What toxins should be sought in the evaluation of neuromuscular symptoms?
• Organophosphates: These are used in pesticides, petroleum additives, and modifiers of plastic. Their toxicity affects peripheral nerves and the neuromuscular junction leading to flaccid weakness, depressed deep tendon reflexes, and pupillary dilation. Signs of cholinergic excess should be present.
• Lead: Lead toxicity can result in encephalopathy and psychiatric problems (children), abdominal pain, and peripheral neuropathy appearing in the hands before the feet (adults).
• Thallium: This toxin is used in rodenticides and industrial processes. Patients present with a sensory and autonomic neuropathy. Alopecia usually develops at the onset of symptoms.
• Arsenic, mercury (electrical and chemical industry): Arsenic, mercury, and industrial solvents containing aliphatic compounds can also cause neuromuscular symptoms.