[Clinical and stabilometric analysis of postural instability in Parkinson's disease].
A disturbance of postural control is one of the most invalidating symptoms of Parkinson's disease (PD), and mechanisms underlying its development have not been so far elucidated. To specify the postural control features in different PD forms, clinico-neurophysiological analysis was conducted in 61 patients divided into 3 groups according to PD forms: tremor-rigid, rigid-tremor and akinetic-rigid. Dissociation between clinical expression of postural instability and its stabilometric reflection--the square of statokinesogram was found, indicating importance of differentiated approach in performance of stabilometric analysis in patients with different PD forms. The square of statokinesogram may be regarded as a neurophysiological marker of postural instability only in patients with rigid forms, in tremor parkinsonian phenotypes an increased square of stabilogram being mainly a stabilometric reflection of tremor. The importance of stabilometric test performance with cognitive loading, allowing switching out of voluntary posture control, is shown. Possible neuromediator mechanisms involved in postural instability in PD are discussed.