Neurologic manifestations in welders with pallidal MRI T1 hyperintensity

Background: Neurologic symptoms have been attributed to manganese fumes generated during welding. Increased T1 MRI signal in the basal ganglia is a biologic marker of manganese accumulation. Recent studies have associated welding and parkinsonism, but generally without MRI corroboration. Objective: To characterize the clinical and neuropsychological features of patients with MRI basal ganglia T1 hyperintensity, who were ultimately diagnosed with neurotoxicity from welding fumes. Methods: The medical records of welders referred to the Department of Neurology with neurologic problems and basal ganglia T1 hyperintensity were reviewed. Results: All eight patients were male career welders with increased T1 basal ganglia signal on MRI of the brain. Several different clinical syndromes were recognized: a parkinsonian syndrome (three patients), a syndrome of multifocal myoclonus and limited cognitive impairment (two patients), a mixed syndrome with vestibular-auditory dysfunction (two patients), and minor subjective cognitive impairment, anxiety, and sleep apnea (one patient). Neuropsychometric testing suggested subcortical or frontal involvement. Inadequate ventilation or lack of personal respiratory protection during welding was a common theme. Conclusions: Welding without proper protection was associated with syndromes of parkinsonism, multifocal myoclonus, mild cognitive impairment, and vestibular - auditory dysfunction. The MRI T1 hyperintensity in the basal ganglia suggests that these may have been caused by manganese neurotoxicity.