Spiral Analysis in Subjects with Parkinson's Disease before and after Levodopa Treatment: A New Protocol with Stereophotogrammetric Systems

Purpose A method for the quantification of handwritten spirals in patients with Parkinson's disease (PD) pre and post levodopa treatment is reported. Methods Fifteen PD patients (mean age: 66.80±9.75 years) were assessed in the absence of medication (OFF condition) and under levodopa administration (ON condition). The control group was composed of 15 age-matched healthy (H) individuals (mean age: 63.70±9.40). They were asked to hand draw a spiral at self-selected speed, without resting their forearm on the table. The participants drew on a paper sheet, using a normal pen. The trace of the pen was determined from the 3D coordinates of passive markers placed on the pen and on the sheet, acquired with an optoelectronic system and some parameters were identified and computed. Results The method revealed to be significant in highlighting the differences between H and PD subjects and in detecting pharmacologic effect. PD patients are impaired in spiral drawing execution and levodopa improves drawing performance, evidenced by spatio-temporal parameters and velocity profiles. Conclusions The protocol is easily employable in clinic analysis because of its simplicity, the short duration of the test, and the natural test conditions. These characteristics suggest the applicability of this protocol to other fields of motor and cognitive assessments.