Long-Term Environmental Methylmercury Exposure Is Associated with Peripheral Neuropathy and Cognitive Impairment among an Amazon Indigenous Population.

Widespread contamination of the Amazon basin with mercury has been reported to occur since at least the mid-80s due to heavy gold mining activity. Although initial studies have indicated that this may lead to deleterious neurological consequences to the indigenous populations living in the region, further research is needed to better characterize the neurological burden of such long-term exposure. With this aim, a cross-sectional exploratory study has been conducted with the Yanomami indigenous population residing in a northern Amazon region. All participants underwent a structured interview; detailed neurological examination, including assessment for cognitive, motor, coordination, and sensory functions; and laboratorial testing for serum hemoglobin, blood glucose, and methylmercury levels in hair samples. This study enrolled 154 individuals of 30.9 ± 16.8 years of age, of which 56.1% were female. Mean methylmercury levels in hair were 3.9 ± 1.7 µg/g. Methylmercury levels in hair > 6.0 µg/g were found in 10.3%. Among participants with hair methylmercury levels ≥ 6.0 µg/g, the prevalences of peripheral neuropathy and reduced cognitive performance were, respectively, 78.8% (95%CI 15-177%, p = 0.010) and 95.9% (95%CI 16-230.8%, p = 0.012) higher than those of individuals with lower levels. These results suggest that chronic mercury exposure may lead to significant and potentially irreversible neurotoxicity to Yanomami population living in the northern Amazon basin.

Susceptibilidade à hipertermia maligna em três pacientes com síndrome maligna por neurolépticos / Malignant hyperthermia susceptibility in three patients with malignant neuroleptic syndrome

A hipertermia maligna caracteriza-se por hipertermia, rigidez muscular, rabdomiólise, acidose e insuficiência de múltiplos órgaos. A hipertermia maligna anestésica decorre da exposiçao a halogenados e/ou relaxantes musculares despolarizantes. O método padrao para diagnosticar a suscetibilidade à hipertermia maligna é o teste da contratura muscular in vitro em resposta ao halotano e à cafeína. A síndrome maligna por neurolépticos caracteriza-se por hipertermia, síndrome extrapiramidal, acidose, instabilidade neurovegetativa e alteraçoes neurológicas. Descrevemos três pacientes com síndrome maligna por neurolépticos e testes de contratura muscular positivos. Esse achado demonstra que ocasionalmente o músculo de pacientes com síndrome maligna por neurolépticos pode mostrar as alteraçoes encontradas na hipertermia maligna anestésica