Normal substantia nigra patients treated with levodopa - Clinical, therapeutic and pathological observations.
Level 4 - case-series / case-control
Retrospective clinicopathological case series without a control group.
PubMed 26372624 · doi:10.1016/j.parkreldis.2015.08.029
What was done
A retrospective clinicopathological review evaluated autopsy records collected from a single movement disorders clinic between 1968 and 2014. Certified neuropathologists evaluated substantia nigra status in autopsied patients who had received levodopa treatment during life but were found to have a normal substantia nigra postmortem.
What was found
Twenty-one cases treated with levodopa had a normal substantia nigra at autopsy. Eleven patients continued levodopa until death, and 9 received the medication for four years or longer. No objective motor symptom benefit, dyskinesia, or motor response fluctuations were observed in any of the 21 cases. The most common final diagnosis was essential tremor.
Why it matters
These observations indicate that clinical benefit and motor complications from levodopa require nigral pathology. They also provide human clinicopathological evidence that long-term levodopa use is not neurotoxic to normal substantia nigra.
Limits
The study is a retrospective case series with a small sample size (n = 21) from a single center. The abstract does not report quantitative levodopa doses, objective clinical rating scores, or a control group.
Cited by
- contradicts Patients with essential tremor do not experience a loss of dopamine, and administering dopaminergic drugs to them worsens their tremors.