Measurement of axial rotation: its relevance to screening for night-time hypokinesia in old age and parkinsonism.

A novel device for continuous monitoring of axial rotation of a recumbent person is described. It is self-applicable and small enough to be mailed. A field trial showed that parkinsonian patients change their position less frequently than did their spouses: the difference became smaller where the age of the spouse was equal to or greater than that of the sufferer. The most marked difference between sufferers and their spouses was with respect to total angular displacement, which was nearly four times greater in the spouses. Further work is needed to show whether impaired rotation predates clinical idiopathic Parkinson's disease and so acts as a useful predictor. Measurement of axial rotation seems valuable in judging risk of pressure sores and gauging improvement in mobility in response to therapeutic interventions.