Журнал «Боль. Суставы. Позвоночник» 2 (18) 2015

Статья опубликована на с. 87

Introduction. The advancing age and degenerative lumbar spine diseases are accompanied by a pronounced decreased muscle mass and quality, but investigators lack of available and informative markers of such kind impairments. Electromyography (EMG) has some advantages being not as invasive as biopsy and cheaper than computer tomography (CT). The muscles bioelectrical activity generation is based on the strong relationships between muscle fiber diameter and its conduction velocity. The spectral analysis of complicated interference muscle signal permits to distinguish and recognize the prevailing frequency and amplitude components. The aim of the study is to find out age–related EMG spectral components and to interconnect age–related EMG spectral components with CT results.

Participants. A group of healthy students–volunteers has been recruited from Kharkov higher schools and employees of SISJP UAMS. A group of degenerative diseases of the lumbar spine inpatient patients has been recruited from a vertebral clinic of SISJP UAMS. The participants were divided by age as follows: adolescence (10–15 yrs), youth (16–20 yrs), mature age (21–34 yrs), adulthood (35–54 yrs), advanced age (55–75 yrs), old age (> 75 yrs).

Testing procedure and equipment. The EMG test was performed in the prone position on a horizontal couch. During the test each subject was suggested to fulfill a body isometric back extension and to keep their arms and legs unsupported, and to sustain that position for 60 sec. The electromyography m.erector spinae at lumbar level (L5) was examined on the four–channel electromyograph Neuro–MEP, carried out the registration. There 95 records of 48 healthy volunteers (one record was rejected) and 152 myograms of 76 patients were obtained. The spectral analysis of the records was performed using the software modules developed by the authors posed the problem by department of biomedical engineering of Kharkiv National University of Radio Electronics [1]. The total power (TotalP), mean power (MP), median frequency (MedF), mean frequency (MF), peak frequency (PF), start median frequency (startMedF), end median frequency (endMedF) and MedF rate were calculated. Statistical processing of data was fulfilled by Mann Whitney U–test and Kruskal–Wallis analysis. Furthermore, 663 axial CT images of 129 mature patients (21–75 years) and 93 youth (under 21 years) were stu–died. Some areas of paravertebral muscles were sele–cted on axial slices of CTs of 7–10 mm diameter and were selected 3,978 samples of muscle tissue. The minimum and maximum values of X–ray density, its average value, standard deviation, and two peak values (in Hounsfield units) were analyzed [2].

Results. From EMG analysis we found out a significant difference between the healthy group and degenerative disease patient group in terms of TotalP, MedF, startMedF, MedF rate (р < 0.001). Neither in the healthy, no patients groups, sex was not the influencing factor for those indicators. Also, we found out a significant difference between the youth, mature age and adulthood groups of healthy in terms of MedF rate and sMedF (Kw = 0.328, p > 0.05). We found out a significant difference between groups of mature age, adulthood, advanced age of patients in terms of TotalP (Kw = 0.083, p > 0.05) sMedF (Kw = 0.113, p > 0.05). From analysis of CT and MRI images we established that age–related changes in the youth group occur slightly differently than adults one. At the age of 21 years, the content of muscle tissue with age does not change significantly, but percentage of connective tissue in all muscles is growing, mainly in m.multifidus and in m.erector spinae. In mature age and adulthood, we can observed the decrease in the muscle tissue percentage in the m. erector spine, most pronounced in adulthood after 48 years [2].

Conclusion. The spectral indicators of TotalP, MedF, startMedF of m.erector spinae myograms have significant dependence on age. The findings are in agreement with the values of X–ray density reflecting sarcopenic muscle tissue percentage. EMG can be suggested to measure age–related and degeneration–related changes in paravertebral muscles and it needs further investigation.