Objectives: We had noted cogwheel rigidity in a number of patients with rheumatoid arthritis (RA). Based on this finding, we aimed to investigate formally the presence of rigidity and cogwheeling in RA patients. Our secondary aim was to survey the co-existence of RA and Parkinson's disease (PD).
Methods: A total of 87 consecutive patients with a diagnosis of RA, 78 patients with PD and 67 otherwise healthy patients attending a dedicated headache clinic participated in the study.
Results: Rigidity was observed in 24% of RA, 60% of PD and 2% of headache patients. The frequency among the RA patients was significantly higher compared to that of patients with headache (chi 2 = 15.2; P = 0.00009). The frequency of PD among the RA patients was 2/87 (2.3%), while the frequency of RA among the PD patients was 6/78 (7.7%).
Conclusion: Rigidity can be observed in approximately a quarter of patients with RA.