a state in the treatment of Parkinson disease by l-dopa, in which there is a rapid fluctuation of akinetic (off) and choreoathetotic (on) movements.
on-off phenomenonNeurology An ↑ refractoriness to l-dopa's ability to control the smooth skeletal muscle movement in Parkinson's disease, where periods of excess abnormal movements–'on,' alternate with periods of prolonged immobility or freezing–'off'; 'on-off' also refers to the waxing and waning of parkinsonism itself. See Parkinson's disease.
on-off phe·nom·e·non(on-awf fĕ-nom'ĕ-non)
A phase in the treatment of parkinsonism with l-dopa, in which there is a rapid fluctuation of akinetic (off) and choreoathetotic (on) states.
In Parkinson patients, the alternating periods of good control (on) and poor control (off) of their symptoms. The on-off phenomenon is often experienced in patients undergoing l-dopa therapy.