Study of polysynaptic reflex excitability and somatosensory evoked potentials in patients with myofascial pain syndrome

Introduction. Myofascial pain syndrome (MFPS) is one of the most common pathologies of the musculoskeletal system that causes chronic pain. This type of pain reaches its peak in middle-aged people; women get sick 2,5 times more often than men. The disease leads to significant disability; it is not only a medical but also a social problem. Atthe same time, a number of authors still note the low clinical efficacy of the applied therapy regimens. In this situation there is in demand the further study of the MFPS pathogenesis, in particular, the clinical and electroneurophysiological characteristics of this pathology, in order to search for new, including pathogenetically proved, treatment methods.

The aim of the research was to study the relationship between the indicators of the blinking reflex and somatosensory evoked potentials in patients with active and latent forms of MFPS.

Materials and methods. In order to study the neurophysiological aspects of MFPS, a comprehensive clinical and electroneurophysiological examination was carried out in 92 patients of working age, including 78 women and 14 men, whose average age was 48,1±9,3) years, suffering from MFPS of the scapular area. The patients were subdivided into subgroups depending on the prevalence and severity of pain manifestations: the first subgroup — with an active form (58 people, 63 %), the second subgroup — with a latent form of MFPS (34 people, 37 %). The control group was formed from conditionally healthy volunteers in the amount of 35 people, comparable to the main group by age and sex.

Results. The comparing of the study results, taking into account polysynaptic reflex excitability and the data of somatosensory evoked potentials, revealed the significant positive correlations of the indicators. The obtained results allowed to assess the excitability of spinal cord motor neurons as well as suprasegmental structures in MFPS, involved in the implementation of pain syndrome.

Conclusion. The use of clinical electroneurophysiology methods makes it possible to assess the functional state of the CNS structures involved in the analysis of nociceptive afferentation. In the active form of MFPS, an increase in the excitability of stem and thalamic structures was mainly determined, which could potentially indicate the activation of adaptive processes on the one hand, and on the other hand, the predisposition of neuronal networks to a state of arousal. In the latent form of MFPS, a multidirectional change in reflex excitability was observed.

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