Leg rest tremor response to acute dopaminergic challenge predicts long-term Parkinson?s disease diagnosis

SOFIA FARINA ; MIGUEL WILKEN; MALCO ROSSI; MARCELO MERELLO

Congreso; 19th International Congress of Parkinson?s Disease and Movement Disorders; 2015

Objective: To evaluate leg rest tremor (LRT) response to acute dopaminergic challenge and its relationship to subsequent long term Parkinson?s disease (PD) diagnosis.Background: LRT can be an early sign of PD, essential tremor and other parkinsonisms, such as multiple system atrophy and vascular parkinsonism. Its predictive value for PD clinical diagnosis has not been described.Methods: We conducted a retrospective review of medical records from patients with a short-onset parkinsonism that were submitted to acute levodopa challenge for clinical prediction of sustained long-term dopaminergic response between November 1999 and August 2014. Data was collected on demographics, levodopa response (a modification of UPDRS-III or MDS-UPDRS-III ≥ 30% was considered a positive test and a reduction in at least one point in LRT subscore was considered a positive response of LRT), clinical manifestations and final clinical diagnosis after at least one-year follow-up. Results: A total of 778 patients were evaluated, of which 75 (10%) patients presented LRT. Fifty four (72%) had responsive LRT, of which 41 (76%) showed a positive response to levodopa acute challenge and 49 (65%) fulfilled all UKPDSBB criteria at one-year follow-up. Of the 21 (28%) non-responsive LRTs, only one (5%) showed a total positive response to acute levodopa challenge and a final PD diagnosis, whereas 20 (95%) had negative response to acute challenge, of which 6 (30%) received a PD diagnosis at one-year follow-up (false negatives). A responsive LRT to acute levodopa challenge obtained a sensitivity of 88% and a specificity of 74% with a positive and negative likelihood ratio for a final clinical PD diagnosis of 3.3 and 0.2, respectively. Multivariate analysis revealed that the presence of limb bradykinesia (p