Chronic solvent encephalopathy (CSE) is under-reported worldwide due to difficulties in recognition and differences in national legislation. Although its occurrence in developed countries has declined, new cases continue to be detected. Our aim was to determine whether CSE can be detected in risk trades, using a stepwise screening procedure. Another aim was to evaluate if this method detects more cases than present occupational health service (OHS) practices do in Finland, a country with decreasing exposures, high OHS coverage and an annual rate of around forty cases of suspected CSE and seven cases of occupational CSE. The studied fields, based on the national occurrence of CSE, were industrial and construction painting, floor layering, the printing press industry, boat construction, reinforced plastic laminating and the metal industry. We obtained contact information from trade union registers and municipal OHS. A postal survey including the Euroquest (EQ) neurotoxic symptom questionnaire, Beck's Depression Inventory (BDI) and the Alcohol Use Disorders Identification Test-Consumption (Audit-C), and questions on exposure and medical conditions, was sent to 3,640 workers in the age range of 30-65 years in two Finnish provinces. The survey resulted in 1,730 responses (48%). This was followed by a clinical examination, with methods applicable to OHS, of subjects fulfilling the criteria: three or more EQ memory and concentration symptoms and sufficient exposure, a BDI score=18, an AUDIT-C score=8, and no evident medical condition explaining their symptoms. Of 338 respondents with memory and concentration symptoms, 129 subjects fulfilled all the criteria, of which 83 participated in clinical examinations. We found 38 CSE compatible cases. The study shows that more CSE compatible cases can be detected when the screening is directed towards the occupational fields at greatest risk. This stepwise method is more effective for finding CSE compatible cases than regular OHS activity. The number of cases was similar to the total annual occurrence, of new CSE-suspected cases, although the sample represented approximately 18% of the abundantly exposed workforce in Finland. Combining of exposure and medical differential diagnostics to neurotoxic symptom questionnaire, decreases the amount of cases needing clinical examinations. This two-step procedure can be carried out with methods suitable for OHS and other primary health care, both in industrialized and developed countries.
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.
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 microV; S.D. 3.6) compared to laboratory controls (mean 11.8 microV; S.D. 4.1; F(1,167)=24.4; p
The aim was to study the symptomatology of chronic solvent encephalopathy (CSE), and the persistence of the symptoms. We examined how Euroquest, a neurotoxic symptom questionnaire, distinguished workers with verified CSE from unexposed employees, and evaluated symptom cut-off for CSE. Another aim was to study the effect of age on the responses. CSE cases confirmed at the Finnish Institute of Occupational Health had completed Euroquest either before their first investigation procedure (CSE-1 group, n=33), or before attending a routine control for previously diagnosed CSE (CSE-2, n=43). Non-exposed carpenters served as referents (n=292). We studied responses to single questions and to symptom domains. The domain with the highest AUC (area under the ROC: Receiver Operating Characteristic Curve) value was chosen to study cut-off points. CSE groups reported nearly all 59 symptoms more frequently than the carpenters. There was only little difference between younger and older carpenters. CSE-1 reported 12 symptoms more often than CSE-2, but no significant differences were found in the memory and concentration domain, which had the highest AUC, above 0.9. Using a three out of 10 symptoms cut-off point, 97% of the CSE-1 cases and 80% of the carpenters were classified correctly. At a four-symptom cut-off, the sensitivity was 93% and specificity 87%. The memory and concentration as core symptoms distinguished CSE cases from unexposed workers and remain, even after cessation of exposure. The effect of age on Euroquest was minor. Euroquest is recommended for the screening of CSE in solvent-exposed work-force and in the diagnostic process of CSE. We propose three memory and concentration symptoms as cut-off to minimize under-detection.