Fluktuationer skyldes den aftagende virkning af levodopa, der medfører, at patienten oplever pludselige skift mellem "on- perioder" hvor patienten er i stand til at bevæge sig, og "off- perioder", hvor patienten ikke kan bevæge sig.
Fluctuations are linked with a reduction in the effects of levodopa, when the patient experiences sudden switches between being ‘ on’ and able to move, and being ‘ off’ and immobile.