Efficiency of the transcranial magnetic stimulation in the treatment 
 of occupational polyneuropathy

Abstract

Introduction. In occupational polyneuropathies, along with sensory and autonomic disorders, excessive sensory input can lead to the development of excitation foci in various parts of the central nervous system, clinical significance of which is currently insufficiently studied.
 The aim of the study was the evaluation of the clinical effects of the transcranial magnetic stimulation in the dorsolateral zone of the prefrontal cortex in mine workers with occupational polyneuropathy. 
 Materials and methods. There were examined thirty six workers of coal mining enterprises of Kuzbass with a proven diagnosis of polyneuropathy of the upper extremities, the average age was 50.2±3.7 years, and the average work experience was 23.4±3.5 years. To confirm polyneuropathy, the parameters of sensory conduction along the nerves of the upper extremities were investigated using electroneuromyography, nerve conduction velocity along the median and ulnar nerves was determined. The assessment of autonomic rcontrol was carried out using spectral analysis of heart rate variability. The functional brain status was determined by an electroencephalogram.
 Results. The patients complained of pain in the extremities, numbness and paresthesia. According to electroneuromyography, there was a decrease in the nerve conduction velocity along the somatic sensory nerves of the upper extremities, a reduction in the power of oscillations in all frequency ranges of the heart rate variability spectrum, which was more pronounced in the high frequency range. Transcranial magnetic stimulation of the prefrontal cortex zone of the right hemisphere was performed with a stimulus with a frequency of 1 Hz for 5 min, over a course of 5 procedures, after which a statistically significant increase in the average nerve conduction velocity along the somatic sensory nerves of the upper extremities, and a rise in the spectral parameters of the heart rate variability were observed. An increase in the alpha rhythm index at the electroencephalogram indicated an amplification of the integrative brain activity, which provided a wide range of regulatory processes. The patients noted a decrease in the intensity of pain, the severity of sensitive disorders, and improvement in general well-being.
 Limitations. The study is limited to the number of mine workers with a proven diagnosis of upper extremity polyneuropathy, without cardiac arrhythmias, structural damage and metal implants in the brain.
 Conclusion. Transcranial magnetic stimulation of the dorsolateral zone of the prefrontal cortex is effective in correcting sensory and autonomic disorders in occupationally caused polyneuropathy by activating suprasegmentary autonomic centers involved in systemic adaptation processes. It is promising to further expand the list of stimulation targets and create effective protocols for the use of transcranial magnetic stimulation.