Cognitive control dysfunction in workers exposed to manganese-containing welding fume.

BACKGROUND: Chronic exposure to manganese (Mn) is a health concern in occupations such as welding because of well-established motor effects due to basal ganglia dysfunction. We hypothesized that cognitive control (the ability to monitor, manipulate, and regulate ongoing cognitive demands) would also be affected by chronic Mn exposure. METHODS: We examined the relationship between Mn exposure and cognitive control performance in 95 workers with varying intensity and duration (median 15.5 years) of exposure to welding fume. We performed linear regression to assess the association between exposure to Mn-containing welding fume and cognitive control tasks. RESULTS: Overall performance was inversely related to intensity of welding exposure (P = 0.009) and was driven by the Two-Back and Letter Number Sequencing tests that assess working memory (both P = 0.02). CONCLUSIONS: Occupational exposure to Mn-containing welding fume may be associated with poorer working memory performance, and workers may benefit from practices that reduce exposure intensity. Am. J. Ind. Med. 60:181-188, 2017. © 2016 Wiley Periodicals, Inc.

Physician response to a medication alert system in inpatients with levodopa-treated diseases.

OBJECTIVE: To evaluate the appropriateness of dopamine receptor antagonist prescriptions in hospitalized patients with dopamine-requiring diseases after implementation of an automated prescription alert system. METHODS: We examined dopamine receptor antagonist prescriptions in hospitalized patients with dopamine-requiring diseases and physician response to an automated drug contraindication alert system at Barnes-Jewish Hospital from 2009 to 2013. A detailed review of patient medical records was performed for all alert events generated when a physician prescribed a dopamine receptor antagonist concurrently with a dopamine receptor agonist in hospitalized patients. Two movement disorders neurologists determined the appropriateness of each prescription, based on patient medical history, through consensus. Physician response to alert was compared by indication for the prescription and physician specialty. RESULTS: Of 237 orders, 197 (83.1%) prescriptions for dopamine receptor antagonists were considered inappropriate. The prevalence of inappropriate dopamine receptor antagonist prescriptions per levodopa prescriptions was 16.10% (95% confidence interval 9.47, 22.73) in psychiatry, 7.51% (6.16, 8.86) in general medicine, 6.14% (4.49, 7.79) in the surgical specialties, and 0.85% (0.46, 1.25) in the neurologic/neurosurgical specialties. Of the inappropriate prescriptions, 146 (74.1%) were continued despite the alert. The strongest predictor of discontinuation of dopamine receptor antagonist medications was use of the medication to treat nausea or emesis (p < 0.001). CONCLUSIONS: Despite successfully identifying instances when dopamine antagonists were prescribed to patients with dopamine-requiring diseases, the alert system modestly affected physician prescribing behavior, highlighting the need for improved education of health care providers.

Reduced uptake of FDOPA PET in end-stage liver disease with elevated manganese levels.

OBJECTIVE: To investigate whether manganese toxicity secondary to end-state liver disease is associated with nigrastriatal dysfunction as measured by 6-[(18)F]fluoro-L-DOPA (FDOPA) positron emission tomographic (PET) imaging. DESIGN: Observational case report. SETTING: The Movement Disorder Center at Washington University, St Louis, Missouri. PATIENT: An individual with manganese toxicity secondary to end-stage liver disease. His FDOPA PET was compared with those of 10 idiopathic Parkinson disease patients and 10 age- and sex-matched healthy controls. MAIN OUTCOME MEASURE: The average estimated net FDOPA uptake by Patlak graphical analysis for caudate, anterior putamen, and posterior putamen. RESULTS: The FDOPA uptake for the patient with secondary manganese toxicity was reduced across all regions by more than 2 SDs compared with healthy controls: caudate (reduced 24.7%), anterior putamen (28.0%), and posterior putamen (29.3%). The ratio of uptake between the caudate/posterior putamen was 0.99 and was different from that of idiopathic Parkinson disease patients, in whom the greatest reduction of FDOPA was in the posterior putamen (mean [SD] ratio, 1.65 [0.41]). CONCLUSIONS: Reduce striatal uptake of FDOPA uptake indicates dysfunction of the nigrostriatal pathways in manganese toxicity secondary to end-stage liver disease. The pattern of striatal involvement with equal reduction of FDOPA uptake in the caudate compared with posterior putamen appears different from those previously reported in individuals with occupational manganese toxicity and idiopathic Parkinson disease and may be specific to manganese toxicity secondary to end-stage liver disease.