Handedness and dominant side of symptoms in Parkinson's disease.

BACKGROUND AND OBJECTIVE

To investigate the association between handedness and the side of symptom dominance in Parkinson's disease (PD).

PATIENTS AND METHODS

One hundred and forty-six PD patients with symmetric symptoms (92 males and 54 females), aged 64.3 ± 9.1 years old, from a series of 247 PD patients were assessed for handedness and clinical features. The severity of PD was scored by unified Parkinson's disease rating scale (UPDRS) and Hoehn-Yahr staging on the "ON" state.

RESULTS

Of 134 right-handed patients (91.8%), 83 (61.7%) had an initial onset on the right side (P=0.008), while of 12 left-handed patients (8.2%), 9 (75.0%) had an initial onset on the left side (P=0.013). Out of right-handed patients, 103 (76.9%) had the right-side dominance of PD symptoms (P<0.001). Among the left-handed subjects, 7 patients (58.3%) had left-sided and 5 patients (41.7%) had right-sided symptom dominance (P=0.564). In general, dominant side of symptoms was in accordance with handedness (P=0.008). In right-handed patients, rest tremor was the most common initial symptom (P<0.001), while rest tremor and rigidity-bradykinesia were initial symptoms in left-handed patients (P=0.366).

CONCLUSIONS

PD symptoms emerge more often on the dominant hand-side, and the dominant side of symptoms is in accordance with handedness.