Levodopa Responsiveness in Adult‐onset Lower Limb Dystonia is Associated with the Development of Parkinson's Disease

Abstract

Background: Adult‐onset primary lower limb dystonia (AOPLLD) has been reported as an early sign of Parkinson’s disease (PD) or Parkinson‐plus syndrome in case series. No prior systematic analysis has assessed clinical clues predicting later development of PD or Parkinson‐plus syndrome.Methods: We identified patients with AOPLLD from medical records. We excluded patients who had not been diagnosed by a neurologist, and who had a pre‐existing diagnosis of PD, psychogenic, or secondary dystonia. Records were subdivided into those who later developed PD or Parkinson‐plus disorders and those who did not. The following clinical characteristics were compared between the two groups: dystonia onset age, type of dystonia, levodopa response, anticholinergic response, and family history of Parkinsonism or tremor.Results: Twenty‐two AOPLLD patients were identified: 77% female; the median dystonia onset age was 53 years. Eight (37%) developed Parkinson’s disease; 2 (9%) developed corticobasal syndrome. Twelve patients (54%) did not develop Parkinsonism after a median follow‐up period of 1.5 years. There was a significant difference in leg dystonia levodopa response between the two groups (p = 0.02).Conclusion: In patients with AOPLLD, leg dystonia with levodopa response is associated with the future development of PD.