Parkinsonian abnormality of foot strike: a phenomenon of ageing and/or one responsive to levodopa therapy?

Abstract

1 Normally during walking, the heel strikes the ground before the forefoot. Abnormalities of foot strike in idiopathic Parkinson's disease may be amenable to therapy: objective measurements may reveal response which is not clinically apparent. Occult changes in foot strike leading to instability may parallel the normal, age-related loss of striatal dopamine. 2 The nature of foot strike was studied using pedobarography in 160 healthy volunteers, aged 15 to 91 years. Although 16% of strikes were made simultaneously by heel and forefoot, there were no instances of the forefoot preceding the heel. No significant effect of age on an index of normality of foot strikes was detected (P > 0.3). 3 The effect on foot strike of substituting placebo for a morning dose of a levodopa/ carbidopa combination was studied in a double-blind, cross-over trial in 14 patients, aged 64 to 88 years, with no overt fluctuations in control of their idiopathic Parkinson's disease in relation to dosing. On placebo treatment there was a highly significant (P = 0.004) reduction in the number of more normal strikes, i.e. heel strikes plus simultaneous heel and forefoot strikes. The effect appeared unrelated to the corresponding difference between active and placebo treatments in plasma concentration of levodopa or a metabolite of long half-time, 3-0-methyldopa (30MD). However, it correlated negatively (P < 0.05) with the mean of the 3OMD concentrations. 4 It appears that some abnormalities of foot strike due to Parkinson's disease are reversible. Employing test conditions, designed to provoke abnormalities of foot strike, might be useful in screening for pre-clinical Parkinson's disease.

Defining small differences in efficacy between anti‐parkinsonian agents using gait analysis: a comparison of two controlled release formulations of levodopa/decarboxylase inhibitor.

“…However, delayed time to peak concentrations and/or reduced bioavailability have been reported (Cedarbaum et al, 1989;Crevoisier et al, 1987;Le Witt et al, 1989;Marion et al, 1987;Yeh et al, 1989), and performance may not directly reflect levodopa plasma concentrations with respect to time course or magnitude. Low levodopa concentrations may not be consistently efficacious (Nelson et al, 1990), whilst particularly high concentrations may produce no additional benefit (Bowes et al, 1992a), or may even be associated with deterioration in performance (Bowes et al, 1991;Hughes et al, 1990). The prescriber's concern is primarily with outcome, and there is a need for simple, crossover comparisons of alternatives, designed with this end in mind.…”

Objective evidence for tolerance, against a background of improvement, during maintenance therapy with controlled release levodopa/carbidopa

“…There is previous evidence to suggest that pharmacokinetic tolerance may occur in elderly patients after relatively long periods of therapy, even with formulations with conventional release properties. The ratio of the mean plasma 30MD concentration to the area under the plasma concentration/time curve for levodopa attributed to a test dose decreases with duration of therapy [23], 30MD attenuating the benefit of levodopa [12,19]. That the effect of the time lapse on the response to one tablet of CR was no longer significant after introduction of the long half-time, peripheral metabolite, 30MD into the analysis suggests the tolerance seen here might be pharmacokinetc [24,25].…”

“…Plasma concentrations of levodopa and 30MD were measured [12] by ion-paired, reverse phase, high performance liquid chromatograph); with electrochemical detection. The inter-assay coefficient of variation for levodopa was 7.4 % at a concentration of 500 ng.…”

Aplicação das Análises Biomecânicas da Pressão Plantar na Marcha de Indivíduos com Doença de Parkinson

“…Por isso, técnicas de análise quantitativa de marchas patológicas, como a parkinsoniana, vêm sendo desenvolvidas para fornecer medidas objetivas 13 . Em geral, pacientes nos estágios mais avançados da DP possuem uma tendência a pisar simultaneamente com o calcanhar e o antepé no chão, resultando em um grave pé plano (flat foot strike), podendo, até mesmo, ocorrer o contato dos dedos no chão antes do calcanhar 14 . O objetivo do presente estudo foi realizar uma revisão de literatura sobre análises biomecânicas da marcha de indivíduos com DP, enfatizando àquelas relacionadas aos dados de distribuição da pressão plantar nestas pessoas.…”