Secondary parkinsonism due to other external agents

This code signifies a parkinsonian syndrome that develops as a consequence of exposure to external agents other than prescribed medications. It presents with symptoms characteristic of Parkinson's disease, such as tremor, rigidity, bradykinesia, and postural instability, but is directly attributable to environmental toxins, illicit drugs, or other non-medicinal external substances.

Use this code when documentation clearly links parkinsonian symptoms to exposure to external agents like carbon monoxide, manganese, MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), or other non-pharmacological toxins. The physician's notes must specify the external agent responsible for inducing the parkinsonism.

• Always sequence this code after the code for the specific external agent (e.g., T58.XXX for toxic effect of carbon monoxide).
• Distinguish carefully from drug-induced parkinsonism (G21.1X) and idiopathic Parkinson's disease (G20).
• Ensure the documentation explicitly states "secondary to" or "due to" the identified external agent.