Efficiency of Selected Motor Relearning Program on Electromygraphic Activity of Reaching Pattern in Stroke Patients

Authors: Dr. Waleed Talat Mansour*,Dr. Enas Elsayed*,

Dr. Eman Samir Mohamed Fayez*

*Lecturer of Physical Therapy for Neuromuscular Disorders and Its Surgery, Faculty of Physical Therapy, CairoUniversity.

Abstract

Objective : The aim of this study was to determine the influence of selected motor relearning program (MRP) on the level of motor impairment of reaching pattern in stroke patients .

Subjects and Methods: Thirty stroke patients , their age ranged from 40 to 50 years , were randomly divided into two equal groups (study and control) . The level of motor impairment of the upper limb was assessed before and after treatment through :(1) recording of electromyographic (EMG) amplitudes from calvicular head of pectoralis major, lateral head of triceps brachii and extensor carpi radialis longus & brevis musclesof the affected upper limb during reaching pattern .(2) assessment of upper limb function through reaching performance scale (RPS). Both groups received physical therapy program. In addition, the study group received selected MRP for shoulder, elbow, wrist and hand. Treatment programs were given for two months every other day.

Results: The results showed significant increase in EMG amplitudes of the selected muscles and reaching performance scale in the study group.

Conclusion: Motor relearning program is effective in improving motor performance of reaching pattern in stroke patients.

Key words: Motor relearning, Reaching pattern, Electromyography, Stroke.

INTRODUCTION

Stroke leaves many survivors with physical and mental disability. It is not only an important health problem; but it also imposes sociologic and economic burdens on patients and caregivers. While rehabilitation aims to reduce disability, many patients are significantly disabled and handicappedon discharge. Thus, the persistent disability and handicap experienced by many individuals after stroke raised not only from impairment resulting from stroke but also from the deleterious neural, muscle, psychological, and cardiovascular adaptation that accompany disuse and of use maladaptive behaviors1.Patients with hemiparesisfollowing stroke demonstrate abnormal, stereotyped movementsynergies that limit their ability to coordinate their jointsin flexible and adaptive patterns thus limiting their abilityto perform many functional movements. Specifically, they often have difficulty in performing a variety of reaching and pointing movements2 . Itis emphasized that functional limitations of the stroke patients are mainly in mobility, balance and impaired upper extremity functions. Stroke may affect virtually all functions as well as the ability to carry out activities of daily living and social activities3.Following an acute upper motor neuronlesion (UMNL), it is generally recognized that the major impairments interfering with functional motor performance are paralysis or weakness and loss of dexterity (disordered coordination). In addition, adaptations that occur in response to both the neural lesion and to subsequent disuse (i.e. joint immobility and lack of muscle contractility)4.

Features of the UMNLsyndrome are classified as positive and negative. Many adaptations follow from the lesion-induced features, figure (1) includes features which can be identified from experimental studies as adaptive changes. This classification has some explanatory value for clinical practice in providing guidance to mechanisms underlying clinical signs. However, in reality the human system is so naturally flexible and adaptive that it is difficult to draw a line between the primary impairments and some of the secondary adaptations. Historically, the negative and positive features have been considered relatively independent phenomena, related to site and amount of tissue damage and spontaneous recovery processes 5.

Fig(1): Classification of the positive and negative features of the upper motor neuron lesion and their relationship with the adaptive features(5).

The number of functions of the upper extremity is almost infinite. It ranges from throwing a ball and lifting heavy objects to manipulating objects on a desk top. Reaching movement, a complicated multi-joint movement, is the major action of the arm to bring the hand into interaction with the environment6.It is one of the motor skills of the upper extremity which includestabilizationand movement of the arm and hand for the purpose of contacting an object with the hand 7.

The key elements of upper limb reach, grasp, and manipulation skills are (1) locating a target or visual regard which requires the coordination of eye-head movements.(2) reaching, involving transportation of the arm and hand in space as well as postural support. (3) grasp, including grasp and release. (4)hand manipulation skills. There are also specific neural and musculoskeletal system that contribute to the control of the components of reaching, grasp, and manipulation 8.

Poor recovery of arm functions after stroke has a negative impact on the patient and his/her family. These patients often need assistance from the society and may need to rely on government resources. Numerous therapeutic treatments are currently available for stroke rehabilitation. Traditional rehabilitation strategies (Bobath, Brunnstrom and proprioceptive neuromuscular facilitation) have been used for many years. However,Motor relearning is defined as the recovery of previously learned motor skills lost following brain injury from a stroke, and is thought to be a key component in promoting a sustained and more functional use of the affected limb.It has been tested in clinical trials and thus practiced on an empirical basis.9

So, the aim of this study was to clarify the efficiency of selected motor relearning program onupper extremity functions in stroke patients.

SUBJECTS, MATERIALS and METHODS

Subjects:

Thirty stroke patients were selected from the outpatient clinic ofneurology, faculty of physical therapy, Cairo universitybased on the following criteria:1- The type of stroke was thrombosis of the middle cerebral artery of the left side confirmed by C.T. 2-The degree of spasticity were ranged from grade one to two accordingto Modified Ashworth Scale10.3-The duration of illness ranged from 12 to 18 months after stroke.4-Their ages ranged from 40 to 50 years . Patients were randomly divided into two equalgroups, group (I) which wasthe control while group (II) was the study .

Instrumentations:

Electromyograph :

It is composed of I) EMG apparatus, II) Electrodes and III) Computer unit.

I- EMG Apparatus

Biopac, TEL 100C-MP system is a computer based data acquisition system. The MP unit takes incoming signals and converts them into digital signals that can be processed with the computer. The TEL 100-C is a remote monitoring system; it consists of four major components: TEL 100M-C transmitter with four channel inputs, TEL 100D-C receiver,CBL 117 cable which connects the TEL100M-C to the TEL100D-C, and up to four "Smart Sensor" electrode/transducer assemblies.

II- Electrodes

Bipolar Silver/Silver chloride surface electrodes and a common reference electrode were used in this study. They are of 10-mm self adhesive disposable electrodes.

Tape measurement, conductive gel, double face adhesive strap, and marker to identify the placement of electrodes are also necessary.

III- Data processing computer unit

It was used for processing data from MP system and for statistical analysis. The device model was HEWLETT PACKARD, Pentium III, designed for Microsoft Windows 98.

Procedures:

A- Assessment Procedures:

Muscle tone was assessed according to the Modified Ashworth scale. Motor compensations used for reaching were detected through the RPSwhich is developed to measure the motor impairment by the identification and quantification of movement patterns and their compensations during reach-to-grasp.From sitting position ,the patient was asked to elevate his armalong side his body to grasp an object placed on a table in front of him at the level of the shoulder by the affected arm11 (appendix 1) . EMG amplitudes were recorded from calvicular head of pectoralis major, lateral head of triceps and radial wrist extensors for the affected upper limb during reaching pattern.

EMG electrodes' placement:

  • For clavicular head of pectoralis major, the active electrode was placed over the muscle belly medial to the anterior axillary fold just below the lateral half of the calvicle and the reference electrode was placed just medial to the active electrodewith interelectrode distance of about two cm. The ground electrode was placed on the lateral end of spine of scapula 1).
  • For lateral head of triceps brachii muscle, the pair of electrodes was placed immediately posterior to the insertion of deltoid or deltoid tubercle. The ground electrode was placed on the dorsum of the hand 12.
  • For wrist extensors: The pair of electrodes was placed over the muscle bellies of extensor carpi radialis longus and brevis which are the most superficial muscles in the dorsum of forearm13. The muscle bellies were localized by palpation during voluntary contraction, with pronated forearm, at a distance of one-third the foream length from the elbow. The ground electrode was placed on the dorsum of the hand 14.

B-Treatment Procedures:

Both groups received traditional physical therapy program (ROM exercises, muscle strengthening, PNF techniques, inhibitory and facilitatory approaches, postural and balance training).In addition,the study group received selected MRP for shoulder, elbow, wrist and hand. It consisted of from the following exercises :

From supine lying position

  • Practicing reaching upwards.
  • Maintaining the elbow in extension while the therapist keeping the arm abducted .
  • Following the therapist hand as a concentric contraction of the shoulder.
  • Controlling eccentric contraction of the triceps.
  • Controlling supination.
  • Extending the elbow concentric against gravity.

From sitting in front of a table

  • Reaching for a cup with the shoulder is internally rotated and elevated.
  • Practicing reaching and pointing.
  • Helping the patient to practice reaching forward while shoulder is externally rotated.
  • Assessing the patient to place the hand flat on the plinth and to lean on it.
  • Helping the patient to ensure correct pressure by the thumb and fingers.
  • Extending the wrist with forearm in mid position.
  • Practicing a bimanual activity by pouring water from one cup to the other.
  • Concentrating on controlling thegrasp.
  • Picking an object off the shoulder.

Each exercise was repeated 10 times .

Traditional physical therapy and MR programs were given for two months every other day

RESULTS

A-General characteristics of the patients: -

The patients’ mean values of age and weight are presented in table (1).

Table (1): General characteristics of the patients .

Variable / Mean ± SD / Minimum / Maximum
Age (years) / 44.83± 3.26 / 40 / 50
Weight (kg) / 76.7± 6.62 / 67 / 89

B- Mean values of EMG amplitudes of the selected muscles for study and control groups before and after treatment:

I- The results of EMG amplitude for clavicular head of pectoralis major revealed that there were significant improvements in both groups after treatment compared to that before treatment , with the best result was for the study group ( table (2) & fig (2) ).

Table (2):Mean values of EMG amplitude for clavicular head of pectoralis major musclefor both groups before and after treatment .

Group / Pre / Post / t / p
Mean SD / Mean SD
Control (1) / 3.13 0.43 / 4.82 8.9 / 7.22 / 0.0001***
Study ( 11 ) / 3.28 0.32 / 5.33 0.51 / 11.10 / 0.0001***
t / 1.013 / 1.92
p / 0.31 / 0.06*

* Significant

** Highly significant

*** Very highly significant

Fig (2):Mean values of EMG amplitude for clavicular head of pectoralis major musclefor both groups before and after treatment .

II- The results of EMG amplitude for lateral head oftriceps brachii revealed that there were significant improvements in both groups after treatment compared to that before treatment , with the best result was for the study group ( table (3) & fig (3) ) .

Table (3):Mean values of EMG amplitude forlateral head of triceps brachii musclefor both groups before and after treatment .

Group / Pre / Post / t / P
Mean SD / Mean SD
Control (1) / 2.87 0.58 / 4.07 0.59 / 5.72 / 0.0001***
Study ( 11 ) / 2.61 0.33 / 4.81 0.98 / 18.57 / 0.0001***
t / 1.47 / 2.5
P / 0.15 / 0.02*

Fig (3):Mean values of EMG amplitude for lateral head of triceps brachii muscle

for both groups before and after treatment .

III-The results of EMG amplitude for extensor carpi radialis longus and brevis revealed that there were significant improvements in both groups after treatment compared to that before treatment , with the best result was for the study group ( table (4) & fig (4) ) .

Table (4):Mean values of EMG amplitude forextensor carpi radialis longus and brevis musclesfor both groups before and after treatment .

Group / Pre / Post / t / p
Mean SD / Mean SD
Control (1) / 1.94 0.18 / 2.50 0.41 / 5.60 / 0.0001***
Study ( 11 ) / 1.78 0.21 / 3.46 0.34 / 18.57 / 0.0001***
t / 2.17 / 6.97
p / 0.03* / 0.0001***

Fig (4):Mean values of EMG amplitude for extensor carpi radialis longus and brevis for both groups before and after treatment .

C- Mean values of Reaching Performance Scale for study and control groups before and after treatment:

The results of Reaching Performance Scalerevealed that there were significant improvements in both groups after treatment compared to that before treatment , with the best results for study group (table (5)& fig (5) ) .

Table (5): Mean values of Reaching performance scale for both groups before and after treatment.

Group / Pre / Post / p
Mean SD / Mean SD
Control (1) / 11 4.17 / 13.4 1.12 / 0.001 **
Study ( 11 ) / 12.27 1.03 / 14.06 1.29 / 0.0001 ***
p / 0.98 / 0.01 *

Fig (5): Mean values of Reaching performance scale for both groups before and after treatment .

DISCUSSIN

The current study aimed to investigate the influence of selected motor relearning program on the level of motor impairment of reaching pattern in stroke patients

Following stroke, muscle weakness arises from two sources: primarily from the lesion itself, as a result of a decrease of descending inputs converging on the final motor neuron population, and hence a reduction in the number of motor units available for recruitment. Since skeletal muscle adapts to the level of use imposed upon it, secondary sources of weakness arise as a consequence of lack of muscle activity and immobility .Contrary to previous opinion, weakness in agonist muscles is not due to spasticity (reflex hyperactivity) in an antagonist muscle group, but is a direct result of reduction of descending motor commands, compounded by disuse and adaptive muscle changes15.

The interruption of descending pathways following stroke results in a decrease the number of motor units activated, decreased firing rate of motor units and impaired motor unit synchronization. These factors cause disorganization of motor output at the segmental level and underlie the motor control problems exhibited by patients even when they are able to generate some force16.

Loss of dexterity appears to involve the loss of coordination of muscle activity to meet task and environmental requirements through an impaired ability to fine coordination between muscles. Although impaired dexterity is typically considered in its association with weakness and slowness to contract muscle, there is some evidence that they may be independent phenomena17.

The most evidence in support of constraint plus intensive motor relearning and meaningful exercise and practice comes from studies of brain reorganization after stroke. Studies showed that there is association between increased use of the affected limb, improved motor performance and brain reorganization16.

Strength training is necessary after stroke to improve the force generating capacity and efficiency of weak muscles and to improve functional motor performance. The relationship between strength and re-learning is complex. The amount of strength required depends on the person's physical size, weight of hand, total body weight and the action to be performed. Skilled motor performance, however, requires the following:• Each muscle involved in the action has to generate peak force at the length appropriate to the action.• This force has to be graded and timed so synergic muscle activity is controlled for task and context.• The force has to be sustained over a sufficient period of time.• Peak forces must be generated fast enough to meet environmental and task demands18.

Improvement of motor activity may occur after stroke. It may be because of recovery of functional neurons. It may also occur by relearning, a process that strengthens existing pathways and may lead to new functional or structural changes( neuroplasticity)19.

Functional MRI can identify cortical plasticity in humans. For instance, these motor relearning techniques have identified changes in excitability and body site representation in the motor cortex in patients following motor relearning. Therefore, cortical plasticity and its manipulation may be an important contributor to functional outcome following reconstruction 20.

In stroke, there is denervation of target neuron centers, which are self-organizing maps (SOMs) within the neuraxis. Compensatory reinnervation occurs within those SOMs by acquiring synaptic sprouts from neurons in the neighborhood. Cognitive systems studies indicate that motor paralysis is due to loss of learning. So treatment or rehabilitation should aim therefore to first restore this learning21.

The findings of this study were supported by Carr and Shepherd5 who said that, following a brain lesion affecting the motor system, an immediate need is to help the patient regain the ability to activate paretic muscles and generate force. Task training involves many repetitions under constrained conditions as a means of increasing muscle contractility and strength and laying down a pattern of coordination. Repetitive exercise may be as critical to motor relearning following stroke as it is for healthy individuals learning to play the piano. It is assumed that repetitive practice of a particular movement may drive brain reorganization by which appears to be a process of motor learning. However, repetitive practice of the same movement may not be sufficient for promoting skill.