CLINICAL AND STABILOMETRIC CHARACTERISTICS OF VERTICAL POSTURE OF PATIENTS WIHT BRAIN PATHOLOGY OF DIVERSE GENESIS Lyakhovetskaya V.V., Konovalova N.G., Sharapova I.N., Artemyev A.A.

Novokuznetsk Scientific and Practical Centre for Medical and Social Expertise and Rehabilitation of Disabled Persons,

Novokuznetsk Institute (Branch) of Kemerovo State University,

Novokuznetsk State Extension Course Institute for Medical Practitioners of Russian Medical Academy of Continuing Vocational Education, Novokuznetsk, Russia

Restoration of vertical posture is the important stage of rehabilitation of patients with paresis and plegia. This stage has its own significance and opens some perspectives for walking training. Along with it, this process is based on precise regulation of muscular tone with consideration of information from several sensory entries, and it supposes the combined functioning of multiple regions of central nervous system (CNS).

After CNS injuries to various origin, the strategies for supporting vertical posture can be quite different [1]. Knowledge of the features of postural regulation with consideration of a cause of CNS injury can disclose some mechanisms of sanogenesis that makes restorative treatment more targeted [2, 3].

Objective − to compare the regulation of vertical posture in patients with traumatic brain injury and patients after stroke in the brain arterial systems.

MATERIALS AND METHODS

The study is based on the basis of the department of medico-social rehabilitation, physical therapy and remedial gymnastics at Novokuznetsk State Extension Course Institute for Medical Practitioners of Russian Medical Academy of Continuing Vocational Education.

The follow-up included 200 patients with CNS pathology, including 81 patients in late restorative period of cerebral traumatic disease (CTD) and 119 patients with stroke in vascular basins of the brain. All they were admitted to the clinic of Novokuznetsk Scientific and Practical Centre for Medical and Social Expertise and Rehabilitation of Disabled Persons for restorative treatment in 2018-2020.

The inclusion criteria were possibility for maintenance of vertical posture within 3 minutes, informed consent for participation in the study. The exclusion criteria were presence of contraindications for vertical positioning and refusal from participation in the study.

Along with clinical neurological study, all patients received Romberg's test and optokinetic test with computer force plate Trast-M Stabilo produced by (Neurocor).

Realization of Romberg's testing consisted in supporting vertical posture on the platform of the force plate during 51 seconds with opened and closed eyes. The following moments were considered during analysis of results: amplitude (A, mm) and frequency (F, Hz) of the first maximum of the spectrum in vertical (Z), sagittal (Y) and frontal (X) components; the ratio of length of the statokinesiogram to the square (L/S 1/mm); square (S, mm²); velocity (V, mm/sec.) of movement of the plane of general center of pressure (GCP); consumed work value (A, J); stability (Stab); 60 % of power of the spectrum for each component (Z, Y, X, Hz); deviations of GCP in sagittal (y) and frontal (x) planes.

Optokinetic testing consisted in supporting vertical posture with opened eyes looking at the clear screen of the monitor (the control variant) and at the screen with visual interferences in four variants: when standing near the screen with moving calibrated strips from right to left, from left to right, from top to bottom and from bottom to top. When analyzing the results of optokinetic testing, the length of the statokinesiogram (L, mm) and position of GCP (mm) in relation to sagittal and frontal axes in each variant of posture holding were considered.

The results were analyzed with Statistica (version 10.0.1011.0, StatSoft Inc., USA, the license agreement AXAAR207P396130FA-0). The mean for each value was calculated. Wilcoxon's test was used for estimation of statistical significance of differences in values in all variants of standing in various studies within the limits of the single group. Mann-Whitney's test was used for estimation of significance of differences between the groups. The differences were statistically significant at p < 0.05.

The informed consents of patients for personal preparation of data were received and approved by the ethical committee of Novokuznetsk Scientific and Practical Centre for Medical and Social Expertise and Rehabilitation of Disabled Persons (the protocol No. 5, 15 September, 2020). The study corresponds to the standards of Helsinki Declare − Ethical Principles for Medical Research with Human Subjects, and the Rules for Clinical Practice in the Russian Federation.

RESULTS

Men prevailed in both samples (the table 1); the patients with CTD were much more younger than post-stroke patients.

Table 1

Distribution of patients by sex and age

Diagnosis	Male		Female		Total
Diagnosis	Number, persons	Mean age, years	Number, persons	Mean age, years	Number, persons	Mean age, years
Traumatic brain injury	58	35.1	23	30.2	81	33.7
Stroke	69	59.3	50	54.4	119	57.3

Among post-stroke persons, 29 patients could perform Romberg's test and optokinetic test without additional supporting by hands. Remaining 90 (75.6 %) patients could move holding on to the banister. One-third of the patients with CTD (27 patients) could perform these tests without additional support.

Comparison of stabilogram parameters of both groups showed that patients with CTD had higher amplitude of maximal values and higher square of statokinesiogram than in post-stroke patients. To maintain vertical posture, these patients needed to perform more work and to shift the general center of pressure along the supporting plane with high velocity. At that, the spectrum of waves shifted towards lower frequencies. A difference in vertical component was especially evident. Patients with CTD could perform labor against gravity load more slowly and with higher amplitude than post-stroke patients.

Complication of conditions of vertical posture holding and eyes closing led to unidirectional, but varying change in stabilogram parameters in both groups: increasing square of statokinesiogram and work required for posture holding and velocity of movement of GCP.

Despite of significant difference in mean values, the differences between the groups were statistically insignificant both in comparison of general samples and according to single syndromes. Comparison of subgroups with similar use of additional supporting was more informative.

When patients stood without additional supporting, the differences in the amplitude and frequency of the first maximum of vertical component, 60 % of spectrum of vertical component and consumed work were statistically similar for opened and closed eyes (the table 2). When standing with opened eyes, declinations in the frontal plane were statistically significant. Romberg's ratio was higher in the group of patients with CTD than in post-stroke patients. The differences in stabilogram values in both groups with additional supporting were more intense than in patients without additional supporting (the table 3), although the characteristics of differences did not change. The amplitude of maximal values of the first peak of the spectrum and deviations when standing with opened and closed eyes in patient with CTD exceeded the values in post-stroke patients, and, conversely, the frequency of waves was lower. The square of statokinesiogram and velocity were higher in patients with CTD. To maintain vertical posture in this category of patients, more work was required. Eyes closure led to increasing square and length of statokinesiogram. Moreover, the length increased more significantly than velocity.

Table 2

Results of the Romberg’s test in patients when standing with no additional support

Amplitude of the 1^st maximum of spectrum, mm			L/S 1/mm		S, mm²		A, J		V, mm/s		Deviations, OPC, mm			60 % of the spectrum, Hz
Z	Y	X									Y		X	Z
Standing with eyes opened, traumatic brain injury, n = 27, mean age – 32 years
0.91*	16.13	12.42*	11.88		173.79		120.40*		11.76		4.65		3.70*	1.78*
Standing with eyes closed, traumatic brain injury, n = 27, mean age – 32, RC = 157
0.87*	18.51	14.12	17.2		183.98		165.19*		15.5		5.29		3.67		1.78*
Standing with eyes opened, stroke, n = 29, mean age – 52 years
0.23	15	8.89		9.54		114.15		86.9		9.82		4.03	2.47		4.65
Standing with eyes closed, stroke, n = 29, RC = 134, mean age – 52 years
0.19	16.24	8.77		15.93		137.13		107.43		11.96		4.54	2.62		4.84

Note: here and after * – comparison of patients after stroke and those with TBI, p > 0.05; OPC – overall pressure center, RC – Romberg coefficient;
Z – vertical component; Y – sagittal component; X – front component; L/S 1/mm – ratio of the length of statokinesiogram to the area, S – square, A, J –measure of work done, V – velocity .

Table 3

Results of the Romberg’s test in patients when standing with additional support

Amplitude of the 1st maximum of spectrum, mm						L/S 1/mm		S, mm²			A, J			V, mm/s			Deviations, OPC, mm					60 % of spectrum, Hz			Frequency of the 1^st spectrum, Hz
Z		Y		X													Y			X		Z			Z
Standing with eyes opened, traumatic brain injury, n = 54, mean age – 35 years
1.19*	12.83		13.44*			16.73*		138.53*		108.49*			10.50*			3.19				3.68*		1.06			0.28*
Standing with eyes closed, traumatic brain injury, n = 54, mean age 35, RC = 150
0.64*	11.30*		13.12*			30.43		133.45*		165.09*			12.06*			3.36*			4.08*				1.48*			0.32
Standing with eyes opened, stroke, m = 90, mean age – 59 years
0.59	10.43		11.61			20.81		105.07		72.72			7.95			2.75			3.07				2.14			0.43
Standing with eyes closed, stroke, n = 90, mean age – 59, RC=191
0.5	9.45				10.46		45.31		89.3			77.1			8.34			2.43			2.84			2.49			0.7

The stability value in patients with CTD in standing position with additional supporting was lower than in post-stroke patients: 95.1 and 96.7 when standing with opened eyes, and 94.6 and 97.1 when standing with closed eyes correspondingly.

According to results of optokinetic test, visual noises made lower influence on stabilogram than visual deprivation.

When analyzing the results of optokinetic testing in patients of both groups in standing position without additional supporting, the mean direction of waves in patients with CTD showed higher declination from the sagittal axis than in post-stroke patients. This difference was reliable for all five variants of the study. Deviations in the sagittal axis were higher in post-stroke patients. The differences were statistically significant.

The differences in results of optokinetic testing in groups of patients with additional supporting (the table 4) were more intense in patients who could stand without supporting by hands. In post-stroke patients, the length of statokinesiogram, deviations and velocity of migration of general center of pressure along supporting plane were lower than in injured persons. General center of pressure in the frontal plane was more close to the center of supporting platform, and the mean direction of waves showed higher declination from the sagittal axis. The stability ratio was higher in this group than in patients with TBI.

Table 4

Results of opticokinetic test in patient when standing with additional support

Diagnosis	L, mm	Stab, %	V, mm/s	Mean vibration direction, degrees	Mean position of OPC, mm	Deviations of OPC, mm
					X	Y	X
Traumatic brain injury, n = 54	229.04*	96.18*	11.45*	35.54	-10.16*	3.66*	2.88
Stroke, n = 90	168.8	97.31	8.44	46.32	5.62	2.32	2.38
Movement of bars from left to right
Traumatic brain injury, n = 54	265.81*	96.05*	13.25*	29.57*	-10.25*	3.92*	2.91*
Stroke, n = 90	172.13	97.66	8.58	53.77	5.68	2.03	2.33
Movement of bars from right to left
Traumatic brain injury, n = 54	246.01*	95.86*	12.29*	27.60*	-11.66*	4.34*	3.06*
Stroke, n = 90	173.78	97.56	8.66	49.35	5.49	1.87	2.33
Movement of bars bottom-up
Traumatic brain injury, n = 54	254.54*	95.61*	12.72*	27.07*	-10.17*	4.28*	3.22*
Stroke, n = 90	170.15	97.67	8.5	48.81	5.35	2	2.57
Movement of bars top-down
Traumatic brain injury, n = 54	249.18*	95.66*	12.45*	24.37	-11.90*	3.92*	2.96*
Stroke, n = 90	169.57	97.6	8.47	41.27	5.79	3.57	1.94

DISCUSSION

The comparison of the features of vertical posture holding in post-stroke patients and in patients with CTD was performed in three variants: in common conditions, when sensory information from proprioceptors, vestibular apparatus and sense of vision participate in regulation of posture; in standing with closed eyes when sense of vision does not participate in posture regulation; in conditions of visual noises. In all variants, the group of post-stroke patients showed higher persistence and more economic variant of vertical posture holding.

It is necessary to note that values of energy losses for posture holding were more informative in our studies: amplitude, frequency of the first peak, 60 % of power of the spectrum vertically, and work.

In studies of regulation of vertical posture in patients with ischemic stroke, the authors have the similar conclusions that energy loss index for posture holding is the significant integral value of efficiency of postural regulation and recommend it as the relevant index [2]. There are some surprising results that vertical posture holding is more difficult for patients with CTD than for post-stroke patients. Other authors also indicate the significant increase in square and length of statokinesiogram and waves of general center of pressure in patients with CTD [4]. In normal conditions, for vertical posture holding, such patients show slower response to disturbing effects, and, as result, they have higher maximal values, deviations and square of statokinesiogram. The difference in the vertical component is especially evident − work for elevation of general center of masses goes more slowly and requires higher altitude that increase energy losses for posture holding.

Complication of conditions in view of visual noises or visual deprivation makes these differences more notable, but high scatter inside groups does not make them reliable for general samples and in comparison of patients of both groups with similar neurological syndromes. The most critical moment for strategy of vertical posture holding was presence or absence of additional supporting.

It is quite expected that among young people with CTD, one-third of them could walk without holding onto banister, whereas in more senior patients after stroke, less than one-fourth of patients could do it. As a rule, patients after TBI can stand less firmly than patients after stroke. Disturbing effects hinders postural regulation more intense than in persons after stroke. Among patients of both groups who could stand with additional supporting, the differences were more evident.

This observation is interesting in view of the fact that some studies characterize postural regulation after stroke as quite imperfect [2, 5, 6]. As a rule, stroke is the consequence of systemic disease with lesion of cerebral vessels, and brain injury occurs in young healthy people without previous problems with health. It is quite expected to receive the best values of postural regulation in this group. But it turned out to be otherwise.

We are not ready to give the final explanation to this surprising phenomenon. We can offer two hypotheses.

Possibly, post-stroke persons, before development of acute pathology, in conditions of premorbidity, already have economic postural strategies with working out disturbing effects without vertical work of high amplitude with supporting to proprioception that made postural regulation with lower energy consumption and less dependent on visual information.

However, one can suppose that selection of patients for rehabilitation is associated with less strict rules for young people after CTD as compared to patients after stroke since young and healthy persons do not have contraindications for physical loads as compared to older patients with hypertonic or cerebrovascular disease. As result, older persons with low activity and concurrent pathology, with insufficient motivation for recovery, after vascular accidents, are not included in the group which receives restoration of vertical posture and walking.

CONCLUSION

Patients with cerebral traumatic disease could stand less persistently than patients after stroke: to support vertical posture, patients with CTD need for more forces, mainly in shifting of center of masses vertically.

Deprivation of optical entry and influence of visual noses decrease the persistence of patients in both groups. In patients with CTD, the dependence on optical entry is higher.

The described differences occur in comparison of full samples, but they become unreliable owing to wide individual differences. Randomization according to a sign of presence of additional support makes intergroup differences more statistically significant for persons who can stand without supporting and for those who hold onto banister.

Information on financing and conflict of interests

The study was conducted without sponsorship. The authors declare the absence of any clear or potential conflicts of interests relating to publication of this article.