Central nervous system damage due to acute paraquat poisoning: a neuroimaging study with 3.0 T MRI

Paraquat (PQ) is an organic heterocyclic herbicide that is widely used throughout the world. Epidemiological and neuropathological studies have shown that chronic exposure to PQ increases the risk of Parkinson's disease. Patients with acute PQ poisoning show damage to the lungs, liver, and kidneys, and some also show symptoms of central nervous system (CNS) toxicity. However, few studies have focused on the acute neurotoxic changes caused by PQ. Dynamic pathological changes in the human brain cannot be explored in animal models. Thus, to elucidate the impact of acute PQ poisoning on the CNS, neuroimaging studies of poisoned victims, and especially survivors, should be performed. This study reports the first application of magnetic resonance imaging (MRI) techniques on patients with acute PQ poisoning, including survivors. We found significant abnormal signals in the brains of two patients during the acute post-poisoning phase. Using susceptibility weighted imaging (SWI), we documented changes in the corrected phase values for the extrapyramidal ganglia of survivors, and these values correlate with excessive iron deposition. Our diffusion tensor imaging (DTI) results were suggestive of microstructural changes in the extrapyramidal ganglia and hippocampus after PQ poisoning. These neuroimaging results provide an indirect demonstration that acute PQ neurotoxicity exerts a sustained effect during the acute and recovery stages of poisoning.