the 6th post-treatment week (short-term) and between the 7th and 12th weeks (mid-term) after the intervention were calculated. Ranking probabilities of the WMD were simulated to determine which treatment had the potential to possess the best effectiveness. inplasy.com registration: INPLASY202170018.

FINDINGS

A total of 33 studies comprising 1,930 patients were enrolled. The network meta-analysis revealed that BoNT injections, FSW and RSW were better in spasticity reduction than the control treatment(s) at the short term, with WMDs of -0.69 (95% CI, -0.87 to -0.50), -0.36 (95% CI, -0.69 to -0.03) and -0.62 (95% CI, -0.84 to -0.40), respectively. Likewise, mid-term effects of BoNT injections, FSW and RSW also revealed superiority, with WMDs of -0.44 (95% CI, -0.62 to -0.26), -0.74 (95% CI, -1.26 to -0.23) and -0.79 (95% CI, -1.07 to -0.51), respectively. Ranking probability analysis revealed that RSW had the highest probability of being the best treatment for spasticity reduction at the short-term (62.2%) and mid-term (72.3%) periods during the follow up.

INTERPRETATION

BoNT injections and ESWT are effective in alleviating post-stroke spasticity at the mid-term. The effectiveness of ESWT was comparable to BoNT injections, and RSW had the potential to be the best treatment for spasticity reduction among the three treatment options. More prospective trials incorporating head-to-head comparisons of BoNT injections vs. ESWT are needed to validate the role of ESWT in reducing post-stroke spasticity.

FUNDING

The current research project was supported by (1) National Taiwan University Hospital, Bei-Hu Branch; (2) Ministry of Science and Technology (MOST 106-2314-B-002-180-MY3 and 109-2314-B-002-114-MY3); 3) Taiwan Society of Ultrasound in Medicine.

Age-Related Alterations of Hyaluronan and Collagen in Extracellular Matrix of the Muscle Spindles

Background: Muscle spindles (MSs) play a crucial role in proprioception and locomotor coordination. Although the elasticity and viscosity of the extracellular matrix (ECM) within which MSs are embedded may play a key role in MS function, the impact of aging on ECM components is unclear. The aim of the current study was to investigate the age-related physiological changes of the ECM and to verify if these could be due to alterations of the environment directly surrounding MSs. Methods: Hematoxylin Eosin and picrosirius-red staining was carried out; collagen types I (COLI) and III (COLIII) were assessed, and biotinylated hyaluronan binding protein (HABP) immunohistochemical analysis was undertaken to evaluate alterations of the ECM in the intramuscular connective tissue (IMCT) of the hindlimbs of C57BL/6J male mice. Assessments were carried out on 6-week-old (Group A), 8-month-old (Group B), and 2-year-old (Group C) laboratory mice. Results: The capsule’s outer layer became progressively thicker with aging (it was 3.02 ± 0.26 μm in Group A, 3.64 ± 0.31 μm in Group B, and 5.81 ± 0.85 μm in Group C). The collagen in IMCT around and within the MSs was significantly higher in Group C, but there were no significant differences between Groups A and B. The MS capsules and continuous IMCT were primarily made up of COLI and COLIII. The average optical density (AOD) values of COLI in IMCT surrounding MS were significantly higher after aging (p < 0.05), but there were no significant differences in COLIII in the three groups (p > 0.05). HA was present in IMCT and filled the MSs capsule. The AOD of HABP of MS showed that there were lower HA levels in Group C with respect to Group A (p = 0.022); no significant differences were noted neither between Groups A and B nor between Groups B and C (p > 0.05). Conclusion: Age-related collagen accumulation and lower HA in the ECM in which the MSs were embedded may probably cause more stiffness in the ECM in vivo, which could help to partly explain the peripheral mechanisms underlying the age-related decline in functional changes related to MSs.

Intramuscular hyaluronic acid expression following repetitive power training induced nonfunctional overreaching

Hyaluronic acid (HA) contributes to extracellular matrix viscosity and fiber regeneration. HA role in resistance training (RT) performance adaptations is unclear. RT men performed power training (nonfunctional overreaching (NFOR) or normal training (CG)) over 7.5 days. Post RT, the CG improved power while NFOR did not with HA content decreasing 34.5% in NFOR with no change in CG. HA is critical for muscular recovery; decreased HA may contribute to impaired power adaptations with NFOR RT. Novelty: Nonfunctional over-reaching decreases muscular hyaluronic acid.

Pilot study quantifying muscle glycosaminoglycan using bi-exponential T1ρ mapping in patients with muscle stiffness after stroke

Post stroke muscle stiffness is a common problem, which left untreated can lead to disabling muscle contractures. The purpose of this pilot study was to evaluate the feasibility of bi-exponential T1ρ mapping in patients with arm muscle stiffness after stroke and its ability to measure treatment related changes in muscle glycosaminoglycans (GAGs). Five patients with muscle stiffness after stroke and 5 healthy controls were recruited for imaging of the upper arm with 3D-T1ρ mapping. Patients were scanned before and after treatment with hyaluronidase injections, whereas the controls were scanned once. Wilcoxon Mann-Whitney tests compared patients vs. controls and patients pre-treatment vs. post-treatment. With bi-exponential modeling, the long component, T1ρl was significantly longer in the patients (biceps P = 0.01; triceps P = 0.004) compared to controls. There was also a significant difference in the signal fractions of the long and short components (biceps P = 0.03, triceps P = 0.04). The results suggest that muscle stiffness is characterized by increased muscle free water and GAG content. Post-treatment, the T1ρ parameters shifted toward control values. This pilot study demonstrates the application of bi-exponential T1ρ mapping as a marker for GAG content in muscle and as a potential treatment monitoring tool for patients with muscle stiffness after stroke.

Hamstring strains in professional rugby players result in increased fascial stiffness without muscle quality changes as assessed using shear wave elastography

INTRODUCTION

Hamstring strain injury is common among sports injuries. A previous history of this injury is considered a strong predictor of recurrent hamstring strain injury. Fascial tissue reportedly becomes stiffer after hamstring strain injury. However, the association between fascial stiffness and previous hamstring strain injury has not been investigated in clinical studies. We aimed to determine whether a previous history of hamstring strain injury affects fascial tissue and muscle tissues using shear wave elastography.

METHOD

In eleven male professional rugby players, the stiffness as a shear modulus (kPa) of fascial tissue and muscle was measured on the specific injured area measured by magnetic resonance imaging (MRI) at resting position by using shear wave elastography. The side-to-side differences between the injured and the uninjured side were analyzed. The length and area of the muscle scar tissue were evaluated by MRI in relation to fascial stiffness.

RESULTS

The shear elastic modulus of fascia was stiffer in the injured vs. the uninjured side; however, no difference was observed in the muscle. No significant relationship was detected between the length and area of the muscle scar tissue (all P > 0.05).

DISCUSSION

Rugby players with a previous history of hamstring strain injury exhibited passive stiffness of fascial tissues in the injured leg, regardless of the length or area of the muscle scar tissue. However, the passive stiffness of muscles was same between the injured and the uninjured leg.

CONCLUSION

The results can be beneficial to consider future risk for hamstring strain injuries.

Accumulative Competitive Season Training Stress Affects Neuromuscular Function and Increases Injury Risk in Uninjured D1 Female Athletes

Previous research has shown that acute competition training stress negatively affects neuromuscular function which can perpetuate a predisposition to injury. This study's aim was to investigate the effect of accumulated competition training stress effect on neuromuscular function and incidence of increased injury risk in uninjured female D1 soccer players. Neuromuscular function was evaluated in fifteen female division I soccer athletes who played >85% of competitive season competitions who were tested for mobility/stability, leg length symmetry, and vertical power at three different points across the competitive season (pre, mid, and post time blocks). Leg length symmetry was measured from the anterior superior iliac spine to the lateral malleolus prior to Y-balance testing. The Y-balance testing measures unilateral anterior, posteromedial, and posterolateral reach achieved in single leg stance using metrics that include L/R normalized composite reach (NCOMP), L/R normalized antiorior reach (NANT), and L/R NCOMP/NANT segmental differences across time. Injury risk was evaluated using validated objective criteria that included: (NCOMP total reach <94% of limb length^*3), (NANT reach distance <84% leg length) along with NCOMP and NANT asymmetries >4.0. Maximal vertical power (MVP) was measured via vertical jump. Multiple repeated measures ANOVAs evaluated NCOMP, NANT, MVP, and leg length symmetry across time with LSD post hoc testing when relevant (X ± SD). A significant main effect was found [F_{(1, 14)} = 62.92, p < 0.001; η² =0.82] with training stress and neuromuscular function without affecting maximal vertical power. Eighty percent of subject's bilateral NCOMP scores fell below the YBT reach standard at midseason (ES = 0.95, p = 0.02) while all subjects NANT reach distance remained below the reach threshold (ES = 0.74, p = 0.003) indicating a 6.5× and 2.5× greater injury risk, respectively. Competition stress affected neuromuscular function without affecting maximal power, which negatively impacted stability and increased injury risk.

The Use of Botulinum Toxin for Treatment of Spasticity

Spasticity is one component of the upper motor neuron (UMN) syndrome resulting from a multitude of neurologic conditions, such as stroke, brain injury, spinal cord injury, multiple sclerosis, and cerebral palsy. It is clinically recognized as a phenomenon of velocity-dependent increase in resistance, i.e., hypertonia. Recent advances in the pathophysiology of spasticity improve our understanding of mechanisms underlying this complex phenomenon and its relations to other components of UMN syndrome (weakness and disordered motor control), as well as the resultant clinical problems. This theoretical framework provides a foundation to set up treatment goals and to guide goal-oriented clinical assessment and treatment. Among a spectrum of treatment options, botulinum toxin (BoNT) therapy is the preferred treatment for focal spasticity. The evidence is very robust that BoNT therapy effectively reduces spasticity; however, it does not improve voluntary movement. In this chapter, we highlight a few issues on how to achieve the best clinical outcomes of BoNT therapy, such as dosing, dilution, guidance techniques, adjunctive therapies, early treatment, repeated injections, and central effects, as well as the ways to improve motor function in selected subgroups of patients with spasticity. We also discuss the reasons of poor responses to BoNT therapy and when not to use BoNT therapy.

Added Value of Dynamic EMG in the Assessment of the Equinus and the Equinovarus Foot Deviation in Stroke Patients and Barriers Limiting Its Usage

Equinus (EFD) and equinovarus foot deviation (EVFD) are the most frequent lower limb deformities in stroke survivors. The equinus component can be triggered by a combination of dorsiflexor deficits, plantar flexor overactivity, muscle stiffness, and contractures. The varus component is typically due to an imbalance between invertor and evertor muscle actions. An improvement in identifying its causes leads to a more targeted treatment. These deformities are typically assessed via a thorough clinical evaluation including the assessment of range of motions, force, spasticity, pain, and observational gait analysis. Diagnostic nerve blocks are also being increasingly used. An advantage of dynamic electromyography (dEMG) is the possibility of measuring muscle activity, overactivity or lack thereof, during specific movements, e.g., activity of both ankle plantar flexors and dorsiflexors during the swing phase of gait. Moreover, fine-wire electrodes can be used to measure the activity of deep muscles, e.g., the tibialis posterior. An impediment to systematic use of dEMG in the assessment of EFD and EVFD, as a complimentary tool to the clinical evaluation, is a lack of evidence of its usefulness. Unfortunately, there are few studies found in literature. In order to fill this void, we studied three pairs of patients suffering from chronic hemiparesis consequent to a stroke, with EFD or EVFD. At the initial evaluation they all displayed the same clinical traits, very similar walking patterns, and an overlapping gait kinematics. However, the patterns of muscle activity differed considerably. dEMG data acquired during walking provided information that was not available from the sole clinical assessment. The contribution of this information to the subsequent clinical and rehabilitation process was discusses along with the barriers that limit the use of dEMG as a routine tool in neurorehabilitation.

A Novel Quantitative Spasticity Evaluation Method Based on Surface Electromyogram Signals and Adaptive Neuro Fuzzy Inference System

Stroke patients often suffer from spasticity. Before treatment of spasticity, there are often practical demands for objective and quantitative assessment of muscle spasticity. However, the common quantitative spasticity assessment method, the tonic stretch reflex threshold (TSRT), is time-consuming and complicated to implement due to the requirement of multiple passive stretches. To evaluate spasticity conveniently, a novel spasticity evaluation method based on surface electromyogram (sEMG) signals and adaptive neuro fuzzy inference system (i.e., the sEMG-ANFIS method) was presented in this paper. Eleven stroke patients with spasticity and four healthy subjects were recruited to participate in the experiment. During the experiment, the Modified Ashworth scale (MAS) scores of each subject was obtained and sEMG signals from four elbow flexors or extensors were collected from several times (4–5) repetitions of passive stretching. Four time-domain features (root mean square, the zero-cross rate, the wavelength and a 4th-order autoregressive model coefficient) and one frequency-domain feature (the mean power frequency) were extracted from the collected sEMG signals to reflect the spasticity information. Using the ANFIS classifier, excellent regression performance was achieved [mean accuracy = 0.96, mean root-mean-square error (RMSE) = 0.13], outperforming the classical TSRT method (accuracy = 0.88, RMSE = 0.28). The results showed that the sEMG-ANFIS method not only has higher accuracy but also is convenient to implement by requiring fewer repetitions (4–5) of passive stretches. The sEMG-ANFIS method can help stroke patients develop proper rehabilitation training programs and can potentially be used to provide therapeutic feedback for some new spasticity interventions, such as shockwave therapy and repetitive transcranial magnetic stimulation.

Comparison of Spasticity in Spinal Cord Injury and Stroke Patients Using Reflex Period in Pendulum Test

Spasticity is a motor impairment present in patients with both stroke and spinal cord injury. In this research, the results from the Wartenberg pendulum test, performed on stroke and spinal cord injury patients using goniometers and electromyogram recordings of the quadriceps, were reviewed and a new parameter to quantify spasticity was extracted. The Reflex Period (RP) of the pendulum test was defined as the time span from 50% of the maximum velocity of the leg swing to the activation of muscle contraction in the quadriceps, determined from the EMG. The results suggest that the reflex period in stroke patients is generally shorter than in those suffering from spinal cord injury.

Advanced quantitative estimation methods for spasticity: a literature review

Post-stroke spasticity seriously affects patients’ quality of life. Spasticity is considered to involve both neural and non-neural factors. Current clinical scales, such as the Modified Ashworth Scale and the Modified Tardieu Scale, lack reliability and reproducibility. These scales are also unable to identify the neural and non-neural contributions to spasticity. Surface electromyography and biomechanical and myotonometry measurement methods for post-stroke spasticity are discussed in this report. Surface electromyography can provide neural information, while myotonometry can estimate muscular properties. Both the neural and non-neural contributions can be estimated by biomechanical measurement. These laboratory methods can quantitatively assess spasticity. They can provide more valuable information for further study on treatment and rehabilitation than clinical scales.

A Regression-Based Framework for Quantitative Assessment of Muscle Spasticity Using Combined EMG and Inertial Data From Wearable Sensors

There have always been practical demands for objective and accurate assessment of muscle spasticity beyond its clinical routine. A novel regression-based framework for quantitative assessment of muscle spasticity is proposed in this paper using wearable surface electromyogram (EMG) and inertial sensors combined with a simple examination procedure. Sixteen subjects with elbow flexor or extensor (i.e., biceps brachii muscle or triceps brachii muscle) spasticity and eight healthy subjects were recruited for the study. The EMG and inertial data were recorded from each subject when a series of passive elbow stretches with different stretch velocities were conducted. In the proposed framework, both lambda model and kinematic model were constructed from the recorded data, and biomarkers were extracted respectively from the two models to describe the neurogenic component and biomechanical component of the muscle spasticity, respectively. Subsequently, three evaluation methods using supervised machine learning algorithms including single-/multi-variable linear regression and support vector regression (SVR) were applied to calibrate biomarkers from each single model or combination of two models into evaluation scores. Each of these evaluation scores can be regarded as a prediction of the modified Ashworth scale (MAS) grade for spasticity assessment with the same meaning and clinical interpretation. In order to validate performance of three proposed methods within the framework, a 24-fold leave-one-out cross validation was conducted for all subjects. Both methods with each individual model achieved satisfactory performance, with low mean square error (MSE, 0.14 and 0.47) between the resultant evaluation score and the MAS. By contrast, the method using SVR to fuse biomarkers from both models outperformed other two methods with the lowest MSE at 0.059. The experimental results demonstrated the usability and feasibility of the proposed framework, and it provides an objective, quantitative and convenient solution to spasticity assessment, suitable for clinical, community, and home-based rehabilitation.

Efficacy of acupotomy for cerebral palsy: A systematic review and meta-analysis

BACKGROUND

In children, cerebral palsy (CP) is one of the most common causes of irreversible neurological sequelae. Acupotomy, a modernized acupuncture form combining the effects of microsurgery and conventional acupuncture, may show specific benefits in the treatment of CP, especially with respect to spasticity. The aim of this review was to evaluate the efficacy of acupotomy for CP.

METHODS

Eleven databases were comprehensively searched from their inception dates to November 27, 2018. Randomized controlled trials (RCTs) or quasi-RCTs evaluating acupotomy as a monotherapy or as adjunctive therapy to rehabilitation treatment for CP were included. The methodological quality of included studies was assessed using the risk of bias tool. The quality of evidence for each main outcome was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation approach. Meta-analysis was performed, and the pooled data were presented as mean difference (MD) with 95% confidence interval (CI) for continuous outcomes and as risk ratio (RR) with 95% CI for dichotomous outcomes.

RESULTS

Eight studies involving 530 participants were included. In 1 study, acupotomy was associated with significantly higher total effective rate (TER) compared with Bobath (P < .01). Acupotomy combined with rehabilitation was associated with significantly higher TER (RR 1.24, 95% CI 1.01-1.52, I = 77%) and gross motor function measure score (MD 12.62, 95% CI 11.75-13.49, I = 54%), and significantly lower muscle tone of gastrocnemius measured by the Ashworth scale or the modified Ashworth scale (MD -0.97, 95% CI -1.07 to -0.88, I = 0%) compared with rehabilitation alone. No studies reported the incidence of adverse events. The methodological quality of the included studies and quality of evidence for the main finding were generally low.

CONCLUSION

Current evidence shows that acupotomy as a monotherapy or as adjunctive therapy to rehabilitation treatment might have benefits in the treatment of CP. However, due to the small number of studies included, the lack of sample size, poor methodological qualities, and low quality of evidence, the findings of this review should be interpreted with caution. Larger and more rigorous, high-quality RCTs should be performed on this topic.

PROSPERO REGISTRATION NUMBER

CRD42018105891.

New Treatment Approaches on the Horizon for Spastic Hemiparesis

This article presents 2 recent articles that propose novel interventions for treating spastic hemiparesis by changing biological infrastructure. In 18 patients with unilateral spastic arm paralysis due to chronic cerebral injury greater than 5 years' duration, Zheng et al transferred the C7 nerve from the nonparalyzed side to the side of the arm that was paralyzed. Over a follow-up period of 12 months, they found greater improvement in function and a reduction of spasticity compared to rehabilitation alone. Using functional magnetic resonance imaging, they also found evidence for physiological connectivity between the ipsilateral cerebral hemisphere and the paralyzed hand. In the second article, Raghavan et al examine the concept of stiffness, a common symptom in patients with spastic hemiparesis, as a physical change in the infrastructure of muscle. Raghavan's non-neural hyaluronan hypothesis postulates that an accumulation of hyaluronan within spastic muscles promotes the development of muscle stiffness in patients with an upper motor neuron syndrome (UMNS). In a case series of 20 patients with spastic hemiparesis, Raghavan et al report that upper limb intramuscular injections of hyaluronidase increased passive and active joint movement and reduced muscle stiffness. Interventions that change biological infrastructure in UMNS is a paradigm on the horizon that bears watching.

Post-stroke Hemiplegic Gait: New Perspective and Insights

Walking dysfunction occurs at a very high prevalence in stroke survivors. Human walking is a phenomenon often taken for granted, but it is mediated by complicated neural control mechanisms. The automatic process includes the brainstem descending pathways (RST and VST) and the intraspinal locomotor network. It is known that leg muscles are organized into modules to serve subtasks for body support, posture and locomotion. Major kinematic mechanisms are recognized to minimize the center of gravity (COG) displacement. Stroke leads to damage to motor cortices and their descending corticospinal tracts and subsequent muscle weakness. On the other hand, brainstem descending pathways and the intraspinal motor network are disinhibited and become hyperexcitable. Recent advances suggest that they mediate post-stroke spasticity and diffuse spastic synergistic activation. As a result of such changes, existing modules are simplified and merged, thus leading to poor body support and walking performance. The wide range and hierarchy of post-stroke hemiplegic gait impairments is a reflection of mechanical consequences of muscle weakness, spasticity, abnormal synergistic activation and their interactions. Given the role of brainstem descending pathways in body support and locomotion and post-stroke spasticity, a new perspective of understanding post-stroke hemiplegic gait is proposed. Its clinical implications for management of hemiplegic gait are discussed. Two cases are presented as clinical application examples.

Emerging Therapies for Spastic Movement Disorders

Spasticity develops as a result of central nervous system (CNS) injury; however, secondary changes within the muscles and connective tissue also contribute to muscle stiffness. The hyaluronan hypothesis postulates that the accumulation of hyaluronan promotes the development of muscle stiffness. Intramuscular injections of the enzyme hyaluronidase, which hydrolyzes long-chained hyaluronan polymers to smaller polymers, was shown to reduce muscle stiffness and increase passive and active range of motion in patients with spasticity. These results provide preliminary evidence of the hyaluronan hypothesis and suggest an emerging therapy to reduce muscle stiffness using the enzyme hyaluronidase.

Botulinum toxin type A affects the transcriptome of cell cultures derived from muscle biopsies of controls and spastic patients

Botulin toxin (BTX) is widely used for treating skeletal muscle spasticity. Experimental reports on BTX treatment were mainly focused on the neuromuscular junction, while relatively little is known about toxin effects on the muscle cell itself. We investigated possible impact of BTX type A on skeletal muscle cell transcriptome by microarray analysis in muscle-derived cell cultures (fibroblasts, myoblasts and myotubes) from controls and spastic patients, and results were then validated at transcript and protein level. BTX-A treatment of control cells induced major changes in the myogenic component of the transcriptome, whereas the same treatment had a negligible effect in the fibrogenic component. BTX-A treatment of cell cultures from spastic patients induced an increased number of genes differentially expressed both in the fibrogenic and myogenic components. Specifically, BTX-A had a major effect on cell cycle-related genes in myoblasts, on muscle contraction-related genes in myotubes, and on extracellular matrix-related genes in fibroblasts from spastic patients. Our findings show that in vitro BTX-A treatment differentially affects transcript expression in muscle cells from spastic patients compared to those from controls suggesting a direct effect of BTX-A on muscle-specific functional pathways.

Different Effects of Cold Stimulation on Reflex and Non-Reflex Components of Poststroke Spastic Hypertonia

OBJECTIVE

To use an established biomechanical approach to quantify reflex and non-reflex responses from spastic-paretic elbow flexors in response to controlled cold and heat stimulation.

METHODS

Thirteen spastic-hemiplegic stroke subjects were tested in the experiment. The spastic elbow joint was stretched into extension for 50° at two speeds (5°/s and 100°/s) in a customized apparatus. Thermal stimulation (HEAT at heat pain threshold, COLD at 0°C, or BASELINE at room temperature) was applied to the thenar eminence of the contralateral hand immediately prior to stretching for at least 30 s.

RESULTS

Total torque was greater at 100°/s than at 5°/s. Total torque was significantly increased after COLD, but not HEAT as compared to BASELINE. When normalized to total torque at baseline, HEAT decreased total torque by 6.3%, while COLD increased total torque by 11.0%. There was no significant difference in the reflex torque among three thermal conditions.

CONCLUSION

The findings demonstrate differentiated effects of cold stimulation on the total resistance from spastic muscles. They provide objective evidence for anecdotal clinical observations of increased muscle spasticity by cold exposure.

Upper Limb Motor Impairment After Stroke

Understanding poststroke upper limb impairment is essential to planning therapeutic efforts to restore function. However, determining which upper limb impairment to treat and how is complex because the impairments are not static and multiple impairments may be present simultaneously. How impairments contribute to upper limb dysfunction may be understood by examining them from the perspective of their functional consequences. There are 3 main functional consequences of impairments on upper limb function: (1) learned nonuse, (2) learned bad use, and (3) forgetting as determined by behavioral analysis of tasks. The impairments that contribute to each of these functional limitations are described.

Viscoelastic Properties of Hyaluronan in Physiological Conditions

Hyaluronan (HA) is a high molecular weight glycosaminoglycan of the extracellular matrix (ECM), which is particularly abundant in soft connective tissues. Solutions of HA can be highly viscous with non-Newtonian flow properties. These properties affect the movement of HA-containing fluid layers within and underlying the deep fascia. Changes in the concentration, molecular weight, or even covalent modification of HA in inflammatory conditions, as well as changes in binding interactions with other macromolecules, can have dramatic effects on the sliding movement of fascia. The high molecular weight and the semi-flexible chain of HA are key factors leading to the high viscosity of dilute solutions, and real HA solutions show additional nonideality and greatly increased viscosity due to mutual macromolecular crowding. The shear rate dependence of the viscosity, and the viscoelasticity of HA solutions, depend on the relaxation time of the molecule, which in turn depends on the HA concentration and molecular weight. Temperature can also have an effect on these properties. High viscosity can additionally affect the lubricating function of HA solutions. Immobility can increase the concentration of HA, increase the viscosity, and reduce lubrication and gliding of the layers of connective tissue and muscle. Over time, these changes can alter both muscle structure and function. Inflammation can further increase the viscosity of HA-containing fluids if the HA is modified via covalent attachment of heavy chains derived from Inter-α-Inhibitor. Hyaluronidase hydrolyzes HA, thus reducing its molecular weight, lowering the viscosity of the extracellular matrix fluid and making outflow easier. It can also disrupt any aggregates or gel-like structures that result from HA being modified. Hyaluronidase is used medically primarily as a dispersion agent, but may also be useful in conditions where altered viscosity of the fascia is desired, such as in the treatment of muscle stiffness.