Communication Impairments in Parkinson's Disease

A number of different approaches have been utilized in recent years for the treatment of Parkinson's disease with varying effects on associated communication disorders. In particular, the drug treatments based on levodopa therapy and, more recently, deep brain stimulation of the sub-thalamic nucleus (STN-DBS) have yielded variable effects on the speech disorders exhibited by the majority of persons with Parkinson's disease. With respect to STN-DBS, although reports indicate significant improvement in the symptomatology in Parkinson's disease associated with limb function, the majority of reports suggest that the procedure has either minimal or, in most cases, negative effects on speech abilities of the affected individuals. By far the most effective speech therapy technique applied to dysarthria in Parkinson's disease reported to date is the Lee Silverman Voice Treatment (LSVT) program. In addition to speech impairment, in recent years there has also been increasing awareness that Parkinson's disease is also associated with the occurrence of language disorders, especially in its later stages. This special issue contains 13 papers of which 10 are related to issues associated with speech impairment and 3 further papers explore aspects of language impairment in Parkinson's disease. The first paper entitled " Perceived changes in communication as an effect of STN surgery in Parkinson's disease: a qualitative interview study " by E. Ahlberg et al. explored the perspective of four individuals with Parkinson's disease on the way their speech and communication changed as a result of STN-DBS. Overall the study confirmed earlier findings of negative effects on speech production; however, irrespective of this, the patients in general were positive as to the outcome of their surgery. The paper by F. Karlsson et al. " Deep brain stimulation of caudal zone incerta and subthalamic nucleus in patients with Parkinson's disease: effects on diadochokinetic rate, " investigated the outcome of STN-DBS and stimulation of the caudal zone incerta (cZi-DBS) on articulation rate and quality of plosive consonants in two articulatory diadochokinetic tasks. Whereas patients receiving STN-DBS increased in articulation rate with no effect on production quality, patients receiving cZi-DBS decreased in articulation rate and further showed reduction in production quality suggesting that cZi-DBS is more detrimental for extended articulatory movements than STN-DBS. The third paper, " Deep brain stimulation of caudal zone incerta and subthalamic nucleus in patients with Parkinson's disease: effects on voice intensity " by S. Lundgren et al. compares the effects of cZi-DBS and STN-DBS on voice …