부산대학교 도서관

Objective: High signal intensity of several regions of the brain is observed on T1-weighted Magnetic Resonance Imaging sequences (MRI) in Parkinson-like syndrome due to manganese (Mn) intoxication. This signal is also described in asymptomatic workers with high blood Mn concentration (MnB) exposed to low levels of Mn. It could be a predictive factor for neurological disorders. As the neurological damages induced with Mn are irreversible even if the exposure has ceased, it would be interesting to know if MRI could be used in the medical follow-up of occupational Mn-exposed workers and if the signal intensity is correlated with other biological or environmental parameters. Methods: 9 active and former workers at a braking Mn and iron factory had to answer to a standardised questionnaire to evaluate exposure and search for subjective neurological symptoms. Environmental and biological parameters (MnB), physical examination, cerebral MRI and neuropsychological tests when possible were conducted. Results: 2 retired subjects with 22 years exposure were asymptomatic and had normal results; one of them had had a high signal on globus pallidus on MRI two years before when he was active. 7 active exposed workers had a 4-years mean length of exposure at an average airborne Mn concentration of 28 mg/[m.sup.3] and a mean MnB of 27 [micro]g/L (N [is less than] 10 [micro]g/L); All had an increase in signal intensity on T1-weighted sequences on the globus pallidus that seemed correlated with MnB. The subject with the highest MnB had physical and neuropsychological disorders. Conclusion: High signal intensity on T1-weighted MRI reflects recent Mn exposure as well as high MnB, and these two parameters seem to be correlated. High signal intensity disappears when the exposure stops. These results are consistent with the literature data.
Martin JC, Benaich N, Le Nouvel JB, Legmann P, Conso F. Pathologie Professionnelle, Radiologie 1. Hopital Cochin, Paris, [...]