Timed Motor Tests Can Detect Subtle Motor Dysfunction in Early Parkinson's Disease

Early diagnosis of Parkinson's disease (PD) is important for putative neuroprotective therapies to be initiated in the earliest stage of the disease. We investigated whether a previously validated timed motor test (TMT) battery could detect subtle motor dysfunction in early PD patients and even in clinically unaffected limbs of strictly hemiparkinsonian patients. We assessed 107 PD patients (symptom duration <or=2 years; dopa-naive) and 100 healthy, age-matched controls with eight simple TMTs based on aspects of (a) walking, (b) writing, (c) single and double-handed pegboard performance, (d) finger tapping, and (e) diadochokinesis. We evaluated the ability of individual and combined TMTs to discriminate patients from controls using ROC curves. Second, we investigated whether these TMTs could identify motor dysfunction of the clinically unaffected limb in 42 strictly hemiparkinsonian patients. The pegboard dexterity test had the best ROC curve (AUC 0.97; 95% sensitivity, 89% specificity) for patients versus controls. It retained reasonable accuracy when testing the clinically unaffected limb of hemiparkinsonian patients versus the mean of right and left-hand scores in controls (AUC 0.73). The pegboard dexterity test is a sensitive and inexpensive instrument to detect motor dysfunction in early PD. Therefore, it may be worth evaluating as a diagnostic tool in everyday clinical practice to assess patients with early symptomatic PD, or as part of a more elaborate screening battery in a defined population at risk.