Coasting effect of n-hexane-induced neuropathy evidenced by electroneuromyography and clinical symptom scales: a 12-month follow-up study

Abstract

To the best of our knowledge, no study so far has investigated the coasting effect of neuropathy caused by occupational exposure to n-hexane through more detailed clinical evaluations than nerve conduction measurements, such that would also include pain assessment and functional status. The aim of our study was therefore to see if our measurements, which include all three elements, would support the coasting effect and reveal associations between electrophysiological measurements and clinical symptom assessments over a 12-month follow-up. Our study included eighteen patients working in the same shoe factory who were diagnosed with occupational neuropathy most likely caused by exposure to n-hexane. After identification of occupational exposure to high, yet unspecified VOC levels by local health authorities, production was suspended and all patients removed from further exposure. All underwent detailed neurological examination, including electroneuromyography (EMG) and the assessment of self-rated pain severity, symptoms, and functionality in everyday activities. All clinical, laboratory, and electrophysiological assessments were performed at baseline and at months 4 and 12 of follow-up. The patients presented with different degrees of numbness, muscle weakness, and sensory disturbances. EMG measurements and clinical scales at month 4 revealed significant worsening from the baseline (p<0.05), and the assessments at month 12 a significant improvement from month 4 (p<0.05), which confirms the coasting effect. Significant correlations were found between baseline motor conduction velocities and subsequent functional outcomes, and between selected sensory parameters and pain severity. Regardless of its limitations, our study points to the real-life consequences of exposure to harmful VOCs in poorly controlled shoe factory environments and establishes the coasting effect through more than one diagnostic parameter. From a preventive perspective, our findings suggest that early electrophysiological evaluation, together with simple and validated clinical scales, may help identify workers at risk of developing neuropathy before irreversible functional impairments occur. Such an approach could inform timely exposure control, medical surveillance, and occupational interventions in high-risk settings.