Factors influencing the symmetry of Parkinson's disease symptoms

The presence of asymmetry in symptoms and clinical signs favours the diagnosis of Parkinson's disease (PD). The aim of this study is to analyse this symptom asymmetry as a function of different variables and compare it with other parkinsonisms.

201 Patients with PD were studied. The sample was supplemented with 29 patients diagnosed with MSA-P (according to the criteria established by the American Academy of Neurology) and 17 with PSP (according to the criteria established by the NINDS-SPSP International Workshop). The symmetry was evaluated, based on items 20-23, 25 and 26 of the Unified Parkinson's Disease Rating Scale, by subtracting the motor score for the left side from that for the right side. Those patients with a difference of one point or more were designated as being asymmetric.

Around 16.4% of patients presented symmetrical clinical symptoms. There were no differences between those patients with or without family history of the disease. Those patients with symmetric symptoms were found to have longer symptomatic disease duration (10.8 vs. 7.9 years), a worse mental state (UPDRS I: 3.9 vs. 3.2), a higher incidence of complications (UPDRS IV: 4.5 vs. 3.2) and had their activities of daily living (ADL) affected to a greater degree (UPDRS II: 13.0 vs. 11.0). Around 48.3% of the MSA-P patients and 52.9% of the PSP patients showed symmetric symptoms.

The degree of symmetry is not useful in differentiating between sporadic and familial PD. However, the observation of highly symmetrical symptoms in a patient with short evolution time indicates that an atypical parkinsonism should be suspected.