Due to ethical concerns, human trials with manganese fume exposure are not conducted. Most information about welding and health hazards is gleaned from animal studies or from analyzing patient cases in which exposure has occurred.
In the Mayo analysis, the researchers examined medical records from eight patients referred to the clinic between 1999 and 2005 for various nervous system complaints. All of their MRI scans showed an area of increased T1 signal intensity in the basal ganglia region of the brain, which appears as a bright spot on the MRI scan and is a biological indicator of manganese accumulation. All were men involved in welding for one to 25 years before symptoms developed. Initial symptoms varied, but multiple symptoms developed over time, including cognitive impairment, headaches and tremor in six of the patients, and balance problems in five patients. Each patient was diagnosed with neurotoxicity from welding fumes after undergoing testing appropriate to the patient's complaints, such as blood and urine testing, brain MRI and psychological testing of intelligence, aptitude and personality traits.
The increased T1 signal in the brains of the eight patients as revealed by MRI is an uncommon finding in brain imaging, according to Keith Josephs, M.D., Mayo Clinic neurologist who spearheaded the analysis. This is the first case series of welders with this abnormal signal highlighting such widespread neurological impairment.
"In the setting of prominent manganese exposure in the environment, as occ
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Contact: Lisa Lucier
newsbureau@mayo.edu
507-284-5005
Mayo Clinic
8-Jun-2005