Problems of Radiation Medicine and Radiobiology

D. I. Zabolotnyi, N. S. Mishchanchuk

State Institution «O.S. Kolomiychenko Institute of Otolaryngology, Natl. Acad. Med. Sci. of Ukraine», Zoolohichna str., 3, Kyiv, 03057, Ukraine

Vestibular and acustic dysfunctions in clean-up workers of Chornobyl accident (30 years of follow-up)

Objective. The objective of the work was to study the clinical and electrophysiological disorders in vestibular and acustic dysfunctions in clean-up workers of Chornobyl accident depending on the dose and duration of action of ion- izing radiation, the peculiarities of determined effects for 30 years after the accident.
Materials and methods. The standard clinical and electrophysiological examinations of vestibular and acoustic ana- lyzers functions were conducted in 7812 males' clean-up workers including 325 persons selected for prolonged stud- ies in 1986-2015. The mathematical methods of analysis were carried out using the software package SYSTAT, EPICURE and EGRET.
Results. Vestibular dysfunction and acoustic dysfunction according the central type of progressive development of inhibitory processes in the brain stem, subcortical and cortical structures of vestibular and acoustic analyzers were determined. The dependence of changes in these structures on the dose and duration of ionizing radiation effect was defined. The regularities of determined radiation effects in correlation with the formation of organic cerebrovascu- lar pathology in the clean-up workers in remote post-accident years that are consistent with neurophysiological, MRI and other examinations confirmed with correlation analysis were established.
Conclusions. It was registered that the vestibular and acoustic dysfunctions in the clean-up workers were manifest- ed by the clinical and electrophysiological changes at the level of central structures in the studied analyzers, which indicate the parallelism of common mechanism of determined radiation effects already at a dose of 0.20 Gy, and also their dose dependency in dynamics of 30 post-accidental years. It was established that vestibular dysfunction in the clean-up workers is clinically early manifested, and the electroacoustic and electrophysiological changes in a case of normal hearing are evidence of preclinical inhibitory processes in the brain stem, subcortical and cortical structures of acoustic analyzer in the early post-accident years. The features of the clinical course of vestibular and acoustic dysfunctions in long-term monitoring of short-term effects of ionizing radiation in high doses in the group of the clean-up workers who have acute radiation sickness, and the manifestation of change is greater and accelerated in time under long-term IR effect, than the relatively short-term ones in similar small doses in distant years. Significant increase of hearing disorders by type of presbyacuzis precox in the respective age categories, which is one of the symptoms of their premature their aging was studied in clean-up workers.
Key words: acoustic and vestibular dysfunctions, static and kinetic equilibrium, spontaneous and experimental nys- tagmus, tone and speech audiometry, auditory induced potentials: (short-time latent or brain stem, long-latent or cortical ones), dynamic impedancemetry, otoacoustic emissions of distored products.

Problems of radiation medicine and radiobiology. 2016;21:218–237.