RU2477620C1 - Diagnostic technique for recovery inconvertibility of severe motor disturbances in patients with chronic hemispheric ischemic strokes - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medicine, namely diagnostic and neurovisualisation techniques in the post-stroke patients. A cerebral corticospinal tract (CST) is examined by means of diffuse-tensor magnetic resonance tomography (DT MRT), and fraction anisotropy (FA) is calculated. The FA index is measured within anterior two one-thirds of a posterior thigh of an internal capsule, a cerebral peduncle, an upper level of a base of pons varolii. The index is presented as the relation of the injured FA to the healthy FA in percentage. The fraction anisotropy in the internal capsule below 50%, in the cerebral peduncle below 42%, in the pons varolii below 63%, motor disturbance inconvertibility is diagnosed.

EFFECT: method enables diagnostic reliability of the recovery inconvertibility of severe motor disturbances in the patients with chronic hemispheric ischemic strokes that is ensured by obtaining threshold FA values.

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Description

The invention relates to medicine, namely to diagnostic methods of neuroimaging in post-stroke patients.

Stroke is the leading cause of long-term disability: more than half of stroke patients still have a motor defect requiring rehabilitation measures [Duncan PW. Goldstein LB. Matchar D. et al. Measurement of motor recovery after stroke: outcome assessment and sample size requirments. Stroke 1992; 23: 1084-1089]. To date, there are no generally accepted standards for predicting the volume and rate of recovery of motor functions. This greatly complicates the choice of the type and duration of rehabilitation and, as a result, the impossibility of calculating the economic costs of restoring patients.

The restoration of impaired motor functions in patients occurs as a result of the reorganization of brain neuronal networks in structurally and functionally intact areas of the brain. This is possible provided that the descending motor paths are capable of implementing a new motor program [Gerloff C, Bushara K, Sailer A et al. Multimodal imaging of brain reorganization in motor areas of the contralesional hemisphere of well recovered patients after capsular stroke. Brain 2006; 129: 791-808. Ward N.S. Future perspectives in functional neuroimaging in stroke recovery. Eura medicophys 2007; 43: 285-94].

The main pathway that provides movement is the corticospinal tract (CCT). Knowledge of its anatomical projection allows using standard MRI modes to approximately evaluate its ischemic lesion and the likelihood of developing motor disorders.

Using different methods of quantitative assessment of postischemic destruction of brain tissue (MRI volumetry of a heart attack, MRI morphometry of a brain leg, diffusion-weighted MRI) to characterize motor disorders and their recovery, mixed results or insufficiently convincing patterns were obtained [Baird AE, Lövblad KO, Dashe JF et al. Clinical correlations of diffusion and perfusion lesion volumes in acute ischemic stroke. Cerebrovasc Dis 2000; 10: 441-448; Rossi ME, Jason E, Marchesotti S et al. Diffusion tensor imaging correlates with lesion volume in cerebral hemisphere infarctions. BMC Medical Imaging 2010; 10: 21-33; Yamada K, Ito H, Nakamura H et al. Stroke patients' evolving symptoms assessed by tractography. J Magn Reson Imaging 2004; 20: 923-9].

Another MRI technique for quantifying the structure of the conduction pathways, both directly adjacent to the ischemic zone and located far from it, is a modification of the DV-MRI - diffusion-tensor MRI (DT-MRI). DT-MRI, in contrast to DV-MRI, determines the direction (anisotropy) of diffusion. The measured values and the direction of motion of water molecules (three eigenvalues and three vectors) in each volumetric image element (bill of exchange) underlie the construction of diffusion tensor maps. Three eigenvalues of the diffusion tensor (fractional anisotropy - FA) give information about the shape of the diffusion voltage in the bill, reflecting the difference between isotropic (non-directional) and linear (directional) diffusion. FA varies between 0 and 1, where 0 is isotropic diffusion, 1 is directional. High FA values correspond to unidirectional diffusion of water molecules, i.e. preserved compactly arranged beams of white matter going in one direction. Low levels of FA are characteristic of the fibers of the affected areas (local tissue damage and / or Waller degeneration) [Werring DJ, Toosy AT, Clark CA et al. Diffusion tensor imaging can detect and quantify corticospinal tract degeneration after stroke. J Neurol Neurosurg Psychiatry 2000; 69 (2): 269-72]. Earlier, in the study of DT-MRI of patients with motor disorders at different stages of ischemic stroke, early, progressive and chronic loss of FA was reported [Thomalla G, Glauche V, Koch MA Diffusion tensor imaging detects early Wallerian degeneration of the pyramidal tract after ischemic stroke. Neuroimage 2004; 22: 1767-74; Thomalla G, Glauche V, Weiller C, Rother J. Time course of wallerian degeneration after ischaemic stroke revealed by diffusion tensor imaging. J Neurol Neurosurg Psychiatry 2005; 76: 266-8; Werring DJ, Toosy AT, Clark CA et al. Diffusion tensor imaging can detect and quantify corticospinal tract degeneration after stroke. J Neurol Neurosurg Psychiatry 2000; 69 (2): 269-72].

A study of a small homogeneous group of patients with deep hemispheric infarction showed large differences in FA between the affected and healthy hemispheres in patients with poor recovery of motor functions [Nelles M, Gieseke J, Flacke S et al. Diffusion tensor pyramidal tractography in patients with anterior choroidal artery infarcts. AJNR Am J Neuroradiol 2008]. However, in all of the above studies, the researchers did not use the FA indicator to quantify the degree of motor impairment and determine its threshold values for irreversibility of motor deficiency. This work was used by the authors as a prototype of the proposed method for the diagnosis of irreversibility of restoration of severe motor impairment.

We used the data of established general patterns of dependence of FA on recovery to clarify the quantitative relationship between the loss of FA in the projection of CTF and the degree of motor impairment in the study of patients with hemispheric infarction in the chronic stage of ischemic stroke (II). The choice of these terms of the study was determined by the stability of the FA in this post-stroke period, which is due to the completeness of the destruction processes, leading to axonal degeneration and gliosis directly in the area of myocardial infarction and Waller degeneration of the removed areas of white matter.

The technical result of the invention is to obtain on the basis of DT-MRI quantitative threshold FA values (index,%) when measured at three points of the projection of the CTF (front two-thirds of the posterior thigh of the inner capsule, the base of the brain leg, the upper level of the base of the bridge), on the basis of which irreversibility is diagnosed recovery of severe motor impairment and the conclusion is made that the further classical rehabilitation is inadvisable in order to increase the range of movements.

This is achieved by the fact that after conducting a study in diffusion tensor MRI (DT-MRI) mode on a Siemens Magnetom Avanto 1.5T MR scanner according to the standard protocol, which includes a single spin-echo mode of an echo planar pulse sequence TR = 3400 ms, TE = 102 ms, in 20 evenly distributed directions of test motion b = 1000 sec / mm ² , FOV = 230 mm, bill size 5.0 × 5.0 × 5.0 mm, diffusion tensors in each bill were calculated (software of the Leonardo Siemens workstation Neuro3D application) . Based on the eigenvalues of diffusion tensors, FA-maps and axial color-coded axial maps of fiber directivity are constructed. In each patient, according to the atlas of MRI of white matter, 3 areas of interest corresponding to the compact location of the CTF were distinguished in both hemispheres of the brain: 1) the front two-thirds of the posterior thigh of the inner capsule; 2) the base of the leg of the brain; 3) the upper level of the base of the bridge (Fig.). The indicated figure shows the areas of the study of CST:

a) Scheme of the anatomical projection of the areas of study of the CST. The first zone of interest is the anterior two-thirds of the posterior thigh of the inner capsule; the second is the base of the leg of the brain; the third is the upper level of the base of the Varoliev bridge.

b) Identification of areas of the study of CTF on axial maps of FA.

In patients with complete destruction of the area of interest on the affected side, the study volume was determined as a mirror image of that on the unaffected side. For all three areas of interest, the normalized ratio (index) was calculated:

, где

where

FA sp - FA on the side of the lesion;

FA ss - FA on the healthy side.

A higher percentage reflects the best structural integrity of the CTC on the affected side.

The study included 19 patients selected at random (11 men, 8 women, cf. age 38.9 ± 6.2 years) with hemiparesis of varying severity, who underwent a single hemispheric localization 6-11 months before the examination. All patients underwent repeated courses of classical rehabilitation, including physiotherapy exercises, massage, physiotherapeutic procedures, and in the presence of severe, severe paresis and plegia - robotic therapy. Motor function was evaluated on a scale of the Research Institute of Neurology of the Russian Academy of Medical Sciences for spastic paresis (1996): lack of motor disorders - 0 points; slight paresis (movement: volume - 75-100% of the norm; character - decrease in pace) - 1 point; moderate paresis (movement: volume - 50-75% of the norm; character - awkward) - 2 points; pronounced paresis (movement: volume - 25-50% of the norm; global character) - 3 points; gross paresis (movement: volume - 25% of the norm; character - extremely limited) - 4 points; Plegia (no active movements) - 5 points [Stolyarova L.G., Kadykov A.S., Tkacheva G.R. The system of assessing the state of motor functions in patients with post-stroke paresis. Zhurn. Neuropathology and Psychiatry 1982; 9: 15-18]. Depending on the outcome of recovery of motor functions, patients were divided into three groups: group I — adverse recovery, severe motor impairment (5 and 4 points, n = 10), group II — moderate recovery (3 points, n = 5), group III - favorable recovery (2 and 1 point, n = 4).

For statistical processing, SPSS 16.0 for Windows was used. The level of statistical significance is p <0.05. The correlation of FA (index,%) in all three studied areas with the degree of paresis in points was clarified using the Spearman correlation analysis. When comparing the FA values (index,%) between groups of patients with different outcomes of recovery, the Mann-Witney U test was used. The threshold FA values (index,%) with the calculation of their sensitivity, specificity and area under the curve were determined for severe motor impairment (unfavorable recovery outcome) using the Receiver Operator Characteristic (ROC) analysis.

Clinical data and the obtained values of FA (index,%) of the examined patients are presented in Table 1.

Table 1 Clinical data and FA (index,%) of the examined patients sick age (years) floor time after AI (months) paresis degree (points) recovery outcome (groups) FA (index,%) ext. capsule brain leg bridge one 42 m 10 5 I 44 28 58 2 37 well 8.5 5 I 38 78 fifty 3 44 m 8 5 I 31 thirty 46 four 47 m 12 5 I 9 36 36 5 40 m 10 5 I fifteen 37 59 6 40 m 6 5 I 21 thirty 33 7 33 m 8.5 four I 16 25 45 8 22 well 12 four I 65 41 63 9 40 m 6 four I 56 39 46 10 37 well 8 four I 46 41 fifty eleven 45 well 6 3 II 68 69 54 12 45 m 6 3 II 58 88 67 13 40 well 10.5 3 II 64 68 73 fourteen 44 m 8 3 II 55 55 65 fifteen 39 well 6 3 II 62 69 63 16 37 well 10.5 2 III 70 67 68 17 thirty m 8 2 III 77 69 70 eighteen 45 m 12 one III 83 97 83 19 32 well 6 one III 98 96 101

The reliability indicator of the selected FA parameter (index,%), which reflects the structural integrity of the CTF to characterize the threshold values of the irreversibility of severe motor impairment, is its significant high negative correlation with the degree of paresis in points in the inner capsule (R = -0.89; p < 0.0001), a pedicle (R = -0.73; p <0.0001), a warolium bridge (R = -0.82; p <0.0001) (Spearman correlation analysis) (Table 2).

table 2 The relationship of FA (index,%) with the degree of paresis (points) (Spearman correlation analysis) FA (index,%) paresis (points) R R inner capsule -0.89 0.0001 brain leg -0.73 0.0001 pons -0.82 0.0001

According to the ROC analysis, the threshold values of FA (index,%) for severe motor disorders were: in the internal capsule - 50% (sensitivity 90%, specificity 80%, area under the curve 0.85, p = 0.008), in the brain leg - 42% (sensitivity 100%, specificity 90%, area under the curve of 0.93, p = 0.001), Varolius bridge - 63% (sensitivity 80%, specificity of 100%, area under the curve of 0.92, p-0.001) ( Table 3).

Table 3 FA threshold values (index,%) of severe motor impairment (unfavorable outcome of movement restoration) (Receiver Operator Characteristic analysis) FA threshold value (index,%) sensitivity (%) specificity (%) area under the curve p inner capsule fifty 90 80 0.85 0.008 brain leg 42 one hundred 90 0.93 0.001 pons 63 80 one hundred 0.92 0.001

The high diagnostic accuracy of the indicators allows us to use them as criteria for identifying patients with severe motor impairment, whose further motor recovery is severely limited, and rehabilitation with the aim of increasing the range of motion is unpromising.

Examples:

1. Patient K., 44 years old, suffered a cerebrovascular accident with the development of a heart attack in the deep parts of the right hemisphere 8 months before the study. In neurological status - left-sided hemiplegia (5 points).

2. Patient T., 30 years old, suffered a cerebrovascular accident with the development of a heart attack in the deep parts of the right hemisphere 8.5 months before the study. In neurological status - moderate left-side hemiparesis (2 points). The data of clinical neuroimaging studies are shown in (Table 4).

Table 4 Clinical and neuroimaging data of patients K. and T. The degree of paresis (points) Heart attack volume (mm ³ ) FA (index,%) ext. capsule brain leg bridge Patient K. 5 31.8 31 thirty 46 Patient T. 2 37.1 77 69 70

As can be seen from Table 4, the volume of heart attacks between patients did not differ significantly. At the same time, FA indices (index,%) in patient K. with hemiplegia were significantly lower than patient T. with moderate hemiparesis and established threshold values characterizing the irreversibility of restoration of movements.

Conclusion: motor disorders in patient K. are irreversible. Conducting classical rehabilitation in order to increase the range of motion is impractical.

Claims (1)

A method for diagnosing the irreversibility of recovering severe motor impairment in patients with hemispheric ischemic localized strokes in the chronic stage, including a study of the corticospinal tract (CT) of the brain in diffuse tensor magnetic resonance imaging (DD MRI) and calculating fractional anisotropy (FA), characterized in that the FA index is calculated in the region of the anterior two-thirds of the posterior thigh of the inner capsule, the base of the peduncle of the brain, the upper level of the base of the warolius bridge according to the formula:

,
where FA sp - FA on the side of the lesion;
FA ss - FA on the healthy side,
and when the indices of fractional anisotropy in the inner capsule are below 50%, in the leg of the brain below 42%, in the warolium bridge below 63%, irreversibility of motor disorders is diagnosed.

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