Chronic Solvent Encephalopathy: Diagnostic tools for the assessment of even mild cognitive impairment

Introduction  Worldwide, occupational exposure to organic solvents is probably one of the most potent health hazards targeting the nervous system. In many industrialized countries chronic solvent encephalopathy (CSE) is a recognized occupational disease. Neuroimaging studies recently demonstrated mild cortical atrophy (Keski-Santti et al. 2008) and effects in dopamine-mediated frontostriatal circuits (Visser et al. 2008). Thus, cognitive impairment is a hallmark of CSE and its diagnosis heavily depends on the neuropsychological assessment.  

Objectives  Within the European countries, there are decades of experience with respect to the neuropsychological assessment of suspected CSE patients. The major aims of this study was the development of clear neuropsychological guidelines for diagnosing CSE that are capable to improve the detection of CSE in workers exposed to solvents.   Methods  Round table discussions among European expert on CSE were used to achieve a consensus of functions and methods that can be recommended to other experts in occupational safety and health.  

Results  In consequence of these discussions a set of four neuropsychological domains (attention, memory and learning, motor performance, concept formation and reasoning) with several sub-domains (e.g. immediate and delayed recall) was proposed. Each sub-domain should be assessed with at least two tests provided reliable normative data for the respective population. Based on these norms a quantitative severity score, averaging the test results, should be used to estimate the degree of the cognitive impairment of the individual patient.  

Discussion/ Conclusions  Within the multidisciplinary assessment that is necessary to identify ‘real’ CSE patients, the proposed qualitative and quantitative assessment of CNS functions could facilitate the sensitivity of the neuropsychological assessment. However, the adaption of this procedure should consider regional distinctions like traditionally used neuropsychological tests in the respective countries