Effect of shock wave therapy on ankle plantar flexors spasticity in stroke patients

Abstract

BACKGROUND: Large number of patients with first-ever stroke developed spasticity. Spasticity can reduce the range of motion, hinder voluntary movements, provoke pain, and result in impairment of functional activities of daily living.

OBJECTIVE: Demonstrate the effect of shock wave therapy on ankle plantar flexors spasticity in stroke patients.

METHODS: We included forty ischemic stroke patients divided into 2 groups; group I were subjected to the selected physical therapy program and shock wave therapy whereas group II received the selected physical therapy program as well as placebo shock wave for six weeks. Both groups were subjected to pre- and post-treatment assessment by H/M ratio, dorsiflexion active range of motion, and time of ten-meters walking.

RESULTS: Baseline characteristics showed no significant difference between the two groups regarding the grades of spasticity. Whereas After treatment, there were a highly significant difference between both groups regarding the grades of spasticity according to the 3 parameters, H/M ratio, dorsiflexion active range of motion, and time of ten-meters walking test (P values; <0.001, 0.006, and 0.009 respectively).

CONCLUSIONS: Shock wave therapy is effective in controlling spasticity, increase dorsiflexion active range of motion of ankle and improving ten- meters walking test in stroke patients.

Keywords

Stroke spasticity H/M ratio extra corporeal shock wave therapy

1 Introduction

Spasticity is one of the major positive clinical signs of stroke, it happens usually due to damage to the pyramidal tracts and their accompanying parapyramidal (corticoreticulospinal) fiber gives rise to the upper motor neuron syndrome (Sommerfeld Elsy, Svensson, Lotta, & Magnus, 2004).

It has been reported that spasticity is considered a major component of hypertonia, also it has been considered as a motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes with exaggerated tendon jerks (Lamy Wargon, Mazevet, Ghanim, & Katz, 2008). Spasticity can decrease the range of motion, impair voluntary movements, provoke pain, and result in a loss of function in activities of daily living (Bowden & Stokic, 2009).

Objective methods for assessing spasticity include Torque devices, and electrophysiological studies including dynamic multichannel EMG, tonic vibratory reflexes, and electrical testes related to the H reflex and F wave (Katz, 1997).

Shock waves are defined as a sequence of single sonic pulses characterized by high peak pressure ranging from 5 to 130 Mpa (milli-Pascals), fast pressure rise, and short duration (less than 1 microsecond). The persistent clinical effects of shock wave treatment on muscular contractures in athletes together with preliminary data reporting a reduction in hypertonia in neurological patients experiencing muscular hypertonia. Thus, it can be hypothesized that muscle hypertonia can decrease after shock wave therapy (Manganotti & Amelio, 2005).

2 Objective

Our goal is to investigate the effect of extra-corporeal shock wave therapy on ankle plantar flexors spasticity in patients with post stroke spasticity.

3 Methods

We studied forty Egyptian stroke patients of both sex who proved to have some degree of spasticity of ankle plantar flexors from 1+ to 2 according to Modified Ashworth Scale (MAS). Patients were selected from the outpatient clinic of faculty of physical therapy, Cairo University, Cairo, Egypt. Patients’ ages ranged from 40 to 60 years old. Duration of illness ranged from 6 to 18 months. All patients were medically and psychologically stable. We excluded patients with other Neurological or orthopedic diseases that may affect walking, patients with deformities of the lower limbs especially ankle, and patients with visual, auditory or other perceptual dysfunctions.

The study population was divided into two equal groups of twenty patients each; group I (considered as the study group) were treated by a designated physiotherapy and shock wave therapy on spastic ankle plantar flexors whereas group II (considered as the control group) received the selected physical therapy program as well as placebo shock wave. This physiotherapy program was applied for one hour per session, three times per week, day after day for successive six weeks.

The physiotherapy program consisted of ankle-foot orthosis, stretching exercises, range of motion exercise, weight bearing exercise, balancing exercise, gait training exercise walking, and functional training.

In addition, group I received shock wave therapy one session per week for the same six weeks. The pressure pulses were focused on calf muscle mainly on the medial head of the gastrocnemius muscle of spastic side. Shots (1,500) were applied in the middle of the belly of the muscle. Different points of application were used to treat several areas of the hypertonic muscles.

An informed consent was obtained from all patients, and both group subjected to the following assessment before the start and at the end of treatment sessions:

3.1 H/M ratio measurement

The H/M ratio (Ratio of maximum H reflex to maximum M response), was assessed using Electromyography (Neuroscreen plus version 1.59 produced by Tonneis, a division of Erich Jseger Gmbh, Germany: 1998). The patient was placed in prone position comfortably on the examining table. The head of the patient was held in mid position and the feet were placed over the edge of the table. Recording was conducted from the soleus muscle. The stimulation duration was one msec, which makes it more selective for stimulating the afferent Ia nerve fibers and evokes a stable H-reflex. Stimulation was at rate of once every three seconds to avoid blocking response and allow full recording of the reflex response.

The maximal amplitude of H-reflex is often obtained with low intensity. With gradual increase of the stimulus intensity, the M-response amplitude was gradually increased while the H-reflex amplitude was gradually decreased (Manganotti & Amelio, 2005). The H/M ratio was calculated as each value is a mean of three consecutive values.

3.2 Dorsiflexion active range of motion measurement

Digital Goniometer (Model SR 360 FLEXOMETER) is a computed device used to measure active range of motion. The patient was instructed to lie down in long setting position. The sensor part was placed around lateral side of sole of the foot and attached to a strap; the second part was put stable on the plinth. The patient was asked to hold the ankle at neutral position which is confirmed by the digital goniometer sensor then the patient began to move as possible as he can toward dorsiflexion. After the readings were recorded on second part hold button was pressed. Three consecutive readings were taken, then the mean score was calculated.

3.3 The timed 10 meters walk test

A line was drawn on the ground at the beginning and other one at the end of the 10 meters. The patient stand at beginning line and was asked to begin walking at normal speed until reaching end line. The time taken by patients was recorded by a stop watch. Three consecutive trial were done and the mean time was calculated.

4 Statistical analysis

The obtained data were collected and statistically analyzed using the arithmetic mean and their standard deviation. Paired t-test was used for comparison of means of pre and post treatment within each group. Unpaired t-test for comparison of means of pre and post treatment of two independent groups (Kirkwood & Sterne, 2003).

5 Results

The baseline characteristics of patients is matched between the 2 groups (Table 1). Comparing the mean values of H/M ratio in group I, group II and between both groups revealed very highly significant difference. Comparison between pre- and post- treatment mean values of active ROM ankle dorsiflexion in group I, group II and between both groups also revealed highly significant difference. Comparison between pre-and post- treatment mean values of 10 meters walk test in in group I, group II and between both groups showed highly significant difference (Table 2).

6 Discussion

The current study showed that there is a very highly significant difference between the mean values of H/M ratio of the 2 groups at the end of the treatment program.

The amplitude of the maximal M wave is known to represents the total number of αMN while the amplitude of the maximal H wave measures only the number of αMN which are recruited reflexively (Angel & Hoffman, 1963; Matthews, 1970). The H max/M max ratio could therefore provide a measure of that fraction of the total motor neuron pool that can be excited reflexively. Accordingly, a decrease in the proportion of αMN pool elicited by reflex excitation indicates a reduction in spasticity (Milanov, 1992).

In agreement with these results, Amelio, Manganotti, and Cugola (2005), found that a single active treatment session of Extracorporeal shock wave therapy (ESWT) on spastic muscles in patients affected by stroke resulted in a significant reduction in muscle spasticity. Also, Yoo, Kim, and June (2008), found a significant improvement in spasticity of elbow and wrist flexors affected by stroke after three sessions of ESWT compared with baseline and shamstimulation.

Min, Kang, Young-Jae, and Seon (2011), reported that one session of ESWT for chronic stroke patients with ankle plantar flexor spasticity produced an immediate effect and the spasticity was significantly improved. The authors stated that variable mechanisms have been proposed to explain the effectiveness of shock wave in treating muscle spasticity, including acting on fibrosis of hypertonic muscles, decreasing spinal excitability and mechanical vibratorystimulation.

Many reports (Vidal, Morral, Costa, & Tur, 2011; Gonkova, Ilieva, Ferriero, & Chavdarov, 2013) support the positive effects of ESWT in the treatment of spasticity in patients with cerebral palsy as measured by decrease in the Modified Ashworth Scale scores and increase in the range of motion of elbow joint, and this significant improvement remained up to the fourth week of treatment. This prolonged efficacy of ESWT can be explained by direct effect of mechanical stimuli of shock wave on the muscle fibers adjacent to the tendon rather than decreasing spinal excitability or mechanical vibratorystimulation.

Wang, Tsai, and Chan (2000), stated that ESWT produces mechanical effects such as regeneration of degenerated tissue, neovascularization, reposition of calcium deposit. Mariotto et al. (2005), added that ESWT produced also physiological responses such as changes of epithelial cell permeability, free radical formation, change of cell membrane permeability, and variable growth factor formation that leads to reduction of spasticity in addition to that ESWT can induce Nitric Oxide (NO) synthesis which is involved in improvement of variable tendon disease. More while the NO is involved in neuromuscular junction formation in peripheral nervous system and physiological functions of central nervous system, including neurotransmission, and synaptic plasticity.

Our study has some limitations that should be addressed in further studies: (1) the study was a pilot study with relatively a small sample size. (2) Spasticity may show further improvement at different intensity of shock wave therapy, a parameter was not utilized in this study. We acknowledge that further research to address objectively the effect of shock wave therapy on physiological and chemical biomarkers of spastic muscles after stroke.

7 Conclusion

Application of shock wave therapy is effective in controlling spasticity, increase dorsiflexion active range of motion of ankle and improving ten- meters walking test in stroke patients.

Conflict of interest

The authors have no conflict of interest to report.

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