What are motor fluctuations?

In Parkinson’s disease (PD), there are times when symptom control is good and the medication seems to be working well – this is called ‘ON time’. At other times, symptom control may be poor with symptoms not appearing to respond to medication – this is called ‘OFF time’. ‘Motor’ is the scientific word that is used to refer to anything to do with movement, and the term ‘motor fluctuations’ (or ‘ON–OFF fluctuations’) refers to a state where a person with PD changes between ON time and OFF time (see Figure, below). This situation is common in people who have been receiving levodopa treatment for many years.

Another change in symptom control can be seen during the peak of levodopa absorption from the digestive system, when a person may experience restless movements known as dyskinesias (‘peak-dose’ dyskinesias) – almost as if there was ‘too much’ movement. On the other hand, when levodopa levels are at their lowest (i.e., before the dose has been absorbed), abnormal and painful posture may occur, which is known as dystonia (usually ‘OFF dystonia’).

Motor fluctuations

(Click on animation to enlarge.)