Neurophysiological characterization of parkinsonian syndromes.

Electrophysiological examination can provide relevant information on functional abnormalities in patients with parkinsonism. The combined use of various electrodiagnostic techniques can contribute to the diagnosis of the illness, to its correct classification and differentiation from other diseases with a clinically similar presentation, and in particular the identification of the pathophysiological processes underlying some of the signs and symptoms characterizing the movement disorder. Tests which are useful in the differential diagnosis of various parkinsonian syndromes can now be performed in most electrodiagnostic laboratories. This article reviews some of the most relevant observations provided by neurophysiological studies on patients with parkinsonism, with a special focus on those that could be of more value in neurological clinical practice through their contribution to the characterization of the disease or to the recognition of underlying pathophysiological processes.