Quantitative Static and Dynamic Assessment of Balance Control in Stroke Patients

Summary

Presented here is a quantitative, clinical balance assessment method suitable for stroke patients with balance disorders.

Abstract

In patients with stroke, damage to the central nervous system (CNS) can affect the postural stability and increase the risk of falling. Therefore, accurately assessing the balance is important to understand the type, extent, and causes of balance deficit, and to identify individualized interventions. Clinical assessment methods for balance function can be broadly divided into observation, scale assessment, and balance instrument testing. Here, a clinical protocol is presented for static and dynamic balance assessment in stroke patients, which includes three semiquantitative balance function scale assessments (i.e., Berg Balance Scale, Timed Up and Go Test, and Fugl-Meyer Assessment) and three quantitative instrumental balance evaluation (i.e., Stability Assessment Module, Proprioceptive Assessment Module, and Limit of Stability Module). It is recommended that clinicians consider the use of both classic clinical balance scales and instrumental balance measurements when assessing stroke patients to improve the accuracy of assessments, leading to a better individualized treatment plan.

Introduction

The human body can maintain posture stability under various conditions, including internal and external disturbances¹. Balance relies on sensory input, integration of the central nervous system (CNS), and motor control². In patients with stroke, damage to the CNS can affect the ability to maintain balance³. Postural instability is an important risk factor for falls⁴. Approximately 70% of patients experience a fall in the first year after stroke, often with serious consequences, such as hip fracture in elderly patients^5,6. Moreover, previous studies have shown that postural sway and increased motor response time to visual stimuli are associated with an increased fall risk^7,8. Because strokes have a substantial impact on mobility, accurate qualitative and quantitative balance assessment is important for understanding the type, extent, cause of balance deficit, as well as guidance for individualized interventions and appropriate gait aids⁹.

Clinical assessment methods for balance can be broadly divided into observation, scale assessment, and balance instrument testing. Observation methods (e.g., the Romberg test¹⁰) are only used as a rough screening for patients with balance dysfunction due to their strong subjectivity. Many balance function scales are commonly used in clinical practice because of their ease-of-use, economy, and relative quantification. These include the Tinetti scale¹¹, Berg Balance Scale (BBS)¹², Fugl-Meyer Assessment (FMA)¹³, and Timed Up and Go (TUG) test¹². These clinical tests are not suitable for determining the fall risk in patients with significant balance disorders, because they are subjective assessments and often are not able to substantiate the self-reported balance problems experienced by individuals with mild-to-moderate balance problems¹⁴. Balance instrument testing, a posturography technique, is a useful tool to quantitatively measure the static and dynamic balance function and require balance evaluation systems, such as a force tilting board with pressure sensors, computers, monitors, balance control panels, and professional balance analysis software. These approaches can assess the degree, type, or cause of the balance damage simultaneously by accurately measuring the center of gravity (COG) and postural sway, thereby precisely and objectively reflecting the patient’s balance function. Balance instrument testing can detect subtle differences or damages that the clinical scales cannot. This can be used to overcome the ceiling effect of the scale assessment. With the increasing application of posturography techniques and popularization of computers, it is necessary to promote objective/quantitative balance assessment into clinical practice.

This article describes a clinical balance assessment method that includes standard clinical balance scales and three-module instrument objective balance assessment for stroke patients with balance disorders. A comparison of the results of the clinical assessment scales versus the instrumental balance assessment, is presented to show the advantages of instrumental balance assessment, especially for stroke patients with mild balance disorders. This protocol can help health professionals achieve accurate evaluation to guide clinical treatments. The representative posturography instrument (see Table of Materials) used in this protocol has been validated for dynamic assessment and statistic assessment in previous studies^15,16,17. The system, which is composed of a screen monitor and a tilting board where the patients stand, can be used for evaluating the visual, auditory, and proprioceptive feedback of the patients.

Protocol

The clinical project was approved by the Medical Ethics Association of the Fifth Affiliated Hospital of Guangzhou Medical University and has been registered at the China Clinical Trial Registration Center (No. ChiCTR1900021291) with the title “The mechanism and effect of Pro-kin system training on static and dynamic balance”.

1. Participant recruitment

1. Include patients with brain hemorrhage or infarction confirmed by magnetic resonance imaging (MRI) or computerized tomography (CT); more than one month onset of stroke; stable vital signs of life; Mini-mental State Examination (MMSE)¹⁸ score of >10 points; able to stand alone for more than 1 min; able to walk 6 m with or without walking aids, that are able to cooperate with the whole assessment protocol.
2. Exclude any patients with any medical condition that would prevent them from following the protocol.
3. Obtain written informed consent from each patient before their participation.
4. Gather demographic information (i.e., date of birth, weight, height, past medical history, and any past or current medications) from all the patients.

2. Clinical scale assessment

1. Conduct the lower extremity subscale of the FMA test¹³. Ask the patient to complete a 7-point subscale (total score of 34 points) for the measurement of motor impairment on reflexes, coordination, and voluntary movements of the paretic leg poststroke. Score the patient. A higher FMA-LE score indicates a better level of motor recovery.
2. Conduct the Timed Up and Go (TUG) test¹⁹. Ask the patient to perform three consecutive TUG trials at a self-selected pace for safety and comfort²⁰.
   1. Ask the patient to sit in a chair with their arms resting comfortably on their lap and hips positioned on the back of the seat.
   2. Ask the patient to rise from the chair, walk 3 m, turn around, return to the chair, and sit down. The therapist will time the whole process using a stopwatch.
   3. Allow the patient to use assistive devices during the TUG test, if needed. The average recorded time of the three tests is the patient’s final score. Score the patient.
3. Conduct the BBS test¹² by asking each patient to perform 14 tasks of a 5-point scale (ranging from 0–4) (total score, 56 points). Some examples of these tasks are provided below.
   1. Ask the patient to stand up and try not to use their hands for support.
   2. Ask the patient to stand for 2 min without holding on to anything.
   3. Ask the patient to sit with their arms folded for 2 min.
   4. Ask the patient to sit down.
   5. Ask the patient to transfer one way towards a seat with armrests and one way towards a seat without armrests.
   6. Ask the patient to stand still for 10 s with their eyes closed.
   7. Ask the patient to place their feet together and stand without holding on to anything.
   8. Ask the patient to lift one arm/two arms to 90˚ , and then stretch out his/her fingers and reach forward as far as he/she can. Measure the distance of forward reach with a ruler.
   9. Ask the patient to pick up the shoe/slipper that is placed in front of his/her feet.
   10. Ask the patient to turn and look directly behind over their left shoulder and then their right shoulder.
   11. Ask the patient to turn completely around in a full circle, and then turn a full circle in the other direction.
   12. Ask the patient to place each foot alternately on a step/stool four times.
   13. Ask the patient to place one foot directly in front of the other.
   14. Ask the patient to stand on one leg as long as they can without holding on to anything.
       NOTE: Items 2.3.2, 2.3.3, 2.3.6, 2.3.7, and 2.3.14 are classified as static items. All other items are classified as dynamic items. Score the patient. Scores of 0-20 indicate a high risk of falling, scores of 21–40 indicate a medium risk of falling, and scores of 41–56 indicate a low fall risk⁹.

3. Static and dynamic balance instrument evaluation

1. Patient preparation
   1. Instruct the patient to take off their shoes and socks and to wear a trunk sensor on the xiphoid. The trunk sensor is a circular signal transmitter used for detecting the inclination of the subject's trunk position (backward forward and mediolateral) and collecting data (Figure 1 ).
   2. Explain all the procedures to the patient and then ask the patient to stand barefoot on the support surface (Figure 1).
   3. Ask the patient to stand on the fixed tilting board with one foot and then both feet to get used to the tilting board for 2 min (Figure 1 ).
      NOTE: During the last three testing modules, the tilting board is used to detect the participant’s COG in real time with four decelerator pistons that can automatically modify the active resistance of the board as needed in dynamic balance measurements. The surface of the tilting board is divided into eight different areas (S1, S2, S3, S4, S5, S6, S7, and S8) with four axes (A1-A5/ Backward – Forward, A2-A6, A3-A7 /Medium – Lateral, and A4-A8) (Figure 1 ), and a built-in computer to accurately calculate swing range of patients during the testing.
2. Stability assessment
   NOTE: The stability assessment is used for assessing the ability to maintain postural stability under static conditions.
   1. Click the Static Stability Assessment button to start the Stability Assessment Module. Then, fix the auxiliary testing equipment onto the tilting board to guarantee that the patient’s foot is always in the same position among the different modules of the tests (Figure 1 and Figure 2B).
   2. Click the Reset button to reset the tilting board.
   3. Instruct the patient to place the medial margin of their both feet against the auxiliary testing equipment and the highest points of the foot arches on the A3 and A7 axis, and then to place their hands at the sides of their body in a natural position (Figure 2A,C).
   4. Click the Reset Trunk button to run the trunk sensor’s automatic calibration program.
   5. Click the Options button to select the Sequence Opened eyes/Closed eyes (Romberg) to begin the Romberg Test¹⁰ for either the open or closed eyes test.
   6. Turn the computer monitor to the side to keep it out of the patient’s view (Figure 2). Then, instruct the patient to stare at the ‘marker’ in front of them (1.5 m distance between the eyes and the marker) and to stand stable with their feet in a stationary position (Figure 2A).
   7. Click the Start button and ask the patient to stand stable with their eyes open for 30 s. The program will be terminated automatically.
   8. Click the Start button and ask the patient to stand stable with their eyes closed for 30 s. The first 5 s phase of the eyes open/eyes closed balance test is for patient adaptation, whereas the next 25 s phase is for the formal testing and data recording. The program will be automatically terminated.
   9. Click the Results button to obtain the report from the built-in software calculations. For the specific calculation formula refer to the user manual (Figure 2D).
3. Proprioceptive assessment
   NOTE: Proprioceptive assessment is used to evaluate the postural stability and fine coordination function of lower limbs of stroke subjects.
   1. Click the Multiaxial Proprioceptive Assessment button to start the Proprioceptive Assessment Module.
   2. Remove the auxiliary testing equipment from the test tilting board and click the Reset button to reset the tilting board.
   3. Ask the patient to get ready into position as shown in Figure 3 (i.e., sagittal foot spread with hands on the bilateral armrest) and with the individual foot to be tested on the mobile tilting board (i.e., the second metatarsal and midpoint of heel located on the A1–A5 line, and the highest point of the arch placed on the A3 and A7 axis), and the other foot resting on the support surface parallel to the foot being tested (Figure 3D).
   4. Click the Options button and click off the Static buttons for both axes (front-behind and left-right) to get the tilting board into a dynamic state for 3 s. Pay attention to the patient’s position in case of falling.
   5. Click the Soft button to set the force absorbers parameter to 1.
      NOTE: The available levels of the force absorbers range from 1 (the most unstable) to 40 (almost static).
   6. Click the Variables to set Limits to “5°-10°”, Rounds (number of circles) to “3”, and Test to “Compared” for the left-right compared model. The left-right compared model indicates the left and right foot tracing will be overlapped in the single graph.
   7. Move the computer monitor in front of the patient at their eye level so that the patient can get visual feedback.
   8. Click the Enable Trunk button for the red crosser (COG position) to show up, and then click the Reset Trunk button.
   9. Click the Start button. The pointer of the footboard (blue cross) is shown on the screen and is responsive to the foot’s movement (Figure 3A,E).
   10. Ask the patient to look at the computer screen to get real-time visual feedback and try to control the blue cross. Instruct the patient to touch the red point first and then follow the blue circle line reference for three circles.
   11. Ensure that the right foot moves in clockwise circles (Figure 3B) and the left foot in counterclockwise circles (Figure 3C). The motion tracking appears red on the screen.
   12. Click the Results button. The software will supply different calculations to analyze.
4. Limits of stability module
   NOTE: This module measures the ability to maintain postural stability under dynamic conditions.
   1. Click the Limits of Stability button to start the Limits of Stability Module.
   2. Click the Reset button to reset the tilting board.
   3. Turn off the testing tilting board fastener to set the tilting board into stable mode. Then, fix the auxiliary testing equipment on the test tilting board.
   4. Ask the patient to maintain an upright stance with their arms resting by their sides and their feet in a standardized foot position as required in the Stability Assessment Model (see step 3.2.3) (Figure 2C).
   5. Position the computer screen directly in front of the patient at eye level. The patient’s COG position is displayed on the screen as the blue cross that moves in response to the movements of their body’s COG (Figure 4A).
   6. Click the Start button and then ask the patient to move the blue COG cross by leaning the body away from the midline as quickly and closely as possible to randomly appearing flashing squares (spread in eight directions, A1-A8, Figure 3B) at first and then the original midpoint (blue square in the middle). Instruct the patient to reach their maximal lean-out toward each of the eight targets for the entire LOS test setup (Figure 4B).
   7. Click the Results button. The software will supply different calculations to analyze.
      NOTE: If the patient lost their balance while leaning (e.g., they took a step, held something, or shifted their foot position during testing), their feet should be repositioned, and the trial should be repeated.

4. Data analysis

1. Obtain and record all demographic characteristics and clinical scale assessment data.
2. Obtain the results of Static and Dynamic Balance Instrumental evaluation using the software associated with the balance system at the end of each test by click the Result button.
   NOTE: The most significant data are presented in graphs like those shown in Figure 5, Figure 6, and Figure 7. Based on the manual, the major parameters and their meanings are listed in Table 1.
3. Transfer the data to statistical software for analysis.

Results

Results from nine stroke patients with balance deficits are shown. The average age of the nine patients recruited in our study was 52.7 years; all of them were male. Four suffered from right hemiplegia. The average FIM-LE, TUG, and BBS values were 23.9 points, 31.8 s, and 46.8 points, respectively. The other demographic characteristics (BMI, stroke type, and onset time) are shown in Table 2. Each item score and the total scores of the BBS assessment of each of the nine stroke patients are shown in

Discussion

Described is a clinical protocol for static and dynamic balance assessment in stroke patients that includes three semiquantitative balance function scale assessments (BBS, TUG, and FMA-LE) and three models of quantitative instrumental balance evaluation (Stability Assessment, Proprioceptive Assessment, and Limit of Stability). The design of this protocol was based on five main points.

First, the BBS is a 14-function-task on a 5-point scale that semiquantitatively assesses static and dynamic ba...

Materials

Name	Company	Catalog Number	Comments
Electric Lifting Bed	Guangzhou Yikang Medical Equipment Industrial Co., Ltd	YK-8000	Required for Fugl-Meyer assessment
Percussion hammer	ICARE-MEDICAL Co., Ltd.	CRT-104	Required for Fugl-Meyer assessment
Prokin Balance System	Tecnobody .S.r.l, Italy	ProKin 252	Balance evaluation and training system
Ruler	M&G Chenguang Stationery Co.,Ltd.	AHT99112	Required for Berg Balance Scale assessment
Stopwatch	95,Shenzhen Junsd Industrial Co., Ltd have been striven all the years de	JS-306	Required for Berg Balance Scale assessment