Occupational Chronic Solvent Encephalopathy Research Articles

Multimodal event-related potentials in occupational chronic solvent encephalopathy

The aim of this study was to test a multimodal event-related potential (ERP) paradigm in chronic solvent encephalopathy (CSE) to develop a sensitive method for the clinical diagnostics to CSE. The study comprised 11 CSE patients and 13 healthy controls. We used three tasks: an auditory odd-ball (AUD), a visual detection (VIS), and a recognition memory (MEM) task. The auditory and visual stimuli were presented in single- and dual-task conditions. The auditory P300 amplitude in single-task condition was smaller in the patient group than in the control group at the parietal (Pz) but not at the frontal midline electrode location. The auditory P300 response in the dual task condition AUD+VIS was unrecognizable in 8 of 11 patients and in 1 of 13 controls and in the AUD+MEM condition in 10 of 11 patients and in 4 of 13 controls. In the AUD+MEM condition, the auditory P300 amplitude at Pz was smaller in the patient group than in the control group. Reaction time for auditory stimuli in both dual conditions as well as for visual stimuli in AUD+VIS condition were in the patient group prolonged.The ERP results indicate that CSE patients present with slowed performance speed and difficulties in allocation of attention. Based on ERP results, the disturbance in brain activity in CSE seems to affect posterior aspects of the frontoparietal continuity. The multimodal paradigm seems promising as a tool for the clinical diagnostics of CSE.

Occupational chronic solvent encephalopathy in Finland 1995–2007: incidence and exposure

The aim of the study was to define the incidence of chronic solvent encephalopathy (CSE) in Finland during 1995-2007, evaluate the duration and nature of exposure, and identify the work tasks where CSE is encountered. Data were from the register and patient records at the Finnish Institute of Occupational Health. The Finnish Job-Exposure Matrix (FINJEM) and National Statistics were used to estimate the incidence of CSE in exposed workforce. CSE cases during 1995-2007 numbered 129. The annual incidence has decreased from 8.6 to 1.2/million employed, i.e. from 18 to 3 patients per year. The number of suspected patients has, however, remained constant (mean 38.6/year). The mean age at diagnosis was 52.8, the mean duration of exposure 28.4 years, and the mean occupational exposure limit years (OELY) 10.5. During 1995-2007, the mean age increased annually by 0.6 and years of exposure by 0.8, but OELY remained constant. In comparison to FINJEM, the highest incidence was in workers exposed to aromatic hydrocarbons. Relative to workforce in occupations with solvent exposure, CSE was most frequent in wooden surface finishers and in industrial, metal, or car painters followed by floor layers and lacquerers. The incidence of CSE has declined due to legislative, technical, and hygienic actions. CSE is most probable in spray painting tasks with main exposure to aromatic hydrocarbons, when occupational solvent exposure exceeds 20 years, and the age of the worker is above 45. Our results indicate slower CSE development at lower exposure levels.

Magnetic resonance imaging in occupational chronic solvent encephalopathy

The aim of this study was to characterize the magnetic resonance imaging (MRI) findings in chronic solvent encephalopathy (CSE) patients and to study whether the findings are associated with solvent exposure indices. The brain MRI scans of 71 CSE patients were independently re-evaluated and rated by two experienced neuroradiologists. All the work tasks were analyzed and the chemical composition of lifetime exposure was categorized. The MRI scans of 27/71 CSE patients (38%) were classified as abnormal. Brain atrophy in any brain area was found in 17/71 CSE patients (24%). Abnormal white matter hyperintensities (WMH) were found in 20/71 CSE patients (28%). Cerebral and cerebellar brain atrophy was associated with the duration of exposure in years, and vermian atrophy was associated with alcohol consumption. Periventricular and brainstem WMH were related to age. Slight brain atrophy is associated with CSE and there is a correlation between brain atrophy and the duration of exposure in years. However, all the MRI findings in CSE are non-specific and thus MRI is useful mainly in the differential diagnosis of CSE.

Quantitative EEG in occupational chronic solvent encephalopathy

The aim of this study was to characterize the quantitative analyzed EEG (electroencephalogram) findings (qEEG) in chronic solvent encephalopathy (CSE) patients and study whether the qEEG findings associate with the duration and intensity of the solvent exposure. Also, the diagnostic value of qEEG in CSE is discussed. The EEG of 47 male CSE patients was analyzed. The laboratory's own reference EEG values of 24 healthy male subjects formed the laboratory control group. We also used an age-matched control group of 100 male blue-collar workers without occupational solvent exposure. The main finding of our study was that the power of the frontal theta band is increased in the CSE patient group compared with the laboratory control group. This suggests that the frontal cortex may be susceptible to the noxious effects of solvents. However, this difference was not seen in comparison with the matched control group, and thus, the connection with solvent effects remains uncertain. The variables indicating the level of solvent exposure did not associate with the power of the theta activity in the frontal area. Because of the small amount and unspecificity of the observed abnormalities, qEEG cannot be recommended to be used in the clinical diagnostics of solvent encephalopathy.

P300 of auditory event related potentials in occupational chronic solvent encephalopathy

This retrospective study characterized the P300 component of the auditory event related potential (ERP) and assessed its diagnostic value in occupational chronic solvent encephalopathy (CSE). The P300 was recorded on 86 CSE patients by the classical oddball paradigm. In addition to the laboratory's reference values, we used an age and education matched control group that consisted of 104 blue-collar workers with no known occupational solvent exposure. The association of P300 values with solvent exposure indices, major depression, alcohol consumption, and neuropsychological parameters was studied. The P300 amplitude was lower in CSE patients (mean 7.5 μV; S.D. 3.6) compared to laboratory controls (mean 11.8 μV; S.D. 4.1; F(1,167) = 24.4; p < 0.001, 95% CI −4.4 to −1.8) and to matched controls (mean 9.0 μV; S.D. 4.0; p = 0.007, 95% CI −2.6 to −0.4). The P300 latency was longer in the CSE patients (mean 358 ms; S.D. 28) compared to laboratory controls (mean 339 ms; S.D. 19, F(1,167) = 7.6, p = 0.006, 95% CI 3.12–18.7) but did not differ from matched controls (mean 358 ms; S.D. 22; p = 0.947, 95% CI −7.4 to 6.9). The solvent exposure indices, major depression, or alcohol consumption did not associate with the P300 values. The P300 amplitude correlated positively with the Digit Symbol test. All the amplitude values in the patient group and in the matched control group were classified as normal (i.e. age corrected mean ± 2.5S.D.) against the laboratory's reference values. Thirty percent of the latencies in the CSE patient group and 26% in the matched control group were classified as abnormal. At group level, the decreased P300 amplitudes in CSE patients may reflect solvent-related pathophysiology. However, the P300 measured with the classical oddball paradigm does not seem to be sensitive at individual level or useful in clinical practice.

Colour vision defects in occupational chronic solvent encephalopathy

Occupational chronic solvent encephalopathy (CSE) is associated with a number of neurobehavioural disorders including defects of visual perception. The purpose of this study was to characterize colour vision defects in CSE patients. Colour vision was tested in bright illumination with the Farnsworth-Munsell 100-hue test in workers who had CSE due to occupational exposure to common industrial solvents. Before assessing colour vision, the subjects' ocular health and visual functions were evaluated. On the basis of this evaluation, 36 subjects with healthy eyes were selected and their colour vision was tested monocularly. The colour vision performance of the patient group was, statistically, significantly inferior to that of a control group matched by age at a group level. A mixed form of reduced colour sensitivity was found in 42% (n=15/36) of the cases, affecting the entire range of Munsell hues. No association was found between the length and intensity of exposure and colour vision performance. Our results show that CSE patients can have significantly impaired colour discrimination ability, although their eyes are healthy and their other visual functions are normal. This may indicate toxic damage to higher level visual processing, possibly the colour selective regions of the cerebral cortex.

Memory Performance Profile in Occupational Chronic Solvent Encephalopathy Suggests Working Memory Dysfunction

This pilot study characterizes memory functioning of 11 men with occupational chronic solvent encephalopathy (CSE). Pattern (PRM) and spatial recognition (SRM), spatial span (SSP), spatial working memory (SWM), and paired associate learning (PAL) from Cambridge Neuropsychological Test Automated Battery were performed twice. The most sensitive variables to show impairment were PAL trials, SRM total correct, and SWM number of between-search errors. The majority of the CSE patients demonstrated mild deficits. The most persistent dysfunction was in tasks demanding working memory processing, which predicted well the CSE status. Qualitatively, the memory deficits resemble those seen in moderate or severe Parkinson's disease.

Visual system disorders in patients with occupational chronic solvent-encephalopathy

Visual system disorders in patients with occupational chronic solvent-encephalopathy