INTRODUCTION

 Stroke is the main cause of long-term disability in adults.¹ Regaining trunk control has been identified as an important early predictor of functional recovery after stroke. Proximal trunk control is a prerequisite for distal limb movement control, balance stability and functional ability.²

Decreased trunk control leads to poor bilateral integration, impaired automatic postural control, and hence increased risk of falls.³ Balance problems have been implicated in the poor recovery of activities of daily living, mobility⁴ and an increased risk of falls.⁵

Also, Prediction of functional abilities at an early stage enables clinicians to select appropriate treatment programs and goals, facilitate a proper discharge plan, and anticipate the need for home adjustments and community support.⁶

 Aim of Work: To examine the trunk muscle control in a group of chronic stroke patients and to find out if there is a direct correlation between poor trunk muscle control on one hand and balance and functional abilities on the other hand. We looked into whether or not one of our outcome measures may be used as a clinical predictor of functional recovery after stroke.

 

PATIENTS AND METHODS

 

Forty adult ambulant ischemic chronic stroke patients (more than 6 months after stroke onset) were recruited from the outpatient clinic and Balance System laboratory of Faculty of Physical Therapy, Cairo University between October 2011 and January 2013.

All patients recruited were experiencing their first ever stroke, had at least average cognitive functions that enabled them to follow commands. Patients were excluded if they had severe proprioceptive deficit, any other neurologic or orthopedic disorders, disabling visual or hearing impairment or unstable medical condition.

All patients were examined using the trunk impairment scale (TIS)⁷ to assess trunk control (primary outcome measure). This scale has a total score of 23 and it includes 7 points for static, 10 points for dynamic sitting balance, and 6 points for coordination. TIS scores of 21 or more indicate normal trunk muscle function.⁸ Balance was also assessed using the dynamic limits of stability test and the overall stability index (OASI) that was done using the automated Biodex Balance System. Subsequent functional limitation was examined using the motor subscale of the Functional Independence Measure (FIM_motor).

 

Statistical Analysis

The collected data were statistically analyzed using SPSS statistical software (version 18). Descriptive statistics (mean and standard deviation) were used to assess the demographic data of all patients. Pearson correlation coefficient (r) was used to study the correlation between TIS (total score and scores of its subscale) and both (balance and functional abilities measures); Univariate regression analysis (R²) was used to determine to what extent trunk control affects balance and functional abilities in stroke patients, and to compare between the subscales of TIS in relation to balance and functional abilities. P<0.05 is considered of statistical significance and P ≤0.0001is considered highly significant.

 

RESULTS

 

Forty patients with first-ever ischemic stroke were recruited. The sample included 29 males (72.5%) and 11 females (27.5%) with a mean age of 56.1±5.45 (Range: 50-65) and mean duration after stroke of 9.8±2.68 (Range: 6-15 months).  Twenty-four patients (60%) had left side affection while 16 (40%) had right side affection. Results of the patients' assessment are described in Table (1).

The TIS total score was low with a median of 16 (IQR 13-20). Only one patient (2.5%) had a score of 21, which represents normal trunk control. Upon correlating the TIS to other measures of balance and function, there was a highly significant direct correlation between the TIS total score and each of the OASI, dynamic limits of stability and the FIM (r=0.929 / P=0.0001 and r=0.985 / P=0.0001, respectively). In addition, there was negative highly significant correlation between the TIS total score and OASI (r =-0.945, P=0.0001). The TIS subscales, namely the static and dynamic sitting balance items also significantly correlated with the OASI, dynamic limits of stability and the FIM_motor scale (Table 2).

Results of univariate regression analysis between the TIS total score and its subscores on one side and measures of balance and functional skills (OASI, dynamic limits of stability, and FIM_motor) on the other side are presented in Table (3). All results for the dynamic sitting balance and total score are significant. This indicates that there is a high probability of having low scores of OASI, dynamic limits of stability and FIM_motor when the TIS total score or dynamic sitting balance are low. Nevertheless, the coordination scale results were all insignificant. For the static sitting balance component of the test, the results were significant except the values between the sitting balance score and the dynamic limits of stability test.

 

Table 1. Sample characteristics.

 

	Median (IQR)	Range
TIS_total	16 (13-20)	11-21
TIS_static sitting balance	7(6-7)	5-7
TIS_dynamic sitting balance	7(5-9)	4-10
TIS_coordination	2 (2-4)	1-4
OASI	3.8 (2.95-5.1)	2.1-7.3
Dynamic limits of stability	13 (10-23)	8-36
FIM_motor	62.5 (57-70)	49-77

FIM_motor: Functional Independence Measure-motor subscale, OASI overall stability index, TIS trunk impairment scale

 

Table 2. Correlation between TIS total score and subscores and each of OASI, overall dynamic limits of stability and FIM.

 

	OASI	Dynamic limits of stability	FIM_motor
TIS_total	r= -0.95 p=0.0001*	r =0.93 p =0.0001*	r =0.99 p =0.0001*
TIS_static sitting balance	r= -0.79 p= 0.0001*	r =0.63 p =0.0001*	r =0.78 p =0.0001*
TIS_dynamic sitting balance	r= -0.93 p= 0.0001*	r =0.92 p =0.0001*	r =0.96 p =0.0001*
TIS_coordination	r= -0.81 p= 0.0001*	r =0.87 p =0.0001*	r =0.88 p =0.0001*

FIM_motor Functional Independence Measure-motor subscale, OASI overall stability index, r correlation coefficient, TIS trunk impairment scale

*significant at P<0.01

 

 

Figure 1.               Correlation between TIS total score and FIM_motor score.

 

Table 3. Univariate regression analysis between TIS total score and subscores and each of OASI, overall dynamic limits of stability and FIM. Values presented as R² (p value).

 

	OASI	Dynamic limits of stability	FIM_motor
TIS_total	0.89 (p <0.0001*)	0.86 (p <0.0001*)	0.97 (p <0.0001*)
TIS_static sitting balance	0.9 (p =0.001*)	0.89 (p >0.05) NS	0.97 (p <0.0001*)
TIS_dynamic sitting balance	0.9 (p <0.0001*)	0.89 (p <0.0001*)	0.97 (p <0.0001*)

FIM_motor Functional Independence Measure-motor subscale, NS not significant, OASI overall stability index, r correlation coefficient, TIS trunk impairment scale

*significant at P<0.01

 

 

 

Figure 2.               Regression model of the TIS total score and FIM_motor score showing

a strong positive interaction between both variables (R² =0.97, p <0.0001).

 

 

DISCUSSION

 

We aimed to assess the state of trunk muscle control in stroke patients at least six months after the onset. Several studies had shown that chronic stroke patients had poor trunk control.^9-11 We investigated the trunk muscle control in chronic stroke patients with good recovery, so we only recruited patients who can walk independently. We used the TIS as it is more sensitive in detecting changes in trunk muscle control.⁹

Our findings showed that 39/40 patients had a degree of trunk muscle control impairment relative to age matched controls reported in the literature.⁸ The median score was 16 which is equivalent to 69.6% of the total score. Trunk impairment can be explained by post-stroke affection of trunk muscle strength, neural control and trunk proprioception which are prerequisites for good trunk control and provision of stable foundation for movement.¹²

Our second aim was to find out whether there is a correlation between trunk muscle control problems and balance and/or functional activities of our selected patient group. Our results demonstrated a highly significant correlation between the TIS total score, TIS subscores on one side and balance and functional activities on the other side. This is concordant with other studies that showed that trunk flexion and extension muscle weakness when assessed clinically¹³ or by CT¹⁴ directly correlated with balance, functional recovery scores^13,14 and speed of gait.¹⁴

The positive highly significant effect of trunk control on balance and functional abilities of stroke patients can be attributed to the fact that, the trunk is the central key point of the body that provides proximal stabilization. Lack of this stabilization after stroke influences the affected limbs profoundly-any attempt to move upright against gravity leads to an increase of distal spasticity-which in turn affect the patient’s balance control, mobility and functional capacity.

In addition, control of movement proceeds from proximal to distal body regions; so, if an improved level of proximal trunk control were attained, a better distal limb control might be anticipated during balance and functional performance.¹⁵

The final target of our study was to look into the best clinical predictors of trunk muscle control and subsequent functional recovery. Regression analysis results showed that the TIS total score and dynamic sitting balance subscore show the best signal in terms of predicting balance and functional outcomes (table 3). We would suggest the use of the dynamic sitting balance portion of the TIS as a valid assessment tool of trunk muscle control that will also serve to predict future functional recovery.

Conclusion

This study highlights the role of trunk muscle control as an independent predictor of functional recovery. This can be rapidly and reliably assessed using the TIS dynamic sitting balance subscale. These findings should propel our neurorehabilitation teams to objectively test and subsequently work on regaining efficient trunk control even in stroke patients who recovered the ability to walk again.

 

[Disclosure: Authors report no conflict of interest]

 

REFERENCES

 

1.        Monaco M, Trucco M, Monaco R, Tappero R, Cavanna A. The relationship between initial trunk control or postural balance and inpatient rehabilitation outcome after stroke: a prospective comparative study. Clin Rehab. 2010; 24(6): 543-54.

2.        Karthikbabu S, Chakrapani M, Ganeshan S, Rakshith K, Nafeez S, Prem V.  A review on assessment and treatment of trunk in stroke: a need or luxury. Neural Regen Res. 2012; 7(25): 1974-77.

3.        Cabanas-Valdés R, Cuchi G, Bagur-Calafat C. Trunk training exercises approaches for improving trunk performance and functional sitting balance in patients with stroke: a systematic review. NeuroRehabilitation. 2013; 33(4): 575-92

4.        Lamb S, Ferrucci L, Volapto S. Risk factors for falling in home-dwelling older women with stroke. Stroke. 2003; 34(2): 494-01.

5.        Visser J, Carpenter M, van der K, Bloem B. The clinical utility of posturography. Clin Neurophysiol. 2008; 119(11):2424-36.

6.        Wang C, Hsueh I, Sheu C, Hsieh C. Discriminative, Predictive, and Evaluative Properties of a Trunk Control Measure in Patients with Stroke. Phys Ther. 2005; 85(9):887-94.

7.        Verheyden G, Mertin J, Preger R, Kiekens C. The Trunk Impairment Scale: a new tool to measure motor impairment of the trunk after stroke. Clin Rehab. 2004; 18:326-34.

8.        Verheyden G, Nieuwboer A, Feys H, Thijs V, Vaes K, De Weerdt W. Discriminant ability of the Trunk Impairment Scale: A comparison between stroke patients and healthy individuals. Disabil Rehabil. 2005; 27(17):1023-8.

9.        Verheyden G, Vereeck L, Truijen S, Troch M, Herregodts I, Lafosse C, et al. Trunk performance after stroke and the relationship with balance,gait and functional ability. Clin Rehabil. 2006; 20(5):451-8.

10.     Messier S, Bourbonnais D, Desrosiers J, Roy Y. Dynamic analysis of trunk flexion after stroke. Arch Phys Med Rehabil. 2004; 85: 1619-24.

11.     Winzeler-Mercay U, Mudie H. The nature of the effects of stroke on trunk flexor and extensor muscles during work and at rest. Disabil Rehabil. 2002; 24:875-86.

12.     Ryerson S, Byl N, Brown D, Wong R. Altered Trunk Position Sense and Balance Functions after Stroke.  J Neurol Phys Ther. 2008; 32(1):14-20.

13.     Karatas M, Cetin N, Bayramoglu M, Dilek A. Trunk muscle strength in relation to balance and functional disability in unihemispheric stroke patients. Am J Phys Med Rehabil. 2004; 83:81-7.

14.     Tsuji T, Liu M, Hase K, Masakado Y, Chino N. Trunk muscles in persons with hemiparetic stroke evaluated with computed tomography. J Rehabil Med. 2003; 35:184-8.

15.     Karthikbabu S, Chakrapani M, Ganeshan S, Rakshith K, Nafeez S, Prem V.  A review on assessment and treatment of trunk in stroke: a need or luxury. Neural Regen Res. 2012; 7(25):1974-7.