EEG spectral analysis and its clinical significance for patients with non-occupationalchronic mercury poisoning

Abstract

Objective To evaluate the features of EEG spectrum and its clinical significance for patients with non-occupational chronic mercury poisoning. Methods Eighteen patients with chronic mercury poisoning were collected continuously as poisoning group at Affiliated Hospital of Academy of Military Medical Sciences from March 2012 to September 2013. At the same time, 12 age- and sex-matched healthy people were selected as control group. All patients underwent video EEG, and EEGLAB in Matlab 2013 software was used to analyze their EEG data. Relevant spectrum data of the 2 groups were compared and analyzed. Results The frequency-energy curves of 12 normal subjects were similar to sine curve, with obvious energy peak at α band. The frequency-energy curves of 18 patients showed as follows: 5 cases had the peak at slow δ wave, and the energy curve decreased since δ band appeared, with α band peak disappearing. The curve of 10 cases had 2 peaks respectively at α and δ band, and δ peak was higher than α peak. The spectrum in other 3 cases was normal. The quantitative analysis of EEG revealed the proportion of δ band for the total energy. The proportion of δ band for total energy of the poisoning group in right middle temporal (P = 0.018) and left posterior temporal (P = 0.039) channel was significantly higher than that of the normal group, while the proportion of δ band in middle frontal (P = 0.003), right frontal (P = 0.016) and right anterior temporal (P = 0.024), left middle temporal (P = 0.036) and right posterior temporal (P = 0.031) was lower than that of the normal group. Conclusions EEG examination plays an important role in assessing the severity of brain injury for patients with non-occupational chronic mercury poisoning. Spectrum analysis is an intuitive and simple method, and can provide some help for clinical diagnosis and treatment. DOI: 10.3969/j.issn.1672-6731.2015.02.013

Keywords

• Mercury poisoning, nervous system
• Electroencephalography