Objective assessment of foot strike in Parkinson's disease*

We assessed the nature of foot strike and the potential effect of acute levodopa dosing in Parkinsonian patients with mild to severe fluctuations of motor performances in comparison with healthy volunteers. Forty-eight patients were enrolled in the study and compared with 33 age and gender matched controls. Each patient was assessed by a computerized electropodographic system before levodopa dosing and 1 and 2-h after intake of a standard fasting morning dose of levodopa plus benserazide. Twelve foot strikes (six right, six left) were analysed per patient. The controls underwent three repeated examinations at 1-h intervals. Patients' motor response to acute levodopa dosing was evaluated at fixed times by a battery of motor tests. Foot strike dynamics differed between patients and controls: in particular, first ground contact of the foot was significantly shifted from heel to forefoot in patients compared to controls. The forward shift in footprint during walking was more marked on the more affected body side but was unrelated to the severity and duration of Parkinsonism and unresponsive to levodopa dosing. Tapping and walking tests were overall responsive to acute levodopa intake. The system seemed suitable to detect irregular patterns of foot strike even at the early stages of Parkinsonism, when lower limb disorder was not clinically overt, and might be useful in the search for clinical markers of Parkinsonian gait.