Objective: To study the effects of levodopa on Archimedes spiral drawings by idiopathic Parkinson’s Disease (PD) patients.

Background: Handwriting difficulty can develop as an early symptom for PD patients and further worsened once upper limb motor blocks develop. Compared to healthy individuals, PD patients draw subjectively smaller, tighter spirals with skewed spiral angles and differences in pressure applied. The effect of levodopa on spiral dynamics has not been well studied.

Method: PD patients on levodopa were consented to participate. Participants were asked to draw a spiral with the right and then left hand in the levodopa OFF- (OFF about 12 hours or more) and then ON-state (~60 minutes post dose). Data were collected using an inking pen and paper affixed to a digitizer tablet (Wacom Intous), synced with Movalyzer software (Neuroscript). Python scripts were developed to analyze vertical zero-crossing segmentation data and XYZ coordinate data to quantify differences between spiral drawings.

Results: A total of 21 PD participants (9 freezers) were enrolled, aged 67.6±8.2 years; 81% were right-handed while 52% were more affected (MA) by PD on the right-side. Disease duration was 9.7±5.9 years, Hoehn and Yahr score was 2.0±0.8, and motor UPDRS OFF/ON scores were 24.1±12.3/16.2±10.4. Participants mean daily and single levodopa dose were  682±370mg/day and 193±88mg, respectively, with levodopa treatment duration of 5.5±3.2 years. Compared to the less affected (LA) hand in the OFF state, participants drew significantly taller (LA: 4.5±0.9cm; MA:4.1±0.6cm; p=0.025), lengthier (LA: 25.6±6.9cm; MA:23.1±4.8cm, p=0.035) spirals with longer radii (LA: 2.8±0.6cm; MA:2.4±0.5cm, p=0.033) with the MA hand. Levodopa significantly improved spiral measures in the MA hands with increased drawing speed (OFF:2.0 ±1.1cm/s; ON:2.4±1.0cm/s, p=0.033) reduced mean time spent at each 360 degree angle of spiral (OFF: 0.016±0.005s; ON:0.014±0.004s, p=0.002), increased pen pressure drawing the left side of the spiral (OFF:84.8 ±92.8; ON:126.2±129.1, p=0.023.), reduced variability in jerkiness (OFF: 35.7±12.5; ON:28.9±9.1, p=0.039)  and reduced variability in number of peak acceleration points (OFF: 49.3±14.8; ON:41.3±15.6 p=0.046).

Conclusion: Levodopa improved spiral drawing dynamics in PD participants and could provide a cheap effective way of monitoring therapeutic response in the future..

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MDS Abstracts - https://www.mdsabstracts.org/abstract/influence-of-levodopa-on-archimedes-spiral-drawings-in-idiopathic-parkinsons-disease/