Background: Only a few studies have reported on the frequency of micrographia in idiopathic Parkinson's disease (IPD), and the definition of micrographia in these studies was based simply on the visual inspection of the patients' free writing.
Objectives: We investigated the frequency of consistent (CM) and progressive (PM) micrographia by quantifying the patients' copying of a target letter or figure.
Methods: Seventy-five IPD patients and 30 sex/age matched healthy controls were assigned the tasks of free writing and letter/figure copying. CM was defined by the average size of the letter or figure written or copied by the patients below the controls' mean-2SD. PM was defined by the slope of reduction in size as a function of the serial positioning of the letters/figures below the mean-2SD of the controls.
Results: In the free writing, of 75 patients, only one met the criteria for the definition of CM and two met the criteria for the definition of PM definition. In contrast, letter/figure copying tasks identified 33 (44%) patients with CM and 19 (25%) with PM.
Conclusion: Our study suggests that the prior definition of CM or PM by visual inspection in free writing task is less valid, and that the definition of CM and PM, based on the letter/figure copying tasks rather than free writing tests, could be more objective.