Effect of Focal Muscle Vibration on Calf Muscle Spasticity: A Proof-of-Concept Study

Relief of post-stroke spasticity with acute vibrotactile stimulation: controlled crossover study of muscle and skin stimulus methods

Background

Prior work suggests that vibratory stimulation can reduce spasticity and hypertonia. It is unknown which of three predominant approaches (stimulation of the spastic muscle, antagonist muscle, or cutaneous regions) most reduces these symptoms.

Objective

Determine which vibrotactile stimulation approach is most effective at reducing spastic hypertonia among post-stroke patients.

Methods

Sham-controlled crossover study with random assignment of condition order in fourteen patients with post-stroke hand spasticity. All patients were studied in four conditions over four visits: three stimulation conditions and a sham control. The primary outcome measure was the Modified Ashworth Scale, and the secondary outcome measure was the Modified Tardieu Scale measured manually and using 3D motion capture. For each condition, measures of spastic hypertonia were taken at four time points: baseline, during stimulation, after stimulation was removed, and after a gripping exercise.

Results

A clinically meaningful difference in spastic hypertonia was found during and after cutaneous stimulation of the hand. Modified Ashworth and Modified Tardieu scores were reduced by a median of 1.1 (SD = 0.84, p = 0.001) and 0.75 (SD = 0.65, p = 0.003), respectively, during cutaneous stimulation, and by 1.25 (SD = 0.94, p = 0.001) and 0.71 (SD = 0.67, p = 0.003), respectively, at 15 min after cutaneous stimulation. Symptom reductions with spastic muscle stimulation and antagonist muscle stimulation were non-zero but not significant. There was no change with sham stimulation.

Conclusions

Cutaneous vibrotactile stimulation of the hand provides significant reductions in spastic hypertonia, compared to muscle stimulation.

Clinical trial registration

www.ClinicalTrials.gov, identifier: NCT03814889.

User Participatory Design of a Wearable Focal Vibration Device for Home-Based Stroke Rehabilitation

Stroke often leads to the significant impairment of upper limb function and is associated with a decreased quality of life. Despite study results from several interventions for muscle activation and motor coordination, wide-scale adoption remains largely elusive due to under-doses and low user compliance and participation. Recent studies have shown that focal vibration has a greater potential to increase and coordinate muscle recruitment and build muscle strength and endurance. This form of treatment could widely benefit stroke survivors and therapists. Thus, this study aimed to design and develop a novel wearable focal vibration device for upper limb rehabilitation in stroke survivors. A user participatory design approach was used for the design and development. Five stroke survivors, three physical therapists, and two occupational therapists were recruited and participated. This pilot study may help to develop a novel sustainable wearable system providing vibration-based muscle activation for upper limb function rehabilitation. It may allow users to apply the prescribed vibratory stimuli in-home and/or in community settings. It may also allow therapists to monitor treatment usage and user performance and adjust the treatment doses based on progression.

Vibration attenuates spasm-like activity in humans with spinal cord injury

KEY POINTS

Cutaneous reflexes were tested to examine the neuronal mechanisms contributing to muscle spasms in humans with chronic spinal cord injury (SCI). Specifically, we tested the effect of Achilles and tibialis anterior tendon vibration on the early and late components of the cutaneous reflex and reciprocal Ia inhibition in the soleus and tibialis anterior muscles in humans with chronic SCI. We found that tendon vibration reduced the amplitude of later but not earlier cutaneous reflex in the antagonist but not in the agonist muscle relative to the location of the vibration. In addition, reciprocal Ia inhibition between antagonist ankle muscles increased with tendon vibration and participants with a larger suppression of the later component of the cutaneous reflex had stronger reciprocal Ia inhibition from the antagonistic muscle. Our study is the first to provide evidence that tendon vibration attenuates late cutaneous spasm-like reflex activity, likely via reciprocal inhibitory mechanisms, and may represent a method, when properly targeted, for controlling spasms in humans with SCI.

ABSTRACT

The neuronal mechanisms contributing to the generation of involuntary muscle contractions (spasms) in humans with spinal cord injury (SCI) remain poorly understood. To address this question, we examined the effect of Achilles and tibialis anterior tendon vibration at 20, 40, 80 and 120 Hz on the amplitude of the long-polysynaptic (LPR, from reflex onset to 500 ms) and long-lasting (LLR, from 500 ms to reflex offset) cutaneous reflex evoked by medial plantar nerve stimulation in the soleus and tibialis anterior, and reciprocal Ia inhibition between these muscles, in 25 individuals with chronic SCI. We found that Achilles tendon vibration at 40 and 80 Hz, but not other frequencies, reduced the amplitude of the LLR in the tibialis anterior, but not the soleus muscle, without affecting the amplitude of the LPR. Vibratory effects were stronger at 80 than 40 Hz. Similar results were found in the soleus muscle when the tibialis anterior tendon was vibrated. Notably, tendon vibration at 80 Hz increased reciprocal Ia inhibition between antagonistic ankle muscles and vibratory-induced increases in reciprocal Ia inhibition were correlated with decreases in the LLR, suggesting that participants with a larger suppression of later cutaneous reflex activity had stronger reciprocal Ia inhibition from the antagonistic muscle. Our study is the first to provide evidence that tendon vibration suppresses late spasm-like activity in antagonist but not agonist muscles, likely via reciprocal inhibitory mechanisms, in humans with chronic SCI. We argue that targeted vibration of antagonistic tendons might help to control spasms after SCI.

The effect of two therapeutic interventions on balance in children with spastic cerebral palsy: A comparative study

Objectives

Postural control involves controlling the position of the body in space to achieve stability and orientation. Core stability is needed to improve balance and postural control. Whole-body vibration is a unique strategy for muscle strengthening in various clinical situations. This study compared the effects of whole-body vibration and a core stability program on balance in children with spastic cerebral palsy, with an intervention period of 12 weeks.

Methods

A total of 72 children with spastic cerebral palsy (hemiplegic and diplegic), of both sexes (age, 5–8 years), were selected from the outpatient clinic of the Faculty of Physical Therapy, Cairo University. The children were randomly assigned to 2 groups. Group A underwent a core stability program for 30 min and group B underwent whole-body vibration training for 10 min, at 3 times a week for 12 weeks for both groups. Balance was assessed using the Biodex Balance System.

Results

A significant improvement in all variables (p < 0.05) was observed in each group, with greater improvement of all stability indices (anteroposterior, mediolateral, and overall) in group B. There were non-significant differences in all stability indices between hemiplegic and diplegic children (p > 0.05).

Conclusion

Whole-body vibration and core stability exercises are recommended for the treatment of children with spastic cerebral palsy. Whole-body vibration was more effective than the core stability program in improving balance in children with spastic cerebral palsy.

Focal Vibration Stretches Muscle Fibers by Producing Muscle Waves

Focal vibration is an effective intervention for the management of spasticity. However, its neuromechanical effects, particularly how tonic vibration reflex is induced explicitly, remain implicit. In this paper, we utilize a high-speed camera and a method of image processing to quantify the muscle vibration rigorously and disclose the neuromechanical mechanism of focal vibration. The vibration of 75 Hz is applied on the muscle belly of the biceps brachii and muscle responses are captured by a high-speed camera in profile. The muscle silhouettes are identified by the Canny edge detector to represent the stretch of muscle fibers, and the consistency between the muscle stretch and profile deformation has been confirmed by the magnetic resonance imaging in advance. Oscillations of muscle points discretized by pixels are identified by the fast Fourier transformation, respectively, and results demonstrate that focal vibration stretches muscle by producing muscle waves. Specifically, each point vibrates harmonically, and, given the linear phase modulation with transverse position, the muscle vibration propagates as traveling waves. The propagation of muscle waves is associated with muscle stretch, whose frequency is the same with the vibrator due to the curved baseline, and thus induces the tonic vibration reflex via spinal circuits.

Adjuvant treatments associated with botulinum toxin injection for managing spasticity: An overview of the literature

BACKGROUND AND OBJECTIVE

A wide range of adjunct therapies after botulinum toxin administration have been proposed. The aim of the present paper is to provide an overview of major writings dealing with adjuvant (non-pharmacological) treatments associated with botulinum toxin for managing spasticity in order to provide some up-to-date information about the usefulness of the most commonly used procedures.

METHODS

The literature in PubMed was searched with the MeSH terms botulinum toxins, muscle spasticity, physical therapy modalities, and rehabilitation. The results were limited to studies focusing on adjuvant treatments associated with botulinum toxin for managing spasticity. We excluded papers on the use of non-drug treatments for spasticity not associated with botulinum toxin serotype A (BoNT-A) injection. Relevant literature known to the authors along with this complementary search represented the basis for this overview of the literature.

RESULTS

Adhesive taping and casting effectively improved the botulinum toxin effect in patients with upper- and lower-limb spasticity. There is level 1 evidence that casting is better than taping for outcomes including spasticity, range of motion and gait. However, consensus about their most appropriate timing, duration, target and material is lacking. In terms of physical modalities combined with botulinum toxin injection, we found level 1 evidence that extracorporeal shock wave therapy is better than electrical stimulation for some post-injection outcomes including spasticity and pain. Furthermore, electrical stimulation of injected muscles might be useful to boost the toxin effect. However, the best stimulation protocol has not been defined. In addition, we found level 2b evidence that whole-body vibration therapy might reduce spasticity with cerebral palsy.

CONCLUSION

Future research in this field should focus on investigating the most appropriate post-injection treatment protocol for each goal to achieve.

The Impact of Whole Body Vibration Therapy on Spasticity and Disability of the Patients with Poststroke Hemiplegia

OBJECTIVE

To determine if whole body vibration therapy (WBV) effectively improves functional outcome in patients with poststroke hemiplegia.

MATERIALS AND METHODS

In this single-blind RCT, WBV group (n = 10) had 40 hz frequency/4 mm amplitude vibration during 5 minutes/session, 3 days a week, for a duration of 4 weeks. The control group (n = 11) had no vibration therapy for the same duration while standing on the same platform. Patients in both of the groups did 15 minutes of stretching and active range of motion exercises before the intervention. Outcome measures were Modified Ashworth Scale (MAS), Functional Independence Measurement (FIM), and Timed 10-Meter Walk Test (10 mWT).

RESULTS

Only 10 mWT improved at the 1st week (p = 0.002), 1st month (p < 0.001), and 3rd month (p < 0.001) in favor of the intervention group. There was positive correlation also between 10 mWT and ankle spasticity (p < 0.001, r = 0.931).

CONCLUSION

This study suggests that WBV therapy may be a complementary therapy in gait rehabilitation and functional outcome of the patients with calf muscle spasticity.

Is two better than one? Muscle vibration plus robotic rehabilitation to improve upper limb spasticity and function: A pilot randomized controlled trial

Even though robotic rehabilitation is very useful to improve motor function, there is no conclusive evidence on its role in reducing post-stroke spasticity. Focal muscle vibration (MV) is instead very useful to reduce segmental spasticity, with a consequent positive effect on motor function. Therefore, it could be possible to strengthen the effects of robotic rehabilitation by coupling MV. To this end, we designed a pilot randomized controlled trial (Clinical Trial NCT03110718) that included twenty patients suffering from unilateral post-stroke upper limb spasticity. Patients underwent 40 daily sessions of Armeo-Power training (1 hour/session, 5 sessions/week, for 8 weeks) with or without spastic antagonist MV. They were randomized into two groups of 10 individuals, which received (group-A) or not (group-B) MV. The intensity of MV, represented by the peak acceleration (a-peak), was calculated by the formula (2πf)2A, where f is the frequency of MV and A is the amplitude. Modified Ashworth Scale (MAS), short intracortical inhibition (SICI), and Hmax/Mmax ratio (HMR) were the primary outcomes measured before and after (immediately and 4 weeks later) the end of the treatment. In all patients of group-A, we observed a greater reduction of MAS (p = 0.007, d = 0.6) and HMR (p<0.001, d = 0.7), and a more evident increase of SICI (p<0.001, d = 0.7) up to 4 weeks after the end of the treatment, as compared to group-B. Likewise, group-A showed a greater function outcome of upper limb (Functional Independence Measure p = 0.1, d = 0.7; Fugl-Meyer Assessment of the Upper Extremity p = 0.007, d = 0.4) up to 4 weeks after the end of the treatment. A significant correlation was found between the degree of MAS reduction and SICI increase in the agonist spastic muscles (p = 0.004). Our data show that this combined rehabilitative approach could be a promising option in improving upper limb spasticity and motor function. We could hypothesize that the greater rehabilitative outcome improvement may depend on a reshape of corticospinal plasticity induced by a sort of associative plasticity between Armeo-Power and MV.

VIBROfocus: Design of a focal vibro-tactile robotic-assistive system for spasticity rehabilitation

The main focus of spasticity treatment is to alleviate pain, improve function and reduce risk of additional complications. In this paper the design of a robotic system with enhanced focal vibro-tactile stimulation for the treatment of spasticity in the upper limbs is presented. Building on emerging evidence on the use of vibrations in the treatment of spasticity, we propose a new integrated approach. Our design combines the use of vibro-tactile stimulation of the high tone muscle with robotic movement assistance to augment rehabilitation outcomes in patients with spasticity in the upper limbs.

Immediate Effect of a Single Session of Whole Body Vibration on Spasticity in Children With Cerebral Palsy

Objective

To investigate the immediate effect of a single session of whole body vibration (WBV) on lower extremity spasticity in children with cerebral palsy (CP).

Methods

Seventeen children with spastic CP were included. A single session of WBV was administered: 10-minute WBV, 1-minute rest, and 10-minute WBV. The effects of WBV were clinically assessed with the Modified Ashworth Scale (MAS) and Modified Tardieu Scale (MTS) before and immediately, 30 minutes, 1 hour, 2 hours, 3 hours, and 4 hours after WBV.

Results

Spasticity of the ankle plantarflexor, as assessed by MAS and MTS scores, was reduced after WBV. Post-hoc analysis demonstrated that, compared to baseline, the MAS significantly improved for a period of 1 hour after WBV, and the R1 and R2–R1 of the MTS significantly improved for a period of 2 hours after WBV.

Conclusion

A single session of WBV improves spasticity of ankle plantarflexors for 1–2 hours in children with CP. Future studies are needed to test whether WBV is an effective preparation before physiotherapy and occupational therapy.