Since the first description of Parkinson's disease (PD), it has been recognized that the condition is associated with motor speech impairment in the form of hypokinetic dysarthria. More recently it has also been recognized that cognitive/linguistic impairments exist in this population. Although a number of medical treatments, such as Levodopa-based drugs and a variety of surgical techniques including thalamotomy, pallidotomy, and deep brain stimulation, have been applied with varying success in relieving the symptoms of PD in relation to limb function, these same treatments have been documented to have much less success, and in many cases have proven detrimental to speech production in persons with PD. The recent years have also seen the introduction of new approaches in speech-language pathology to the treatment of motor speech impairments in PD. Of particular interest in this special issue are the reports that document the nature of speech-language impairments in PD, the effects of various speech-language pathology rehabilitation programs on communication impairments in PD, and the effects of various medical treatments including both drug and surgical approaches on speech-language function in this condition. Potential topics include, but are not limited to:

• Neurophysiology of Parkinson's disease (PD)
• Clinical features of speech and language disorders in PD
• Effect of Levodopa therapy on speech-language function in PD
• Effects of thalamotomy and pallidotomy on speech-language function in PD
• Effect of subthalamic nucleus deep brain stimulation on speech-language function in PD
• Treatment of speech disorders in PD
• Rehabilitation of cognitive/linguistic impairments in PD
• Assessment of motor speech and language disorders in PD

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