Paratonia: a Delphi procedure for consensus definition.

BACKGROUND AND PURPOSE: Paratonia is a motor problem that develops during the course of dementia. Definitions of paratonia used in the literature differ considerably, which has clinical implications and may lead to an undesirable heterogeneity in study populations. For this reason, we initiated a Delphi procedure with known experts in the field to establish an operational consensus definition of paratonia. METHODS: The Delphi procedure involved an anonymous and multistage approach presented as a questionnaire, with each stage building on the results of the previous one in order to reach consensus on the definition of paratonia. RESULTS: Eight of 17 experts agreed to participate in the study. After 4 rounds, the participants reached consensus on the following definition: paratonia is a form of hypertonia with an involuntary variable resistance during passive movement. The nature of paratonia may change with progression of dementia (eg, from active assistance (aka Mitgehen) to active resistance). The degree of resistance depends on the speed of movement (eg, slow > low resistance, fast > high resistance). The degree of paratonia is proportional to the amount of force applied and increases with progression of dementia. The resistance to passive movement is in any direction and there is no clasp-knife phenomenon. CONCLUSION: The Delphi procedure resulted in a comprehensive, operational definition of paratonia. Future research should focus on the reliability and validity of this definition.