Parkinsonism

a progressive condition, occurring in mid to late life, that results in a rigidity of MUSCLES affecting the voice and FACE rather than those in the limbs. A TREMOR also develops, possibly in one hand initially and then spreading to other limbs, and it appears most pronounced when sitting. The disease is usually caused by a deficiency in the DOPAMINE (a NEUROTRANSMITTER ) because of degeneration of the basal ganglia of the brain (see BASAL GANGLION ). There is no cure, but a number of drugs are able, in varying degrees, to control the condition (see DOPA ).