Question: How does secondary Parkinsonism differ from Parkinson’s disease, and what ICD-10 codes should we report for secondary Parkinsonism? Hawaii Subscriber Answer: Secondary Parkinsonism is like Parkinson’s disease; however, the symptoms are caused by certain medicines, a different nervous system disorder, or another illness. You have the following ICD-10-CM choices to report Parkinsonism: G21.0 (Malignant neuroleptic syndrome) G21.11 (Neuroleptic induced parkinsonism) G21.19 [...]