Parkinson's disease (PD), a progressive degenerative disease characterized by death of neurons of pars compacta of substantia nigra and other pigmented nucleii of the brainstem, is associated with dopamine depletion. Clinically, it is characterized primarily by motor deficits which may interfere with communication. Levodopa, which is converted into dopamine, is the most effective drug for the treatment of PD. A myriad of studies show that levodopa improves several vocal paremeters, resulting in increase of fundamental frequency, melodic variation, vocal intensity, speed of the speech, maximum speech time and values of respiratory pressure. Moreover, it improves speech intelligibility and type of voice, as well as reduces or even suppresses vocal tremor. However, more recent data have shown that the effect of this drug on prosodic aspects of parkinsonian speech is quite modest, since few prosodic variables are modified after its use. It has been observed that levodopa improves the duration parameters of speech, whereas speech therapy, alone and combined with the use of levodopa, results in improvements on all prosodic parameters: frequency, duration and intensity. This highlights the importance of the association of these treatments for better communication and global motor benefits.
Parkinson disease; Levodopa; Articulation disorders; Voice disorders; Speech therapy