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I am pleased to share our most recent publication which appears in the America Journal of Industrial Medicine titled "A rare case of Holmes tremor in a worker with occupational carbon monoxide poisoning". In this report we present a rare case of toxic encephalopathy and Holmes-type tremor, in a previously healthy 53-year-old man who was exposed to carbon monoxide while using a concrete saw in a small unventilated space. Holmes tremor is characterized by resting, as well as postural and kinetic/intentional components. Specific lesions sites associated with Holmes tremor include the cerebellum, red nucleus, thalamus, and globus pallidus. The globus pallidus is also vulnerable to carbon monoxide poisoning. This patient's symptoms were ameliorated with the D2 preferring dopamine receptor agonist ropinirole. This case report serves as reminder of the dangers associated with exposure to carbon monoxide in occupational settings.
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A new report appearing in Muscle and Nerve by Angeline Andrew and other members of Elijah Stommel's team at Dartmouth indicates that exposure to the heavy metal neurotoxicant lead and working as a mechanic, painter or construction worker (jobs with increased risk for exposure to industrial chemicals) are associated with greater risk for ALS. Head injury and electrical burns were also associated with an increased risk for ALS.
Although this study, which was funded by the Centers for Disease control (CDC) and the Agency for Toxic Substances and Disease Registry (ATSDR) did not look at duration or intensity of exposure in relationship to age at onset of symptoms, it nevertheless adds to the growing body of literature implicating prior exposure to neurotoxic chemicals such a lead and industrial solvents found in paints in the risk for developing ALS. Link to original article in Muscle and Nerve Air pollution increases risk for neuroanatomical changes associated with Alzheimer's disease.12/7/2020 A new prospective cohort study by Diana Younan and colleagues published in the journal Neurology has found that older women without dementia who are exposed later in life to air pollution consisting of microscopic particles of chemicals, smoke, dust and other pollutants < 2.5 μm in diameter have an increased risk for neuroanatomical changes associated with Alzheimer's disease (AD). The study used MRI data combined with supervised machine learning to measure brain atrophy in areas vulnerable to AD. The observed increased risk could not be explained by geographic region; race; ethnicity; highest education level obtained; smoking or alcohol use; physical activity; BMI scores; diabetes; use of hormone replacement therapy nor by an MRI-measure of cerebrovascular damage.
These data add to the growing body of literature implicating exposure to neurotoxicants in the neuropathogenesis of neurodegenerative diseases such as AD. Link to original article Amyotrophic Lateral Sclerosis like Syndrome Following Subcutaneous Administration of Manganese12/2/2020 A new cast report out of Sweden by Roos and colleagues 2020 suggests that subcutaneous exposure to manganese may be associated with a rapidly progressing form of ALS. This case report is about a 56 year old man who developed ALS in close chronological relationship to his exposure to manganese that was administered as a traditional Kenyan medical practice call Ogosaraka via cuts in the skin of his back near his spinal cord. Within four months the man began to develop neurological symptoms which included symmetrical muscle weakness in his legs, arms, and neck. Neurophysiological testing revealed fibrillation potentials indicative of denervation. The patient died from respiratory failure 10 months post exposure. Although the results of neuroimaging studies showing manganese accumulation n brain nor of post-mortem neuropathological studies confirming the involvement of upper motor neurons in this case were not provided by the authors, this rapidly progressing case of unusual manganese neurotoxicity nevertheless raises concerns about potential risks for interactions between traditional medicine and the onset and progression of latent ALS in vulnerable individuals.
Link to original article in PubMed Researchers from the Mayo Clinic have published an article in JAMA about the results of a recent case-control study of 212 patients (106 patients with inflammatory CNS events and 106 control participants without such events) suggesting that exposure to tumor necrosis factor inhibitors is associated with an increased risk of inflammatory central nervous system events such as optic neuritis, transverse myelitis and multiple sclerosis, and neuromyelitis optica spectrum disorder. The authors discuss some possible mechanisms to account for this paradoxical response including upregulation of TNF expression within the CNS. Patients with central demyelinating disease may want to discuss these findings with their neurologist before using tumor necrosis factor inhibitors.
Link to original article in JAMA Occupational exposures to solvents, pesticides and metals associated increased risk for sporadic ALS5/28/2020 The results of a recently published peer-reviewed population-based case-control study by Filippini and colleagues (2020) who looked at the risk for sporadic Amyotrophic Lateral Sclerosis (ALS) among people living and working in four Italian provinces (Catania, Modena, Novara, and Reggio Emilia) has revealed increased risks for ALS among persons with histories of occupational exposure to paint thinners, fungicides and metals including lead and mercury. A longer duration of working in the agricultural sector was also associated with an increased of developing ALS. Subjects reporting a history of ALS in their relatives were excluded from the study.
These findings add to the growing body of literature implicating occupational exposures to neurotoxicants in the onset of sporadic ALS. Link to original article in PubMed Dickerson and colleagues (Eur J Epidemiol, 2020) have shown that among ALS patients from the Danish National Patient Registry men exposed to mixtures of solvents are an increased risk for developing ALS. These findings add to the growing body of evidence suggesting solvent exposure is a disease modifying risk factor in ALS.
Link to original article Colbeth and colleagues (2019) analyzed questionnaire data gathered from Fire Department of the City of New York (FDNY) World Trade Center (WTC)-exposed firefighters and emergency medical service (EMS) workers to evaluate the risk for peripheral neuropathy based on Diabetic Neuropathy Symptom scores. While these questionnaire data do not provide objective measures they do nevertheless suggest that working at the WTC site increases an individual's risk for developing peripheral nervous system dysfunction with aging 15 years after these workers were exposed to particulates and gases while working at the WTC after 9/11.
Future studies are needed to ascertain if these symptoms of peripheral nerve damage are associated with the increased risk for cognitive deficits and increased accumulation of amyloid and tau pathology in the brain observed by Clouston and colleagues. Link to Colbeth et al 2019 in PubMed Link to Alzforum article reporting on Clouston et al findings A new study by Cacciottolo and colleagues indicates that J20-APPswe mice exposed to nano-sized traffic-related particulate matter (nPM) for 150 hours have increased markers of lipid oxidation (4-HNE) and increased the pro-amyloidogenic processing of APP in lipid raft fractions in cerebral cortex but not in the cerebellum a find which parallels that seen for selectivity of Aβ deposits in Alzheimer's disease (AD). In addition, in vitro, studies showed that nPM induced similar oxidative responses in N2a-APPswe cells, which showed dose-dependent production of NO, oxidative damage (4-HNE, 3NT), and lipid raft alterations of APP with increased Aβ peptides. Furthermore, treatment with the antioxidant N-acetyl-cysteine (NAC) attenuated nPM-induced oxidative damage and alterations of APP processing.
These findings provide additional evidence of the mechanisms via which exogenous toxicants found in the environment and workplace interact with neuropathological mechanisms implicated in the onset and progression of AD. Link to orignal article in PubMed A group of researchers from Hawaii (Ross et al., 2019) investigating subjects from the Honolulu-Asia Aging Study (HAAS) has obsevered that the prevalence of Lewy neuropathology is nearly doubled in the presence versus the absence of heptachlor epoxide. Similar but slightly weaker associations were observed with two other organochlorine compounds such as hexachlorobenzene and α-chlordane which are both metabolized to heptachlor epoxide. These results were significant after exclusion of subjects with Parkinson's disease (PD). These findings implicate organochlorine compounds in the severity of Lewy neuropathology in subjects without PD. These findings also reveal a potential point of interaction between organochlorine exposure and a neuropathological process implicated in PD.
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AuthorDr. Marcia Ratner shares and reviews the news. Archives
January 2025
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